Development and Validation of a Monte Carlo Simulation Tool for Multi-Pinhole SPECT

PubMed Central

Mok, Greta S. P.; Du, Yong; Wang, Yuchuan; Frey, Eric C.; Tsui, Benjamin M. W.

2011-01-01

Purpose In this work, we developed and validated a Monte Carlo simulation (MCS) tool for investigation and evaluation of multi-pinhole (MPH) SPECT imaging. Procedures This tool was based on a combination of the SimSET and MCNP codes. Photon attenuation and scatter in the object, as well as penetration and scatter through the collimator detector, are modeled in this tool. It allows accurate and efficient simulation of MPH SPECT with focused pinhole apertures and user-specified photon energy, aperture material, and imaging geometry. The MCS method was validated by comparing the point response function (PRF), detection efficiency (DE), and image profiles obtained from point sources and phantom experiments. A prototype single-pinhole collimator and focused four- and five-pinhole collimators fitted on a small animal imager were used for the experimental validations. We have also compared computational speed among various simulation tools for MPH SPECT, including SimSET-MCNP, MCNP, SimSET-GATE, and GATE for simulating projections of a hot sphere phantom. Results We found good agreement between the MCS and experimental results for PRF, DE, and image profiles, indicating the validity of the simulation method. The relative computational speeds for SimSET-MCNP, MCNP, SimSET-GATE, and GATE are 1: 2.73: 3.54: 7.34, respectively, for 120-view simulations. We also demonstrated the application of this MCS tool in small animal imaging by generating a set of low-noise MPH projection data of a 3D digital mouse whole body phantom. Conclusions The new method is useful for studying MPH collimator designs, data acquisition protocols, image reconstructions, and compensation techniques. It also has great potential to be applied for modeling the collimator-detector response with penetration and scatter effects for MPH in the quantitative reconstruction method. PMID:19779896

Value of gated SPECT in the analysis of regional wall motion of the interventricular septum after coronary artery bypass grafting.

PubMed

Giubbini, Raffaele; Rossini, Pierluigi; Bertagna, Francesco; Bosio, Giovanni; Paghera, Barbara; Pizzocaro, Claudio; Canclini, Silvana; Terzi, Arturo; Germano, Guido

2004-10-01

The aim of this study was the evaluation of septal wall motion, perfusion and wall thickening after CABG in two groups of consecutive patients, one with grafted left anterior coronary artery and no history of myocardial infarction, and the other with previous anteroseptal myocardial infarction and impaired septal motion before surgery. The issue addressed was the ability of gated SPECT to differentiate between true paradoxical septal motion, characterised by paradoxical wall motion, depressed ejection fraction (EF), poor viability and compromised wall thickening, and pseudo-paradoxical motion, characterised by abnormal wall motion and regional EF but preserved perfusion and wall thickening. One hundred and thirty-two patients with previous anterior myocardial infarction, 82 patients with left anterior descending coronary disease and no history of myocardial infarction and 27 normal subjects underwent rest gated SPECT after 99mTc-sestamibi injection, according to the standard QGS protocol. Quantitative regional EF, regional perfusion, regional wall motion and regional wall thickening were determined using a 20-segment model. Despite the presence of similar regional wall motion impairment in patients with and patients without septal infarction, in terms of regional EF (2.5%+/-3% vs 1.9%+/-4.9% p=NS) and inward septal motion (3+/-4.9 mm vs 2.3+/-6.1 mm p=NS), significant differences were observed in both perfusion (74.7%+/-6.2% vs 63.3%+/-13%, p>0.0001) and regional wall thickening (17.2%+/-7.4% vs 12.6%+/-7.2%, p>0.0001). Gated SPECT with perfusion tracers can reliably differentiate pseudo-paradoxical from true paradoxical septal motion in patients with previous CABG, and it may be the method of choice for evaluating left ventricular performance in this patient population.

LV dyssynchrony as assessed by phase analysis of gated SPECT myocardial perfusion imaging in patients with Wolff-Parkinson-White syndrome

PubMed Central

Chen, Chun; Miao, Changqing; Feng, Jianlin; Zhou, Yanli; Cao, Kejiang; Lloyd, Michael S.; Chen, Ji

2013-01-01

Purpose The purpose of this study was to evaluate left ventricular (LV) mechanical dyssynchrony in patients with Wolff-Parkinson-White (WPW) syndrome pre- and post-radiofrequency catheter ablation (RFA) using phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Methods Forty-five WPW patients were enrolled and had gated SPECT MPI pre- and 2–3 days post-RFA. Electrophysiological study (EPS) was used to locate accessory pathways (APs) and categorize the patients according to the AP locations (septal, left and right free wall). Electrocardiography (ECG) was performed pre- and post-RFA to confirm successful elimination of the APs. Phase analysis of gated SPECT MPI was used to assess LV dyssynchrony pre- and post-RFA. Results Among the 45 patients, 3 had gating errors, and thus 42 had SPECT phase analysis. Twenty-two patients (52.4 %) had baseline LV dyssynchrony. Baseline LV dyssynchrony was more prominent in the patients with septal APs than in the patients with left or right APs (p<0.05). RFA improved LV synchrony in the entire cohort and in the patients with septal APs (p<0.01). Conclusion Phase analysis of gated SPECT MPI demonstrated that LV mechanical dyssynchrony can be present in patients with WPW syndrome. Septal APs result in the greatest degree of LV mechanical dyssynchrony and afford the most benefit after RFA. This study supports further investigation in the relationship between electrical and mechanical activation using EPS and phase analysis of gated SPECT MPI. PMID:22532253

Myocardial perfusion and left ventricular function indices assessed by gated myocardial perfusion SPECT in methamphetamine abusers.

PubMed

Dadpour, Bita; Dabbagh Kakhki, Vahid R; Afshari, Reza; Dorri-Giv, Masoumeh; Mohajeri, Seyed A R; Ghahremani, Somayeh

2016-12-01

Methamphetamine (MA) is associated with alterations of cardiac structure and function, although it is less known. In this study, we assessed possible abnormality in myocardial perfusion and left ventricular function using gated myocardial perfusion SPECT. Fifteen patients with MA abuse, on the basis of Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) MA dependency determined by Structured Clinical Interview for DSM-IV, underwent 2-day dipyridamole stress/rest Tc-sestamibi gated myocardial perfusion SPECT. An average daily dose of MA use was 0.91±1.1 (0.2-4) g. The duration of MA use was 3.4±2.1 (1-7) years. In visual and semiquantitative analyses, all patients had normal gated myocardial perfusion SPECT, with no perfusion defects. In all gated SPECT images, there was no abnormality in left ventricular wall motion and thickening. All summed stress scores and summed rest scores were below 3. Calculated left ventricular functional indices including the end-diastolic volume, end-systolic volume, and left ventricular ejection fraction were normal. Many cardiac findings because of MA mentioned in previous reports are less likely because of significant epicardial coronary artery stenosis.

An automatic alignment tool to improve repeatability of left ventricular function and dyssynchrony parameters in serial gated myocardial perfusion SPECT studies

PubMed Central

Zhou, Yanli; Faber, Tracy L.; Patel, Zenic; Folks, Russell D.; Cheung, Alice A.; Garcia, Ernest V.; Soman, Prem; Li, Dianfu; Cao, Kejiang; Chen, Ji

2013-01-01

Objective Left ventricular (LV) function and dyssynchrony parameters measured from serial gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) using blinded processing had a poorer repeatability than when manual side-by-side processing was used. The objective of this study was to validate whether an automatic alignment tool can reduce the variability of LV function and dyssynchrony parameters in serial gated SPECT MPI. Methods Thirty patients who had undergone serial gated SPECT MPI were prospectively enrolled in this study. Thirty minutes after the first acquisition, each patient was repositioned and a gated SPECT MPI image was reacquired. The two data sets were first processed blinded from each other by the same technologist in different weeks. These processed data were then realigned by the automatic tool, and manual side-by-side processing was carried out. All processing methods used standard iterative reconstruction and Butterworth filtering. The Emory Cardiac Toolbox was used to measure the LV function and dyssynchrony parameters. Results The automatic tool failed in one patient, who had a large, severe scar in the inferobasal wall. In the remaining 29 patients, the repeatability of the LV function and dyssynchrony parameters after automatic alignment was significantly improved from blinded processing and was comparable to manual side-by-side processing. Conclusion The automatic alignment tool can be an alternative method to manual side-by-side processing to improve the repeatability of LV function and dyssynchrony measurements by serial gated SPECT MPI. PMID:23211996

Regional cardiac wall motion from gated myocardial perfusion SPECT studies

NASA Astrophysics Data System (ADS)

Smith, M. F.; Brigger, P.; Ferrand, S. K.; Dilsizian, V.; Bacharach, S. L.

1999-06-01

A method for estimating regional epicardial and endocardial wall motion from gated myocardial perfusion SPECT studies has been developed. The method uses epicardial and endocardial boundaries determined from four long-axis slices at each gate of the cardiac cycle. The epicardial and endocardial wall position at each time gate is computed with respect to stationary reference ellipsoids, and wall motion is measured along lines normal to these ellipsoids. An initial quantitative evaluation of the method was made using the beating heart from the dynamic mathematical cardiac torso (MCAT) phantom, with and without a 1.5-cm FWHM Gaussian blurring filter. Epicardial wall motion was generally well-estimated within a fraction of a 3.56-mm voxel, although apical motion was overestimated with the Gaussian filter. Endocardial wall motion was underestimated by about two voxels with and without the Gaussian filter. The MCAT heart phantom was modified to model hypokinetic and dyskinetic wall motion. The wall motion analysis method enabled this abnormal motion to be differentiated from normal motion. Regional cardiac wall motion also was analyzed for /sup 201/Tl patient studies. Estimated wall motion was consistent with a nuclear medicine physician's visual assessment of motion from gated long-axis slices for male and female study examples. Additional research is required for a comprehensive evaluation of the applicability of the method to patient studies with normal and abnormal wall motion.

Cardiac contraction motion compensation in gated myocardial perfusion SPECT: A comparative study.

PubMed

Salehi, Narges; Rahmim, Arman; Fatemizadeh, Emad; Akbarzadeh, Afshin; Farahani, Mohammad Hossein; Farzanefar, Saeed; Ay, Mohammad Reza

2018-05-01

Cardiac contraction significantly degrades quality and quantitative accuracy of gated myocardial perfusion SPECT (MPS) images. In this study, we aimed to explore different techniques in motion-compensated temporal processing of MPS images and their impact on image quality and quantitative accuracy. 50 patients without known heart condition underwent gated MPS. 3D motion compensation methods using Motion Freezing by Cedars Sinai (MF), Log-domain Diffeomorphic Demons (LDD) and Free-Form Deformation (FFD) were applied to warp all image phases to fit the end-diastolic (ED) phase. Afterwards, myocardial wall thickness, myocardial to blood pool contrast, and image contrast-to noise ratio (CNR) were measured in summed images with no motion compensation (NoMC) and compensated images (MF, LDD and FFD). Total Perfusion Defect (TPD) was derived from Cedars-Sinai software, on the basis of sex-specific normal limits. Left ventricle (LV) lateral wall thickness was reduced after applying motion compensation (p < 0.05). Myocardial to blood pool contrast and CNR in compensated images were greater than NoMC (p < 0.05). TPD_LDD was in good agreement with the corresponding TPD_MF (p = 0.13). All methods have improved image quality and quantitative performance relative to NoMC. LDD and FFD are fully automatic and do not require any manual intervention, while MF is dependent on contour definition. In terms of diagnostic parameters LDD is in good agreement with MF which is a clinically accepted method. Further investigation along with diagnostic reference standards, in order to specify diagnostic value of each technique is recommended. Copyright © 2018 Associazione Italiana di Fisica Medica. All rights reserved.

Early detection of radiation-induced heart disease using (99m)Tc-MIBI SPECT gated myocardial perfusion imaging in patients with oesophageal cancer during radiotherapy.

PubMed

Zhang, Peng; Hu, Xudong; Yue, Jinbo; Meng, Xue; Han, Dali; Sun, Xindong; Yang, Guoren; Wang, Shijiang; Wang, Xiaohui; Yu, Jinming

2015-05-01

The primary aim of this prospective study was to investigate the value of (99m)Tc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) gated myocardial perfusion imaging (GMPI) in the detection of radiation-induced heart disease (RIHD) as early as during radiotherapy (RT) for oesophageal cancer (EC). The second aim was to analyse the correlation between cardiac toxicity and the dose-volume factors. The (99m)Tc-MIBI SPECT GMPI was performed both pre-RT and during RT (40Gray). The results of the SPECT were quantitatively analysed with QGS/QPS software and read by two experienced nuclear medicine physicians. The correlation between the changes in the SPECT parameters and the RT dosimetric data was analysed. Eighteen patients with locally advanced EC were enrolled in the study. Compared with the baseline, the imaging during RT showed not only significant decreases in the wall motion (WM) (1/20 segments), wall thickening (WT) (2/20 segments), end-diastolic perfusion (EDP) (5/20 segments) and end-systolic perfusion (ESP) (8/20 segments) (p<0.05) but also a significant increase in the heart rate (74.63±7.79 vs 81.49±9.90, p=0.036). New myocardial perfusion defects were observed in 8 of the 18 patients. The V37-V40 was significantly higher (p<0.05) in the patients with the new perfusion defects during RT than in the patients who did not exhibit these defects. Radiotherapy for EC induces cardiac damage from an early stage. (99m)Tc-MIBI SPECT GMPI can detect the occurrence of cardiac impairment during RT. The WM, WT, EDP and ESP may be valuable as early indicators of RIHD. The percentage of the heart volume that receives a high dose is an important factor that is correlated with RIHD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Electrocardiograph-gated single photon emission computed tomography radionuclide angiography presents good interstudy reproducibility for the quantification of global systolic right ventricular function.

PubMed

Daou, Doumit; Coaguila, Carlos; Vilain, Didier

2007-05-01

Electrocardiograph-gated single photon emission computed tomography (SPECT) radionuclide angiography provides accurate measurement of right ventricular ejection fraction and end-diastolic and end-systolic volumes. In this study, we report the interstudy precision and reliability of SPECT radionuclide angiography for the measurement of global systolic right ventricular function using two, three-dimensional volume processing methods (SPECT-QBS, SPECT-35%). These were compared with equilibrium planar radionuclide angiography. Ten patients with chronic coronary artery disease having two SPECT and planar radionuclide angiography acquisitions were included. For the right ventricular ejection fraction, end-diastolic volume and end-systolic volume, the interstudy precision and reliability were better with SPECT-35% than with SPECT-QBS. The sample sizes needed to objectify a change in right ventricular volumes or ejection fraction were lower with SPECT-35% than with SPECT-QBS. The interstudy precision and reliability of SPECT-35% and SPECT-QBS for the right ventricle were better than those of equilibrium planar radionuclide angiography, but poorer than those previously reported for the left ventricle with SPECT radionuclide angiography on the same population. SPECT-35% and SPECT-QBS present good interstudy precision and reliability for right ventricular function, with the results favouring the use of SPECT-35%. The results are better than those of equilibrium planar radionuclide angiography, but poorer than those previously reported for the left ventricle with SPECT radionuclide angiography. They need to be confirmed in a larger population.

Physics process level discrimination of detections for GATE: assessment of contamination in SPECT and spurious activity in PET.

PubMed

De Beenhouwer, Jan; Staelens, Steven; Vandenberghe, Stefaan; Verhaeghe, Jeroen; Van Holen, Roel; Rault, Erwann; Lemahieu, Ignace

2009-04-01

The GEANT4 application for tomographic emission (GATE) is one of the most detailed Monte Carlo simulation tools for SPECT and PET. It allows for realistic phantoms, complex decay schemes, and a large variety of detector geometries. However, only a fraction of the information in each particle history is available for postprocessing. In order to extend the analysis capabilities of GATE, a flexible framework was developed. This framework allows all detected events to be subdivided according to their type: In PET, true coincidences from others, and in SPECT, geometrically collimated photons from others. The framework of the authors can be applied to any isotope, phantom, and detector geometry available in GATE. It is designed to enhance the usability of GATE for the study of contamination and for the investigation of the properties of current and future prototype detectors. The authors apply the framework to a case study of Bexxar, first assuming labeling with 124I, then with 131I. It is shown that with 124I PET, results with an optimized window improve upon those with the standard window but achieve less than half of the ideal improvement. Nevertheless, 124I PET shows improved resolution compared to 131I SPECT with triple-energy-window scatter correction.

Left ventricular functional parameters by gated SPECT myocardial perfusion imaging in a Latin American country.

PubMed

Kapitan, Miguel; Beltran, Alvaro; Beretta, Mario; Mut, Fernando

2018-04-01

There is paucity of data on left ventricular (LV) functional parameters using gated SPECT myocardial perfusion imaging (MPI) from the Latin American region. This study provides detailed information in low-risk patients both at rest and during exercise. We studied 90 patients (50 men) with a very low likelihood of coronary artery disease. Gated-SPECT MPI was performed with Tc-99m MIBI using a 2-day protocol, with 16 frames/R-R cycle. The LV ejection fraction and volumes were not different between the rest and post-stress images. LVEF was 68 ± 7% post-stress and 70 ± 7% at rest in women, and 62 ± 7% and 63 ± 7%, respectively, in men (P = .19, .26). LV volumes were larger in men than women (P < .01). There were no differences in most variables obtained at rest or post-stress. Transient ischemic dilatation was similar, with upper limits of 1.20 and 1.19 in women and men, respectively (P = NS). These data could prove helpful for the interpretation of gated SPECT MPI data in Latin America using identical protocol as used in this study.

A quantitative reconstruction software suite for SPECT imaging

NASA Astrophysics Data System (ADS)

Namías, Mauro; Jeraj, Robert

2017-11-01

Quantitative Single Photon Emission Tomography (SPECT) imaging allows for measurement of activity concentrations of a given radiotracer in vivo. Although SPECT has usually been perceived as non-quantitative by the medical community, the introduction of accurate CT based attenuation correction and scatter correction from hybrid SPECT/CT scanners has enabled SPECT systems to be as quantitative as Positron Emission Tomography (PET) systems. We implemented a software suite to reconstruct quantitative SPECT images from hybrid or dedicated SPECT systems with a separate CT scanner. Attenuation, scatter and collimator response corrections were included in an Ordered Subset Expectation Maximization (OSEM) algorithm. A novel scatter fraction estimation technique was introduced. The SPECT/CT system was calibrated with a cylindrical phantom and quantitative accuracy was assessed with an anthropomorphic phantom and a NEMA/IEC image quality phantom. Accurate activity measurements were achieved at an organ level. This software suite helps increasing quantitative accuracy of SPECT scanners.

Determination of Three-Dimensional Left Ventricle Motion to Analyze Ventricular Dyssyncrony in SPECT Images

NASA Astrophysics Data System (ADS)

Rebelo, Marina de Sá; Aarre, Ann Kirstine Hummelgaard; Clemmesen, Karen-Louise; Brandão, Simone Cristina Soares; Giorgi, Maria Clementina; Meneghetti, José Cláudio; Gutierrez, Marco Antonio

2009-12-01

A method to compute three-dimension (3D) left ventricle (LV) motion and its color coded visualization scheme for the qualitative analysis in SPECT images is proposed. It is used to investigate some aspects of Cardiac Resynchronization Therapy (CRT). The method was applied to 3D gated-SPECT images sets from normal subjects and patients with severe Idiopathic Heart Failure, before and after CRT. Color coded visualization maps representing the LV regional motion showed significant difference between patients and normal subjects. Moreover, they indicated a difference between the two groups. Numerical results of regional mean values representing the intensity and direction of movement in radial direction are presented. A difference of one order of magnitude in the intensity of the movement on patients in relation to the normal subjects was observed. Quantitative and qualitative parameters gave good indications of potential application of the technique to diagnosis and follow up of patients submitted to CRT.

Diagnostic accuracy and functional parameters of myocardial perfusion scintigraphy using accelerated cardiac acquisition with IQ SPECT technique in comparison to conventional imaging.

PubMed

Pirich, Christian; Keinrath, Peter; Barth, Gabriele; Rendl, Gundula; Rettenbacher, Lukas; Rodrigues, Margarida

2017-03-01

IQ SPECT consists of a new pinhole-like collimator, cardio-centric acquisition, and advanced 3D iterative SPECT reconstruction. The aim of this paper was to compare diagnostic accuracy and functional parameters obtained with IQ SPECT versus conventional SPECT in patients undergoing myocardial perfusion scintigraphy with adenosine stress and at rest. Eight patients with known or suspected coronary artery disease underwent [99mTc] tetrofosmin gated SPECT. Acquisition was performed on a Symbia T6 equipped with IQ SPECT and on a conventional gamma camera system. Gated SPECT data were used to calculate functional parameters. Scores analysis was performed on a 17-segment model. Coronary angiography and clinical follow-up were considered as diagnostic reference standard. Mean acquisition time was 4 minutes with IQ SPECT and 21 minutes with conventional SPECT. Agreement degree on the diagnostic accuracy between both systems was 0.97 for stress studies, 0.91 for rest studies and 0.96 for both studies. Perfusion abnormalities scores obtained by using IQ SPECT and conventional SPECT were not significant different: SSS, 9.7±8.8 and 10.1±6.4; SRS, 7.1±6.1 and 7.5±7.3; SDS, 4.0±6.1 and 3.9±4.3, respectively. However, a significant difference was found in functional parameters derived from IQ SPECT and conventional SPECT both after stress and at rest. Mean LVEF was 8% lower using IQ SPECT. Differences in LVEF were found in patients with normal LVEF and patients with reduced LVEF. Functional parameters using accelerated cardiac acquisition with IQ SPECT are significantly different to those obtained with conventional SPECT, while agreement for clinical interpretation of myocardial perfusion scintigraphy with both techniques is high.

GATE: a simulation toolkit for PET and SPECT.

PubMed

Jan, S; Santin, G; Strul, D; Staelens, S; Assié, K; Autret, D; Avner, S; Barbier, R; Bardiès, M; Bloomfield, P M; Brasse, D; Breton, V; Bruyndonckx, P; Buvat, I; Chatziioannou, A F; Choi, Y; Chung, Y H; Comtat, C; Donnarieix, D; Ferrer, L; Glick, S J; Groiselle, C J; Guez, D; Honore, P F; Kerhoas-Cavata, S; Kirov, A S; Kohli, V; Koole, M; Krieguer, M; van der Laan, D J; Lamare, F; Largeron, G; Lartizien, C; Lazaro, D; Maas, M C; Maigne, L; Mayet, F; Melot, F; Merheb, C; Pennacchio, E; Perez, J; Pietrzyk, U; Rannou, F R; Rey, M; Schaart, D R; Schmidtlein, C R; Simon, L; Song, T Y; Vieira, J M; Visvikis, D; Van de Walle, R; Wieërs, E; Morel, C

2004-10-07

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

GATE - Geant4 Application for Tomographic Emission: a simulation toolkit for PET and SPECT

PubMed Central

Jan, S.; Santin, G.; Strul, D.; Staelens, S.; Assié, K.; Autret, D.; Avner, S.; Barbier, R.; Bardiès, M.; Bloomfield, P. M.; Brasse, D.; Breton, V.; Bruyndonckx, P.; Buvat, I.; Chatziioannou, A. F.; Choi, Y.; Chung, Y. H.; Comtat, C.; Donnarieix, D.; Ferrer, L.; Glick, S. J.; Groiselle, C. J.; Guez, D.; Honore, P.-F.; Kerhoas-Cavata, S.; Kirov, A. S.; Kohli, V.; Koole, M.; Krieguer, M.; van der Laan, D. J.; Lamare, F.; Largeron, G.; Lartizien, C.; Lazaro, D.; Maas, M. C.; Maigne, L.; Mayet, F.; Melot, F.; Merheb, C.; Pennacchio, E.; Perez, J.; Pietrzyk, U.; Rannou, F. R.; Rey, M.; Schaart, D. R.; Schmidtlein, C. R.; Simon, L.; Song, T. Y.; Vieira, J.-M.; Visvikis, D.; Van de Walle, R.; Wieërs, E.; Morel, C.

2012-01-01

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols, and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document, and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at the address http://www-lphe.ep.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects toward the gridification of GATE and its extension to other domains such as dosimetry are also discussed. PMID:15552416

Comparative utility of gated myocardial perfusion imaging and transthoracic coronary flow reserve for the assessment of coronary artery disease in patients with left bundle branch block.

PubMed

Pavlovic, Smiljana; Sobic-Saranovic, Dragana; Djordjevic-Dikic, Ana; Beleslin, Branko; Stepanovic, Jelena; Artiko, Vera; Giga, Vojislav; Petrasinovic, Zorica; Ostojic, Miodrag; Vujisic-Tesic, Bosiljka; Obradovic, Vladimir

2010-04-01

To compare the diagnostic utility of gated single-photon emission computed tomography (SPECT) methoxy isobutyl isonitrile (MIBI) myocardial perfusion imaging and transthoracic Doppler echocardiography (TTDE) coronary flow reserve (CFR) to coronary angiography for detecting coronary artery disease (CAD) in patients with left bundle branch block (LBBB). Forty-three patients with complete LBBB and an intermediate pretest probability for CAD underwent dipyridamole stress TTDE and gated SPECT MIBI during the same session and coronary angiography within a month. The parameters of myocardial perfusion (summed stress score, summed difference scores) regional wall function (wall motion score, wall thickening score) and ejection fraction were derived using the 17-segment model and 4D-MSPECT software. TTDE variables included peak flow velocity at rest and during hyperemia in left anterior descending artery (LAD), based on which CFR was calculated (normal>2). Perfusion ischemic scores were significantly higher in group 1 with angiographic evidence of greater than 50% LAD stenosis compared with group 2 with less than 50% LAD stenosis (summed stress score 12.4+/-5.5 vs. 8.3+/-3.5, P<0.05, summed difference score 3.7+/-1.2 vs. 1.1+/-0.3, P<0.01, respectively). Left ventricular regional wall function and ejection fraction were not different between the two groups. CFR was significantly lower in group 1 than in group 2 (1.65+/-0.21 vs. 2.31+/-0.28, P<0.001). Gated SPECT MIBI and CFR had similar sensitivity (88 vs. 88%), specificity (80 vs. 84%), and accuracy (84 vs. 86%) for detecting CAD in patients with LBBB. The agreement between the two methods was 85%. Our results show comparable diagnostic utility and high agreement between gated SPECT MIBI perfusion imaging and TTDE CFR assessment for detecting CAD in patients with LBBB. The advantage of gated SPECT MIBI over TTDE CFR measurements is the ability to assess the perfusion abnormalities in multiple vascular territories during the same procedure, which is convenient for detecting multi-vessel disease in patients with LBBB.

An evaluation to design high performance pinhole array detector module for four head SPECT: a simulation study

NASA Astrophysics Data System (ADS)

Rahman, Tasneem; Tahtali, Murat; Pickering, Mark R.

2014-09-01

The purpose of this study is to derive optimized parameters for a detector module employing an off-the-shelf X-ray camera and a pinhole array collimator applicable for a range of different SPECT systems. Monte Carlo simulations using the Geant4 application for tomographic emission (GATE) were performed to estimate the performance of the pinhole array collimators and were compared to that of low energy high resolution (LEHR) parallel-hole collimator in a four head SPECT system. A detector module was simulated to have 48 mm by 48 mm active area along with 1mm, 1.6mm and 2 mm pinhole aperture sizes at 0.48 mm pitch on a tungsten plate. Perpendicular lead septa were employed to verify overlapping and non-overlapping projections against a proper acceptance angle without lead septa. A uniform shape cylindrical water phantom was used to evaluate the performance of the proposed four head SPECT system of the pinhole array detector module. For each head, 100 pinhole configurations were evaluated based on sensitivity and detection efficiency for 140 keV γ-rays, and compared to LEHR parallel-hole collimator. SPECT images were reconstructed based on filtered back projection (FBP) algorithm where neither scatter nor attenuation corrections were performed. A better reconstruction algorithm development for this specific system is in progress. Nevertheless, activity distribution was well visualized using the backprojection algorithm. In this study, we have evaluated several quantitative and comparative analyses for a pinhole array imaging system providing high detection efficiency and better system sensitivity over a large FOV, comparing to the conventional four head SPECT system. The proposed detector module is expected to provide improved performance in various SPECT imaging.

Ejection fraction in myocardial perfusion imaging assessed with a dynamic phantom: comparison between IQ-SPECT and LEHR.

PubMed

Hippeläinen, Eero; Mäkelä, Teemu; Kaasalainen, Touko; Kaleva, Erna

2017-12-01

Developments in single photon emission tomography instrumentation and reconstruction methods present a potential for decreasing acquisition times. One of such recent options for myocardial perfusion imaging (MPI) is IQ-SPECT. This study was motivated by the inconsistency in the reported ejection fraction (EF) and left ventricular (LV) volume results between IQ-SPECT and more conventional low-energy high-resolution (LEHR) collimation protocols. IQ-SPECT and LEHR quantitative results were compared while the equivalent number of iterations (EI) was varied. The end-diastolic (EDV) and end-systolic volumes (ESV) and the derived EF values were investigated. A dynamic heart phantom was used to produce repeatable ESVs, EDVs and EFs. Phantom performance was verified by comparing the set EF values to those measured from a gated multi-slice X-ray computed tomography (CT) scan (EF True ). The phantom with an EF setting of 45, 55, 65 and 70% was imaged with both IQ-SPECT and LEHR protocols. The data were reconstructed with different EI, and two commonly used clinical myocardium delineation software were used to evaluate the LV volumes. The CT verification showed that the phantom EF settings were repeatable and accurate with the EF True being within 1% point from the manufacture's nominal value. Depending on EI both MPI protocols can be made to produce correct EF estimates, but IQ-SPECT protocol produced on average 41 and 42% smaller EDV and ESV when compared to the phantom's volumes, while LEHR protocol underestimated volumes by 24 and 21%, respectively. The volume results were largely similar between the delineation methods used. The reconstruction parameters can greatly affect the volume estimates obtained from perfusion studies. IQ-SPECT produces systematically smaller LV volumes than the conventional LEHR MPI protocol. The volume estimates are also software dependent.

Three-dimensional ordered-subset expectation maximization iterative protocol for evaluation of left ventricular volumes and function by quantitative gated SPECT: a dynamic phantom study.

PubMed

Ceriani, Luca; Ruberto, Teresa; Delaloye, Angelika Bischof; Prior, John O; Giovanella, Luca

2010-03-01

The purposes of this study were to characterize the performance of a 3-dimensional (3D) ordered-subset expectation maximization (OSEM) algorithm in the quantification of left ventricular (LV) function with (99m)Tc-labeled agent gated SPECT (G-SPECT), the QGS program, and a beating-heart phantom and to optimize the reconstruction parameters for clinical applications. A G-SPECT image of a dynamic heart phantom simulating the beating left ventricle was acquired. The exact volumes of the phantom were known and were as follows: end-diastolic volume (EDV) of 112 mL, end-systolic volume (ESV) of 37 mL, and stroke volume (SV) of 75 mL; these volumes produced an LV ejection fraction (LVEF) of 67%. Tomographic reconstructions were obtained after 10-20 iterations (I) with 4, 8, and 16 subsets (S) at full width at half maximum (FWHM) gaussian postprocessing filter cutoff values of 8-15 mm. The QGS program was used for quantitative measurements. Measured values ranged from 72 to 92 mL for EDV, from 18 to 32 mL for ESV, and from 54 to 63 mL for SV, and the calculated LVEF ranged from 65% to 76%. Overall, the combination of 10 I, 8 S, and a cutoff filter value of 10 mm produced the most accurate results. The plot of the measures with respect to the expectation maximization-equivalent iterations (I x S product) revealed a bell-shaped curve for the LV volumes and a reverse distribution for the LVEF, with the best results in the intermediate range. In particular, FWHM cutoff values exceeding 10 mm affected the estimation of the LV volumes. The QGS program is able to correctly calculate the LVEF when used in association with an optimized 3D OSEM algorithm (8 S, 10 I, and FWHM of 10 mm) but underestimates the LV volumes. However, various combinations of technical parameters, including a limited range of I and S (80-160 expectation maximization-equivalent iterations) and low cutoff values (< or =10 mm) for the gaussian postprocessing filter, produced results with similar accuracies and without clinically relevant differences in the LV volumes and the estimated LVEF.

Systolic and diastolic assessment by 3D-ASM segmentation of gated-SPECT Studies: a comparison with MRI

NASA Astrophysics Data System (ADS)

Tobon-Gomez, C.; Bijnens, B. H.; Huguet, M.; Sukno, F.; Moragas, G.; Frangi, A. F.

2009-02-01

Gated single photon emission tomography (gSPECT) is a well-established technique used routinely in clinical practice. It can be employed to evaluate global left ventricular (LV) function of a patient. The purpose of this study is to assess LV systolic and diastolic function from gSPECT datasets in comparison with cardiac magnetic resonance imaging (CMR) measurements. This is achieved by applying our recently implemented 3D active shape model (3D-ASM) segmentation approach for gSPECT studies. This methodology allows for generation of 3D LV meshes for all cardiac phases, providing volume time curves and filling rate curves. Both systolic and diastolic functional parameters can be derived from these curves for an assessment of patient condition even at early stages of LV dysfunction. Agreement of functional parameters, with respect to CMR measurements, were analyzed by means of Bland-Altman plots. The analysis included subjects presenting either LV hypertrophy, dilation or myocardial infarction.

Co-registered perfusion SPECT/CT: utility for prediction of improved postoperative outcome in lung volume reduction surgery candidates.

PubMed

Takenaka, Daisuke; Ohno, Yoshiharu; Koyama, Hisanobu; Nogami, Munenobu; Onishi, Yumiko; Matsumoto, Keiko; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Sugimura, Kazuro

2010-06-01

To directly compare the capabilities of perfusion scan, SPECT, co-registered SPECT/CT, and quantitatively and qualitatively assessed MDCT (i.e. quantitative CT and qualitative CT) for predicting postoperative clinical outcome for lung volume reduction surgery (LVRS) candidates. Twenty-five consecutive candidates (19 men and six women, age range: 42-72 years) for LVRS underwent preoperative CT and perfusion scan with SPECT. Clinical outcome of LVRS for all subjects was also assessed by determining the difference between pre- and postoperative forced expiratory volume in 1s (FEV(1)) and 6-min walking distance (6MWD). All SPECT examinations were performed on a SPECT scanner, and co-registered to thin-section CT by using commercially available software. On planar imaging, SPECT and SPECT/CT, upper versus lower zone or lobe ratios (U/Ls) were calculated from regional uptakes between upper and lower lung fields in the operated lung. On quantitatively assessed CT, U/L for all subjects was assessed from regional functional lung volumes. On qualitatively assessed CT, planar imaging, SPECT and co-registered SPECT/CT, U/Ls were assessed with a 4-point visual scoring system. To compare capabilities of predicting clinical outcome, each U/L was statistically correlated with the corresponding clinical outcome. Significantly fair or moderate correlations were observed between quantitatively and qualitatively assessed U/Ls obtained with all four methods and clinical outcomes (-0.60

Dual-energy micro-CT imaging of pulmonary airway obstruction: correlation with micro-SPECT

NASA Astrophysics Data System (ADS)

Badea, C. T.; Befera, N.; Clark, D.; Qi, Y.; Johnson, G. A.

2014-03-01

To match recent clinical dual energy (DE) CT studies focusing on the lung, similar developments for DE micro-CT of the rodent lung are required. Our group has been actively engaged in designing pulmonary gating techniques for micro- CT, and has also introduced the first DE micro-CT imaging method of the rodent lung. The aim of this study was to assess the feasibility of DE micro-CT imaging for the evaluation of airway obstruction in mice, and to compare the method with micro single photon emission computed tomography (micro-SPECT) using technetium-99m labeled macroaggregated albumin (99mTc-MAA). The results suggest that the induced pulmonary airway obstruction causes either atelectasis, or air-trapping similar to asthma or chronic bronchitis. Atelectasis could only be detected at early time points in DE micro-CT images, and is associated with a large increase in blood fraction and decrease in air fraction. Air trapping had an opposite effect with larger air fraction and decreased blood fraction shown by DE micro-CT. The decrease in perfusion to the hypoventilated lung (hypoxic vasoconstriction) is also seen in micro-SPECT. The proposed DE micro-CT technique for imaging localized airway obstruction performed well in our evaluation, and provides a higher resolution compared to micro-SPECT. Both DE micro-CT and micro-SPECT provide critical, quantitative lung biomarkers for image-based anatomical and functional information in the small animal. The methods are readily linked to clinical methods allowing direct comparison of preclinical and clinical results.

Low-dose dobutamine gated-SPECT analysis of left ventricular segmental wall thickening in ischemic cardiomyopathy.

PubMed

Candell-Riera, Jaume; Romero-Farina, Guillermo; Milá, Marta; Aguadé-Bruix, Santiago

2008-10-01

The objective of this study was to use low-dose dobutamine (LDD) gated single-photon emission computed tomography (SPECT) to evaluate segmental thickening of the left ventricle (LV) and its relationship with changes in ejection fraction (EF) and ventricular volumes in patients with ischemic cardiomyopathy. This prospective multicenter study involved 89 patients with ischemic cardiomyopathy (i.e., EF < or =40%) who underwent LDD gated-SPECT at rest. The LV was divided into 17 segments and systolic thickening was assessed in a total of 1513 segments during LDD infusion. RESULTS; A significant increase in LVEF (33.2% vs. 30.8%; P< .001) was observed during LDD infusion and occurred at the expense of a reduction in end-systolic volume (130.5 mL vs. 136.4 mL; P=.005). The increase in EF was > or =5% in 33.7% of patients, while the EF decreased by > or =5% in 5.6% of patients. With LDD infusion, both an improvement in > or =3 segments with severely decreased baseline thickening (odds ratio [OR] = 18.3; 95% confidence interval [CI], 5.3-63) and an improvement in > or =10 segments with mild-to-moderate alterations in baseline thickening (OR = 4.53; 95% CI, 1.26-16.16) were associated with a > or =5% increase in LVEF. During the assessment of global left ventricular contractile reserve by LDD gated-SPECT, attention should be paid not only to the behavior of segments with severely decreased baseline thickening, which are generally regarded as indicating viability, but also to segments with mild-to-moderate alterations and to those in which thickening decreases.

Quantitative Comparison of PET and Bremsstrahlung SPECT for Imaging the In Vivo Yttrium-90 Microsphere Distribution after Liver Radioembolization

PubMed Central

Elschot, Mattijs; Vermolen, Bart J.; Lam, Marnix G. E. H.; de Keizer, Bart; van den Bosch, Maurice A. A. J.; de Jong, Hugo W. A. M.

2013-01-01

Background After yttrium-90 (90Y) microsphere radioembolization (RE), evaluation of extrahepatic activity and liver dosimetry is typically performed on 90Y Bremsstrahlung SPECT images. Since these images demonstrate a low quantitative accuracy, 90Y PET has been suggested as an alternative. The aim of this study is to quantitatively compare SPECT and state-of-the-art PET on the ability to detect small accumulations of 90Y and on the accuracy of liver dosimetry. Methodology/Principal Findings SPECT/CT and PET/CT phantom data were acquired using several acquisition and reconstruction protocols, including resolution recovery and Time-Of-Flight (TOF) PET. Image contrast and noise were compared using a torso-shaped phantom containing six hot spheres of various sizes. The ability to detect extra- and intrahepatic accumulations of activity was tested by quantitative evaluation of the visibility and unique detectability of the phantom hot spheres. Image-based dose estimates of the phantom were compared to the true dose. For clinical illustration, the SPECT and PET-based estimated liver dose distributions of five RE patients were compared. At equal noise level, PET showed higher contrast recovery coefficients than SPECT. The highest contrast recovery coefficients were obtained with TOF PET reconstruction including resolution recovery. All six spheres were consistently visible on SPECT and PET images, but PET was able to uniquely detect smaller spheres than SPECT. TOF PET-based estimates of the dose in the phantom spheres were more accurate than SPECT-based dose estimates, with underestimations ranging from 45% (10-mm sphere) to 11% (37-mm sphere) for PET, and 75% to 58% for SPECT, respectively. The differences between TOF PET and SPECT dose-estimates were supported by the patient data. Conclusions/Significance In this study we quantitatively demonstrated that the image quality of state-of-the-art PET is superior over Bremsstrahlung SPECT for the assessment of the 90Y microsphere distribution after radioembolization. PMID:23405207

SU-C-201-02: Quantitative Small-Animal SPECT Without Scatter Correction Using High-Purity Germanium Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gearhart, A; Peterson, T; Johnson, L

2015-06-15

Purpose: To evaluate the impact of the exceptional energy resolution of germanium detectors for preclinical SPECT in comparison to conventional detectors. Methods: A cylindrical water phantom was created in GATE with a spherical Tc-99m source in the center. Sixty-four projections over 360 degrees using a pinhole collimator were simulated. The same phantom was simulated using air instead of water to establish the true reconstructed voxel intensity without attenuation. Attenuation correction based on the Chang method was performed on MLEM reconstructed images from the water phantom to determine a quantitative measure of the effectiveness of the attenuation correction. Similarly, a NEMAmore » phantom was simulated, and the effectiveness of the attenuation correction was evaluated. Both simulations were carried out using both NaI detectors with an energy resolution of 10% FWHM and Ge detectors with an energy resolution of 1%. Results: Analysis shows that attenuation correction without scatter correction using germanium detectors can reconstruct a small spherical source to within 3.5%. Scatter analysis showed that for standard sized objects in a preclinical scanner, a NaI detector has a scatter-to-primary ratio between 7% and 12.5% compared to between 0.8% and 1.5% for a Ge detector. Preliminary results from line profiles through the NEMA phantom suggest that applying attenuation correction without scatter correction provides acceptable results for the Ge detectors but overestimates the phantom activity using NaI detectors. Due to the decreased scatter, we believe that the spillover ratio for the air and water cylinders in the NEMA phantom will be lower using germanium detectors compared to NaI detectors. Conclusion: This work indicates that the superior energy resolution of germanium detectors allows for less scattered photons to be included within the energy window compared to traditional SPECT detectors. This may allow for quantitative SPECT without implementing scatter correction, reducing uncertainties introduced by scatter correction algorithms. Funding provided by NIH/NIBIB grant R01EB013677; Todd Peterson, Ph.D., has had a research contract with PHDs Co., Knoxville, TN.« less

Use of bio-informatics assessment schema (BIAS) to improve diagnosis and prognosis of myocardial perfusion data: results from the NHLBI-sponsored women's ischemia syndrome evaluation (WISE).

PubMed

Doyle, Mark; Pohost, Gerald M; Bairey Merz, C Noel; Shaw, Leslee J; Sopko, George; Rogers, William J; Sharaf, Barry L; Pepine, Carl J; Thompson, Diane V; Rayarao, Geetha; Tauxe, Lindsey; Kelsey, Sheryl F; Biederman, Robert W W

2016-10-01

We introduce an algorithmic approach to optimize diagnostic and prognostic value of gated cardiac single photon emission computed tomography (SPECT) and magnetic resonance (MR) myocardial perfusion imaging (MPI) modalities in women with suspected myocardial ischemia. The novel approach: bio-informatics assessment schema (BIAS) forms a mathematical model utilizing MPI data and cardiac metrics generated by one modality to predict the MPI status of another modality. The model identifies cardiac features that either enhance or mask the image-based evidence of ischemia. For each patient, the BIAS model value is used to set an appropriate threshold for the detection of ischemia. Women (n=130), with symptoms and signs of suspected myocardial ischemia, underwent MPI assessment for regional perfusion defects using two different modalities: gated SPECT and MR. To determine perfusion status, MR data were evaluated qualitatively (MRI QL ) and semi-quantitatively (MRI SQ ) while SPECT data were evaluated using conventional clinical criteria. Evaluators were masked to results of the alternate modality. These MPI status readings were designated "original". Two regression models designated "BIAS" models were generated to model MPI status obtained with one modality (e.g., MRI) compared with a second modality (e.g., SPECT), but importantly, the BIAS models did not include the primary Original MPI reading of the predicting modality. Instead, the BIAS models included auxiliary measurements like left ventricular chamber volumes and myocardial wall thickness. For each modality, the BIAS model was used to set a progressive threshold for interpretation of MPI status. Women were then followed for 38±14 months for the development of a first major adverse cardiovascular event [MACE: CV death, nonfatal myocardial infarction (MI) or hospitalization for heart failure]. Original and BIAS-augmented perfusion status were compared in their ability to detect coronary artery disease (CAD) and for prediction of MACE. Adverse events occurred in 14 (11%) women and CAD was present in 13 (10%). There was a positive correlation of maximum coronary artery stenosis and BIAS score for MRI and SPECT (P<0.001). Receiver operator characteristic (ROC) analysis was conducted and showed an increase in the area under the curve of the BIAS-augmented MPI interpretation of MACE vs . the original for MRI SQ (0.78 vs . 0.54), MRI QL (0.78 vs . 0.64), SPECT (0.82 vs . 0.63) and the average of the three readings (0.80±0.02 vs . 0.60±0.05, P<0.05). Increasing values of the BIAS score generated by both MRI and SPECT corresponded to the increasing prevalence of CAD and MACE. The BIAS-augmented detection of ischemia better predicted MACE compared with the Original reading for the MPI data for both MRI and SPECT.

Use of bio-informatics assessment schema (BIAS) to improve diagnosis and prognosis of myocardial perfusion data: results from the NHLBI-sponsored women’s ischemia syndrome evaluation (WISE)

PubMed Central

Pohost, Gerald M.; Bairey Merz, C. Noel; Shaw, Leslee J.; Sopko, George; Rogers, William J.; Sharaf, Barry L.; Pepine, Carl J.; Thompson, Diane V.; Rayarao, Geetha; Tauxe, Lindsey; Kelsey, Sheryl F.; Biederman, Robert W. W.

2016-01-01

Background We introduce an algorithmic approach to optimize diagnostic and prognostic value of gated cardiac single photon emission computed tomography (SPECT) and magnetic resonance (MR) myocardial perfusion imaging (MPI) modalities in women with suspected myocardial ischemia. The novel approach: bio-informatics assessment schema (BIAS) forms a mathematical model utilizing MPI data and cardiac metrics generated by one modality to predict the MPI status of another modality. The model identifies cardiac features that either enhance or mask the image-based evidence of ischemia. For each patient, the BIAS model value is used to set an appropriate threshold for the detection of ischemia. Methods Women (n=130), with symptoms and signs of suspected myocardial ischemia, underwent MPI assessment for regional perfusion defects using two different modalities: gated SPECT and MR. To determine perfusion status, MR data were evaluated qualitatively (MRIQL) and semi-quantitatively (MRISQ) while SPECT data were evaluated using conventional clinical criteria. Evaluators were masked to results of the alternate modality. These MPI status readings were designated “original”. Two regression models designated “BIAS” models were generated to model MPI status obtained with one modality (e.g., MRI) compared with a second modality (e.g., SPECT), but importantly, the BIAS models did not include the primary Original MPI reading of the predicting modality. Instead, the BIAS models included auxiliary measurements like left ventricular chamber volumes and myocardial wall thickness. For each modality, the BIAS model was used to set a progressive threshold for interpretation of MPI status. Women were then followed for 38±14 months for the development of a first major adverse cardiovascular event [MACE: CV death, nonfatal myocardial infarction (MI) or hospitalization for heart failure]. Original and BIAS-augmented perfusion status were compared in their ability to detect coronary artery disease (CAD) and for prediction of MACE. Results Adverse events occurred in 14 (11%) women and CAD was present in 13 (10%). There was a positive correlation of maximum coronary artery stenosis and BIAS score for MRI and SPECT (P<0.001). Receiver operator characteristic (ROC) analysis was conducted and showed an increase in the area under the curve of the BIAS-augmented MPI interpretation of MACE vs. the original for MRISQ (0.78 vs. 0.54), MRIQL (0.78 vs. 0.64), SPECT (0.82 vs. 0.63) and the average of the three readings (0.80±0.02 vs. 0.60±0.05, P<0.05). Conclusions Increasing values of the BIAS score generated by both MRI and SPECT corresponded to the increasing prevalence of CAD and MACE. The BIAS-augmented detection of ischemia better predicted MACE compared with the Original reading for the MPI data for both MRI and SPECT. PMID:27747165

Evaluation of 209At as a theranostic isotope for 209At-radiopharmaceutical development using high-energy SPECT

NASA Astrophysics Data System (ADS)

Crawford, J. R.; Robertson, A. K. H.; Yang, H.; Rodríguez-Rodríguez, C.; Esquinas, P. L.; Kunz, P.; Blinder, S.; Sossi, V.; Schaffer, P.; Ruth, T. J.

2018-02-01

The development of alpha-emitting radiopharmaceuticals using 211At requires quantitative determination of the time-dependent nature of the 211At biodistribution. However, imaging-based methods for acquiring this information with 211At have not found wide-spread use because of its low abundance of decay emissions suitable for external detection. In this publication we demonstrate the theranostic abilities of the 211At/209At isotope pair and present the first-ever 209At SPECT images. The VECTor microSPECT/PET/CT scanner was used to image 209At with a collimator suitable for the 511 keV annihilation photons of PET isotopes. Data from distinct photopeaks of the 209At energy spectrum (195 keV (22.6%), 239 keV (12.4 %), 545 keV (91.0 %), a combined 782/790 keV peak (147 %), and 209Po x-rays (139.0 %)) were independently evaluated for use in image reconstructions using Monte Carlo (GATE) simulations and phantom studies. 209At-imaging in vivo was demonstrated in a healthy mouse injected with 10 MBq of free [209At]astatide. Image-based measurements of 209At uptake in organs of interest—acquired in 5 min intervals—were compared to ex vivo gamma counter measurements of the same organs. Simulated and measured data indicated that—due to the large amount of scatter from high energy (>750 keV) gammas—reconstructed images using the x-ray peak outperformed those obtained from other peaks in terms of image uniformity and spatial resolution, determined to be  <0.85 mm. 209At imaging using the x-ray peak revealed a biodistribution that matched the known distribution of free astatide, and in vivo image-based measurements of 209At uptake in organs of interest matched ex vivo measurements within 10%. We have acquired the first 209At SPECT images and demonstrated the ability of quantitative SPECT imaging with 209At to accurately determine astatine biodistributions with high spatial and temporal resolution.

Utility of Quantitative Parameters from Single-Photon Emission Computed Tomography/Computed Tomography in Patients with Destructive Thyroiditis.

PubMed

Kim, Ji-Young; Kim, Ji Hyun; Moon, Jae Hoon; Kim, Kyoung Min; Oh, Tae Jung; Lee, Dong-Hwa; So, Young; Lee, Won Woo

2018-01-01

Quantitative parameters from Tc-99m pertechnetate single-photon emission computed tomography/computed tomography (SPECT/CT) are emerging as novel diagnostic markers for functional thyroid diseases. We intended to assess the utility of SPECT/CT parameters in patients with destructive thyroiditis. Thirty-five destructive thyroiditis patients (7 males and 28 females; mean age, 47.3 ± 13.0 years) and 20 euthyroid patients (6 males and 14 females; mean age, 45.0 ± 14.8 years) who underwent Tc-99m pertechnetate quantitative SPECT/CT were retrospectively enrolled. Quantitative parameters from the SPECT/CT (%uptake, standardized uptake value [SUV], thyroid volume, and functional thyroid mass [SUVmean × thyroid volume]) and thyroid hormone levels were investigated to assess correlations and predict the prognosis for destructive thyroiditis. The occurrence of hypothyroidism was the outcome for prognosis. All the SPECT/CT quantitative parameters were significantly lower in the 35 destructive thyroiditis patients compared to the 20 euthyroid patients using the same SPECT/CT scanner and protocol ( p < 0.001 for all parameters). T3 and free T4 did not correlate with any SPECT/CT parameters, but thyroid-stimulating hormone (TSH) significantly correlated with %uptake ( p = 0.004), SUVmean ( p < 0.001), SUVmax ( p = 0.002), and functional thyroid mass ( p < 0.001). Of the 35 destructive thyroiditis patients, 16 progressed to hypothyroidism. On univariate and multivariate analyses, only T3 levels were associated with the later occurrence of hypothyroidism ( p = 0.002, exp(β) = 1.022, 95% confidence interval: 1.008 - 1.035). Novel quantitative SPECT/CT parameters could discriminate patients with destructive thyroiditis from euthyroid patients, suggesting the robustness of the quantitative SPECT/CT approach. However, disease progression of destructive thyroiditis could not be predicted using the parameters, as these only correlated with TSH, but not with T3, the sole predictor of the later occurrence of hypothyroidism.

Utility of Quantitative Parameters from Single-Photon Emission Computed Tomography/Computed Tomography in Patients with Destructive Thyroiditis

PubMed Central

Kim, Ji-Young; Kim, Ji Hyun; Moon, Jae Hoon; Kim, Kyoung Min; Oh, Tae Jung; Lee, Dong-Hwa; So, Young

2018-01-01

Objective Quantitative parameters from Tc-99m pertechnetate single-photon emission computed tomography/computed tomography (SPECT/CT) are emerging as novel diagnostic markers for functional thyroid diseases. We intended to assess the utility of SPECT/CT parameters in patients with destructive thyroiditis. Materials and Methods Thirty-five destructive thyroiditis patients (7 males and 28 females; mean age, 47.3 ± 13.0 years) and 20 euthyroid patients (6 males and 14 females; mean age, 45.0 ± 14.8 years) who underwent Tc-99m pertechnetate quantitative SPECT/CT were retrospectively enrolled. Quantitative parameters from the SPECT/CT (%uptake, standardized uptake value [SUV], thyroid volume, and functional thyroid mass [SUVmean × thyroid volume]) and thyroid hormone levels were investigated to assess correlations and predict the prognosis for destructive thyroiditis. The occurrence of hypothyroidism was the outcome for prognosis. Results All the SPECT/CT quantitative parameters were significantly lower in the 35 destructive thyroiditis patients compared to the 20 euthyroid patients using the same SPECT/CT scanner and protocol (p < 0.001 for all parameters). T3 and free T4 did not correlate with any SPECT/CT parameters, but thyroid-stimulating hormone (TSH) significantly correlated with %uptake (p = 0.004), SUVmean (p < 0.001), SUVmax (p = 0.002), and functional thyroid mass (p < 0.001). Of the 35 destructive thyroiditis patients, 16 progressed to hypothyroidism. On univariate and multivariate analyses, only T3 levels were associated with the later occurrence of hypothyroidism (p = 0.002, exp(β) = 1.022, 95% confidence interval: 1.008 – 1.035). Conclusion Novel quantitative SPECT/CT parameters could discriminate patients with destructive thyroiditis from euthyroid patients, suggesting the robustness of the quantitative SPECT/CT approach. However, disease progression of destructive thyroiditis could not be predicted using the parameters, as these only correlated with TSH, but not with T3, the sole predictor of the later occurrence of hypothyroidism. PMID:29713225

Effects of aortic tortuosity on left ventricular diastolic parameters derived from gated myocardial perfusion single photon emission computed tomography in patients with normal myocardial perfusion.

PubMed

Kurisu, Satoshi; Nitta, Kazuhiro; Sumimoto, Yoji; Ikenaga, Hiroki; Ishibashi, Ken; Fukuda, Yukihiro; Kihara, Yasuki

2018-06-01

Aortic tortuosity is often found on chest radiograph, especially in aged patients. We tested the hypothesis that aortic tortuosity was associated with LV diastolic parameters derived from gated SPECT in patients with normal myocardial perfusion. One-hundred and twenty-two patients with preserved LV ejection fraction and normal myocardial perfusion were enrolled. Descending aortic deviation was defined as the horizontal distance from the left line of the aortic knob to the most prominent left line of the descending aorta. This parameter was measured for the quantitative assessment of aortic tortuosity. Peak filling rate (PFR) and one-third mean filling rate (1/3 MFR) were obtained from redistribution images as LV diastolic parameters. Descending aortic deviation ranged from 0 to 22 mm with a mean distance of 4.5 ± 6.3 mm. Descending aortic deviation was significantly correlated with age (r = 0.38, p < 0.001) and estimated glomerular filtration rate (eGFR) (r = - 0.21, p = 0.02). Multivariate linear regression analysis revealed that eGFR (β = 0.23, p = 0.02) and descending aortic deviation (β = - 0.23, p = 0.01) were significantly associated with PFR, and that only descending aortic deviation (β = - 0.21, p = 0.03) was significantly associated with 1/3 MFR. Our data suggest that aortic tortuosity is associated with LV diastolic parameters derived from gated SPECT in patients with normal myocardial perfusion.

Combined visual and semi-quantitative assessment of 123I-FP-CIT SPECT for the diagnosis of dopaminergic neurodegenerative diseases.

PubMed

Ueda, Jun; Yoshimura, Hajime; Shimizu, Keiji; Hino, Megumu; Kohara, Nobuo

2017-07-01

Visual and semi-quantitative assessments of 123 I-FP-CIT single-photon emission computed tomography (SPECT) are useful for the diagnosis of dopaminergic neurodegenerative diseases (dNDD), including Parkinson's disease, dementia with Lewy bodies, progressive supranuclear palsy, multiple system atrophy, and corticobasal degeneration. However, the diagnostic value of combined visual and semi-quantitative assessment in dNDD remains unclear. Among 239 consecutive patients with a newly diagnosed possible parkinsonian syndrome who underwent 123 I-FP-CIT SPECT in our medical center, 114 patients with a disease duration less than 7 years were diagnosed as dNDD with the established criteria or as non-dNDD according to clinical judgment. We retrospectively examined their clinical characteristics and visual and semi-quantitative assessments of 123 I-FP-CIT SPECT. The striatal binding ratio (SBR) was used as a semi-quantitative measure of 123 I-FP-CIT SPECT. We calculated the sensitivity and specificity of visual assessment alone, semi-quantitative assessment alone, and combined visual and semi-quantitative assessment for the diagnosis of dNDD. SBR was correlated with visual assessment. Some dNDD patients with a normal visual assessment had an abnormal SBR, and vice versa. There was no statistically significant difference between sensitivity of the diagnosis with visual assessment alone and semi-quantitative assessment alone (91.2 vs. 86.8%, respectively, p = 0.29). Combined visual and semi-quantitative assessment demonstrated superior sensitivity (96.7%) to visual assessment (p = 0.03) or semi-quantitative assessment (p = 0.003) alone with equal specificity. Visual and semi-quantitative assessments of 123 I-FP-CIT SPECT are helpful for the diagnosis of dNDD, and combined visual and semi-quantitative assessment shows superior sensitivity with equal specificity.

[Image fusion of gated-SPECT and CT angiography in coronary artery disease. Importance of anatomic-functional correlation].

PubMed

Nazarena Pizzi, M; Aguadé Bruix, S; Cuéllar Calabria, H; Aliaga, V; Candell Riera, J

2010-01-01

A 77-year old patient was admitted for acute coronary syndrome without ST elevation. His risk was stratified using the myocardial perfusion gated SPECT, mild inferior ischemia being observed. Thus, medical therapy was optimized and the patient was discharged. He continued with exertional dyspnea so a coronary CT angiography was performed. It revealed severe lesions in the proximal RCA. SPECT-CT fusion images correlated the myocardial perfusion defect with a posterior descending artery from the RCA, in a co-dominant coronary area. Subsequently, cardiac catheterism was indicated for his treatment. The current use of image fusion studies is limited to patients in whom it is difficult to attribute a perfusion defect to a specific coronary artery. In our patient, the fusion images helped to distinguish between the RCA and the circumflex artery as the culprit artery of ischemia. Copyright © 2010 Elsevier España, S.L. y SEMNIM. All rights reserved.

Evaluation of mechanical dyssynchrony and myocardial perfusion using phase analysis of gated SPECT imaging in patients with left ventricular dysfunction

PubMed Central

Trimble, Mark A.; Borges-Neto, Salvador; Honeycutt, Emily F.; Shaw, Linda K.; Pagnanelli, Robert; Chen, Ji; Iskandrian, Ami E.; Garcia, Ernest V.; Velazquez, Eric J.

2010-01-01

Background Using phase analysis of gated single photon emission computed tomography (SPECT) imaging, we examined the relation between myocardial perfusion, degree of electrical dyssynchrony, and degree of SPECT-derived mechanical dyssynchrony in patients with left ventricular (LV) dysfunction. Methods and Results We retrospectively examined 125 patients with LV dysfunction and ejection fraction of 35% or lower. Fourier analysis converts regional myocardial counts into a continuous thickening function, allowing resolution of phase of onset of myocardial thickening. The SD of LV phase distribution (phase SD) and histogram bandwidth describe LV phase dispersion as a measure of dyssynchrony. Heart failure (HF) patients with perfusion abnormalities ities have higher degrees of dyssynchrony measured by median phase SD (45.5° vs 27.7°, P < .0001) and bandwidth (117.0° vs 73.0°, P = .0006). HF patients with prolonged QRS durations have higher degrees of dyssynchrony measured by median phase SD (54.1° vs 34.7°, P < .0001) and bandwidth (136.5° vs 99.0°, P = .0005). Mild to moderate correlations exist between QRS duration and phase analysis indices of phase SD (r = 0.50) and bandwidth (r = 0.40). Mechanical dyssynchrony (phase SD >43°) was 43.2%. Conclusions HF patients with perfusion abnormalities or prolonged QRS durations QRS durations have higher degrees of mechanical dyssynchrony. Gated SPECT myocardial perfusion imaging can quantify myocardial function, perfusion, and dyssynchrony and may help in evaluating patients for cardiac resynchronization therapy. PMID:18761269

Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT

NASA Astrophysics Data System (ADS)

Lee, Taek-Soo; Frey, Eric C.; Tsui, Benjamin M. W.

2015-04-01

This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical observer model extends the conventional channelized Hotelling observer (CHO) based on a set of 2D spatial channels and the second is a proposed model that uses a set of 4D space-time channels. Simulated projection data were generated using the 4D NURBS-based cardiac-torso (NCAT) phantom with 16 gates/cardiac cycle. The activity distribution modelled uptake of 99mTc MIBI with normal perfusion and a regional wall motion defect. An analytical projector was used in the simulation and the filtered backprojection (FBP) algorithm was used in image reconstruction followed by spatial and temporal low-pass filtering with various cut-off frequencies. Then, we extracted 2D image slices from each time frame and reorganized them into a set of cine images. For the first model, we applied 2D spatial channels to the cine images and generated a set of feature vectors that were stacked for the images from different slices of the heart. The process was repeated for each of the 1,024 noise realizations, and CHO and receiver operating characteristics (ROC) analysis methodologies were applied to the ensemble of the feature vectors to compute areas under the ROC curves (AUCs). For the second model, a set of 4D space-time channels was developed and applied to the sets of cine images to produce space-time feature vectors to which the CHO methodology was applied. The AUC values of the second model showed better agreement (Spearman’s rank correlation (SRC) coefficient = 0.8) to human observer results than those from the first model (SRC coefficient = 0.4). The agreement with human observers indicates the proposed 4D mathematical observer model provides a good predictor of the performance of human observers in detecting regional motion defects in 4D gated MP SPECT images. The result supports the use of the observer model in the optimization and evaluation of 4D image reconstruction and compensation methods for improving the detection of motion abnormalities in 4D gated MP SPECT images.

A priori motion models for four-dimensional reconstruction in gated cardiac SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalush, D.S.; Tsui, B.M.W.; Cui, Lin

1996-12-31

We investigate the benefit of incorporating a priori assumptions about cardiac motion in a fully four-dimensional (4D) reconstruction algorithm for gated cardiac SPECT. Previous work has shown that non-motion-specific 4D Gibbs priors enforcing smoothing in time and space can control noise while preserving resolution. In this paper, we evaluate methods for incorporating known heart motion in the Gibbs prior model. The new model is derived by assigning motion vectors to each 4D voxel, defining the movement of that volume of activity into the neighboring time frames. Weights for the Gibbs cliques are computed based on these {open_quotes}most likely{close_quotes} motion vectors.more » To evaluate, we employ the mathematical cardiac-torso (MCAT) phantom with a new dynamic heart model that simulates the beating and twisting motion of the heart. Sixteen realistically-simulated gated datasets were generated, with noise simulated to emulate a real Tl-201 gated SPECT study. Reconstructions were performed using several different reconstruction algorithms, all modeling nonuniform attenuation and three-dimensional detector response. These include ML-EM with 4D filtering, 4D MAP-EM without prior motion assumption, and 4D MAP-EM with prior motion assumptions. The prior motion assumptions included both the correct motion model and incorrect models. Results show that reconstructions using the 4D prior model can smooth noise and preserve time-domain resolution more effectively than 4D linear filters. We conclude that modeling of motion in 4D reconstruction algorithms can be a powerful tool for smoothing noise and preserving temporal resolution in gated cardiac studies.« less

Left ventricular energy model predicts adverse events in women with suspected myocardial ischemia: results from the NHLBI-sponsored women’s ischemia syndrome evaluation (WISE) study

PubMed Central

Weinberg, Nicole; Pohost, Gerald M.; Bairey Merz, C. Noel; Shaw, Leslee J.; Sopko, George; Fuisz, Anthon; Rogers, William J.; Walsh, Edward G.; Johnson, B. Delia; Sharaf, Barry L.; Pepine, Carl J.; Mankad, Sunil; Reis, Steven E.; Rayarao, Geetha; Vido, Diane A.; Bittner, Vera; Tauxe, Lindsey; Olson, Marian B.; Kelsey, Sheryl F.; Biederman, Robert WW

2013-01-01

Objectives To assess the prognostic value of a left ventricular energy-model in women with suspected myocardial ischemia. Background The prognostic value of internal energy utilization (IEU) of the left ventricle in women with suspected myocardial ischemia is unknown. Methods Women [n=227, mean age 59±12 years (range, 31-86 years)], with symptoms of myocardial ischemia, underwent myocardial perfusion imaging (MPI) assessment for regional perfusion defects along with measurement of ventricular volumes separately by gated Single Photon Emission Computed Tomography (SPECT) (n=207) and magnetic resonance imaging (MRI) (n=203). During follow-up (40±17 months), time to first major adverse cardiovascular event (MACE, death, myocardial infarction or hospitalization for congestive heart failure) was analyzed using MRI and gated SPECT variables. Results Adverse events occurred in 31 (14%). Multivariable Cox models were formed for each modality: IEU and wall thickness by MRI (Chi-squared 34, P<0.005) and IEU and systolic blood pressure by gated SEPCT (Chi-squared 34, P<0.005). The models remained predictive after adjustment for age, disease history and Framingham risk score. For each Cox model, patients were categorized as high-risk if the model hazard was positive and not high-risk otherwise. Kaplan-Meier analysis of time to MACE was performed for high-risk vs. not high-risk for MR (log rank 25.3, P<0.001) and gated SEPCT (log rank 18.2, P<0.001) models. Conclusions Among women with suspected myocardial ischemia a high internal energy utilization has higher prognostic value than either a low EF or the presence of a myocardial perfusion defect assessed using two independent modalities of MR or gated SPECT. PMID:24015377

A CZT-based blood counter for quantitative molecular imaging.

PubMed

Espagnet, Romain; Frezza, Andrea; Martin, Jean-Pierre; Hamel, Louis-André; Lechippey, Laëtitia; Beauregard, Jean-Mathieu; Després, Philippe

2017-12-01

Robust quantitative analysis in positron emission tomography (PET) and in single-photon emission computed tomography (SPECT) typically requires the time-activity curve as an input function for the pharmacokinetic modeling of tracer uptake. For this purpose, a new automated tool for the determination of blood activity as a function of time is presented. The device, compact enough to be used on the patient bed, relies on a peristaltic pump for continuous blood withdrawal at user-defined rates. Gamma detection is based on a 20 × 20 × 15 mm 3 cadmium zinc telluride (CZT) detector, read by custom-made electronics and a field-programmable gate array-based signal processing unit. A graphical user interface (GUI) allows users to select parameters and easily perform acquisitions. This paper presents the overall design of the device as well as the results related to the detector performance in terms of stability, sensitivity and energy resolution. Results from a patient study are also reported. The device achieved a sensitivity of 7.1 cps/(kBq/mL) and a minimum detectable activity of 2.5 kBq/ml for 18 F. The gamma counter also demonstrated an excellent stability with a deviation in count rates inferior to 0.05% over 6 h. An energy resolution of 8% was achieved at 662 keV. The patient study was conclusive and demonstrated that the compact gamma blood counter developed has the sensitivity and the stability required to conduct quantitative molecular imaging studies in PET and SPECT.

Effect of streptozotocin-induced diabetes on left ventricular function in adult rats: an in vivo Pinhole Gated SPECT study

PubMed Central

Cosyns, Bernard; Droogmans, Steven; Weytjens, Caroline; Lahoutte, Tony; Van Camp, Guy; Schoors, Danny; Franken, Philippe R

2007-01-01

Background Recent studies have suggested that diabetes mellitus (DM) may cause left ventricular (LV) dysfunction directly resulting in increased susceptibility to heart failure. Using pinhole collimators and advances in data processing, gated SPECT was recently adapted to image the rat heart. The present study was aimed to assess this new imaging technique for quantifying LV function and remodeling from the Streptozotocin (STZ) rat model compared to controls. Methods Twenty one rats were randomly assigned to control or diabetic group. Six months after the induction of diabetes by STZ, Pinhole 99 m Tc-sestamibi gated SPECT was performed for determining rat LV volumes and function. Post-mortem histopathologic analysis was performed to evaluate the determinant of LV remodeling in this model. Results After six months, the normalized to body weight LV End-systolic volume was significantly different in diabetic rats compared to controls (0.46 ± 0.02 vs 0.33 ± 0.03 μL/g; p = 0.01). The normalized LV End-diastolic volume was also different in both groups (1.51 ± 0.03 vs 0.88 ± 0.05 μL/g; p = 0.001) and the normalized stroke volume was significantly higher in STZ-rats (1.05 ± 0.02 vs 0.54 ± 0.06 μL/g; p = 0.001). The muscular fibers were thinner at histology in the diabetic rats (0.44 ± 0.07 vs 0.32 ± 0.06 AU; p = 0.01). Conclusion Pinhole 99 m Tc-sestamibi gated SPECT can successfully be applied for the evaluation of cardiac function and remodeling in STZ-induced diabetic rats. In this model, LV volumes were significantly changed compared to a control population, leading to a LV dysfunction. These findings were consistent with the histopathological abnormalities. Finally, these data further suggest the presence of diabetes cardiomyopathy. PMID:17937784

The Use of Quantitative SPECT/CT Imaging to Assess Residual Limb Health

DTIC Science & Technology

2016-10-01

AWARD NUMBER: W81XWH-15-1-0669 TITLE: The Use of Quantitative SPECT/CT Imaging to Assess Residual Limb Health PRINCIPAL INVESTIGATOR...3. DATES COVERED 30 Sep 2015 - 29 Sep 2016 4. TITLE AND SUBTITLE The Use of Quantitative SPECT/CT Imaging to Assess Residual Limb Health 5a...amputation and subsequently evaluate the utility of non-invasive imaging for evaluating the impact of next-generation socket technologies on the health of

Use of quantitative SPECT/CT reconstruction in 99mTc-sestamibi imaging of patients with renal masses.

PubMed

Jones, Krystyna M; Solnes, Lilja B; Rowe, Steven P; Gorin, Michael A; Sheikhbahaei, Sara; Fung, George; Frey, Eric C; Allaf, Mohamad E; Du, Yong; Javadi, Mehrbod S

2018-02-01

Technetium-99m ( 99m Tc)-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) has previously been shown to allow for the accurate differentiation of benign renal oncocytomas and hybrid oncocytic/chromophobe tumors (HOCTs) apart from other malignant renal tumor histologies, with oncocytomas/HOCTs showing high uptake and renal cell carcinoma (RCC) showing low uptake based on uptake ratios from non-quantitative single-photon emission computed tomography (SPECT) reconstructions. However, in this study, several tumors fell close to the uptake ratio cutoff, likely due to limitations in conventional SPECT/CT reconstruction methods. We hypothesized that application of quantitative SPECT/CT (QSPECT) reconstruction methods developed by our group would provide more robust separation of hot and cold lesions, serving as an imaging framework on which quantitative biomarkers can be validated for evaluation of renal masses with 99m Tc-sestamibi. Single-photon emission computed tomography data were reconstructed using the clinical Flash 3D reconstruction and QSPECT methods. Two blinded readers then characterized each tumor as hot or cold. Semi-quantitative uptake ratios were calculated by dividing lesion activity by background renal activity for both Flash 3D and QSPECT reconstructions. The difference between median (mean) hot and cold tumor uptake ratios measured 0.655 (0.73) with the QSPECT method and 0.624 (0.67) with the conventional method, resulting in increased separation between hot and cold tumors. Sub-analysis of 7 lesions near the separation point showed a higher absolute difference (0.16) between QPSECT and Flash 3D mean uptake ratios compared to the remaining lesions. Our finding of improved separation between uptake ratios of hot and cold lesions using QSPECT reconstruction lays the foundation for additional quantitative SPECT techniques such as SPECT-UV in the setting of renal 99m Tc-sestamibi and other SPECT/CT exams. With robust quantitative image reconstruction and biomarker analysis, there may be an expanded role for SPECT/CT imaging in renal masses and other pathologic conditions.

Performance Evaluation and Quantitative Accuracy of Multipinhole NanoSPECT/CT Scanner for Theranostic Lu-177 Imaging

NASA Astrophysics Data System (ADS)

Gupta, Arun; Kim, Kyeong Yun; Hwang, Donghwi; Lee, Min Sun; Lee, Dong Soo; Lee, Jae Sung

2018-06-01

SPECT plays important role in peptide receptor targeted radionuclide therapy using theranostic radionuclides such as Lu-177 for the treatment of various cancers. However, SPECT studies must be quantitatively accurate because the reliable assessment of tumor uptake and tumor-to-normal tissue ratios can only be performed using quantitatively accurate images. Hence, it is important to evaluate performance parameters and quantitative accuracy of preclinical SPECT systems for therapeutic radioisotopes before conducting pre- and post-therapy SPECT imaging or dosimetry studies. In this study, we evaluated system performance and quantitative accuracy of NanoSPECT/CT scanner for Lu-177 imaging using point source and uniform phantom studies. We measured recovery coefficient, uniformity, spatial resolution, system sensitivity and calibration factor for mouse whole body standard aperture. We also performed the experiments using Tc-99m to compare the results with that of Lu-177. We found that the recovery coefficient of more than 70% for Lu-177 at the optimum noise level when nine iterations were used. The spatial resolutions of Lu-177 with and without adding uniform background was comparable to that of Tc-99m in axial, radial and tangential directions. System sensitivity measured for Lu-177 was almost three times less than that of Tc-99m.

C-SPECT - a Clinical Cardiac SPECT/Tct Platform: Design Concepts and Performance Potential

PubMed Central

Chang, Wei; Ordonez, Caesar E.; Liang, Haoning; Li, Yusheng; Liu, Jingai

2013-01-01

Because of scarcity of photons emitted from the heart, clinical cardiac SPECT imaging is mainly limited by photon statistics. The sub-optimal detection efficiency of current SPECT systems not only limits the quality of clinical cardiac SPECT imaging but also makes more advanced potential applications difficult to be realized. We propose a high-performance system platform - C-SPECT, which has its sampling geometry optimized for detection of emitted photons in quality and quantity. The C-SPECT has a stationary C-shaped gantry that surrounds the left-front side of a patient’s thorax. The stationary C-shaped collimator and detector systems in the gantry provide effective and efficient detection and sampling of photon emission. For cardiac imaging, the C-SPECT platform could achieve 2 to 4 times the system geometric efficiency of conventional SPECT systems at the same sampling resolution. This platform also includes an integrated transmission CT for attenuation correction. The ability of C-SPECT systems to perform sequential high-quality emission and transmission imaging could bring cost-effective high-performance to clinical imaging. In addition, a C-SPECT system could provide high detection efficiency to accommodate fast acquisition rate for gated and dynamic cardiac imaging. This paper describes the design concepts and performance potential of C-SPECT, and illustrates how these concepts can be implemented in a basic system. PMID:23885129

Quantitative single-photon emission computed tomography/computed tomography for technetium pertechnetate thyroid uptake measurement

PubMed Central

Lee, Hyunjong; Kim, Ji Hyun; Kang, Yeon-koo; Moon, Jae Hoon; So, Young; Lee, Won Woo

2016-01-01

Abstract Objectives: Technetium pertechnetate (99mTcO4) is a radioactive tracer used to assess thyroid function by thyroid uptake system (TUS). However, the TUS often fails to deliver accurate measurements of the percent of thyroid uptake (%thyroid uptake) of 99mTcO4. Here, we investigated the usefulness of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) after injection of 99mTcO4 in detecting thyroid function abnormalities. Materials and methods: We retrospectively reviewed data from 50 patients (male:female = 15:35; age, 46.2 ± 16.3 years; 17 Graves disease, 13 thyroiditis, and 20 euthyroid). All patients underwent 99mTcO4 quantitative SPECT/CT (185 MBq = 5 mCi), which yielded %thyroid uptake and standardized uptake value (SUV). Twenty-one (10 Graves disease and 11 thyroiditis) of the 50 patients also underwent conventional %thyroid uptake measurements using a TUS. Results: Quantitative SPECT/CT parameters (%thyroid uptake, SUVmean, and SUVmax) were the highest in Graves disease, second highest in euthyroid, and lowest in thyroiditis (P < 0.0001, Kruskal–Wallis test). TUS significantly overestimated the %thyroid uptake compared with SPECT/CT (P < 0.0001, paired t test) because other 99mTcO4 sources in addition to thyroid, such as salivary glands and saliva, contributed to the %thyroid uptake result by TUS, whereas %thyroid uptake, SUVmean and SUVmax from the SPECT/CT were associated with the functional status of thyroid. Conclusions: Quantitative SPECT/CT is more accurate than conventional TUS for measuring 99mTcO4 %thyroid uptake. Quantitative measurements using SPECT/CT may facilitate more accurate assessment of thyroid tracer uptake. PMID:27399139

Effects of Piecewise Spatial Smoothing in 4-D SPECT Reconstruction

NASA Astrophysics Data System (ADS)

Qi, Wenyuan; Yang, Yongyi; King, Michael A.

2014-02-01

In nuclear medicine, cardiac gated SPECT images are known to suffer from significantly increased noise owing to limited data counts. Consequently, spatial (and temporal) smoothing has been indispensable for suppressing the noise artifacts in SPECT reconstruction. However, recently we demonstrated that the benefit of spatial processing in motion-compensated reconstruction of gated SPECT (aka 4-D) could be outweighed by its adverse effects on the myocardium, which included degraded wall motion and perfusion defect detectability. In this work, we investigate whether we can alleviate these adverse effects by exploiting an alternative spatial smoothing prior in 4-D based on image total variation (TV). TV based prior is known to induce piecewise smoothing which can preserve edge features (such as boundaries of the heart wall) in reconstruction. However, it is not clear whether such a property would necessarily be beneficial for improving the accuracy of the myocardium in 4-D reconstruction. In particular, it is unknown whether it would adversely affect the detectability of perfusion defects that are small in size or low in contrast. In our evaluation study, we first use Monte Carlo simulated imaging with 4-D NURBS-based cardiac-torso (NCAT) phantom wherein the ground truth is known for quantitative comparison. We evaluated the accuracy of the reconstructed myocardium using a number of metrics, including regional and overall accuracy of the myocardium, accuracy of the phase activity curve (PAC) of the LV wall for wall motion, uniformity and spatial resolution of the LV wall, and detectability of perfusion defects using a channelized Hotelling observer (CHO). For lesion detection, we simulated perfusion defects with different sizes and contrast levels with the focus being on perfusion defects that are subtle. As a preliminary demonstration, we also tested on three sets of clinical acquisitions. From the quantitative results, it was demonstrated that TV smoothing could further reduce the error level in the myocardium in 4-D reconstruction along with motion-compensated temporal smoothing. In contrast to quadratic spatial smoothing, TV smoothing could reduce the noise level in the LV at a faster pace than the increase in the bias level, thereby achieving a net decrease in the error level. In particular, at the same noise level, TV smoothing could reduce the bias by about 30% compared to quadratic smoothing. Moreover, the CHO results indicate that TV could also improve the lesion detectability even when the lesion is small. The PAC results show that, at the same noise level, TV smoothing achieved lower temporal bias, which is also consistent with the improved spatial resolution of the LV in reconstruction. The improvement in blurring effects by TV was also observed in the clinical images.

CT-SPECT fusion plus conjugate views for determining dosimetry in iodine-131-monoclonal antibody therapy of lymphoma patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koral, K.F.; Zasadny, K.R.; Kessler, M.L.

A method of performing {sup 131}I quantitative SPECT imaging is described which uses the superimposition of markers placed on the skin to accomplish fusion of computed tomography (CT) and SPECT image sets. To calculate mean absorbed dose after administration of one of two {sup 131}I-labeled monoclonal antibodies (Mabs), the shape of the time-activity curve is measured by daily diagnostic conjugate views, the y-axis of that curve is normalized by a quantitative SPECT measurement (usually intra-therapy), and the tumor mass is deduced from a concurrent CT volume measurement. The method is applied to six B-cell non-Hodgkin`s lymphoma patients. For four tumorsmore » in three patients treated with the MB1 Mab, a correlation appears to be present between resulting mean absorbed dose and disease response. Including all dosimetric estimates for both antibodies, the range for the specific absorbed dose is within that found by others in treating B-cell lymphoma patients. Excluding a retreated anti-B1 patient, the tumor-specific absorbed dose during anti-B1 therapy is from 1.4 to 1.7 mGy/MBq. For the one anti-B1 patient, where quantitative SPECT and conjugate-view imaging was carried out back to back , the quantitative SPECT-measured activity was somewhat less for the spleen and much less for the tumor than that from conjugate views. The quantitative SPECT plus conjugate views method may be of general utility for macro-dosimetry of {sup 131}If therapies. 18 refs., 3 figs., 5 tabs.« less

Segmented slant hole collimator for stationary cardiac SPECT: Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Yanfei, E-mail: ymao@ucair.med.utah.edu; Yu, Zhicong; Zeng, Gengsheng L.

2015-09-15

Purpose: This work is a preliminary study of a stationary cardiac SPECT system. The goal of this research is to propose a stationary cardiac SPECT system using segmented slant-hole collimators and to perform computer simulations to test the feasibility. Compared to the rotational SPECT, a stationary system has a benefit of acquiring temporally consistent projections. The most challenging issue in building a stationary system is to provide sufficient projection view-angles. Methods: A GATE (GEANT4 application for tomographic emission) Monte Carlo model was developed to simulate a two-detector stationary cardiac SPECT that uses segmented slant-hole collimators. Each detector contains seven segmentedmore » slant-hole sections that slant to a common volume at the rotation center. Consequently, 14 view-angles over 180° were acquired without any gantry rotation. The NCAT phantom was used for data generation and a tailored maximum-likelihood expectation-maximization algorithm was used for image reconstruction. Effects of limited number of view-angles and data truncation were carefully evaluated in the paper. Results: Simulation results indicated that the proposed segmented slant-hole stationary cardiac SPECT system is able to acquire sufficient data for cardiac imaging without a loss of image quality, even when the uptakes in the liver and kidneys are high. Seven views are acquired simultaneously at each detector, leading to 5-fold sensitivity gain over the conventional dual-head system at the same total acquisition time, which in turn increases the signal-to-noise ratio by 19%. The segmented slant-hole SPECT system also showed a good performance in lesion detection. In our prototype system, a short hole-length was used to reduce the dead zone between neighboring collimator segments. The measured sensitivity gain is about 17-fold over the conventional dual-head system. Conclusions: The GATE Monte Carlo simulations confirm the feasibility of the proposed stationary cardiac SPECT system with segmented slant-hole collimators. The proposed collimator consists of combined parallel and slant holes, and the image on the detector is not reduced in size.« less

One-year follow-up of myocardial perfusion and function evaluated by gated SPECT MIBI in patients with earlier myocardial infarction and chronic total occlusion.

PubMed

Pavlovic, Smiljana V; Sobic-Saranovic, Dragana P; Beleslin, Branko D; Ostojic, Miodrag C; Nedeljkovic, Milan A; Giga, Vojislav L; Petrasinovic, Zorica R; Artiko, Vera M; Todorovic-Tirnanic, Mila V; Obradovic, Vladimir B

2009-01-01

Optimal treatment for chronic total occlusion (CTO) in the infarct-related coronary artery is not clear. Our aim was to assess myocardial perfusion, left ventricular ejection fraction (EF), and left ventricular size using gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging with 99mTc-methoxy-isobutyl-isonitrile in patients with CTO before and 1 year after recanalization. Thirty patients with earlier myocardial infarction and at least one CTO underwent percutaneous coronary intervention (PCI) as well as nitrate-enhanced gated SPECT myocardial perfusion and dobutamine stress echocardiography before and 11 +/- 1 months after recanalization. They were divided into three groups based on the outcome of the follow-up angiography: (i) successful recanalization with no evidence of in-stent restenosis (n=13); (ii) successful recanalization with in-stent restenosis (n=7) and (iii) unsuccessful recanalization (n=10). Overall success of recanalization for CTO was 74%. In group 1, myocardial viability was preserved in 11 of 13 (85%) patients at baseline. Gated SPECT at 1 year showed a significant decrease in perfusion abnormalities (29 +/- 12 to 23 +/- 14%, P < 0.05) and left ventricular end-diastolic volume (EDV) (168 +/- 47 to 151 +/- 47 ml, P < 0.05). Improvement in EF (51 +/- 11 to 54 +/- 13%, P > 0.05) and reduction in left ventricular end-systolic volume (ESV) (84 +/- 37 to 77 +/- 40 ml, P > 0.05) did not reach the level of significance. Myocardial viability was preserved in only two of seven patients (28%) in group 2. Neither mean perfusion abnormalities (37 +/- 24 to 35 +/- 22%, P > 0.05) nor global left ventricular parameters (EF 41 +/- 15 vs. 42 +/- 19%, EDV 298 +/- 33 vs. 299 +/- 57 mL, ESV 197 +/- 12 vs. 195 +/- 32 ml; P > 0.05) changed at the follow-up. In group 3, myocardial viability was preserved in seven of 10 patients (70%) at baseline, but no significant changes in perfusion (40 +/- 18 vs. 41 +/- 19%, P > 0.05) and left ventricular function (EF 42 +/- 17 vs. 44 +/- 14%, EDV 228 +/- 101 vs. 227 +/- 81 ml, ESV 143 +/- 87 vs. 146 +/- 8 ml; P > 0.05) were seen at the follow-up. Myocardial perfusion and EDV may significantly improve 1 year after PCI provided recanalization of CTO was successful. Our preliminary findings suggest that successful recanalization of CTO may have favorable outcome on left ventricular perfusion and function, particularly in patients with viable myocardium before PCI. The gated SPECT myocardial perfusion imaging with 99mTc-methoxy-isobutyl-isonitrile may be useful for monitoring long-term functional outcome of PCI in patients with CTO.

Global scaling for semi-quantitative analysis in FP-CIT SPECT.

PubMed

Kupitz, D; Apostolova, I; Lange, C; Ulrich, G; Amthauer, H; Brenner, W; Buchert, R

2014-01-01

Semi-quantitative characterization of dopamine transporter availability from single photon emission computed tomography (SPECT) with 123I-ioflupane (FP-CIT) is based on uptake ratios relative to a reference region. The aim of this study was to evaluate the whole brain as reference region for semi-quantitative analysis of FP-CIT SPECT. The rationale was that this might reduce statistical noise associated with the estimation of non-displaceable FP-CIT uptake. 150 FP-CIT SPECTs were categorized as neurodegenerative or non-neurodegenerative by an expert. Semi-quantitative analysis of specific binding ratios (SBR) was performed with a custom-made tool based on the Statistical Parametric Mapping software package using predefined regions of interest (ROIs) in the anatomical space of the Montreal Neurological Institute. The following reference regions were compared: predefined ROIs for frontal and occipital lobe and whole brain (without striata, thalamus and brainstem). Tracer uptake in the reference region was characterized by the mean, median or 75th percentile of its voxel intensities. The area (AUC) under the receiver operating characteristic curve was used as performance measure. The highest AUC of 0.973 was achieved by the SBR of the putamen with the 75th percentile in the whole brain as reference. The lowest AUC for the putamen SBR of 0.937 was obtained with the mean in the frontal lobe as reference. We recommend the 75th percentile in the whole brain as reference for semi-quantitative analysis in FP-CIT SPECT. This combination provided the best agreement of the semi-quantitative analysis with visual evaluation of the SPECT images by an expert and, therefore, is appropriate to support less experienced physicians.

Factors That Impact Evaluation of Left Ventricular Systolic Parameters in Myocardial Perfusion Gated SPECT with 16 Frame and 8 Frame Acquisition Models.

PubMed

Ansari, Mojtaba; Hashemi, Hoda; Soltanshahi, Mehdi; Qutbi, Mohsen; Azizmohammadi, Zahra; Tabeie, Faraj; Javadi, Hamid; Jafari, Esmail; Barekat, Maryam; Assadi, Majid

2018-06-07

Evaluating the effects of heart cavity volume, presence and absence of perfusion defect, gender and type of study (stress and rest) on the difference of systolic parameters of myocardial perfusion scan in 16 and 8 framing gated SPECT imaging. Cardiac gated SPECT in both 16 and 8 framing simultaneously and both stress and rest phases at one-day protocol was performed for 50 patients. Data have been reconstructed by filter back projection (FBP) method and left ventricular (LV) systolic parameters were calculated by using QGS software. The effect of some factors such as LV cavity volume, presence and absence of perfusion defect, gender and type of study on data difference between 8 and 16 frames were evaluated. The differences in ejection fraction (EF), end-diastolic volume (EDV) and end-systolic volume (ESV) in both stress and rest were statistically significant. Difference in both framing was more in stress for EF and ESV, and was more in rest for EDV. Study type had a significant effect on differences in systolic parameters while gender had a significant effect on differences in EF and ESV in rest between both framings. In conclusion, results of this study revealed that difference of both 16 and 8 frames data in systolic phase were statistically significant and it seems that because of better efficiency of 16 frames, it cannot be replaced by 8 frames. Further well-designed studies are required to verify these findings.

Validation of gated blood-pool SPECT cardiac measurements tested using a biventricular dynamic physical phantom.

PubMed

De Bondt, Pieter; Nichols, Kenneth; Vandenberghe, Stijn; Segers, Patrick; De Winter, Olivier; Van de Wiele, Christophe; Verdonck, Pascal; Shazad, Arsalan; Shoyeb, Abu H; De Sutter, Johan

2003-06-01

We have developed a biventricular dynamic physical cardiac phantom to test gated blood-pool (GBP) SPECT image-processing algorithms. Such phantoms provide absolute values against which to assess accuracy of both right and left computed ventricular volume and ejection fraction (EF) measurements. Two silicon-rubber chambers driven by 2 piston pumps simulated crescent-shaped right ventricles wrapped partway around ellopsoid left ventricles. Twenty experiments were performed at Ghent University, for which right and left ventricular true volume and EF ranges were 65-275 mL and 55-165 mL and 7%-49% and 12%-69%, respectively. Resulting 64 x 64 simulated GBP SPECT images acquired at 16 frames per R-R interval were sent to Columbia University, where 2 observers analyzed images independently of each other, without knowledge of true values. Algorithms automatically segmented right ventricular activity volumetrically from left ventricular activity. Automated valve planes, midventricular planes, and segmentation regions were presented to observers, who accepted these choices or modified them as necessary. One observer repeated measurements >1 mo later without reference to previous determinations. Linear correlation coefficients (r) of the mean of the 3 GBP SPECT observations versus true values for right and left ventricles were 0.80 and 0.94 for EF and 0.94 and 0.95 for volumes, respectively. Correlations for right and left ventricles were 0.97 and 0.97 for EF and 0.96 and 0.89 for volumes, respectively, for interobserver agreement and 0.97 and 0.98 for EF and 0.96 and 0.90 for volumes, respectively, for intraobserver agreement. No trends were detected, though volumes and right ventricular EFs were significantly higher than true values. Overall, GBP SPECT measurements correlated strongly with true values. The phantom evaluated shows considerable promise for helping to guide algorithm developments for improved GBP SPECT accuracy.

Development of a Position Decoding ASIC for SPECT using Silicon Photomultiplier

NASA Astrophysics Data System (ADS)

Cho, M.; Kim, H.; Lim, K. T.; Cho, G.

2016-01-01

Single Photon Emission Computed Tomography(SPECT) is a widely used diagnosis modality for detecting metabolic diseases. In general, SPECT system is consisted of a sensor, a pre-amplifier, position decoding circuits(PDC) and a data acquisition(DAQ) system. Due to such complexity, it is quite costly to assemble SPECT system by putting discrete components together. Moreover, using discrete components would make the system rather bulky. In this work, we designed a channel module ASIC for SPECT system. This system was composed of a transimpedance amplifier(TIA), comparators and digital logics. In this particular module, a TIA was selected as a preamplifier because the decay time and the rise time are shorter than that of other preamplifier topologies. In the proposed module, the amplified pulse from the TIA was split into two separate signals and each signal was then fed into two comparators with different reference levels, e.g., a low and high level. Then an XOR gate combined the comparator outputs and the output of XOR gate was sent to the suceeding digital logic. Furthermore, the output of each component in the module is composed of a signal packet. The packet includes the information on the energy, the time and the position of the incident photon. The energy and position information of a detected radiation can be derived from the output of the D-flipflop(DFF) in the module via time-over-threshold(TOT). The timing information was measured using a delayed rising edge from the low-level referenced comparator. There are several advantages in developing the channel module ASIC. First of all, the ASIC has only digital outputs and thus a correction circuit for analog signal distortion can be neglected. In addition, it is possible to cut down the system production cost because the volume of the system can be reduced due to the compactness of ASIC. The benefits of channel module is not only limited to SPECT but also beneficial to many other radiation detecting systems.

Accelerated GPU based SPECT Monte Carlo simulations.

PubMed

Garcia, Marie-Paule; Bert, Julien; Benoit, Didier; Bardiès, Manuel; Visvikis, Dimitris

2016-06-07

Monte Carlo (MC) modelling is widely used in the field of single photon emission computed tomography (SPECT) as it is a reliable technique to simulate very high quality scans. This technique provides very accurate modelling of the radiation transport and particle interactions in a heterogeneous medium. Various MC codes exist for nuclear medicine imaging simulations. Recently, new strategies exploiting the computing capabilities of graphical processing units (GPU) have been proposed. This work aims at evaluating the accuracy of such GPU implementation strategies in comparison to standard MC codes in the context of SPECT imaging. GATE was considered the reference MC toolkit and used to evaluate the performance of newly developed GPU Geant4-based Monte Carlo simulation (GGEMS) modules for SPECT imaging. Radioisotopes with different photon energies were used with these various CPU and GPU Geant4-based MC codes in order to assess the best strategy for each configuration. Three different isotopes were considered: (99m) Tc, (111)In and (131)I, using a low energy high resolution (LEHR) collimator, a medium energy general purpose (MEGP) collimator and a high energy general purpose (HEGP) collimator respectively. Point source, uniform source, cylindrical phantom and anthropomorphic phantom acquisitions were simulated using a model of the GE infinia II 3/8" gamma camera. Both simulation platforms yielded a similar system sensitivity and image statistical quality for the various combinations. The overall acceleration factor between GATE and GGEMS platform derived from the same cylindrical phantom acquisition was between 18 and 27 for the different radioisotopes. Besides, a full MC simulation using an anthropomorphic phantom showed the full potential of the GGEMS platform, with a resulting acceleration factor up to 71. The good agreement with reference codes and the acceleration factors obtained support the use of GPU implementation strategies for improving computational efficiency of SPECT imaging simulations.

Toward Quantitative Small Animal Pinhole SPECT: Assessment of Quantitation Accuracy Prior to Image Compensations

PubMed Central

Chen, Chia-Lin; Wang, Yuchuan; Lee, Jason J. S.; Tsui, Benjamin M. W.

2011-01-01

Purpose We assessed the quantitation accuracy of small animal pinhole single photon emission computed tomography (SPECT) under the current preclinical settings, where image compensations are not routinely applied. Procedures The effects of several common image-degrading factors and imaging parameters on quantitation accuracy were evaluated using Monte-Carlo simulation methods. Typical preclinical imaging configurations were modeled, and quantitative analyses were performed based on image reconstructions without compensating for attenuation, scatter, and limited system resolution. Results Using mouse-sized phantom studies as examples, attenuation effects alone degraded quantitation accuracy by up to −18% (Tc-99m or In-111) or −41% (I-125). The inclusion of scatter effects changed the above numbers to −12% (Tc-99m or In-111) and −21% (I-125), respectively, indicating the significance of scatter in quantitative I-125 imaging. Region-of-interest (ROI) definitions have greater impacts on regional quantitation accuracy for small sphere sources as compared to attenuation and scatter effects. For the same ROI, SPECT acquisitions using pinhole apertures of different sizes could significantly affect the outcome, whereas the use of different radii-of-rotation yielded negligible differences in quantitation accuracy for the imaging configurations simulated. Conclusions We have systematically quantified the influence of several factors affecting the quantitation accuracy of small animal pinhole SPECT. In order to consistently achieve accurate quantitation within 5% of the truth, comprehensive image compensation methods are needed. PMID:19048346

Quantitation of benzodiazepine receptor binding with PET [11C]iomazenil and SPECT [123I]iomazenil: preliminary results of a direct comparison in healthy human subjects.

PubMed

Bremner, J D; Baldwin, R; Horti, A; Staib, L H; Ng, C K; Tan, P Z; Zea-Ponce, Y; Zoghbi, S; Seibyl, J P; Soufer, R; Charney, D S; Innis, R B

1999-08-31

Although positron emission tomography (PET) and single photon emission computed tomography (SPECT) are increasingly used for quantitation of neuroreceptor binding, almost no studies to date have involved a direct comparison of the two. One study found a high level of agreement between the two techniques, although there was a systematic 30% increase in measures of benzodiazepine receptor binding in SPECT compared with PET. The purpose of the current study was to directly compare quantitation of benzodiazepine receptor binding in the same human subjects using PET and SPECT with high specific activity [11C]iomazenil and [123I]iomazenil, respectively. All subjects were administered a single bolus of high specific activity iomazenil labeled with 11C or 123I followed by dynamic PET or SPECT imaging of the brain. Arterial blood samples were obtained for measurement of metabolite-corrected radioligand in plasma. Compartmental modeling was used to fit values for kinetic rate constants of transfer of radioligand between plasma and brain compartments. These values were used for calculation of binding potential (BP = Bmax/Kd) and product of BP and the fraction of free non-protein-bound parent compound (V3'). Mean values for V3' in PET and SPECT were as follows: temporal cortex 23+/-5 and 22+/-3 ml/g, frontal cortex23+/-6 and 22+/-3 ml/g, occipital cortex 28+/-3 and 31+/-5 ml/g, and striatum 4+/-4 and 7+/-4 ml/g. These preliminary findings indicate that PET and SPECT provide comparable results in quantitation of neuroreceptor binding in the human brain.

State-of-the-art radiological techniques improve the assessment of postoperative lung function in patients with non-small cell lung cancer.

PubMed

Ohno, Yoshiharu; Koyama, Hisanobu; Nogami, Munenobu; Takenaka, Daisuke; Onishi, Yumiko; Matsumoto, Keiko; Matsumoto, Sumiaki; Maniwa, Yoshimasa; Yoshimura, Masahiro; Nishimura, Yoshihiro; Sugimura, Kazuro

2011-01-01

The purpose of this study was to compare predictive capabilities for postoperative lung function in non-small cell lung cancer (NSCLC) patients of the state-of-the-art radiological methods including perfusion MRI, quantitative CT and SPECT/CT with that of anatomical method (i.e. qualitative CT) and traditional nuclear medicine methods such as planar imaging and SPECT. Perfusion MRI, CT, nuclear medicine study and measurements of %FEV(1) before and after lung resection were performed for 229 NSCLC patients (125 men and 104 women). For perfusion MRI, postoperative %FEV(1) (po%FEV(1)) was predicted from semi-quantitatively assessed blood volumes within total and resected lungs, for quantitative CT, it was predicted from the functional lung volumes within total and resected lungs, for qualitative CT, from the number of segments of total and resected lungs, and for nuclear medicine studies, from uptakes within total and resected lungs. All SPECTs were automatically co-registered with CTs for preparation of SPECT/CTs. Predicted po%FEV(1)s were then correlated with actual po%FEV(1)s, which were measured %FEV(1)s after operation. The limits of agreement were also evaluated. All predicted po%FEV(1)s showed good correlation with actual po%FEV(1)s (0.83≤r≤0.88, p<0.0001). Perfusion MRI, quantitative CT and SPECT/CT demonstrated better correlation than other methods. The limits of agreement of perfusion MRI (4.4±14.2%), quantitative CT (4.7±14.2%) and SPECT/CT (5.1±14.7%) were less than those of qualitative CT (6.0±17.4%), planar imaging (5.8±18.2%), and SPECT (5.5±16.8%). State-of-the-art radiological methods can predict postoperative lung function in NSCLC patients more accurately than traditional methods. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

GATE simulation of a new design of pinhole SPECT system for small animal brain imaging

NASA Astrophysics Data System (ADS)

Uzun Ozsahin, D.; Bläckberg, L.; El Fakhri, G.; Sabet, H.

2017-01-01

Small animal SPECT imaging has gained an increased interest over the past decade since it is an excellent tool for developing new drugs and tracers. Therefore, there is a huge effort on the development of cost-effective SPECT detectors with high capabilities. The aim of this study is to simulate the performance characteristics of new designs for a cost effective, stationary SPECT system dedicated to small animal imaging with a focus on mice brain. The conceptual design of this SPECT system platform, Stationary Small Animal SSA-SPECT, is to use many pixelated CsI:TI detector modules with 0.4 mm × 0.4 mm pixels in order to achieve excellent intrinsic detector resolution where each module is backed by a single pinhole collimator with 0.3 mm hole diameter. In this work, we present the simulation results of four variations of the SSA-SPECT platform where the number of detector modules and FOV size is varied while keeping the detector size and collimator hole size constant. Using the NEMA NU-4 protocol, we performed spatial resolution, sensitivity, image quality simulations followed by a Derenzo-like phantom evaluation. The results suggest that all four SSA-SPECT systems can provide better than 0.063% system sensitivity and < 1.5 mm FWHM spatial resolution without resolution recovery or other correction techniques. Specifically, SSA-SPECT-1 showed a system sensitivity of 0.09% in combination with 1.1 mm FWHM spatial resolution.

Anatomical-based partial volume correction for low-dose dedicated cardiac SPECT/CT

NASA Astrophysics Data System (ADS)

Liu, Hui; Chan, Chung; Grobshtein, Yariv; Ma, Tianyu; Liu, Yaqiang; Wang, Shi; Stacy, Mitchel R.; Sinusas, Albert J.; Liu, Chi

2015-09-01

Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused field-of-view over a clinically relevant range of high and low count levels for two different radiotracer distributions. These PVC methods include perturbation geometry transfer matrix (pGTM), pGTM followed by multi-target correction (MTC), pGTM with known concentration in blood pool, the former followed by MTC and our newly proposed methods, which perform the MTC method iteratively, where the mean values in all regions are estimated and updated by the MTC-corrected images each time in the iterative process. The NCAT phantom was simulated for cardiovascular imaging with 99mTc-tetrofosmin, a myocardial perfusion agent, and 99mTc-red blood cell (RBC), a pure intravascular imaging agent. Images were acquired at six different count levels to investigate the performance of PVC methods in both high and low count levels for low-dose applications. We performed two large animal in vivo cardiac imaging experiments following injection of 99mTc-RBC for evaluation of intramyocardial blood volume (IMBV). The simulation results showed our proposed iterative methods provide superior performance than other existing PVC methods in terms of image quality, quantitative accuracy, and reproducibility (standard deviation), particularly for low-count data. The iterative approaches are robust for both 99mTc-tetrofosmin perfusion imaging and 99mTc-RBC imaging of IMBV and blood pool activity even at low count levels. The animal study results indicated the effectiveness of PVC to correct the overestimation of IMBV due to blood pool contamination. In conclusion, the iterative PVC methods can achieve more accurate quantification, particularly for low count cardiac SPECT studies, typically obtained from low-dose protocols, gated studies, and dynamic applications.

EduGATE - basic examples for educative purpose using the GATE simulation platform.

PubMed

Pietrzyk, Uwe; Zakhnini, Abdelhamid; Axer, Markus; Sauerzapf, Sophie; Benoit, Didier; Gaens, Michaela

2013-02-01

EduGATE is a collection of basic examples to introduce students to the fundamental physical aspects of medical imaging devices. It is based on the GATE platform, which has received a wide acceptance in the field of simulating medical imaging devices including SPECT, PET, CT and also applications in radiation therapy. GATE can be configured by commands, which are, for the sake of simplicity, listed in a collection of one or more macro files to set up phantoms, multiple types of sources, detection device, and acquisition parameters. The aim of the EduGATE is to use all these helpful features of GATE to provide insights into the physics of medical imaging by means of a collection of very basic and simple GATE macros in connection with analysis programs based on ROOT, a framework for data processing. A graphical user interface to define a configuration is also included. Copyright © 2012. Published by Elsevier GmbH.

Quantification of osteoblastic activity in epiphyseal growth plates by quantitative bone SPECT/CT.

PubMed

Yamane, Tomohiko; Kuji, Ichiei; Seto, Akira; Matsunari, Ichiro

2018-06-01

Quantifying the function of the epiphyseal plate is worthwhile for the management of children with growth disorders. The aim of this retrospective study was to quantify the osteoblastic activity at the epiphyseal plate using the quantitative bone SPECT/CT. We enrolled patients under the age of 20 years who received Tc-99m hydroxymethylene diphosphonate bone scintigraphy acquired by a quantitative SPECT/CT scanner. The images were reconstructed by ordered subset conjugate-gradient minimizer, and the uptake on the distal margin of the femur was quantified by peak standardized uptake value (SUVpeak). A public database of standard body height was used to calculate growth velocities (cm/year). Fifteen patients (6.9-19.7 years, 9 female, 6 male) were enrolled and a total of 25 legs were analyzed. SUVpeak in the epiphyseal plate was 18.9 ± 2.4 (average ± standard deviation) in the subjects under 15 years and decreased gradually by aging. The SUVpeak correlated significantly with the age- and sex-matched growth velocity obtained from the database (R 2  = 0.83, p < 0.0001). The SUV measured by quantitative bone SPECT/CT was increased at the epiphyseal plates of children under the age of 15 years in comparison with the older group, corresponding to higher osteoblastic activity. Moreover, this study suggested a correlation between growth velocity and the SUV. Although this is a small retrospective pilot study, the objective and quantitative values measured by the quantitative bone SPECT/CT has the potential to improve the management of children with growth disorder.

Objective evaluation of reconstruction methods for quantitative SPECT imaging in the absence of ground truth.

PubMed

Jha, Abhinav K; Song, Na; Caffo, Brian; Frey, Eric C

2015-04-13

Quantitative single-photon emission computed tomography (SPECT) imaging is emerging as an important tool in clinical studies and biomedical research. There is thus a need for optimization and evaluation of systems and algorithms that are being developed for quantitative SPECT imaging. An appropriate objective method to evaluate these systems is by comparing their performance in the end task that is required in quantitative SPECT imaging, such as estimating the mean activity concentration in a volume of interest (VOI) in a patient image. This objective evaluation can be performed if the true value of the estimated parameter is known, i.e. we have a gold standard. However, very rarely is this gold standard known in human studies. Thus, no-gold-standard techniques to optimize and evaluate systems and algorithms in the absence of gold standard are required. In this work, we developed a no-gold-standard technique to objectively evaluate reconstruction methods used in quantitative SPECT when the parameter to be estimated is the mean activity concentration in a VOI. We studied the performance of the technique with realistic simulated image data generated from an object database consisting of five phantom anatomies with all possible combinations of five sets of organ uptakes, where each anatomy consisted of eight different organ VOIs. Results indicate that the method provided accurate ranking of the reconstruction methods. We also demonstrated the application of consistency checks to test the no-gold-standard output.

Simultaneous dual-radionuclide myocardial perfusion imaging with a solid-state dedicated cardiac camera.

PubMed

Ben-Haim, Simona; Kacperski, Krzysztof; Hain, Sharon; Van Gramberg, Dean; Hutton, Brian F; Erlandsson, Kjell; Sharir, Tali; Roth, Nathaniel; Waddington, Wendy A; Berman, Daniel S; Ell, Peter J

2010-08-01

We compared simultaneous dual-radionuclide (DR) stress and rest myocardial perfusion imaging (MPI) with a novel solid-state cardiac camera and a conventional SPECT camera with separate stress and rest acquisitions. Of 27 consecutive patients recruited, 24 (64.5+/-11.8 years of age, 16 men) were injected with 74 MBq of (201)Tl (rest) and 250 MBq (99m)Tc-MIBI (stress). Conventional MPI acquisition times for stress and rest are 21 min and 16 min, respectively. Rest (201)Tl for 6 min and simultaneous DR 15-min list mode gated scans were performed on a D-SPECT cardiac scanner. In 11 patients DR D-SPECT was performed first and in 13 patients conventional stress (99m)Tc-MIBI SPECT imaging was performed followed by DR D-SPECT. The DR D-SPECT data were processed using a spill-over and scatter correction method. DR D-SPECT images were compared with rest (201)Tl D-SPECT and with conventional SPECT images by visual analysis employing the 17-segment model and a five-point scale (0 normal, 4 absent) to calculate the summed stress and rest scores. Image quality was assessed on a four-point scale (1 poor, 4 very good) and gut activity was assessed on a four-point scale (0 none, 3 high). Conventional MPI studies were abnormal at stress in 17 patients and at rest in 9 patients. In the 17 abnormal stress studies DR D-SPECT MPI showed 113 abnormal segments and conventional MPI showed 93 abnormal segments. In the nine abnormal rest studies DR D-SPECT showed 45 abnormal segments and conventional MPI showed 48 abnormal segments. The summed stress and rest scores on conventional SPECT and DR D-SPECT were highly correlated (r=0.9790 and 0.9694, respectively). The summed scores of rest (201)Tl D-SPECT and DR-DSPECT were also highly correlated (r=0.9968, p<0.0001 for all). In six patients stress perfusion defects were significantly larger on stress DR D-SPECT images, and five of these patients were imaged earlier by D-SPECT than by conventional SPECT. Fast and high-quality simultaneous DR MPI is feasible with D-SPECT in a single imaging session with comparable diagnostic performance and image quality to conventional SPECT and to a separate rest (201)Tl D-SPECT acquisition.

Normal values and standardization of parameters in nuclear cardiology: Japanese Society of Nuclear Medicine working group database.

PubMed

Nakajima, Kenichi; Matsumoto, Naoya; Kasai, Tokuo; Matsuo, Shinro; Kiso, Keisuke; Okuda, Koichi

2016-04-01

As a 2-year project of the Japanese Society of Nuclear Medicine working group activity, normal myocardial imaging databases were accumulated and summarized. Stress-rest with gated and non-gated image sets were accumulated for myocardial perfusion imaging and could be used for perfusion defect scoring and normal left ventricular (LV) function analysis. For single-photon emission computed tomography (SPECT) with multi-focal collimator design, databases of supine and prone positions and computed tomography (CT)-based attenuation correction were created. The CT-based correction provided similar perfusion patterns between genders. In phase analysis of gated myocardial perfusion SPECT, a new approach for analyzing dyssynchrony, normal ranges of parameters for phase bandwidth, standard deviation and entropy were determined in four software programs. Although the results were not interchangeable, dependency on gender, ejection fraction and volumes were common characteristics of these parameters. Standardization of (123)I-MIBG sympathetic imaging was performed regarding heart-to-mediastinum ratio (HMR) using a calibration phantom method. The HMRs from any collimator types could be converted to the value with medium-energy comparable collimators. Appropriate quantification based on common normal databases and standard technology could play a pivotal role for clinical practice and researches.

A combined static-dynamic single-dose imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT.

PubMed

Sciammarella, Maria; Shrestha, Uttam M; Seo, Youngho; Gullberg, Grant T; Botvinick, Elias H

2017-08-03

SPECT myocardial perfusion imaging (MPI) is a clinical mainstay that is typically performed with static imaging protocols and visually or semi-quantitatively assessed for perfusion defects based upon the relative intensity of myocardial regions. Dynamic cardiac SPECT presents a new imaging technique based on time-varying information of radiotracer distribution, which permits the evaluation of regional myocardial blood flow (MBF) and coronary flow reserve (CFR). In this work, a preliminary feasibility study was conducted in a small patient sample designed to implement a unique combined static-dynamic single-dose one-day visit imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT for improving the diagnosis of coronary artery disease (CAD). Fifteen patients (11 males, four females, mean age 71 ± 9 years) were enrolled for a combined dynamic and static SPECT (Infinia Hawkeye 4, GE Healthcare) imaging protocol with a single dose of 99m Tc-tetrofosmin administered at rest and a single dose administered at stress in a one-day visit. Out of 15 patients, eleven had selective coronary angiography (SCA), 8 within 6 months and the rest within 24 months of SPECT imaging, without intervening symptoms or interventions. The extent and severity of perfusion defects in each myocardial region was graded visually. Dynamically acquired data were also used to estimate the MBF and CFR. Both visually graded images and estimated CFR were tested against SCA as a reference to evaluate the validity of the methods. Overall, conventional static SPECT was normal in ten patients and abnormal in five patients, dynamic SPECT was normal in 12 patients and abnormal in three patients, and CFR from dynamic SPECT was normal in nine patients and abnormal in six patients. Among those 11 patients with SCA, conventional SPECT was normal in 5, 3 with documented CAD on SCA with an overall accuracy of 64%, sensitivity of 40% and specificity of 83%. Dynamic SPECT image analysis also produced a similar accuracy, sensitivity, and specificity. CFR was normal in 6, each with CAD on SCA with an overall accuracy of 91%, sensitivity of 80%, and specificity of 100%. The mean CFR was significantly lower for SCA detected abnormal than for normal patients (3.86±1.06 vs 1.94±0. 0.67, P < 0.001). The visually assessed image findings in static and dynamic SPECT are subjective, and may not reflect direct physiologic measures of coronary lesion based on SCA. The CFR measured with dynamic SPECT is fully objective, with better sensitivity and specificity, available only with the data generated from the dynamic SPECT method.

Exercise may cause myocardial ischemia at the anaerobic threshold in cardiac rehabilitation programs.

PubMed

Fuchs, A R C N; Meneghelo, R S; Stefanini, E; De Paola, A V; Smanio, P E P; Mastrocolla, L E; Ferraz, A S; Buglia, S; Piegas, L S; Carvalho, A A C

2009-03-01

Myocardial ischemia may occur during an exercise session in cardiac rehabilitation programs. However, it has not been established whether it is elicited when exercise prescription is based on heart rate corresponding to the anaerobic threshold as measured by cardiopulmonary exercise testing. Our objective was to determine the incidence of myocardial ischemia in cardiac rehabilitation programs according to myocardial perfusion SPECT in exercise programs based on the anaerobic threshold. Thirty-nine patients (35 men and 4 women) diagnosed with coronary artery disease by coronary angiography and stress technetium-99m-sestamibi gated SPECT associated with a baseline cardiopulmonary exercise test were assessed. Ages ranged from 45 to 75 years. A second cardiopulmonary exercise test determined training intensity at the anaerobic threshold. Repeat gated-SPECT was obtained after a third cardiopulmonary exercise test at the prescribed workload and heart rate. Myocardial perfusion images were analyzed using a score system of 6.4 at rest, 13.9 at peak stress, and 10.7 during the prescribed exercise (P < 0.05). The presence of myocardial ischemia during exercise was defined as a difference > or = 2 between the summed stress score and summed rest score. Accordingly, 25 (64%) patients were classified as ischemic and 14 (36%) as nonischemic. MIBI-SPECT showed myocardial ischemia during exercise within the anaerobic threshold. The 64% prevalence of ischemia observed in the study should not be looked on as representative of the whole population of patients undergoing exercise programs. Changes in patient care and exercise programs were implemented as a result of our finding of ischemia during the prescribed exercise.

Three modality image registration of brain SPECT/CT and MR images for quantitative analysis of dopamine transporter imaging

NASA Astrophysics Data System (ADS)

Yamaguchi, Yuzuho; Takeda, Yuta; Hara, Takeshi; Zhou, Xiangrong; Matsusako, Masaki; Tanaka, Yuki; Hosoya, Kazuhiko; Nihei, Tsutomu; Katafuchi, Tetsuro; Fujita, Hiroshi

2016-03-01

Important features in Parkinson's disease (PD) are degenerations and losses of dopamine neurons in corpus striatum. 123I-FP-CIT can visualize activities of the dopamine neurons. The activity radio of background to corpus striatum is used for diagnosis of PD and Dementia with Lewy Bodies (DLB). The specific activity can be observed in the corpus striatum on SPECT images, but the location and the shape of the corpus striatum on SPECT images only are often lost because of the low uptake. In contrast, MR images can visualize the locations of the corpus striatum. The purpose of this study was to realize a quantitative image analysis for the SPECT images by using image registration technique with brain MR images that can determine the region of corpus striatum. In this study, the image fusion technique was used to fuse SPECT and MR images by intervening CT image taken by SPECT/CT. The mutual information (MI) for image registration between CT and MR images was used for the registration. Six SPECT/CT and four MR scans of phantom materials are taken by changing the direction. As the results of the image registrations, 16 of 24 combinations were registered within 1.3mm. By applying the approach to 32 clinical SPECT/CT and MR cases, all of the cases were registered within 0.86mm. In conclusions, our registration method has a potential in superimposing MR images on SPECT images.

Comparison of quantitative Y-90 SPECT and non-time-of-flight PET imaging in post-therapy radioembolization of liver cancer

PubMed Central

Yue, Jianting; Mauxion, Thibault; Reyes, Diane K.; Lodge, Martin A.; Hobbs, Robert F.; Rong, Xing; Dong, Yinfeng; Herman, Joseph M.; Wahl, Richard L.; Geschwind, Jean-François H.; Frey, Eric C.

2016-01-01

Purpose: Radioembolization with yttrium-90 microspheres may be optimized with patient-specific pretherapy treatment planning. Dose verification and validation of treatment planning methods require quantitative imaging of the post-therapy distribution of yttrium-90 (Y-90). Methods for quantitative imaging of Y-90 using both bremsstrahlung SPECT and PET have previously been described. The purpose of this study was to compare the two modalities quantitatively in humans. Methods: Calibration correction factors for both quantitative Y-90 bremsstrahlung SPECT and a non-time-of-flight PET system without compensation for prompt coincidences were developed by imaging three phantoms. The consistency of these calibration correction factors for the different phantoms was evaluated. Post-therapy images from both modalities were obtained from 15 patients with hepatocellular carcinoma who underwent hepatic radioembolization using Y-90 glass microspheres. Quantitative SPECT and PET images were rigidly registered and the total liver activities and activity distributions estimated for each modality were compared. The activity distributions were compared using profiles, voxel-by-voxel correlation and Bland–Altman analyses, and activity-volume histograms. Results: The mean ± standard deviation of difference in the total activity in the liver between the two modalities was 0% ± 9% (range −21%–18%). Voxel-by-voxel comparisons showed a good agreement in regions corresponding roughly to treated tumor and treated normal liver; the agreement was poorer in regions with low or no expected activity, where PET appeared to overestimate the activity. The correlation coefficients between intrahepatic voxel pairs for the two modalities ranged from 0.86 to 0.94. Cumulative activity volume histograms were in good agreement. Conclusions: These data indicate that, with appropriate reconstruction methods and measured calibration correction factors, either Y-90 SPECT/CT or Y-90 PET/CT can be used for quantitative post-therapy monitoring of Y-90 activity distribution following hepatic radioembolization. PMID:27782730

Evaluation of patients with painful total hip arthroplasty using combined single photon emission tomography and conventional computerized tomography (SPECT/CT) - a comparison of semi-quantitative versus 3D volumetric quantitative measurements.

PubMed

Barthassat, Emilienne; Afifi, Faik; Konala, Praveen; Rasch, Helmut; Hirschmann, Michael T

2017-05-08

It was the primary purpose of our study to evaluate the inter- and intra-observer reliability of a standardized SPECT/CT algorithm for evaluating patients with painful primary total hip arthroplasty (THA). The secondary purpose was a comparison of semi-quantitative and 3D volumetric quantification method for assessment of bone tracer uptake (BTU) in those patients. A novel SPECT/CT localization scheme consisting of 14 femoral and 4 acetabular regions on standardized axial and coronal slices was introduced and evaluated in terms of inter- and intra-observer reliability in 37 consecutive patients with hip pain after THA. BTU for each anatomical region was assessed semi-quantitatively using a color-coded Likert type scale (0-10) and volumetrically quantified using a validated software. Two observers interpreted the SPECT/CT findings in all patients two times with six weeks interval between interpretations in random order. Semi-quantitative and quantitative measurements were compared in terms of reliability. In addition, the values were correlated using Pearson`s correlation. A factorial cluster analysis of BTU was performed to identify clinically relevant regions, which should be grouped and analysed together. The localization scheme showed high inter- and intra-observer reliabilities for all femoral and acetabular regions independent of the measurement method used (semiquantitative versus 3D volumetric quantitative measurements). A high to moderate correlation between both measurement methods was shown for the distal femur, the proximal femur and the acetabular cup. The factorial cluster analysis showed that the anatomical regions might be summarized into three distinct anatomical regions. These were the proximal femur, the distal femur and the acetabular cup region. The SPECT/CT algorithm for assessment of patients with pain after THA is highly reliable independent from the measurement method used. Three clinically relevant anatomical regions (proximal femoral, distal femoral, acetabular) were identified.

Comparison of quantitative Y-90 SPECT and non-time-of-flight PET imaging in post-therapy radioembolization of liver cancer.

PubMed

Yue, Jianting; Mauxion, Thibault; Reyes, Diane K; Lodge, Martin A; Hobbs, Robert F; Rong, Xing; Dong, Yinfeng; Herman, Joseph M; Wahl, Richard L; Geschwind, Jean-François H; Frey, Eric C

2016-10-01

Radioembolization with yttrium-90 microspheres may be optimized with patient-specific pretherapy treatment planning. Dose verification and validation of treatment planning methods require quantitative imaging of the post-therapy distribution of yttrium-90 (Y-90). Methods for quantitative imaging of Y-90 using both bremsstrahlung SPECT and PET have previously been described. The purpose of this study was to compare the two modalities quantitatively in humans. Calibration correction factors for both quantitative Y-90 bremsstrahlung SPECT and a non-time-of-flight PET system without compensation for prompt coincidences were developed by imaging three phantoms. The consistency of these calibration correction factors for the different phantoms was evaluated. Post-therapy images from both modalities were obtained from 15 patients with hepatocellular carcinoma who underwent hepatic radioembolization using Y-90 glass microspheres. Quantitative SPECT and PET images were rigidly registered and the total liver activities and activity distributions estimated for each modality were compared. The activity distributions were compared using profiles, voxel-by-voxel correlation and Bland-Altman analyses, and activity-volume histograms. The mean ± standard deviation of difference in the total activity in the liver between the two modalities was 0% ± 9% (range -21%-18%). Voxel-by-voxel comparisons showed a good agreement in regions corresponding roughly to treated tumor and treated normal liver; the agreement was poorer in regions with low or no expected activity, where PET appeared to overestimate the activity. The correlation coefficients between intrahepatic voxel pairs for the two modalities ranged from 0.86 to 0.94. Cumulative activity volume histograms were in good agreement. These data indicate that, with appropriate reconstruction methods and measured calibration correction factors, either Y-90 SPECT/CT or Y-90 PET/CT can be used for quantitative post-therapy monitoring of Y-90 activity distribution following hepatic radioembolization.

Avoiding full corrections in dynamic SPECT images impacts the performance of SPECT myocardial blood flow quantitation.

PubMed

Wang, Lei; Wu, Dayong; Yang, Yong; Chen, Ing-Jou; Lin, Chih-Yuan; Hsu, Bailing; Fang, Wei; Tang, Yi-Da

2017-08-01

This study investigated the performance of SPECT myocardial blood flow (MBF) quantitation lacking full physical corrections (All Corr) in dynamic SPECT (DySPECT) images. Eleven healthy normal volunteers (HVT) and twenty-four patients with angiography-documented CAD were assessed. All Corr in 99m Tc-sestamibi DySPECT encompassed noise reduction (NR), resolution recovery (RR), and corrections for scatter (SC) and attenuation (AC), otherwise no correction (NC) or only partial corrections. The performance was evaluated by quality index (R 2 ) and blood-pool spillover index (FBV) in kinetic modeling, and by rest flow (RMBF) and stress flow (SMBF) compared with those of All Corr. In HVT group, NC diminished 2-fold flow uniformity with the most degraded quality (15%-18% reduced R 2 ) and elevated spillover effect (45%-50% increased FBV). Consistently higher RMBF and SMBF were discovered in both groups (HVT 1.54/2.31 higher; CAD 1.60/1.72; all P < .0001). Bland-Altman analysis revealed positive flow bias (HVT 0.9-2.6 mL/min/g; CAD 0.7-1.3) with wide ranges of 95% CI of agreement (HVT NC -1.9-7.1; NR -0.4-4.4; NR + SC -1.1-4.3; NR + SC + RR -0.7-2.5) (CAD NC -1.2-3.8; NR -1.0-2.8; NR + SC -1.0-2.5; NR + SC + RR -1.1-2.6). Uncorrected physical interference in DySPECT images can extensively impact the performance of MBF quantitation. Full physical corrections should be considered to warrant this tool for clinical utilization.

Relationship Between Coronary Contrast-Flow Quantitative Flow Ratio and Myocardial Ischemia Assessed by SPECT MPI.

PubMed

Smit, Jeff M; Koning, Gerhard; van Rosendael, Alexander R; Dibbets-Schneider, Petra; Mertens, Bart J; Jukema, J Wouter; Delgado, Victoria; Reiber, Johan H C; Bax, Jeroen J; Scholte, Arthur J

2017-10-01

A new method has been developed to calculate fractional flow reserve (FFR) from invasive coronary angiography, the so-called "contrast-flow quantitative flow ratio (cQFR)". Recently, cQFR was compared to invasive FFR in intermediate coronary lesions showing an overall diagnostic accuracy of 85%. The purpose of this study was to investigate the relationship between cQFR and myocardial ischemia assessed by single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI). Patients who underwent SPECT MPI and coronary angiography within 3 months were included. The cQFR computation was performed offline, using dedicated software. The cQFR computation was based on 3-dimensional quantitative coronary angiography (QCA) and computational fluid dynamics. The standard 17-segment model was used to determine the vascular territories. Myocardial ischemia was defined as a summed difference score ≥2 in a vascular territory. A cQFR of ≤0.80 was considered abnormal. Two hundred and twenty-four coronary arteries were analysed in 85 patients. Overall accuracy of cQFR to detect ischemia on SPECT MPI was 90%. In multivariable analysis, cQFR was independently associated with ischemia on SPECT MPI (OR per 0.01 decrease of cQFR: 1.10; 95% CI 1.04-1.18, p = 0.002), whereas clinical and QCA parameters were not. Furthermore, cQFR showed incremental value for the detection of ischemia compared to clinical and QCA parameters (global chi square 48.7 to 62.6; p <0.001). A good relationship between cQFR and SPECT MPI was found. cQFR was independently associated with ischemia on SPECT MPI and showed incremental value to detect ischemia compared to clinical and QCA parameters.

[Follow-up of patients with good exercise capacity in stress test with myocardial single-photon emission computed tomography (SPECT)].

PubMed

González, Javiera; Prat, Hernán; Swett, Eduardo; Berrocal, Isabel; Fernández, René; Zhindon, Juan Pablo; Castro, Ariel; Massardo, Teresa

2015-11-01

The evaluation of coronary artery disease (CAD) can be performed with stress test and myocardial SPECT tomography. To assess the predictive value of myocardial SPECT using stress test for cardiovascular events in patients with good exercise capacity. We included 102 males aged 56 ± 10 years and 19 females aged 52 ± 10 years, all able to achieve 10 METs and ≥ 85% of the theoretical maximum heart rate and at least 8 min in their stress test with gated 99mTc-sestamibi SPECT. Eighty two percent of patients were followed clinically for 33 ± 17 months. Sixty seven percent of patients were studied for CAD screening and the rest for known disease assessment. Treadmill stress test was negative in 75.4%; 37% of patients with moderate to severe Duke Score presented ischemia. Normal myocardial perfusion SPECT was observed in 70.2%. Reversible defects appeared in 24.8% of cases, which were of moderate or severe degree (> 10% left ventricular extension) in 56.6%. Only seven cases had coronary events after the SPECT. Two major (myocardial infarction and emergency coronary revascularization) and 5 minor events (elective revascularization) ere observed in the follow-up. In a multivariate analysis, SPECT ischemia was the only statistically significant parameter that increased the probability of having a major or minor event. Nearly a quarter of our patients with good exercise capacity demonstrated reversible defects in their myocardial perfusion SPECT. In the intermediate-term follow-up, a low rate of cardiac events was observed, being the isotopic ischemia the only significant predictive parameter.

[A computer tomography assisted method for the automatic detection of region of interest in dynamic kidney images].

PubMed

Jing, Xueping; Zheng, Xiujuan; Song, Shaoli; Liu, Kai

2017-12-01

Glomerular filtration rate (GFR), which can be estimated by Gates method with dynamic kidney single photon emission computed tomography (SPECT) imaging, is a key indicator of renal function. In this paper, an automatic computer tomography (CT)-assisted detection method of kidney region of interest (ROI) is proposed to achieve the objective and accurate GFR calculation. In this method, the CT coronal projection image and the enhanced SPECT synthetic image are firstly generated and registered together. Then, the kidney ROIs are delineated using a modified level set algorithm. Meanwhile, the background ROIs are also obtained based on the kidney ROIs. Finally, the value of GFR is calculated via Gates method. Comparing with the clinical data, the GFR values estimated by the proposed method were consistent with the clinical reports. This automatic method can improve the accuracy and stability of kidney ROI detection for GFR calculation, especially when the kidney function has been severely damaged.

Comparison of conventional and cadmium-zinc-telluride single-photon emission computed tomography for analysis of thallium-201 myocardial perfusion imaging: an exploratory study in normal databases for different ethnicities.

PubMed

Ishihara, Masaru; Onoguchi, Masahisa; Taniguchi, Yasuyo; Shibutani, Takayuki

2017-12-01

The aim of this study was to clarify the differences in thallium-201-chloride (thallium-201) myocardial perfusion imaging (MPI) scans evaluated by conventional anger-type single-photon emission computed tomography (conventional SPECT) versus cadmium-zinc-telluride SPECT (CZT SPECT) imaging in normal databases for different ethnic groups. MPI scans from 81 consecutive Japanese patients were examined using conventional SPECT and CZT SPECT and analyzed with the pre-installed quantitative perfusion SPECT (QPS) software. We compared the summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for the two SPECT devices. For a normal MPI reference, we usually use Japanese databases for MPI created by the Japanese Society of Nuclear Medicine, which can be used with conventional SPECT but not with CZT SPECT. In this study, we used new Japanese normal databases constructed in our institution to compare conventional and CZT SPECT. Compared with conventional SPECT, CZT SPECT showed lower SSS (p < 0.001), SRS (p = 0.001), and SDS (p = 0.189) using the pre-installed SPECT database. In contrast, CZT SPECT showed no significant difference from conventional SPECT in QPS analysis using the normal databases from our institution. Myocardial perfusion analyses by CZT SPECT should be evaluated using normal databases based on the ethnic group being evaluated.

Comparison of Dynamic Contrast Enhanced MRI and Quantitative SPECT in a Rat Glioma Model

PubMed Central

Skinner, Jack T.; Yankeelov, Thomas E.; Peterson, Todd E.; Does, Mark D.

2012-01-01

Pharmacokinetic modeling of dynamic contrast enhanced (DCE)-MRI data provides measures of the extracellular volume fraction (ve) and the volume transfer constant (Ktrans) in a given tissue. These parameter estimates may be biased, however, by confounding issues such as contrast agent and tissue water dynamics, or assumptions of vascularization and perfusion made by the commonly used model. In contrast to MRI, radiotracer imaging with SPECT is insensitive to water dynamics. A quantitative dual-isotope SPECT technique was developed to obtain an estimate of ve in a rat glioma model for comparison to the corresponding estimates obtained using DCE-MRI with a vascular input function (VIF) and reference region model (RR). Both DCE-MRI methods produced consistently larger estimates of ve in comparison to the SPECT estimates, and several experimental sources were postulated to contribute to these differences. PMID:22991315

A Computer-Aided Analysis Method of SPECT Brain Images for Quantitative Treatment Monitoring: Performance Evaluations and Clinical Applications.

PubMed

Zheng, Xiujuan; Wei, Wentao; Huang, Qiu; Song, Shaoli; Wan, Jieqing; Huang, Gang

2017-01-01

The objective and quantitative analysis of longitudinal single photon emission computed tomography (SPECT) images are significant for the treatment monitoring of brain disorders. Therefore, a computer aided analysis (CAA) method is introduced to extract a change-rate map (CRM) as a parametric image for quantifying the changes of regional cerebral blood flow (rCBF) in longitudinal SPECT brain images. The performances of the CAA-CRM approach in treatment monitoring are evaluated by the computer simulations and clinical applications. The results of computer simulations show that the derived CRMs have high similarities with their ground truths when the lesion size is larger than system spatial resolution and the change rate is higher than 20%. In clinical applications, the CAA-CRM approach is used to assess the treatment of 50 patients with brain ischemia. The results demonstrate that CAA-CRM approach has a 93.4% accuracy of recovered region's localization. Moreover, the quantitative indexes of recovered regions derived from CRM are all significantly different among the groups and highly correlated with the experienced clinical diagnosis. In conclusion, the proposed CAA-CRM approach provides a convenient solution to generate a parametric image and derive the quantitative indexes from the longitudinal SPECT brain images for treatment monitoring.

Novel Application of Quantitative Single-Photon Emission Computed Tomography/Computed Tomography to Predict Early Response to Methimazole in Graves' Disease

PubMed Central

Kim, Hyun Joo; Bang, Ji-In; Kim, Ji-Young; Moon, Jae Hoon; So, Young

2017-01-01

Objective Since Graves' disease (GD) is resistant to antithyroid drugs (ATDs), an accurate quantitative thyroid function measurement is required for the prediction of early responses to ATD. Quantitative parameters derived from the novel technology, single-photon emission computed tomography/computed tomography (SPECT/CT), were investigated for the prediction of achievement of euthyroidism after methimazole (MMI) treatment in GD. Materials and Methods A total of 36 GD patients (10 males, 26 females; mean age, 45.3 ± 13.8 years) were enrolled for this study, from April 2015 to January 2016. They underwent quantitative thyroid SPECT/CT 20 minutes post-injection of 99mTc-pertechnetate (5 mCi). Association between the time to biochemical euthyroidism after MMI treatment and %uptake, standardized uptake value (SUV), functional thyroid mass (SUVmean × thyroid volume) from the SPECT/CT, and clinical/biochemical variables, were investigated. Results GD patients had a significantly greater %uptake (6.9 ± 6.4%) than historical control euthyroid patients (n = 20, 0.8 ± 0.5%, p < 0.001) from the same quantitative SPECT/CT protocol. Euthyroidism was achieved in 14 patients at 156 ± 62 days post-MMI treatment, but 22 patients had still not achieved euthyroidism by the last follow-up time-point (208 ± 80 days). In the univariate Cox regression analysis, the initial MMI dose (p = 0.014), %uptake (p = 0.015), and functional thyroid mass (p = 0.016) were significant predictors of euthyroidism in response to MMI treatment. However, only %uptake remained significant in a multivariate Cox regression analysis (p = 0.034). A %uptake cutoff of 5.0% dichotomized the faster responding versus the slower responding GD patients (p = 0.006). Conclusion A novel parameter of thyroid %uptake from quantitative SPECT/CT is a predictive indicator of an early response to MMI in GD patients. PMID:28458607

Noise suppressed partial volume correction for cardiac SPECT/CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Chung; Liu, Chi, E-mail: chi.liu@yale.edu

Purpose: Partial volume correction (PVC) methods typically improve quantification at the expense of increased image noise and reduced reproducibility. In this study, the authors developed a novel voxel-based PVC method that incorporates anatomical knowledge to improve quantification while suppressing noise for cardiac SPECT/CT imaging. Methods: In the proposed method, the SPECT images were first reconstructed using anatomical-based maximum a posteriori (AMAP) with Bowsher’s prior to penalize noise while preserving boundaries. A sequential voxel-by-voxel PVC approach (Yang’s method) was then applied on the AMAP reconstruction using a template response. This template response was obtained by forward projecting a template derived frommore » a contrast-enhanced CT image, and then reconstructed using AMAP to model the partial volume effects (PVEs) introduced by both the system resolution and the smoothing applied during reconstruction. To evaluate the proposed noise suppressed PVC (NS-PVC), the authors first simulated two types of cardiac SPECT studies: a {sup 99m}Tc-tetrofosmin myocardial perfusion scan and a {sup 99m}Tc-labeled red blood cell (RBC) scan on a dedicated cardiac multiple pinhole SPECT/CT at both high and low count levels. The authors then applied the proposed method on a canine equilibrium blood pool study following injection with {sup 99m}Tc-RBCs at different count levels by rebinning the list-mode data into shorter acquisitions. The proposed method was compared to MLEM reconstruction without PVC, two conventional PVC methods, including Yang’s method and multitarget correction (MTC) applied on the MLEM reconstruction, and AMAP reconstruction without PVC. Results: The results showed that the Yang’s method improved quantification, however, yielded increased noise and reduced reproducibility in the regions with higher activity. MTC corrected for PVE on high count data with amplified noise, although yielded the worst performance among all the methods tested on low-count data. AMAP effectively suppressed noise and reduced the spill-in effect in the low activity regions. However it was unable to reduce the spill-out effect in high activity regions. NS-PVC yielded superior performance in terms of both quantitative assessment and visual image quality while improving reproducibility. Conclusions: The results suggest that NS-PVC may be a promising PVC algorithm for application in low-dose protocols, and in gated and dynamic cardiac studies with low counts.« less

SU-E-I-80: Quantification of Respiratory and Cardiac Motion Effect in SPECT Acquisitions Using Anthropomorphic Models: A Monte Carlo Simulation Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papadimitroulas, P; Kostou, T; Kagadis, G

Purpose: The purpose of the present study was to quantify, evaluate the impact of cardiac and respiratory motion on clinical nuclear imaging protocols. Common SPECT and scintigraphic scans are studied using Monte Carlo (MC) simulations, comparing the resulted images with and without motion. Methods: Realistic simulations were executed using the GATE toolkit and the XCAT anthropomorphic phantom as a reference model for human anatomy. Three different radiopharmaceuticals based on 99mTc were studied, namely 99mTc-MDP, 99mTc—N—DBODC and 99mTc—DTPA-aerosol for bone, myocardium and lung scanning respectively. The resolution of the phantom was set to 3.5 mm{sup 3}. The impact of the motionmore » on spatial resolution was quantified using a sphere with 3.5 mm diameter and 10 separate time frames, in the ECAM modeled SPECT scanner. Finally, respiratory motion impact on resolution and imaging of lung lesions was investigated. The MLEM algorithm was used for data reconstruction, while the literature derived biodistributions of the pharmaceuticals were used as activity maps in the simulations. Results: FWHM was extracted for a static and a moving sphere which was ∼23 cm away from the entrance of the SPECT head. The difference in the FWHM was 20% between the two simulations. Profiles in thorax were compared in the case of bone scintigraphy, showing displacement and blurring of the bones when respiratory motion was inserted in the simulation. Large discrepancies were noticed in the case of myocardium imaging when cardiac motion was incorporated during the SPECT acquisition. Finally the borders of the lungs are blurred when respiratory motion is included resulting to a dislocation of ∼2.5 cm. Conclusion: As we move to individualized imaging and therapy procedures, quantitative and qualitative imaging is of high importance in nuclear diagnosis. MC simulations combined with anthropomorphic digital phantoms can provide an accurate tool for applications like motion correction techniques’ optimization. This research has been co-funded by the European Union (European Social Fund) and Greek national resources under the framework of the ‘Archimedes III: Funding of Research Groups in TEI of Athens’ project of the ‘Education & Lifelong Learning’ Operational Programme.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naseri, M; Rajabi, H; Wang, J

Purpose: Respiration causes lesion smearing, image blurring and quality degradation, affecting lesion contrast and the ability to define correct lesion size. The spatial resolution of current multi pinhole SPECT (MPHS) scanners is sub-millimeter. Therefore, the effect of motion is more noticeable in comparison to conventional SPECT scanner. Gated imaging aims to reduce motion artifacts. A major issue in gating is the lack of statistics and individual reconstructed frames are noisy. The increased noise in each frame, deteriorates the quantitative accuracy of the MPHS Images. The objective of this work, is to enhance the image quality in 4D-MPHS imaging, by 4Dmore » image reconstruction. Methods: The new algorithm requires deformation vector fields (DVFs) that are calculated by non-rigid Demons registration. The algorithm is based on the motion-incorporated version of ordered subset expectation maximization (OSEM) algorithm. This iterative algorithm is capable to make full use of all projections to reconstruct each individual frame. To evaluate the performance of the proposed algorithm a simulation study was conducted. A fast ray tracing method was used to generate MPHS projections of a 4D digital mouse phantom with a small tumor in liver in eight different respiratory phases. To evaluate the 4D-OSEM algorithm potential, tumor to liver activity ratio was compared with other image reconstruction methods including 3D-MPHS and post reconstruction registered with Demons-derived DVFs. Results: Image quality of 4D-MPHS is greatly improved by the 4D-OSEM algorithm. When all projections are used to reconstruct a 3D-MPHS, motion blurring artifacts are present, leading to overestimation of the tumor size and 24% tumor contrast underestimation. This error reduced to 16% and 10% for post reconstruction registration methods and 4D-OSEM respectively. Conclusion: 4D-OSEM method can be used for motion correction in 4D-MPHS. The statistics and quantification are improved since all projection data are combined together to update the image.« less

Fully automatic multi-atlas segmentation of CTA for partial volume correction in cardiac SPECT/CT

NASA Astrophysics Data System (ADS)

Liu, Qingyi; Mohy-ud-Din, Hassan; Boutagy, Nabil E.; Jiang, Mingyan; Ren, Silin; Stendahl, John C.; Sinusas, Albert J.; Liu, Chi

2017-05-01

Anatomical-based partial volume correction (PVC) has been shown to improve image quality and quantitative accuracy in cardiac SPECT/CT. However, this method requires manual segmentation of various organs from contrast-enhanced computed tomography angiography (CTA) data. In order to achieve fully automatic CTA segmentation for clinical translation, we investigated the most common multi-atlas segmentation methods. We also modified the multi-atlas segmentation method by introducing a novel label fusion algorithm for multiple organ segmentation to eliminate overlap and gap voxels. To evaluate our proposed automatic segmentation, eight canine 99mTc-labeled red blood cell SPECT/CT datasets that incorporated PVC were analyzed, using the leave-one-out approach. The Dice similarity coefficient of each organ was computed. Compared to the conventional label fusion method, our proposed label fusion method effectively eliminated gaps and overlaps and improved the CTA segmentation accuracy. The anatomical-based PVC of cardiac SPECT images with automatic multi-atlas segmentation provided consistent image quality and quantitative estimation of intramyocardial blood volume, as compared to those derived using manual segmentation. In conclusion, our proposed automatic multi-atlas segmentation method of CTAs is feasible, practical, and facilitates anatomical-based PVC of cardiac SPECT/CT images.

Alzheimer disease: Quantitative analysis of I-123-iodoamphetamine SPECT brain imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hellman, R.S.; Tikofsky, R.S.; Collier, B.D.

1989-07-01

To enable a more quantitative diagnosis of senile dementia of the Alzheimer type (SDAT), the authors developed and tested a semiautomated method to define regions of interest (ROIs) to be used in quantitating results from single photon emission computed tomography (SPECT) of regional cerebral blood flow performed with N-isopropyl iodine-123-iodoamphetamine. SPECT/IMP imaging was performed in ten patients with probable SDAT and seven healthy subjects. Multiple ROIs were manually and semiautomatically generated, and uptake was quantitated for each ROI. Mean cortical activity was estimated as the average of the mean activity in 24 semiautomatically generated ROIs; mean cerebellar activity was determinedmore » from the mean activity in separate ROIs. A ratio of parietal to cerebellar activity less than 0.60 and a ratio of parietal to mean cortical activity less than 0.90 allowed correct categorization of nine of ten and eight of ten patients, respectively, with SDAT and all control subjects. The degree of diminished mental status observed in patients with SDAT correlated with both global and regional changes in IMP uptake.« less

Quantitative diagnostic performance of myocardial perfusion SPECT with attenuation correction in women.

PubMed

Wolak, Arik; Slomka, Piotr J; Fish, Mathews B; Lorenzo, Santiago; Berman, Daniel S; Germano, Guido

2008-06-01

Attenuation correction (AC) for myocardial perfusion SPECT (MPS) had not been evaluated separately in women despite specific considerations in this group because of breast photon attenuation. We aimed to evaluate the performance of AC in women by using automated quantitative analysis of MPS to avoid any bias. Consecutive female patients--134 with a low likelihood (LLk) of coronary artery disease (CAD) and 114 with coronary angiography performed within less than 3 mo of MPS--who were referred for rest-stress electrocardiography-gated 99mTc-sestamibi MPS with AC were considered. Imaging data were evaluated for contour quality control. An additional 50 LLk studies in women were used to create equivalent normal limits for studies with AC and with no correction (NC). An experienced technologist unaware of the angiography and other results performed the contour quality control. All other processing was performed in a fully automated manner. Quantitative analysis was performed with the Cedars-Sinai myocardial perfusion analysis package. All automated segmental analyses were performed with the 17-segment, 5-point American Heart Association model. Summed stress scores (SSS) of > or =3 were considered abnormal. CAD (> or =70% stenosis) was present in 69 of 114 patients (60%). The normalcy rates were 93% for both NC and AC studies. The SSS for patients with CAD and without CAD for NC versus AC were 10.0 +/- 9.0 (mean +/- SD) versus 10.2 +/- 8.5 and 1.6 +/- 2.3 versus 1.8 +/- 2.5, respectively; P was not significant (NS) for all comparisons of NC versus AC. The SSS for LLk patients for NC versus AC were 0.51 +/- 1.0 versus 0.6 +/- 1.1, respectively; P was NS. The specificity for both NC and AC was 73%. The sensitivities for NC and AC were 80% and 81%, respectively, and the accuracies for NC and AC were 77% and 78%, respectively; P was NS for both comparisons. There are no significant diagnostic differences between automated quantitative MPS analyses performed in studies processed with and without AC in women.

Impact of reconstruction parameters on quantitative I-131 SPECT

NASA Astrophysics Data System (ADS)

van Gils, C. A. J.; Beijst, C.; van Rooij, R.; de Jong, H. W. A. M.

2016-07-01

Radioiodine therapy using I-131 is widely used for treatment of thyroid disease or neuroendocrine tumors. Monitoring treatment by accurate dosimetry requires quantitative imaging. The high energy photons however render quantitative SPECT reconstruction challenging, potentially requiring accurate correction for scatter and collimator effects. The goal of this work is to assess the effectiveness of various correction methods on these effects using phantom studies. A SPECT/CT acquisition of the NEMA IEC body phantom was performed. Images were reconstructed using the following parameters: (1) without scatter correction, (2) with triple energy window (TEW) scatter correction and (3) with Monte Carlo-based scatter correction. For modelling the collimator-detector response (CDR), both (a) geometric Gaussian CDRs as well as (b) Monte Carlo simulated CDRs were compared. Quantitative accuracy, contrast to noise ratios and recovery coefficients were calculated, as well as the background variability and the residual count error in the lung insert. The Monte Carlo scatter corrected reconstruction method was shown to be intrinsically quantitative, requiring no experimentally acquired calibration factor. It resulted in a more accurate quantification of the background compartment activity density compared with TEW or no scatter correction. The quantification error relative to a dose calibrator derived measurement was found to be  <1%,-26% and 33%, respectively. The adverse effects of partial volume were significantly smaller with the Monte Carlo simulated CDR correction compared with geometric Gaussian or no CDR modelling. Scatter correction showed a small effect on quantification of small volumes. When using a weighting factor, TEW correction was comparable to Monte Carlo reconstruction in all measured parameters, although this approach is clinically impractical since this factor may be patient dependent. Monte Carlo based scatter correction including accurately simulated CDR modelling is the most robust and reliable method to reconstruct accurate quantitative iodine-131 SPECT images.

GATE Simulations of Small Animal SPECT for Determination of Scatter Fraction as a Function of Object Size

NASA Astrophysics Data System (ADS)

Konik, Arda; Madsen, Mark T.; Sunderland, John J.

2012-10-01

In human emission tomography, combined PET/CT and SPECT/CT cameras provide accurate attenuation maps for sophisticated scatter and attenuation corrections. Having proven their potential, these scanners are being adapted for small animal imaging using similar correction approaches. However, attenuation and scatter effects in small animal imaging are substantially less than in human imaging. Hence, the value of sophisticated corrections is not obvious for small animal imaging considering the additional cost and complexity of these methods. In this study, using GATE Monte Carlo package, we simulated the Inveon small animal SPECT (single pinhole collimator) scanner to find the scatter fractions of various sizes of the NEMA-mouse (diameter: 2-5.5 cm , length: 7 cm), NEMA-rat (diameter: 3-5.5 cm, length: 15 cm) and MOBY (diameter: 2.1-5.5 cm, length: 3.5-9.1 cm) phantoms. The simulations were performed for three radionuclides commonly used in small animal SPECT studies:99mTc (140 keV), 111In (171 keV 90% and 245 keV 94%) and 125I (effective 27.5 keV). For the MOBY phantoms, the total Compton scatter fractions ranged (over the range of phantom sizes) from 4-10% for 99mTc (126-154 keV), 7-16% for 111In (154-188 keV), 3-7% for 111In (220-270 keV) and 17-30% for 125I (15-45 keV) including the scatter contributions from the tungsten collimator, lead shield and air (inside and outside the camera heads). For the NEMA-rat phantoms, the scatter fractions ranged from 10-15% (99mTc), 17-23% 111In: 154-188 keV), 8-12% (111In: 220-270 keV) and 32-40% (125I). Our results suggest that energy window methods based on solely emission data are sufficient for all mouse and most rat studies for 99mTc and 111In. However, more sophisticated methods may be needed for 125I.

Time course evaluation of myocardial perfusion after reperfusion therapy by 99mTc-tetrofosmin SPECT in patients with acute myocardial infarction.

PubMed

Tanaka, R; Nakamura, T

2001-09-01

Myocardial perfusion imaging with 99mTc-labeled agents immediately after reperfusion therapy can underestimate myocardial salvage. It is also conceivable that delayed imaging is useful for assessing the risk area. However, to our knowledge, very few studies have sequentially evaluated these image changes. We conducted 99mTc-tetrofosmin (TF) and 123I-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) SPECT before and after reperfusion to treat acute myocardial infarction and quantified changes in TF myocardial accumulation and reverse redistribution. Seventeen patients with a first myocardial infarction underwent successful reperfusion. We examined SPECT images obtained at the onset (preimage), those acquired 30 min (early image) and 6 h (delayed image) after TF injection, and images acquired 1, 4, 7, and 20 d after reperfusion (post-1-d, post-4-d, post-7-d, and post-20-d image, respectively). We also examined BMIPP SPECT images after 7 +/- 1.8 d (BMIPP image). Polar maps were divided into 48 segments to calculate percentage uptake, and time course changes in segment numbers below 60% were observed as abnormal area. Moreover, cardiac function was analyzed by gated TF SPECT on 1 and 20 d after reperfusion. In reference to the abnormal area on the early images, the post-1-d image was significantly improved compared with the preimage (P < 0.01) as was the post-7-d image compared with the post-1-d and post-4-d images (P < 0.05, respectively). However, post-20-d and post-7-d images did not significantly differ. Therefore, the improvement in myocardial accumulation reached a plateau 7 d after reperfusion. On the other hand, the abnormal area on the delayed images was significantly greater (P < 0.01) compared with that on the early images from 4 to 20 d after reperfusion, as the value was essentially constant. The correlations of the abnormal area between the preimage and the post-7-d delayed image, the preimage and the BMIPP image, and the post-7-d delayed image and the BMIPP image were very close (r = 0.963, r = 0.981, and r = 0.975, respectively). Gated TF SPECT revealed that the left ventricular ejection fraction was not significantly different (P = not significant) between 1 and 20 d after reperfusion, but regional wall motion was significantly different after reperfusion (P < 0.05). These results suggest that the interval between reperfusion therapy and TF SPECT should be 7 d to evaluate the salvage effect and that TF delayed and BMIPP images are both useful in estimation of risk area.

Can DCE-MRI Explain the Heterogeneity in Radiopeptide Uptake Imaged by SPECT in a Pancreatic Neuroendocrine Tumor Model?

PubMed Central

Groen, Harald C.; Niessen, Wiro J.; Bernsen, Monique R.; de Jong, Marion; Veenland, Jifke F.

2013-01-01

Although efficient delivery and distribution of treatment agents over the whole tumor is essential for successful tumor treatment, the distribution of most of these agents cannot be visualized. However, with single-photon emission computed tomography (SPECT), both delivery and uptake of radiolabeled peptides can be visualized in a neuroendocrine tumor model overexpressing somatostatin receptors. A heterogeneous peptide uptake is often observed in these tumors. We hypothesized that peptide distribution in the tumor is spatially related to tumor perfusion, vessel density and permeability, as imaged and quantified by DCE-MRI in a neuroendocrine tumor model. Four subcutaneous CA20948 tumor-bearing Lewis rats were injected with the somatostatin-analog 111In-DTPA-Octreotide (50 MBq). SPECT-CT and MRI scans were acquired and MRI was spatially registered to SPECT-CT. DCE-MRI was analyzed using semi-quantitative and quantitative methods. Correlation between SPECT and DCE-MRI was investigated with 1) Spearman’s rank correlation coefficient; 2) SPECT uptake values grouped into deciles with corresponding median DCE-MRI parametric values and vice versa; and 3) linear regression analysis for median parameter values in combined datasets. In all tumors, areas with low peptide uptake correlated with low perfusion/density/ /permeability for all DCE-MRI-derived parameters. Combining all datasets, highest linear regression was found between peptide uptake and semi-quantitative parameters (R2>0.7). The average correlation coefficient between SPECT and DCE-MRI-derived parameters ranged from 0.52-0.56 (p<0.05) for parameters primarily associated with exchange between blood and extracellular extravascular space. For these parameters a linear relation with peptide uptake was observed. In conclusion, the ‘exchange-related’ DCE-MRI-derived parameters seemed to predict peptide uptake better than the ‘contrast amount- related’ parameters. Consequently, fast and efficient diffusion through the vessel wall into tissue is an important factor for peptide delivery. DCE-MRI helps to elucidate the relation between vascular characteristics, peptide delivery and treatment efficacy, and may form a basis to predict targeting efficiency. PMID:24116203

Impact of the Adaptive Statistical Iterative Reconstruction Technique on Radiation Dose and Image Quality in Bone SPECT/CT.

PubMed

Sibille, Louis; Chambert, Benjamin; Alonso, Sandrine; Barrau, Corinne; D'Estanque, Emmanuel; Al Tabaa, Yassine; Collombier, Laurent; Demattei, Christophe; Kotzki, Pierre-Olivier; Boudousq, Vincent

2016-07-01

The purpose of this study was to compare a routine bone SPECT/CT protocol using CT reconstructed with filtered backprojection (FBP) with an optimized protocol using low-dose CT images reconstructed with adaptive statistical iterative reconstruction (ASiR). In this prospective study, enrolled patients underwent bone SPECT/CT, with 1 SPECT acquisition followed by 2 randomized CT acquisitions: FBP CT (FBP; noise index, 25) and ASiR CT (70% ASiR; noise index, 40). The image quality of both attenuation-corrected SPECT and CT images was visually (5-point Likert scale, 2 interpreters) and quantitatively (contrast ratio [CR] and signal-to-noise ratio [SNR]) estimated. The CT dose index volume, dose-length product, and effective dose were compared. Seventy-five patients were enrolled in the study. Quantitative attenuation-corrected SPECT evaluation showed no inferiority for contrast ratio and SNR issued from FBP CT or ASiR CT (respectively, 13.41 ± 7.83 vs. 13.45 ± 7.99 and 2.33 ± 0.83 vs. 2.32 ± 0.84). Qualitative image analysis showed no difference between attenuation-corrected SPECT images issued from FBP CT or ASiR CT for both interpreters (respectively, 3.5 ± 0.6 vs. 3.5 ± 0.6 and 3.6 ± 0.5 vs. 3.6 ± 0.5). Quantitative CT evaluation showed no inferiority for SNR between FBP and ASiR CT images (respectively, 0.93 ± 0.16 and 1.07 ± 0.17). Qualitative image analysis showed no quality difference between FBP and ASiR CT images for both interpreters (respectively, 3.8 ± 0.5 vs. 3.6 ± 0.5 and 4.0 ± 0.1 vs. 4.0 ± 0.2). Mean CT dose index volume, dose-length product, and effective dose for ASiR CT (3.0 ± 2.0 mGy, 148 ± 85 mGy⋅cm, and 2.2 ± 1.3 mSv) were significantly lower than for FBP CT (8.5 ± 3.7 mGy, 365 ± 160 mGy⋅cm, and 5.5 ± 2.4 mSv). The use of 70% ASiR blending in bone SPECT/CT can reduce the CT radiation dose by 60%, with no sacrifice in attenuation-corrected SPECT and CT image quality, compared with the conventional protocol using FBP CT reconstruction technique. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

MIRD Pamphlet No. 23: Quantitative SPECT for Patient-Specific 3-Dimensional Dosimetry in Internal Radionuclide Therapy

PubMed Central

Dewaraja, Yuni K.; Frey, Eric C.; Sgouros, George; Brill, A. Bertrand; Roberson, Peter; Zanzonico, Pat B.; Ljungberg, Michael

2012-01-01

In internal radionuclide therapy, a growing interest in voxel-level estimates of tissue-absorbed dose has been driven by the desire to report radiobiologic quantities that account for the biologic consequences of both spatial and temporal nonuniformities in these dose estimates. This report presents an overview of 3-dimensional SPECT methods and requirements for internal dosimetry at both regional and voxel levels. Combined SPECT/CT image-based methods are emphasized, because the CT-derived anatomic information allows one to address multiple technical factors that affect SPECT quantification while facilitating the patient-specific voxel-level dosimetry calculation itself. SPECT imaging and reconstruction techniques for quantification in radionuclide therapy are not necessarily the same as those designed to optimize diagnostic imaging quality. The current overview is intended as an introduction to an upcoming series of MIRD pamphlets with detailed radionuclide-specific recommendations intended to provide best-practice SPECT quantification–based guidance for radionuclide dosimetry. PMID:22743252

Pinhole Micro-SPECT/CT for Noninvasive Monitoring and Quantitation of Oncolytic Virus Dispersion and Percent Infection in Solid Tumors

PubMed Central

Penheiter, Alan R.; Griesmann, Guy E.; Federspiel, Mark J.; Dingli, David; Russell, Stephen J.; Carlson, Stephanie K.

2011-01-01

The purpose of our study was to validate the ability of pinhole micro-single-photon emission computed tomography/computed tomography (SPECT/CT) to 1) accurately resolve the intratumoral dispersion pattern and 2) quantify the infection percentage in solid tumors of an oncolytic measles virus encoding the human sodium iodide symporter (MV-NIS). NIS RNA level and dispersion pattern were determined in control and MV-NIS infected BxPC-3 pancreatic tumor cells and mouse xenografts using quantitative, real-time, reverse transcriptase, polymerase chain reaction, autoradiography, and immunohistochemistry (IHC). Mice with BxPC-3 xenografts were imaged with 123I or 99TcO4 micro-SPECT/CT. Tumor dimensions and radionuclide localization were determined with imaging software. Linear regression and correlation analyses were performed to determine the relationship between tumor infection percentage and radionuclide uptake (% injected dose per gram) above background and a highly significant correlation was observed (r2 = 0.947). A detection threshold of 1.5-fold above the control tumor uptake (background) yielded a sensitivity of 2.7% MV-NIS infected tumor cells. We reliably resolved multiple distinct intratumoral zones of infection from noninfected regions. Pinhole micro-SPECT/CT imaging using the NIS reporter demonstrated precise localization and quantitation of oncolytic MV-NIS infection and can replace more time-consuming and expensive analyses (eg, autoradiography and IHC) that require animal sacrifice. PMID:21753796

Comparison of image quality, myocardial perfusion, and LV function between standard imaging and single-injection ultra-low-dose imaging using a high-efficiency SPECT camera: the MILLISIEVERT study

PubMed Central

Einstein, Andrew J.; Blankstein, Ron; Andrews, Howard; Fish, Mathews; Padgett, Richard; Hayes, Sean W.; Friedman, John D.; Qureshi, Mehreen; Rakotoarivelo, Harivony; Slomka, Piotr; Nakazato, Ryo; Bokhari, Sabahat; Di Carli, Marcello; Berman, Daniel S.

2015-01-01

SPECT myocardial perfusion imaging (MPI) plays a central role in coronary artery disease diagnosis; but concerns exist regarding its radiation burden. Compared to standard Anger-SPECT (A-SPECT) cameras, new high-efficiency (HE) cameras with specialized collimators and solid-state cadmium-zinc-telluride detectors offer potential to maintain image quality (IQ), while reducing administered activity and thus radiation dose to patients. No previous study has compared IQ, interpretation, total perfusion deficit (TPD), or ejection fraction (EF) in patients receiving both ultra-low-dose (ULD) imaging on a HE-SPECT camera and standard low-dose (SLD) A-SPECT imaging. Methods We compared ULD-HE-SPECT to SLD-A-SPECT imaging by dividing the rest dose in 101 patients at 3 sites scheduled to undergo clinical A-SPECT MPI using a same day rest/stress Tc-99m protocol. Patients received HE-SPECT imaging following an initial ~130 MBq (3.5mCi) dose, and SLD-A-SPECT imaging following the remainder of the planned dose. Images were scored visually by 2 blinded readers for IQ and summed rest score (SRS). TPD and EF were assessed quantitatively. Results Mean activity was 134 MBq (3.62 mCi) for ULD-HE-SPECT (effective dose 1.15 mSv) and 278 MBq (7.50 mCi, 2.39 mSv) for SLD-A-SPECT. Overall IQ was superior for ULD-HE-SPECT (p<0.0001), with twice as many studies graded excellent quality. Extracardiac activity and overall perfusion assessment were similar. Between-method correlations were high for SRS (r=0.87), TPD (r=0.91), and EF (r=0.88). Conclusion ULD-HE-SPECT rest imaging correlates highly with SLD-A-SPECT. It has improved image quality, comparable extracardiac activity, and achieves radiation dose reduction to 1 mSv for a single injection. PMID:24982439

Quantitative high-efficiency cadmium-zinc-telluride SPECT with dedicated parallel-hole collimation system in obese patients: results of a multi-center study.

PubMed

Nakazato, Ryo; Slomka, Piotr J; Fish, Mathews; Schwartz, Ronald G; Hayes, Sean W; Thomson, Louise E J; Friedman, John D; Lemley, Mark; Mackin, Maria L; Peterson, Benjamin; Schwartz, Arielle M; Doran, Jesse A; Germano, Guido; Berman, Daniel S

2015-04-01

Obesity is a common source of artifact on conventional SPECT myocardial perfusion imaging (MPI). We evaluated image quality and diagnostic performance of high-efficiency (HE) cadmium-zinc-telluride parallel-hole SPECT MPI for coronary artery disease (CAD) in obese patients. 118 consecutive obese patients at three centers (BMI 43.6 ± 8.9 kg·m(-2), range 35-79.7 kg·m(-2)) had upright/supine HE-SPECT and invasive coronary angiography > 6 months (n = 67) or low likelihood of CAD (n = 51). Stress quantitative total perfusion deficit (TPD) for upright (U-TPD), supine (S-TPD), and combined acquisitions (C-TPD) was assessed. Image quality (IQ; 5 = excellent; < 3 nondiagnostic) was compared among BMI 35-39.9 (n = 58), 40-44.9 (n = 24) and ≥45 (n = 36) groups. ROC curve area for CAD detection (≥50% stenosis) for U-TPD, S-TPD, and C-TPD were 0.80, 0.80, and 0.87, respectively. Sensitivity/specificity was 82%/57% for U-TPD, 74%/71% for S-TPD, and 80%/82% for C-TPD. C-TPD had highest specificity (P = .02). C-TPD normalcy rate was higher than U-TPD (88% vs 75%, P = .02). Mean IQ was similar among BMI 35-39.9, 40-44.9 and ≥45 groups [4.6 vs 4.4 vs 4.5, respectively (P = .6)]. No patient had a nondiagnostic stress scan. In obese patients, HE-SPECT MPI with dedicated parallel-hole collimation demonstrated high image quality, normalcy rate, and diagnostic accuracy for CAD by quantitative analysis of combined upright/supine acquisitions.

Quantitative High-Efficiency Cadmium-Zinc-Telluride SPECT with Dedicated Parallel-Hole Collimation System in Obese Patients: Results of a Multi-Center Study

PubMed Central

Nakazato, Ryo; Slomka, Piotr J.; Fish, Mathews; Schwartz, Ronald G.; Hayes, Sean W.; Thomson, Louise E.J.; Friedman, John D.; Lemley, Mark; Mackin, Maria L.; Peterson, Benjamin; Schwartz, Arielle M.; Doran, Jesse A.; Germano, Guido; Berman, Daniel S.

2014-01-01

Background Obesity is a common source of artifact on conventional SPECT myocardial perfusion imaging (MPI). We evaluated image quality and diagnostic performance of high-efficiency (HE) cadmium-zinc-telluride (CZT) parallel-hole SPECT-MPI for coronary artery disease (CAD) in obese patients. Methods and Results 118 consecutive obese patients at 3 centers (BMI 43.6±8.9 kg/m2, range 35–79.7 kg/m2) had upright/supine HE-SPECT and ICA >6 months (n=67) or low-likelihood of CAD (n=51). Stress quantitative total perfusion deficit (TPD) for upright (U-TPD), supine (S-TPD) and combined acquisitions (C-TPD) was assessed. Image quality (IQ; 5=excellent; <3 nondiagnostic) was compared among BMI 35–39.9 (n=58), 40–44.9 (n=24) and ≥45 (n=36) groups. ROC-curve area for CAD detection (≥50% stenosis) for U-TPD, S-TPD, and C-TPD were 0.80, 0.80, and 0.87, respectively. Sensitivity/specificity was 82%/57% for U-TPD, 74%/71% for S-TPD, and 80%/82% for C-TPD. C-TPD had highest specificity (P=.02). C-TPD normalcy rate was higher than U-TPD (88% vs. 75%, P=.02). Mean IQ was similar among BMI 35–39.9, 40–44.9 and ≥45 groups [4.6 vs. 4.4 vs. 4.5, respectively (P=.6)]. No patient had a non-diagnostic stress scan. Conclusions In obese patients, HE-SPECT MPI with dedicated parallel-hole collimation demonstrated high image quality, normalcy rate, and diagnostic accuracy for CAD by quantitative analysis of combined upright/supine acquisitions. PMID:25388380

Morphology supporting function: attenuation correction for SPECT/CT, PET/CT, and PET/MR imaging

PubMed Central

Lee, Tzu C.; Alessio, Adam M.; Miyaoka, Robert M.; Kinahan, Paul E.

2017-01-01

Both SPECT, and in particular PET, are unique in medical imaging for their high sensitivity and direct link to a physical quantity, i.e. radiotracer concentration. This gives PET and SPECT imaging unique capabilities for accurately monitoring disease activity for the purposes of clinical management or therapy development. However, to achieve a direct quantitative connection between the underlying radiotracer concentration and the reconstructed image values several confounding physical effects have to be estimated, notably photon attenuation and scatter. With the advent of dual-modality SPECT/CT, PET/CT, and PET/MR scanners, the complementary CT or MR image data can enable these corrections, although there are unique challenges for each combination. This review covers the basic physics underlying photon attenuation and scatter and summarizes technical considerations for multimodal imaging with regard to PET and SPECT quantification and methods to address the challenges for each multimodal combination. PMID:26576737

Quantitative multi-pinhole small-animal SPECT: uniform versus non-uniform Chang attenuation correction.

PubMed

Wu, C; de Jong, J R; Gratama van Andel, H A; van der Have, F; Vastenhouw, B; Laverman, P; Boerman, O C; Dierckx, R A J O; Beekman, F J

2011-09-21

Attenuation of photon flux on trajectories between the source and pinhole apertures affects the quantitative accuracy of reconstructed single-photon emission computed tomography (SPECT) images. We propose a Chang-based non-uniform attenuation correction (NUA-CT) for small-animal SPECT/CT with focusing pinhole collimation, and compare the quantitative accuracy with uniform Chang correction based on (i) body outlines extracted from x-ray CT (UA-CT) and (ii) on hand drawn body contours on the images obtained with three integrated optical cameras (UA-BC). Measurements in phantoms and rats containing known activities of isotopes were conducted for evaluation. In (125)I, (201)Tl, (99m)Tc and (111)In phantom experiments, average relative errors comparing to the gold standards measured in a dose calibrator were reduced to 5.5%, 6.8%, 4.9% and 2.8%, respectively, with NUA-CT. In animal studies, these errors were 2.1%, 3.3%, 2.0% and 2.0%, respectively. Differences in accuracy on average between results of NUA-CT, UA-CT and UA-BC were less than 2.3% in phantom studies and 3.1% in animal studies except for (125)I (3.6% and 5.1%, respectively). All methods tested provide reasonable attenuation correction and result in high quantitative accuracy. NUA-CT shows superior accuracy except for (125)I, where other factors may have more impact on the quantitative accuracy than the selected attenuation correction.

New Trends in Radionuclide Myocardial Perfusion Imaging

PubMed Central

Hung, Guang-Uei; Wang, Yuh-Feng; Su, Hung-Yi; Hsieh, Te-Chun; Ko, Chi-Lun; Yen, Ruoh-Fang

2016-01-01

Radionuclide myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has been widely used clinically as one of the major functional imaging modalities for patients with coronary artery disease (CAD) for decades. Ample evidence has supported the use of MPI as a useful and important tool in the diagnosis, risk stratification and treatment planning for CAD. Although popular in the United States, MPI has become the most frequently used imaging modality among all nuclear medicine tests in Taiwan. However, it should be acknowledged that MPI SPECT does have its limitations. These include false-positive results due to certain artifacts, false-negative due to balanced ischemia, complexity and adverse reaction arising from current pharmacological stressors, time consuming nature of the imaging procedure, no blood flow quantitation and relatively high radiation exposure. The purpose of this article was to review the recent trends in nuclear cardiology, including the utilization of positron emission tomography (PET) for MPI, new stressor, new SPECT camera with higher resolution and higher sensitivity, dynamic SPECT protocol for blood flow quantitation, new software of phase analysis for evaluation of LV dyssynchrony, and measures utilized for reducing radiation exposure of MPI. PMID:27122946

Fixed forced detection for fast SPECT Monte-Carlo simulation

NASA Astrophysics Data System (ADS)

Cajgfinger, T.; Rit, S.; Létang, J. M.; Halty, A.; Sarrut, D.

2018-03-01

Monte-Carlo simulations of SPECT images are notoriously slow to converge due to the large ratio between the number of photons emitted and detected in the collimator. This work proposes a method to accelerate the simulations based on fixed forced detection (FFD) combined with an analytical response of the detector. FFD is based on a Monte-Carlo simulation but forces the detection of a photon in each detector pixel weighted by the probability of emission (or scattering) and transmission to this pixel. The method was evaluated with numerical phantoms and on patient images. We obtained differences with analog Monte Carlo lower than the statistical uncertainty. The overall computing time gain can reach up to five orders of magnitude. Source code and examples are available in the Gate V8.0 release.

Fixed forced detection for fast SPECT Monte-Carlo simulation.

PubMed

Cajgfinger, T; Rit, S; Létang, J M; Halty, A; Sarrut, D

2018-03-02

Monte-Carlo simulations of SPECT images are notoriously slow to converge due to the large ratio between the number of photons emitted and detected in the collimator. This work proposes a method to accelerate the simulations based on fixed forced detection (FFD) combined with an analytical response of the detector. FFD is based on a Monte-Carlo simulation but forces the detection of a photon in each detector pixel weighted by the probability of emission (or scattering) and transmission to this pixel. The method was evaluated with numerical phantoms and on patient images. We obtained differences with analog Monte Carlo lower than the statistical uncertainty. The overall computing time gain can reach up to five orders of magnitude. Source code and examples are available in the Gate V8.0 release.

Evaluation of attenuation and scatter correction requirements in small animal PET and SPECT imaging

NASA Astrophysics Data System (ADS)

Konik, Arda Bekir

Positron emission tomography (PET) and single photon emission tomography (SPECT) are two nuclear emission-imaging modalities that rely on the detection of high-energy photons emitted from radiotracers administered to the subject. The majority of these photons are attenuated (absorbed or scattered) in the body, resulting in count losses or deviations from true detection, which in turn degrades the accuracy of images. In clinical emission tomography, sophisticated correction methods are often required employing additional x-ray CT or radionuclide transmission scans. Having proven their potential in both clinical and research areas, both PET and SPECT are being adapted for small animal imaging. However, despite the growing interest in small animal emission tomography, little scientific information exists about the accuracy of these correction methods on smaller size objects, and what level of correction is required. The purpose of this work is to determine the role of attenuation and scatter corrections as a function of object size through simulations. The simulations were performed using Interactive Data Language (IDL) and a Monte Carlo based package, Geant4 application for emission tomography (GATE). In IDL simulations, PET and SPECT data acquisition were modeled in the presence of attenuation. A mathematical emission and attenuation phantom approximating a thorax slice and slices from real PET/CT data were scaled to 5 different sizes (i.e., human, dog, rabbit, rat and mouse). The simulated emission data collected from these objects were reconstructed. The reconstructed images, with and without attenuation correction, were compared to the ideal (i.e., non-attenuated) reconstruction. Next, using GATE, scatter fraction values (the ratio of the scatter counts to the total counts) of PET and SPECT scanners were measured for various sizes of NEMA (cylindrical phantoms representing small animals and human), MOBY (realistic mouse/rat model) and XCAT (realistic human model) digital phantoms. In addition, PET projection files for different sizes of MOBY phantoms were reconstructed in 6 different conditions including attenuation and scatter corrections. Selected regions were analyzed for these different reconstruction conditions and object sizes. Finally, real mouse data from the real version of the same small animal PET scanner we modeled in our simulations were analyzed for similar reconstruction conditions. Both our IDL and GATE simulations showed that, for small animal PET and SPECT, even the smallest size objects (˜2 cm diameter) showed ˜15% error when both attenuation and scatter were not corrected. However, a simple attenuation correction using a uniform attenuation map and object boundary obtained from emission data significantly reduces this error in non-lung regions (˜1% for smallest size and ˜6% for largest size). In lungs, emissions values were overestimated when only attenuation correction was performed. In addition, we did not observe any significant improvement between the uses of uniform or actual attenuation map (e.g., only ˜0.5% for largest size in PET studies). The scatter correction was not significant for smaller size objects, but became increasingly important for larger sizes objects. These results suggest that for all mouse sizes and most rat sizes, uniform attenuation correction can be performed using emission data only. For smaller sizes up to ˜ 4 cm, scatter correction is not required even in lung regions. For larger sizes if accurate quantization needed, additional transmission scan may be required to estimate an accurate attenuation map for both attenuation and scatter corrections.

Influence of reconstruction algorithms on image quality in SPECT myocardial perfusion imaging.

PubMed

Davidsson, Anette; Olsson, Eva; Engvall, Jan; Gustafsson, Agnetha

2017-11-01

We investigated if image- and diagnostic quality in SPECT MPI could be maintained despite a reduced acquisition time adding Depth Dependent Resolution Recovery (DDRR) for image reconstruction. Images were compared with filtered back projection (FBP) and iterative reconstruction using Ordered Subsets Expectation Maximization with (IRAC) and without (IRNC) attenuation correction (AC). Stress- and rest imaging for 15 min was performed on 21 subjects with a dual head gamma camera (Infinia Hawkeye; GE Healthcare), ECG-gating with 8 frames/cardiac cycle and a low-dose CT-scan. A 9 min acquisition was generated using five instead of eight gated frames and was reconstructed with DDRR, with (IRACRR) and without AC (IRNCRR) as well as with FBP. Three experienced nuclear medicine specialists visually assessed anonymized images according to eight criteria on a four point scale, three related to image quality and five to diagnostic confidence. Statistical analysis was performed using Visual Grading Regression (VGR). Observer confidence in statements on image quality was highest for the images that were reconstructed using DDRR (P<0·01 compared to FBP). Iterative reconstruction without DDRR was not superior to FBP. Interobserver variability was significant for statements on image quality (P<0·05) but lower in the diagnostic statements on ischemia and scar. The confidence in assessing ischemia and scar was not different between the reconstruction techniques (P = n.s.). SPECT MPI collected in 9 min, reconstructed with DDRR and AC, produced better image quality than the standard procedure. The observers expressed the highest diagnostic confidence in the DDRR reconstruction. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

99 mTc-MIBI washout as a complementary factor in the evaluation of idiopathic dilated cardiomyopathy (IDCM) using myocardial perfusion imaging.

PubMed

Shiroodi, Mohammad Kazem; Shafiei, Babak; Baharfard, Nastaran; Gheidari, Mohammad Esmail; Nazari, Babak; Pirayesh, Elaheh; Kiasat, Ali; Hoseinzadeh, Samaneh; Hashemi, Abolghassem; Akbarzadeh, Mohammad Ali; Javadi, Hamid; Nabipour, Iraj; Assadi, Majid

2012-01-01

Rapid technetium-99 m methoxyisobutylisonitrile (99 mTc-MIBI) washout has been shown to occur in impaired myocardia. This study is based on the hypothesis that scintigraphy can be applied to calculate the myocardial 99 mTc-MIBI washout rate (WR) to diagnose and evaluate heart failure severity and other left ventricular functional parameters specifically in idiopathic dilated cardiomyopathy (IDCM) patients. Patients with IDCMP (n = 17; 52.65 ± 11.47 years) and normal subjects (n = 6; 49.67 ± 10.15 years) were intravenously administered 99 mTc-hexakis-2-methoxyisobutylisonitrile (99 mTc-MIBI). Next, early and delayed planar data were acquired (at 3.5-h intervals), and electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) was performed. The 99 mTc-MIBI WR was calculated using early and delayed planar images. Left ventricular functional parameters were also analyzed using quantitative gated SPECT (QGS) data. In target group, myocardial WRs (29.13 ± 6.68%) were significantly higher than those of control subjects (14.17 ± 3.31%; P < 0.001). The 99 mTc-MIBI WR increased with the increasing severity of the NYHA functional class (23.16 ± 1.72% for class I, 30.25 ± 0.95% for class II, 32.60 ± 6.73% for class III, and 37.50 ± 7.77% for class IV; P = 0.02). The WR was positively correlated with the end-diastolic volume (EDV) index (r (2) = 0.216; β = 0.464; P = 0.02 [ml/m(2)], the end-systolic volume (ESV) index (r (2) = 0.234; β = 0.484; P = 0.01 [ml/m(2)]), the summed motion score (SMS) (r (2) = 0.544; β = 0.738; P = 0.00), and the summed thickening score (STS) (r (2) = 0.656; β = 0.810; P = 0.00); it was negatively correlated with the left ventricular ejection fraction (LVEF) (r (2) = 0.679; β = -0.824; P = 0.00). It can be concluded that 99 mTc-MIBI scintigraphy might be a valuable molecular imaging tool for the diagnosis and evaluation of myocardial damage or dysfunction severity.

Efficient simulation of voxelized phantom in GATE with embedded SimSET multiple photon history generator.

PubMed

Lin, Hsin-Hon; Chuang, Keh-Shih; Lin, Yi-Hsing; Ni, Yu-Ching; Wu, Jay; Jan, Meei-Ling

2014-10-21

GEANT4 Application for Tomographic Emission (GATE) is a powerful Monte Carlo simulator that combines the advantages of the general-purpose GEANT4 simulation code and the specific software tool implementations dedicated to emission tomography. However, the detailed physical modelling of GEANT4 is highly computationally demanding, especially when tracking particles through voxelized phantoms. To circumvent the relatively slow simulation of voxelized phantoms in GATE, another efficient Monte Carlo code can be used to simulate photon interactions and transport inside a voxelized phantom. The simulation system for emission tomography (SimSET), a dedicated Monte Carlo code for PET/SPECT systems, is well-known for its efficiency in simulation of voxel-based objects. An efficient Monte Carlo workflow integrating GATE and SimSET for simulating pinhole SPECT has been proposed to improve voxelized phantom simulation. Although the workflow achieves a desirable increase in speed, it sacrifices the ability to simulate decaying radioactive sources such as non-pure positron emitters or multiple emission isotopes with complex decay schemes and lacks the modelling of time-dependent processes due to the inherent limitations of the SimSET photon history generator (PHG). Moreover, a large volume of disk storage is needed to store the huge temporal photon history file produced by SimSET that must be transported to GATE. In this work, we developed a multiple photon emission history generator (MPHG) based on SimSET/PHG to support a majority of the medically important positron emitters. We incorporated the new generator codes inside GATE to improve the simulation efficiency of voxelized phantoms in GATE, while eliminating the need for the temporal photon history file. The validation of this new code based on a MicroPET R4 system was conducted for (124)I and (18)F with mouse-like and rat-like phantoms. Comparison of GATE/MPHG with GATE/GEANT4 indicated there is a slight difference in energy spectra for energy below 50 keV due to the lack of x-ray simulation from (124)I decay in the new code. The spatial resolution, scatter fraction and count rate performance are in good agreement between the two codes. For the case studies of (18)F-NaF ((124)I-IAZG) using MOBY phantom with 1  ×  1 × 1 mm(3) voxel sizes, the results show that GATE/MPHG can achieve acceleration factors of approximately 3.1 × (4.5 ×), 6.5 × (10.7 ×) and 9.5 × (31.0 ×) compared with GATE using the regular navigation method, the compressed voxel method and the parameterized tracking technique, respectively. In conclusion, the implementation of MPHG in GATE allows for improved efficiency of voxelized phantom simulations and is suitable for studying clinical and preclinical imaging.

A methodology for generating normal and pathological brain perfusion SPECT images for evaluation of MRI/SPECT fusion methods: application in epilepsy

NASA Astrophysics Data System (ADS)

Grova, C.; Jannin, P.; Biraben, A.; Buvat, I.; Benali, H.; Bernard, A. M.; Scarabin, J. M.; Gibaud, B.

2003-12-01

Quantitative evaluation of brain MRI/SPECT fusion methods for normal and in particular pathological datasets is difficult, due to the frequent lack of relevant ground truth. We propose a methodology to generate MRI and SPECT datasets dedicated to the evaluation of MRI/SPECT fusion methods and illustrate the method when dealing with ictal SPECT. The method consists in generating normal or pathological SPECT data perfectly aligned with a high-resolution 3D T1-weighted MRI using realistic Monte Carlo simulations that closely reproduce the response of a SPECT imaging system. Anatomical input data for the SPECT simulations are obtained from this 3D T1-weighted MRI, while functional input data result from an inter-individual analysis of anatomically standardized SPECT data. The method makes it possible to control the 'brain perfusion' function by proposing a theoretical model of brain perfusion from measurements performed on real SPECT images. Our method provides an absolute gold standard for assessing MRI/SPECT registration method accuracy since, by construction, the SPECT data are perfectly registered with the MRI data. The proposed methodology has been applied to create a theoretical model of normal brain perfusion and ictal brain perfusion characteristic of mesial temporal lobe epilepsy. To approach realistic and unbiased perfusion models, real SPECT data were corrected for uniform attenuation, scatter and partial volume effect. An anatomic standardization was used to account for anatomic variability between subjects. Realistic simulations of normal and ictal SPECT deduced from these perfusion models are presented. The comparison of real and simulated SPECT images showed relative differences in regional activity concentration of less than 20% in most anatomical structures, for both normal and ictal data, suggesting realistic models of perfusion distributions for evaluation purposes. Inter-hemispheric asymmetry coefficients measured on simulated data were found within the range of asymmetry coefficients measured on corresponding real data. The features of the proposed approach are compared with those of other methods previously described to obtain datasets appropriate for the assessment of fusion methods.

Quantitative PET and SPECT performance characteristics of the Albira Trimodal pre-clinical tomograph

NASA Astrophysics Data System (ADS)

Spinks, T. J.; Karia, D.; Leach, M. O.; Flux, G.

2014-02-01

The Albira Trimodal pre-clinical scanner comprises PET, SPECT and CT sub-systems and thus provides a range of pre-clinical imaging options. The PET component consists of three rings of single-crystal LYSO detectors with axial/transverse fields-of-view (FOVs) of 148/80 mm. The SPECT component has two opposing CsI detectors (100 × 100 mm2) with single-pinhole (SPH) or multi(9)-pinhole (MPH) collimators; the detectors rotate in 6° increments and their spacing can be adjusted to provide different FOVs (25 to 120 mm). The CT sub-system provides ‘low’ (200 µA, 35 kVp) or ‘high’ (400 µA, 45 kVp) power x-rays onto a flat-panel CsI detector. This study examines the performance characteristics and quantitative accuracy of the PET and SPECT components. Using the NEMA NU 4-2008 specifications (22Na point source), the PET spatial resolution is 1.5 + 0.1 mm on axis and sensitivity 6.3% (axial centre) and 4.6% (central 70 mm). The usable activity range is ≤ 10 MBq (18F) over which good linearity (within 5%) is obtained for a uniform cylinder spanning the axial FOV; increasing deviation from linearity with activity is, however, observed for the NEMA (mouse) line source phantom. Image uniformity axially is within 5%. Spatial resolution (SPH/MPH) for the minimum SPECT FOV used for mouse imaging (50 mm) is 1.5/1.7 mm and point source sensitivity 69/750 cps MBq-1. Axial uniformity of SPECT images (%CV of regions-of-interest counts along the axis) is mostly within 8% although there is a range of 30-40% for the largest FOV. The variation is significantly smaller within the central 40 mm. Instances of count rate nonlinearity (PET) and axial non-uniformity (SPECT) were found to be reproducible and thus amenable to empirical correction.

A collimator optimization method for quantitative imaging: application to Y-90 bremsstrahlung SPECT.

PubMed

Rong, Xing; Frey, Eric C

2013-08-01

Post-therapy quantitative 90Y bremsstrahlung single photon emission computed tomography (SPECT) has shown great potential to provide reliable activity estimates, which are essential for dose verification. Typically 90Y imaging is performed with high- or medium-energy collimators. However, the energy spectrum of 90Y bremsstrahlung photons is substantially different than typical for these collimators. In addition, dosimetry requires quantitative images, and collimators are not typically optimized for such tasks. Optimizing a collimator for 90Y imaging is both novel and potentially important. Conventional optimization methods are not appropriate for 90Y bremsstrahlung photons, which have a continuous and broad energy distribution. In this work, the authors developed a parallel-hole collimator optimization method for quantitative tasks that is particularly applicable to radionuclides with complex emission energy spectra. The authors applied the proposed method to develop an optimal collimator for quantitative 90Y bremsstrahlung SPECT in the context of microsphere radioembolization. To account for the effects of the collimator on both the bias and the variance of the activity estimates, the authors used the root mean squared error (RMSE) of the volume of interest activity estimates as the figure of merit (FOM). In the FOM, the bias due to the null space of the image formation process was taken in account. The RMSE was weighted by the inverse mass to reflect the application to dosimetry; for a different application, more relevant weighting could easily be adopted. The authors proposed a parameterization for the collimator that facilitates the incorporation of the important factors (geometric sensitivity, geometric resolution, and septal penetration fraction) determining collimator performance, while keeping the number of free parameters describing the collimator small (i.e., two parameters). To make the optimization results for quantitative 90Y bremsstrahlung SPECT more general, the authors simulated multiple tumors of various sizes in the liver. The authors realistically simulated human anatomy using a digital phantom and the image formation process using a previously validated and computationally efficient method for modeling the image-degrading effects including object scatter, attenuation, and the full collimator-detector response (CDR). The scatter kernels and CDR function tables used in the modeling method were generated using a previously validated Monte Carlo simulation code. The hole length, hole diameter, and septal thickness of the obtained optimal collimator were 84, 3.5, and 1.4 mm, respectively. Compared to a commercial high-energy general-purpose collimator, the optimal collimator improved the resolution and FOM by 27% and 18%, respectively. The proposed collimator optimization method may be useful for improving quantitative SPECT imaging for radionuclides with complex energy spectra. The obtained optimal collimator provided a substantial improvement in quantitative performance for the microsphere radioembolization task considered.

Muscarinic cholinergic receptor binding: in vivo depiction using single photon emission computed tomography and radioiodinated quinuclidinyl benzilate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drayer, B.; Jaszczak, R.; Coleman, E.

1982-06-01

An attempt was made to characterize, in vivo, specific binding to the muscarinic cholinergic receptor in the calf using the radioiodinated ligand quinuclidinyl benzilate (/sup 123/I-OH-QNB) and single photon detection emission computed tomography (SPECT). The supratentorial brain activity was significantly increased after the intravenous infusion of /sup 123/I-OH-QNB as compared to free /sup 123/I. Scopolamine, a muscarinic cholinergic receptor antagonist, decreased the measured brain activity when infused prior to /sup 123/I-OH-QNB consistent with pharmacologic blockade of specific receptor binding. Quantitative in vitro tissue distribution studies obtained following SPECT imaging were consistent with regionally distinct specific receptor binding in the striatummore » and cortical gray matter, nonspecific binding in the cerebellum, and pharmacologic blockade of specific binding sites with scopolamine. Although /sup 123/I-OH-QNB is not the ideal radioligand, our limited success will hopefully encourage the development of improved binding probes for SPECT imaging and quantitation.« less

Comparison of 99mTc-MDP SPECT qualitative vs quantitative results in patients with suspected condylar hyperplasia.

PubMed

López Buitrago, D F; Ruiz Botero, J; Corral, C M; Carmona, A R; Sabogal, A

To compare qualitative vs quantitative results of Single Photon Emission Computerised Tomography (SPECT), calculated from percentage of 99m Tc-MDP (methylene diphosphonate) uptake, in condyles of patients with a presumptive clinical diagnosis of condylar hyperplasia. A retrospective, descriptive study was conducted on the 99m Tc-MDP SPECT bone scintigraphy reports from 51 patients, with clinical impression of facial asymmetry related to condylar hyperplasia referred by their specialist in orthodontics or maxillofacial surgery, to a nuclear medicine department in order to take this type of test. Quantitative data from 99m Tc-MDP condylar uptake of each were obtained and compared with qualitative image interpretation reported by a nuclear medicine expert. The concordances between the 51 qualitative and quantitative reports results was established. The total sample included 32 women (63%) and 19 men (37%). The patient age range was 13-45 years (21±8 years). According to qualitative reports, 19 patients were positive for right side condylar hyperplasia, 12 for left side condylar hyperplasia, with 8 bilateral, and 12 negative. The quantitative reports diagnosed 16 positives for right side condylar hyperplasia, 10 for left side condylar hyperplasia, and 25 negatives. Nuclear medicine images are an important diagnostic tool, but the qualitative interpretation of the images is not as reliable as the quantitative calculation. The agreement between the two types of report is low (39.2%, Kappa=0.13; P>.2). The main limitation of quantitative reports is that they do not register bilateral condylar hyperplasia cases. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Creation and characterization of normal myocardial perfusion imaging databases using the IQ·SPECT system.

PubMed

Okuda, Koichi; Nakajima, Kenichi; Matsuo, Shinro; Kondo, Chisato; Sarai, Masayoshi; Horiguchi, Yoriko; Konishi, Takahiro; Onoguchi, Masahisa; Shimizu, Takeshi; Kinuya, Seigo

2017-01-03

Image acquisition by short-time single-photon emission-computed tomography (SPECT) has been made feasible by IQ·SPECT. The aim of this study was to generate normal databases (NDBs) of thallium-201 ( 201 Tl) myocardial perfusion imaging for IQ·SPECT, and characterize myocardial perfusion distribution. We retrospectively enrolled 159 patients with a low likelihood of cardiac diseases from four hospitals in Japan. All patients underwent short-time 201 Tl myocardial perfusion IQ·SPECT with or without attenuation and scatter correction (ACSC) in either supine or prone position. The mean myocardial counts were calculated using 17-segment polar maps. Three NDBs were derived from supine and prone images as well as supine images with ACSC. Differences between the supine and prone positions were observed in the uncorrected sex-segregated NDBs in the mid-inferolateral counts (p ≤ 0.016 for males and p ≤ 0.002 for females). Differences between IQ·SPECT and conventional SPECT were also observed in the mid-anterior, inferolateral, and apical lateral counts (p ≤ 0.009 for males and p ≤ 0.003 for females). Apical low counts attributed to myocardial thinning were observed in the apical anterior and apex segments in the supine IQ·SPECT NDB with ACSC. There were significant differences between uncorrected supine and prone NDBs, between uncorrected supine NDB and supine NDB with ACSC, and between uncorrected supine NDB and conventional SPECT NDB. Understanding the pattern of normal distribution in IQ-SPECT short-time acquisitions with and without ACSC will be helpful for interpretation of imaging findings in patients with coronary artery disease (CAD) or low likelihood of CAD and the NDBs will aid in quantitative analysis.

Patient-specific dosimetry based on quantitative SPECT imaging and 3D-DFT convolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akabani, G.; Hawkins, W.G.; Eckblade, M.B.

1999-01-01

The objective of this study was to validate the use of a 3-D discrete Fourier Transform (3D-DFT) convolution method to carry out the dosimetry for I-131 for soft tissues in radioimmunotherapy procedures. To validate this convolution method, mathematical and physical phantoms were used as a basis of comparison with Monte Carlo transport (MCT) calculations which were carried out using the EGS4 system code. The mathematical phantom consisted of a sphere containing uniform and nonuniform activity distributions. The physical phantom consisted of a cylinder containing uniform and nonuniform activity distributions. Quantitative SPECT reconstruction was carried out using the Circular Harmonic Transformmore » (CHT) algorithm.« less

A template-based approach to semi-quantitative SPECT myocardial perfusion imaging: Independent of normal databases.

PubMed

Hughes, Tyler; Shcherbinin, Sergey; Celler, Anna

2011-07-01

Normal patient databases (NPDs) are used to distinguish between normal and abnormal perfusion in SPECT myocardial perfusion imaging (MPI) and have gained wide acceptance in the clinical environment, yet there are limitations to this approach. This study introduces a template-based method for semi-quantitative MPI, which attempts to overcome some of the NPD limitations. Our approach involves the construction of a 3D digital healthy heart template from the delineation of the patient's left ventricle in the SPECT image. This patient-specific template of the heart, filled with uniform activity, is then analytically projected and reconstructed using the same algorithm as the original image. Subsequent to generating bulls-eye maps for the patient image (PB) and the template image (TB), a ratio (PB/TB) is calculated, which produces a reconstruction-artifact corrected image (CB). Finally, a threshold is used to define defects within CB enabling measurements of the perfusion defect extent (EXT). The SPECT-based template (Ts) measurements were compared to those of a CT-based "ideal" template (TI). Twenty digital phantoms were simulated: male and female, each with one healthy heart and nine hearts with various defects. Four physical phantom studies were performed modeling a healthy heart and three hearts with different defects. The phantom represented a thorax with spine, lung, and left ventricle inserts. Images were acquired on General Electric's (GE) Infinia Hawkeye SPECT/CT camera using standard clinical MPI protocol. Finally, our method was applied to 14 patient MPI rest/stress studies acquired on the GE Infinia Hawkeye SPECT/CT camera and compared to the results obtained from Cedars-Sinai's QPS software. In the simulation studies, the true EXT correlated well with the TI (slope= 1.08; offset = -0.40%; r = 0.99) and Ts (slope = 0.90; offset = 0.27%; r = 0.99) methods with no significant differences between them. Similarly, strong correlations were measured for EXT obtained from QPS and the template method for patient studies (slope =0.91; offset = 0.45%; r = 0.98). Mean errors in extent for the Ts method using simulation, physical phantom, and patient data were 2.7% +/- 2.4%, 0.9% +/- 0.5%, 2.0% +/- 2.7%, respectively. The authors introduced a method for semi-quantitative SPECT MPI, which offers a patient-specific approach to define the perfusion defect regions within the heart, as opposed to the patient-averaged NPD methodology.

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification.

PubMed

Wang, Shouyi; Bowen, Stephen R; Chaovalitwongse, W Art; Sandison, George A; Grabowski, Thomas J; Kinahan, Paul E

2014-02-21

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUV(peak)) over lesions of interest. Relative differences in SUV(peak) between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUV(peak) values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion compensation when clinicians quantitatively assess PET/CT for therapy target definition and response assessment.

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

NASA Astrophysics Data System (ADS)

Wang, Shouyi; Bowen, Stephen R.; Chaovalitwongse, W. Art; Sandison, George A.; Grabowski, Thomas J.; Kinahan, Paul E.

2014-02-01

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUVpeak) over lesions of interest. Relative differences in SUVpeak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUVpeak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion compensation when clinicians quantitatively assess PET/CT for therapy target definition and response assessment.

Scatter and cross-talk correction for one-day acquisition of 123I-BMIPP and 99mtc-tetrofosmin myocardial SPECT.

PubMed

Kaneta, Tomohiro; Kurihara, Hideyuki; Hakamatsuka, Takashi; Ito, Hiroshi; Maruoka, Shin; Fukuda, Hiroshi; Takahashi, Shoki; Yamada, Shogo

2004-12-01

123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and 99mTc-tetrofosmin (TET) are widely used for evaluation of myocardial fatty acid metabolism and perfusion, respectively. ECG-gated TET SPECT is also used for evaluation of myocardial wall motion. These tests are often performed on the same day to minimize both the time required and inconvenience to patients and medical staff. However, as 123I and 99mTc have similar emission energies (159 keV and 140 keV, respectively), it is necessary to consider not only scattered photons, but also primary photons of each radionuclide detected in the wrong window (cross-talk). In this study, we developed and evaluated the effectiveness of a new scatter and cross-talk correction imaging protocol. Fourteen patients with ischemic heart disease or heart failure (8 men and 6 women with a mean age of 69.4 yr, ranging from 45 to 94 yr) were enrolled in this study. In the routine one-day acquisition protocol, BMIPP SPECT was performed in the morning, with TET SPECT performed 4 h later. An additional SPECT was performed just before injection of TET with the energy window for 99mTc. These data correspond to the scatter and cross-talk factor of the next TET SPECT. The correction was performed by subtraction of the scatter and cross-talk factor from TET SPECT. Data are presented as means +/- S.E. Statistical analyses were performed using Wilcoxon's matched-pairs signed-ranks test, and p < 0.05 was considered significant. The percentage of scatter and cross-talk relative to the corrected total count was 26.0 +/- 5.3%. EDV and ESV after correction were significantly greater than those before correction (p = 0.019 and 0.016, respectively). After correction, EF was smaller than that before correction, but the difference was not significant. Perfusion scores (17 segments per heart) were significantly lower after as compared with those before correction (p < 0.001). Scatter and cross-talk correction revealed significant differences in EDV, ESV, and perfusion scores. These observations indicate that scatter and cross-talk correction is required for one-day acquisition of 123I-BMIPP and 99mTc-tetrofosmin SPECT.

SPECT3D - A multi-dimensional collisional-radiative code for generating diagnostic signatures based on hydrodynamics and PIC simulation output

NASA Astrophysics Data System (ADS)

MacFarlane, J. J.; Golovkin, I. E.; Wang, P.; Woodruff, P. R.; Pereyra, N. A.

2007-05-01

SPECT3D is a multi-dimensional collisional-radiative code used to post-process the output from radiation-hydrodynamics (RH) and particle-in-cell (PIC) codes to generate diagnostic signatures (e.g. images, spectra) that can be compared directly with experimental measurements. This ability to post-process simulation code output plays a pivotal role in assessing the reliability of RH and PIC simulation codes and their physics models. SPECT3D has the capability to operate on plasmas in 1D, 2D, and 3D geometries. It computes a variety of diagnostic signatures that can be compared with experimental measurements, including: time-resolved and time-integrated spectra, space-resolved spectra and streaked spectra; filtered and monochromatic images; and X-ray diode signals. Simulated images and spectra can include the effects of backlighters, as well as the effects of instrumental broadening and time-gating. SPECT3D also includes a drilldown capability that shows where frequency-dependent radiation is emitted and absorbed as it propagates through the plasma towards the detector, thereby providing insights on where the radiation seen by a detector originates within the plasma. SPECT3D has the capability to model a variety of complex atomic and radiative processes that affect the radiation seen by imaging and spectral detectors in high energy density physics (HEDP) experiments. LTE (local thermodynamic equilibrium) or non-LTE atomic level populations can be computed for plasmas. Photoabsorption rates can be computed using either escape probability models or, for selected 1D and 2D geometries, multi-angle radiative transfer models. The effects of non-thermal (i.e. non-Maxwellian) electron distributions can also be included. To study the influence of energetic particles on spectra and images recorded in intense short-pulse laser experiments, the effects of both relativistic electrons and energetic proton beams can be simulated. SPECT3D is a user-friendly software package that runs on Windows, Linux, and Mac platforms. A parallel version of SPECT3D is supported for Linux clusters for large-scale calculations. We will discuss the major features of SPECT3D, and present example results from simulations and comparisons with experimental data.

Decreased Lung Perfusion After Breast/Chest Wall Irradiation: Quantitative Results From a Prospective Clinical Trial

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liss, Adam L., E-mail: adamliss68@gmail.com; Marsh, Robin B.; Kapadia, Nirav S.

Purpose: To quantify lung perfusion changes after breast/chest wall radiation therapy (RT) using pre- and post-RT single photon emission computed tomography/computed tomography (SPECT/CT) attenuation-corrected perfusion scans; and correlate decreased perfusion with adjuvant RT dose for breast cancer in a prospective clinical trial. Methods and Materials: As part of an institutional review board–approved trial studying the impact of RT technique on lung function in node-positive breast cancer, patients received breast/chest wall and regional nodal irradiation including superior internal mammary node RT to 50 to 52.2 Gy with a boost to the tumor bed/mastectomy scar. All patients underwent quantitative SPECT/CT lung perfusion scanningmore » before RT and 1 year after RT. The SPECT/CT scans were co-registered, and the ratio of decreased perfusion after RT relative to the pre-RT perfusion scan was calculated to allow for direct comparison of SPECT/CT perfusion changes with delivered RT dose. The average ratio of decreased perfusion was calculated in 10-Gy dose increments from 0 to 60 Gy. Results: Fifty patients had complete lung SPECT/CT perfusion data available. No patient developed symptoms consistent with pulmonary toxicity. Nearly all patients demonstrated decreased perfusion in the left lung according to voxel-based analyses. The average ratio of lung perfusion deficits increased for each 10-Gy increment in radiation dose to the lung, with the largest changes in regions of lung that received 50 to 60 Gy (ratio 0.72 [95% confidence interval 0.64-0.79], P<.001) compared with the 0- to 10-Gy region. For each increase in 10 Gy to the left lung, the lung perfusion ratio decreased by 0.06 (P<.001). Conclusions: In the assessment of 50 patients with node-positive breast cancer treated with RT in a prospective clinical trial, decreased lung perfusion by SPECT/CT was demonstrated. Our study allowed for quantification of lung perfusion defects in a prospective cohort of breast cancer patients for whom attenuation-corrected SPECT/CT scans could be registered directly to RT treatment fields for precise dose estimates.« less

Mesenchymal Stem Cells from Fetal Heart Attenuate Myocardial Injury after Infarction: An In Vivo Serial Pinhole Gated SPECT-CT Study in Rats

PubMed Central

Garikipati, Venkata Naga Srikanth; Jadhav, Sachin; Pal, Lily; Prakash, Prem; Dikshit, Madhu; Nityanand, Soniya

2014-01-01

Mesenchymal stem cells (MSC) have emerged as a potential stem cell type for cardiac regeneration after myocardial infarction (MI). Recently, we isolated and characterized mesenchymal stem cells derived from rat fetal heart (fC-MSC), which exhibited potential to differentiate into cardiomyocytes, endothelial cells and smooth muscle cells in vitro. In the present study, we investigated the therapeutic efficacy of intravenously injected fC-MSC in a rat model of MI using multi-pinhole gated SPECT-CT system. fC-MSC were isolated from the hearts of Sprague Dawley (SD) rat fetuses at gestation day 16 and expanded ex vivo. One week after induction of MI, 2×106 fC-MSC labeled with PKH26 dye (n = 6) or saline alone (n = 6) were injected through the tail vein of the rats. Initial in vivo tracking of 99mTc-labeled fC-MSC revealed a focal uptake of cells in the anterior mid-ventricular region of the heart. At 4 weeks of fC-MSC administration, the cells labeled with PKH26 were located in abundance in infarct/peri-infarct region and the fC-MSC treated hearts showed a significant increase in left ventricular ejection fraction and a significant decrease in the end diastolic volume, end systolic volume and left ventricular myo-mass in comparison to the saline treated group. In addition, fC-MSC treated hearts had a significantly better myocardial perfusion and attenuation in the infarct size, in comparison to the saline treated hearts. The engrafted PKH26-fC-MSC expressed cardiac troponin T, endothelial CD31 and smooth muscle sm-MHC, suggesting their differentiation into all major cells of cardiovascular lineage. The fC-MSC treated hearts demonstrated an up-regulation of cardio-protective growth factors, anti-fibrotic and anti-apoptotic molecules, highlighting that the observed left ventricular functional recovery may be due to secretion of paracrine factors by fC-MSC. Taken together, our results suggest that fC-MSC therapy may be a new therapeutic strategy for MI and multi-pinhole gated SPECT-CT system may be a useful tool to evaluate cardiac perfusion, function and cell tracking after stem cell therapy in acute myocardial injury setting. PMID:24971627

Evaluating low pass filters on SPECT reconstructed cardiac orientation estimation

NASA Astrophysics Data System (ADS)

Dwivedi, Shekhar

2009-02-01

Low pass filters can affect the quality of clinical SPECT images by smoothing. Appropriate filter and parameter selection leads to optimum smoothing that leads to a better quantification followed by correct diagnosis and accurate interpretation by the physician. This study aims at evaluating the low pass filters on SPECT reconstruction algorithms. Criteria for evaluating the filters are estimating the SPECT reconstructed cardiac azimuth and elevation angle. Low pass filters studied are butterworth, gaussian, hamming, hanning and parzen. Experiments are conducted using three reconstruction algorithms, FBP (filtered back projection), MLEM (maximum likelihood expectation maximization) and OSEM (ordered subsets expectation maximization), on four gated cardiac patient projections (two patients with stress and rest projections). Each filter is applied with varying cutoff and order for each reconstruction algorithm (only butterworth used for MLEM and OSEM). The azimuth and elevation angles are calculated from the reconstructed volume and the variation observed in the angles with varying filter parameters is reported. Our results demonstrate that behavior of hamming, hanning and parzen filter (used with FBP) with varying cutoff is similar for all the datasets. Butterworth filter (cutoff > 0.4) behaves in a similar fashion for all the datasets using all the algorithms whereas with OSEM for a cutoff < 0.4, it fails to generate cardiac orientation due to oversmoothing, and gives an unstable response with FBP and MLEM. This study on evaluating effect of low pass filter cutoff and order on cardiac orientation using three different reconstruction algorithms provides an interesting insight into optimal selection of filter parameters.

An Adaptation of the Distance Driven Projection Method for Single Pinhole Collimators in SPECT Imaging

NASA Astrophysics Data System (ADS)

Ihsani, Alvin; Farncombe, Troy

2016-02-01

The modelling of the projection operator in tomographic imaging is of critical importance especially when working with algebraic methods of image reconstruction. This paper proposes a distance-driven projection method which is targeted to single-pinhole single-photon emission computed tomograghy (SPECT) imaging since it accounts for the finite size of the pinhole, and the possible tilting of the detector surface in addition to other collimator-specific factors such as geometric sensitivity. The accuracy and execution time of the proposed method is evaluated by comparing to a ray-driven approach where the pinhole is sub-sampled with various sampling schemes. A point-source phantom whose projections were generated using OpenGATE was first used to compare the resolution of reconstructed images with each method using the full width at half maximum (FWHM). Furthermore, a high-activity Mini Deluxe Phantom (Data Spectrum Corp., Durham, NC, USA) SPECT resolution phantom was scanned using a Gamma Medica X-SPECT system and the signal-to-noise ratio (SNR) and structural similarity of reconstructed images was compared at various projection counts. Based on the reconstructed point-source phantom, the proposed distance-driven approach results in a lower FWHM than the ray-driven approach even when using a smaller detector resolution. Furthermore, based on the Mini Deluxe Phantom, it is shown that the distance-driven approach has consistently higher SNR and structural similarity compared to the ray-driven approach as the counts in measured projections deteriorates.

Quantitative evaluation improves specificity of myocardial perfusion SPECT in the assessment of functionally significant intermediate coronary artery stenoses: a comparative study with fractional flow reserve measurements.

PubMed

Sahiner, Ilgin; Akdemir, Umit O; Kocaman, Sinan A; Sahinarslan, Asife; Timurkaynak, Timur; Unlu, Mustafa

2013-02-01

Myocardial perfusion SPECT (MPS) is a noninvasive method commonly used for assessment of the hemodynamic significance of intermediate coronary stenoses. Fractional flow reserve (FFR) measurement is a well-validated invasive method used for the evaluation of intermediate stenoses. We aimed to determine the association between MPS and FFR findings in intermediate degree stenoses and evaluate the added value of quantification in MPS. Fifty-eight patients who underwent intracoronary pressure measurement in the catheterization laboratory to assess the physiological significance of intermediate (40-70%) left anterior descending (LAD) artery lesions, and who also underwent stress myocardial perfusion SPECT either for the assessment of an intermediate stenosis or for suspected coronary artery disease were analyzed retrospectively in the study. Quantitative analysis was performed using the 4DMSPECT program, with visual assessment performed by two experienced nuclear medicine physicians blinded to the angiographic findings. Summed stress scores (SSS) and summed difference scores (SDS) in the LAD artery territory according to the 20 segment model were calculated. A summed stress score of ≥ 3 and an SDS of ≥ 2 were assumed as pathologic, indicating significance of the lesion; a cutoff value of 0.75 was used to define abnormal FFR. Both visual and quantitative assessment results were compared with FFR using Chi-square (χ²) test. The mean time interval between two studies was 13 ± 11 days. FFR was normal in 45 and abnormal in 13 patients. Considering the FFR results as the gold standard method for assessing the significance of the lesion, the sensitivity and specificity of quantitative analysis determining the abnormal flow reserve were 85 and 84%, respectively, while visual analysis had a sensitivity of 77% and a specificity of 51%. There was a good agreement between the observers (κ = 0.856). Summed stress and difference scores demonstrated moderate inverse correlations with FFR values (r = -0.542, p < 0.001 and r = -0.506, p < 0.001, respectively). Quantitative analysis of the myocardial perfusion SPECT increases the specificity in evaluating the significance of intermediate degree coronary lesions.

Technetium-99m-HMPAO SPECT, CT and MRI in the evaluation of patients with chronic traumatic brain injury: a correlation with neuropsychological performance.

PubMed

Ichise, M; Chung, D G; Wang, P; Wortzman, G; Gray, B G; Franks, W

1994-02-01

The purposes of this study were: (1) to compare 99mTc-hexamethylpropyleneamineoxime (HMPAO) SPECT with CT and MRI in chronic traumatic brain injury (TBI) patients and (2) to correlate both functional and structural neuroimaging measurements of brain damage with neuropsychological (NP) performance. Twenty-nine patients (minor TBI, n = 15 and major TBI, n = 14) and 17 normal controls (NC) underwent HMPAO SPECT, CT, MRI and NP testing. Imaging data were analyzed both visually and quantitatively. Nineteen (66%) patients showed 42 abnormalities on SPECT images, whereas 13 (45%) and 10 (34%) patients showed 29 abnormalities on MRI and 24 abnormalities on CT. SPECT detected relatively more abnormalities than CT or MRI in the minor TBI subgroup. The TBI group showed impairment on 11 tests for memory, attention and executive function. Of these, the anterior-posterior ratio (APR) correlated with six tests, whereas the ventricle-to-brain ratio (VBR), a known structural index of a poor NP outcome, correlated with only two tests. In evaluating chronic TBI patients, HMPAO SPECT, as a complement to CT or MRI, may play a useful role by demonstrating brain dysfunction in morphologically intact brain regions and providing objective evidence for some of the impaired NP performance.

Quantitative cardiac SPECT reconstruction with reduced image degradation due to patient anatomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsui, B.M.W.; Zhao, X.D.; Gregoriou, G.K.

1994-12-01

Patient anatomy has complicated effects on cardiac SPECT images. The authors investigated reconstruction methods which substantially reduced these effects for improved image quality. A 3D mathematical cardiac-torso (MCAT) phantom which models the anatomical structures in the thorax region were used in the study. The phantom was modified to simulate variations in patient anatomy including regions of natural thinning along the myocardium, body size, diaphragmatic shape, gender, and size and shape of breasts for female patients. Distributions of attenuation coefficients and Tl-201 uptake in different organs in a normal patient were also simulated. Emission projection data were generated from the phantomsmore » including effects of attenuation and detector response. The authors have observed the attenuation-induced artifacts caused by patient anatomy in the conventional FBP reconstructed images. Accurate attenuation compensation using iterative reconstruction algorithms and attenuation maps substantially reduced the image artifacts and improved quantitative accuracy. They conclude that reconstruction methods which accurately compensate for non-uniform attenuation can substantially reduce image degradation caused by variations in patient anatomy in cardiac SPECT.« less

Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects.

PubMed

Matsuo, Shinro; Nakajima, Kenichi; Onoguchi, Masahisa; Wakabayash, Hiroshi; Okuda, Koichi; Kinuya, Seigo

2015-06-01

A novel multifocal collimator, IQ-SPECT (Siemens) consists of SMARTZOOM, cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ((201)Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging. Forty patients (eight women, mean age of 75 years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administering (201)Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal SMARTZOOM collimator. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT). Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all myocardial perfusion images. A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software. IQ-SPECT provided good or excellent image quality. The quality of IQ-SPECT images without AC was similar to those of conventional LEHR study. Mid-inferior defect score (0.3 ± 0.5) in the conventional LEHR study was increased significantly in IQ-SPECT with AC (0 ± 0). IQ-SPECT with AC improved the mid-inferior decreased perfusion shown in conventional images. The apical tracer count in IQ-SPECT with AC was decreased compared to that in LEHR (0.1 ± 0.3 vs. 0.5 ± 0.7, p < 0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p = 0.0009). The images of IQ-SPECT acquired in a short time are equivalent to that of conventional LEHR. The results indicated that the IQ-SPECT system with AC is capable of correcting inferior artifacts with high image quality.

Quantification of the spatial distribution of rectally applied surrogates for microbicide and semen in colon with SPECT and magnetic resonance imaging

PubMed Central

Cao, Ying J; Caffo, Brian S; Fuchs, Edward J; Lee, Linda A; Du, Yong; Li, Liye; Bakshi, Rahul P; Macura, Katarzyna; Khan, Wasif A; Wahl, Richard L; Grohskopf, Lisa A; Hendrix, Craig W

2012-01-01

AIMS We sought to describe quantitatively the distribution of rectally administered gels and seminal fluid surrogates using novel concentration–distance parameters that could be repeated over time. These methods are needed to develop rationally rectal microbicides to target and prevent HIV infection. METHODS Eight subjects were dosed rectally with radiolabelled and gadolinium-labelled gels to simulate microbicide gel and seminal fluid. Rectal doses were given with and without simulated receptive anal intercourse. Twenty-four hour distribution was assessed with indirect single photon emission computed tomography (SPECT)/computed tomography (CT) and magnetic resonance imaging (MRI), and direct assessment via sigmoidoscopic brushes. Concentration–distance curves were generated using an algorithm for fitting SPECT data in three dimensions. Three novel concentration–distance parameters were defined to describe quantitatively the distribution of radiolabels: maximal distance (Dmax), distance at maximal concentration (DCmax) and mean residence distance (Dave). RESULTS The SPECT/CT distribution of microbicide and semen surrogates was similar. Between 1 h and 24 h post dose, the surrogates migrated retrograde in all three parameters (relative to coccygeal level; geometric mean [95% confidence interval]): maximal distance (Dmax), 10 cm (8.6–12) to 18 cm (13–26), distance at maximal concentration (DCmax), 3.8 cm (2.7–5.3) to 4.2 cm (2.8–6.3) and mean residence distance (Dave), 4.3 cm (3.5–5.1) to 7.6 cm (5.3–11). Sigmoidoscopy and MRI correlated only roughly with SPECT/CT. CONCLUSIONS Rectal microbicide surrogates migrated retrograde during the 24 h following dosing. Spatial kinetic parameters estimated using three dimensional curve fitting of distribution data should prove useful for evaluating rectal formulations of drugs for HIV prevention and other indications. PMID:22404308

High-resolution clustered pinhole (131)Iodine SPECT imaging in mice.

PubMed

van der Have, Frans; Ivashchenko, Oleksandra; Goorden, Marlies C; Ramakers, Ruud M; Beekman, Freek J

2016-08-01

High-resolution pre-clinical (131)I SPECT can facilitate development of new radioiodine therapies for cancer. To this end, it is important to limit resolution-degrading effects of pinhole edge penetration by the high-energy γ-photons of iodine. Here we introduce, optimize and validate (131)I SPECT performed with a dedicated high-energy clustered multi-pinhole collimator. A SPECT-CT system (VECTor/CT) with stationary gamma-detectors was equipped with a tungsten collimator with clustered pinholes. Images were reconstructed with pixel-based OSEM, using a dedicated (131)I system matrix that models the distance- and energy-dependent resolution and sensitivity of each pinhole, as well as the intrinsic detector blurring and variable depth of interaction in the detector. The system performance was characterized with phantoms and in vivo static and dynamic (131)I-NaI scans of mice. Reconstructed image resolution reached 0.6mm, while quantitative accuracy measured with a (131)I filled syringe reaches an accuracy of +3.6±3.5% of the gold standard value. In vivo mice scans illustrated a clear shape of the thyroid and biodistribution of (131)I within the animal. Pharmacokinetics of (131)I was assessed with 15-s time frames from the sequence of dynamic images and time-activity curves of (131)I-NaI. High-resolution quantitative and fast dynamic (131)I SPECT in mice is possible by means of a high-energy collimator and optimized system modeling. This enables analysis of (131)I uptake even within small organs in mice, which can be highly valuable for development and optimization of targeted cancer therapies. Copyright © 2016 Elsevier Inc. All rights reserved.

Y-90 SPECT ML image reconstruction with a new model for tissue-dependent bremsstrahlung production using CT information: a proof-of-concept study

NASA Astrophysics Data System (ADS)

Lim, Hongki; Fessler, Jeffrey A.; Wilderman, Scott J.; Brooks, Allen F.; Dewaraja, Yuni K.

2018-06-01

While the yield of positrons used in Y-90 PET is independent of tissue media, Y-90 SPECT imaging is complicated by the tissue dependence of bremsstrahlung photon generation. The probability of bremsstrahlung production is proportional to the square of the atomic number of the medium. Hence, the same amount of activity in different tissue regions of the body will produce different numbers of bremsstrahlung photons. Existing reconstruction methods disregard this tissue-dependency, potentially impacting both qualitative and quantitative imaging of heterogeneous regions of the body such as bone with marrow cavities. In this proof-of-concept study, we propose a new maximum-likelihood method that incorporates bremsstrahlung generation probabilities into the system matrix, enabling images of the desired Y-90 distribution to be reconstructed instead of the ‘bremsstrahlung distribution’ that is obtained with existing methods. The tissue-dependent probabilities are generated by Monte Carlo simulation while bone volume fractions for each SPECT voxel are obtained from co-registered CT. First, we demonstrate the tissue dependency in a SPECT/CT imaging experiment with Y-90 in bone equivalent solution and water. Visually, the proposed reconstruction approach better matched the true image and the Y-90 PET image than the standard bremsstrahlung reconstruction approach. An XCAT phantom simulation including bone and marrow regions also demonstrated better agreement with the true image using the proposed reconstruction method. Quantitatively, compared with the standard reconstruction, the new method improved estimation of the liquid bone:water activity concentration ratio by 40% in the SPECT measurement and the cortical bone:marrow activity concentration ratio by 58% in the XCAT simulation.

G-CSF treatment after myocardial infarction: impact on bone marrow-derived vs cardiac progenitor cells.

PubMed

Brunner, Stefan; Huber, Bruno C; Fischer, Rebekka; Groebner, Michael; Hacker, Marcus; David, Robert; Zaruba, Marc-Michael; Vallaster, Marcus; Rischpler, Christoph; Wilke, Andrea; Gerbitz, Armin; Franz, Wolfgang-Michael

2008-06-01

Besides its classical function in the field of autologous and allogenic stem cell transplantation, granulocyte colony-stimulating factor (G-CSF) was shown to have protective effects after myocardial infarction (MI) by mobilization of bone marrow-derived progenitor cells (BMCs) and in addition by activation of multiple signaling pathways. In the present study, we focused on the impact of G-CSF on migration of BMCs and the impact on resident cardiac cells after MI. Mice (C57BL/6J) were sublethally irradiated, and BM from green fluorescent protein (GFP)-transgenic mice was transplanted. Coronary artery ligation was performed 10 weeks later. G-CSF (100 microg/kg) was daily injected for 6 days. Subpopulations of enhanced GFP(+) cells in peripheral blood, bone marrow, and heart were characterized by flow cytometry. Growth factor expression in the heart was analyzed by quantitative real-time polymerase chain reaction. Perfusion was investigated in vivo by gated single photon emission computed tomography (SPECT). G-CSF-treated animals revealed a reduced migration of c-kit(+) and CXCR-4(+) BMCs associated with decreased expression levels of the corresponding growth factors, namely stem cell factor and stromal-derived factor-1 alpha in ischemic myocardium. In contrast, the number of resident cardiac Sca-1(+) cells was significantly increased. However, SPECT-perfusion showed no differences in infarct size between G-CSF-treated and control animals 6 days after MI. Our study shows that G-CSF treatment after MI reduces migration capacity of BMCs into ischemic tissue, but increases the number of resident cardiac cells. To optimize homing capacity a combination of G-CSF with other agents may optimize cytokine therapy after MI.

Comparison of TOF-PET and Bremsstrahlung SPECT Images of Yttrium-90: A Monte Carlo Simulation Study.

PubMed

Takahashi, Akihiko; Himuro, Kazuhiko; Baba, Shingo; Yamashita, Yasuo; Sasaki, Masayuki

2018-01-01

Yttrium-90 ( 90 Y) is a beta particle nuclide used in targeted radionuclide therapy which is available to both single-photon emission computed tomography (SPECT) and time-of-flight (TOF) positron emission tomography (PET) imaging. The purpose of this study was to assess the image quality of PET and Bremsstrahlung SPECT by simulating PET and SPECT images of 90 Y using Monte Carlo simulation codes under the same conditions and to compare them. In-house Monte Carlo codes, MCEP-PET and MCEP-SPECT, were employed to simulate images. The phantom was a torso-shaped phantom containing six hot spheres of various sizes. The background concentrations of 90 Y were set to 50, 100, 150, and 200 kBq/mL, and the concentrations of the hot spheres were 10, 20, and 40 times of those of the background concentrations. The acquisition time was set to 30 min, and the simulated sinogram data were reconstructed using the ordered subset expectation maximization method. The contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR) were employed to evaluate the image qualities. The CRC values of SPECT images were less than 40%, while those of PET images were more than 40% when the hot sphere was larger than 20 mm in diameter. The CNR values of PET images of hot spheres of diameter smaller than 20 mm were larger than those of SPECT images. The CNR values mostly exceeded 4, which is a criterion to evaluate the discernibility of hot areas. In the case of SPECT, hot spheres of diameter smaller than 20 mm were not discernable. On the contrary, the CNR values of PET images decreased to the level of SPECT, in the case of low concentration. In almost all the cases examined in this investigation, the quantitative indexes of TOF-PET 90 Y images were better than those of Bremsstrahlung SPECT images. However, the superiority of PET image became critical in the case of low activity concentrations.

Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV.

PubMed

Maigne, L; Perrot, Y; Schaart, D R; Donnarieix, D; Breton, V

2011-02-07

The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV.

Brain regions associated with cognitive impairment in patients with Parkinson disease: quantitative analysis of cerebral blood flow using 123I iodoamphetamine SPECT.

PubMed

Hattori, Naoya; Yabe, Ichiro; Hirata, Kenji; Shiga, Tohru; Sakushima, Ken; Tsuji-Akimoto, Sachiko; Sasaki, Hidenao; Tamaki, Nagara

2013-05-01

Cognitive impairment is a representative neuropsychiatric presentation that accompanies Parkinson disease (PD). The purpose of this study was to localize the cerebral regions associated with cognitive impairment in patients with PD using quantitative SPECT. Thirty-two patients with PD (mean [SD] age, 75 [8] years; 25 women; Hoehn-Yahr scores from 2 to 5) underwent quantitative brain SPECT using 123I iodoamphetamine. Parametric images of regional cerebral blood flow (rCBF) were spatially normalized to the standard brain atlas. First, voxel-by-voxel comparison between patients with PD with versus without cognitive impairment was performed to visualize overall trend of regional differences. Next, the individual quantitative rCBF values were extracted in representative cortical regions using a standard region-of-interest template to compare the quantitative rCBF values. Patients with cognitive impairment showed trends of lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices in the voxel-by-voxel analyses. Region-of-interest-based analysis demonstrated significantly lower rCBF in the bilateral anterior cingulate cortices (right, 25.8 [5.5] vs 28.9 [5.7] mL per 100 g/min, P < 0.05; left, 25.8 [5.8] vs 29.1 [5.7] mL per 100 g/min, P < 0.05) associated with cognitive impairment. Patients with cognitive impairment showed lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices. The results suggested dysexecutive function as an underlining mechanism of cognitive impairment in patients with PD.

Correction of nonuniform attenuation and image fusion in SPECT imaging by means of separate X-ray CT.

PubMed

Kashiwagi, Toru; Yutani, Kenji; Fukuchi, Minoru; Naruse, Hitoshi; Iwasaki, Tadaaki; Yokozuka, Koichi; Inoue, Shinichi; Kondo, Shoji

2002-06-01

Improvements in image quality and quantitation measurement, and the addition of detailed anatomical structures are important topics for single-photon emission tomography (SPECT). The goal of this study was to develop a practical system enabling both nonuniform attenuation correction and image fusion of SPECT images by means of high-performance X-ray computed tomography (CT). A SPECT system and a helical X-ray CT system were placed next to each other and linked with Ethernet. To avoid positional differences between the SPECT and X-ray CT studies, identical flat patient tables were used for both scans; body distortion was minimized with laser beams from the upper and lateral directions to detect the position of the skin surface. For the raw projection data of SPECT, a scatter correction was performed with the triple energy window method. Image fusion of the X-ray CT and SPECT images was performed automatically by auto-registration of fiducial markers attached to the skin surface. After registration of the X-ray CT and SPECT images, an X-ray CT-derived attenuation map was created with the calibration curve for 99mTc. The SPECT images were then reconstructed with scatter and attenuation correction by means of a maximum likelihood expectation maximization algorithm. This system was evaluated in torso and cylindlical phantoms and in 4 patients referred for myocardial SPECT imaging with Tc-99m tetrofosmin. In the torso phantom study, the SPECT and X-ray CT images overlapped exactly on the computer display. After scatter and attenuation correction, the artifactual activity reduction in the inferior wall of the myocardium improved. Conversely, the incresed activity around the torso surface and the lungs was reduced. In the abdomen, the liver activity, which was originally uniform, had recovered after scatter and attenuation correction processing. The clinical study also showed good overlapping of cardiac and skin surface outlines on the fused SPECT and X-ray CT images. The effectiveness of the scatter and attenuation correction process was similar to that observed in the phantom study. Because the total time required for computer processing was less than 10 minutes, this method of attenuation correction and image fusion for SPECT images is expected to become popular in clinical practice.

Improvement of Cerebral Hypoperfusion with Levothyroxine Therapy in Hashimoto's Encephalopathy Demonstrated by 99mTc-HMPAO-SPECT

PubMed Central

Schnedl, Wolfgang J.; Mirzaei, Siroos; Wallner-Liebmann, Sandra J.; Tafeit, Erwin; Mangge, Harald; Krause, Robert; Lipp, Rainer W.

2013-01-01

Background Hashimoto's encephalopathy (HE) is a rare immune-mediated encephalopathy associated with autoimmune Hashimoto's thyroiditis. Objectives and Methods We report on a patient with HE and significant clinical improvement correlating with an increase in cerebral blood flow demonstrated by hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT). HMPAO-SPECT was performed with 740 MBq of technetium-99m-HMPAO. To demonstrate the improvement in regional cerebral blood flow, individual regions of interest were drawn around visually diminished HMPAO uptake, the lesion to reference region ratio was calculated and transverse section images and semi-quantitative measurements were performed. Results We show a 5-year follow-up with significant clinical improvement, a 10-fold reduction in autoantibodies to thyroid peroxidase and an approximately 20% improvement in cerebral blood flow with HMPAO-SPECT. Conclusion Adequate levothyroxine treatment achieving and maintaining euthyroidism should be considered as therapy to lower autoantibodies and improve clinical outcome in patients with Hashimoto's thyroiditis and encephalopathy. PMID:24783049

Novel SPECT Technologies and Approaches in Cardiac Imaging

PubMed Central

Slomka, Piotr; Hung, Guang-Uei; Germano, Guido; Berman, Daniel S.

2017-01-01

Recent novel approaches in myocardial perfusion single photon emission CT (SPECT) have been facilitated by new dedicated high-efficiency hardware with solid-state detectors and optimized collimators. New protocols include very low-dose (1 mSv) stress-only, two-position imaging to mitigate attenuation artifacts, and simultaneous dual-isotope imaging. Attenuation correction can be performed by specialized low-dose systems or by previously obtained CT coronary calcium scans. Hybrid protocols using CT angiography have been proposed. Image quality improvements have been demonstrated by novel reconstructions and motion correction. Fast SPECT acquisition facilitates dynamic flow and early function measurements. Image processing algorithms have become automated with virtually unsupervised extraction of quantitative imaging variables. This automation facilitates integration with clinical variables derived by machine learning to predict patient outcome or diagnosis. In this review, we describe new imaging protocols made possible by the new hardware developments. We also discuss several novel software approaches for the quantification and interpretation of myocardial perfusion SPECT scans. PMID:29034066

Development and validation of technique for in-vivo 3D analysis of cranial bone graft survival

NASA Astrophysics Data System (ADS)

Bernstein, Mark P.; Caldwell, Curtis B.; Antonyshyn, Oleh M.; Ma, Karen; Cooper, Perry W.; Ehrlich, Lisa E.

1997-05-01

Bone autografts are routinely employed in the reconstruction of facial deformities resulting from trauma, tumor ablation or congenital malformations. The combined use of post- operative 3D CT and SPECT imaging provides a means for quantitative in vivo evaluation of bone graft volume and osteoblastic activity. The specific objectives of this study were: (1) Determine the reliability and accuracy of interactive computer-assisted analysis of bone graft volumes based on 3D CT scans; (2) Determine the error in CT/SPECT multimodality image registration; (3) Determine the error in SPECT/SPECT image registration; and (4) Determine the reliability and accuracy of CT-guided SPECT uptake measurements in cranial bone grafts. Five human cadaver heads served as anthropomorphic models for all experiments. Four cranial defects were created in each specimen with inlay and onlay split skull bone grafts and reconstructed to skull and malar recipient sites. To acquire all images, each specimen was CT scanned and coated with Technetium doped paint. For purposes of validation, skulls were landmarked with 1/16-inch ball-bearings and Indium. This study provides a new technique relating anatomy and physiology for the analysis of cranial bone graft survival.

Using normalization 3D model for automatic clinical brain quantative analysis and evaluation

NASA Astrophysics Data System (ADS)

Lin, Hong-Dun; Yao, Wei-Jen; Hwang, Wen-Ju; Chung, Being-Tau; Lin, Kang-Ping

2003-05-01

Functional medical imaging, such as PET or SPECT, is capable of revealing physiological functions of the brain, and has been broadly used in diagnosing brain disorders by clinically quantitative analysis for many years. In routine procedures, physicians manually select desired ROIs from structural MR images and then obtain physiological information from correspondent functional PET or SPECT images. The accuracy of quantitative analysis thus relies on that of the subjectively selected ROIs. Therefore, standardizing the analysis procedure is fundamental and important in improving the analysis outcome. In this paper, we propose and evaluate a normalization procedure with a standard 3D-brain model to achieve precise quantitative analysis. In the normalization process, the mutual information registration technique was applied for realigning functional medical images to standard structural medical images. Then, the standard 3D-brain model that shows well-defined brain regions was used, replacing the manual ROIs in the objective clinical analysis. To validate the performance, twenty cases of I-123 IBZM SPECT images were used in practical clinical evaluation. The results show that the quantitative analysis outcomes obtained from this automated method are in agreement with the clinical diagnosis evaluation score with less than 3% error in average. To sum up, the method takes advantage of obtaining precise VOIs, information automatically by well-defined standard 3-D brain model, sparing manually drawn ROIs slice by slice from structural medical images in traditional procedure. That is, the method not only can provide precise analysis results, but also improve the process rate for mass medical images in clinical.

TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Marie-Paule, E-mail: marie-paule.garcia@univ-brest.fr; Villoing, Daphnée; McKay, Erin

Purpose: The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. Methods: The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of amore » given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit GATE offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on GATE to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user’s imaging requirements and generates automatically command files used as input for GATE. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant GATE input files are generated for the virtual patient model and associated pharmacokinetics. Results: Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body “step and shoot” acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry computation performed on the ICRP 110 model is also presented. Conclusions: The proposed platform offers a generic framework to implement any scintigraphic imaging protocols and voxel/organ-based dosimetry computation. Thanks to the modular nature of TestDose, other imaging modalities could be supported in the future such as positron emission tomography.« less

TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry.

PubMed

Garcia, Marie-Paule; Villoing, Daphnée; McKay, Erin; Ferrer, Ludovic; Cremonesi, Marta; Botta, Francesca; Ferrari, Mahila; Bardiès, Manuel

2015-12-01

The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of a given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit gate offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on gate to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user's imaging requirements and generates automatically command files used as input for gate. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant gate input files are generated for the virtual patient model and associated pharmacokinetics. Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body "step and shoot" acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry computation performed on the ICRP 110 model is also presented. The proposed platform offers a generic framework to implement any scintigraphic imaging protocols and voxel/organ-based dosimetry computation. Thanks to the modular nature of TestDose, other imaging modalities could be supported in the future such as positron emission tomography.

Performance evaluation of a novel high performance pinhole array detector module using NEMA NU-4 image quality phantom for four head SPECT Imaging

NASA Astrophysics Data System (ADS)

Rahman, Tasneem; Tahtali, Murat; Pickering, Mark R.

2015-03-01

Radiolabeled tracer distribution imaging of gamma rays using pinhole collimation is considered promising for small animal imaging. The recent availability of various radiolabeled tracers has enhanced the field of diagnostic study and is simultaneously creating demand for high resolution imaging devices. This paper presents analyses to represent the optimized parameters of a high performance pinhole array detector module using two different characteristics phantoms. Monte Carlo simulations using the Geant4 application for tomographic emission (GATE) were executed to assess the performance of a four head SPECT system incorporated with pinhole array collimators. The system is based on a pixelated array of NaI(Tl) crystals coupled to an array of position sensitive photomultiplier tubes (PSPMTs). The detector module was simulated to have 48 mm by 48 mm active area along with different pinhole apertures on a tungsten plate. The performance of this system has been evaluated using a uniform shape cylindrical water phantom along with NEMA NU-4 image quality (IQ) phantom filled with 99mTc labeled radiotracers. SPECT images were reconstructed where activity distribution is expected to be well visualized. This system offers the combination of an excellent intrinsic spatial resolution, good sensitivity and signal-to-noise ratio along with high detection efficiency over an energy range between 20-160 keV. Increasing number of heads in a stationary system configuration offers increased sensitivity at a spatial resolution similar to that obtained with the current SPECT system design with four heads.

Development and optimization of SPECT gated blood pool cluster analysis for the prediction of CRT outcome.

PubMed

Lalonde, Michel; Wells, R Glenn; Birnie, David; Ruddy, Terrence D; Wassenaar, Richard

2014-07-01

Phase analysis of single photon emission computed tomography (SPECT) radionuclide angiography (RNA) has been investigated for its potential to predict the outcome of cardiac resynchronization therapy (CRT). However, phase analysis may be limited in its potential at predicting CRT outcome as valuable information may be lost by assuming that time-activity curves (TAC) follow a simple sinusoidal shape. A new method, cluster analysis, is proposed which directly evaluates the TACs and may lead to a better understanding of dyssynchrony patterns and CRT outcome. Cluster analysis algorithms were developed and optimized to maximize their ability to predict CRT response. About 49 patients (N = 27 ischemic etiology) received a SPECT RNA scan as well as positron emission tomography (PET) perfusion and viability scans prior to undergoing CRT. A semiautomated algorithm sampled the left ventricle wall to produce 568 TACs from SPECT RNA data. The TACs were then subjected to two different cluster analysis techniques, K-means, and normal average, where several input metrics were also varied to determine the optimal settings for the prediction of CRT outcome. Each TAC was assigned to a cluster group based on the comparison criteria and global and segmental cluster size and scores were used as measures of dyssynchrony and used to predict response to CRT. A repeated random twofold cross-validation technique was used to train and validate the cluster algorithm. Receiver operating characteristic (ROC) analysis was used to calculate the area under the curve (AUC) and compare results to those obtained for SPECT RNA phase analysis and PET scar size analysis methods. Using the normal average cluster analysis approach, the septal wall produced statistically significant results for predicting CRT results in the ischemic population (ROC AUC = 0.73;p < 0.05 vs. equal chance ROC AUC = 0.50) with an optimal operating point of 71% sensitivity and 60% specificity. Cluster analysis results were similar to SPECT RNA phase analysis (ROC AUC = 0.78, p = 0.73 vs cluster AUC; sensitivity/specificity = 59%/89%) and PET scar size analysis (ROC AUC = 0.73, p = 1.0 vs cluster AUC; sensitivity/specificity = 76%/67%). A SPECT RNA cluster analysis algorithm was developed for the prediction of CRT outcome. Cluster analysis results produced results equivalent to those obtained from Fourier and scar analysis.

Development and optimization of SPECT gated blood pool cluster analysis for the prediction of CRT outcome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalonde, Michel, E-mail: mlalonde15@rogers.com; Wassenaar, Richard; Wells, R. Glenn

2014-07-15

Purpose: Phase analysis of single photon emission computed tomography (SPECT) radionuclide angiography (RNA) has been investigated for its potential to predict the outcome of cardiac resynchronization therapy (CRT). However, phase analysis may be limited in its potential at predicting CRT outcome as valuable information may be lost by assuming that time-activity curves (TAC) follow a simple sinusoidal shape. A new method, cluster analysis, is proposed which directly evaluates the TACs and may lead to a better understanding of dyssynchrony patterns and CRT outcome. Cluster analysis algorithms were developed and optimized to maximize their ability to predict CRT response. Methods: Aboutmore » 49 patients (N = 27 ischemic etiology) received a SPECT RNA scan as well as positron emission tomography (PET) perfusion and viability scans prior to undergoing CRT. A semiautomated algorithm sampled the left ventricle wall to produce 568 TACs from SPECT RNA data. The TACs were then subjected to two different cluster analysis techniques, K-means, and normal average, where several input metrics were also varied to determine the optimal settings for the prediction of CRT outcome. Each TAC was assigned to a cluster group based on the comparison criteria and global and segmental cluster size and scores were used as measures of dyssynchrony and used to predict response to CRT. A repeated random twofold cross-validation technique was used to train and validate the cluster algorithm. Receiver operating characteristic (ROC) analysis was used to calculate the area under the curve (AUC) and compare results to those obtained for SPECT RNA phase analysis and PET scar size analysis methods. Results: Using the normal average cluster analysis approach, the septal wall produced statistically significant results for predicting CRT results in the ischemic population (ROC AUC = 0.73;p < 0.05 vs. equal chance ROC AUC = 0.50) with an optimal operating point of 71% sensitivity and 60% specificity. Cluster analysis results were similar to SPECT RNA phase analysis (ROC AUC = 0.78, p = 0.73 vs cluster AUC; sensitivity/specificity = 59%/89%) and PET scar size analysis (ROC AUC = 0.73, p = 1.0 vs cluster AUC; sensitivity/specificity = 76%/67%). Conclusions: A SPECT RNA cluster analysis algorithm was developed for the prediction of CRT outcome. Cluster analysis results produced results equivalent to those obtained from Fourier and scar analysis.« less

Clinical evaluation of reducing acquisition time on single-photon emission computed tomography image quality using proprietary resolution recovery software.

PubMed

Aldridge, Matthew D; Waddington, Wendy W; Dickson, John C; Prakash, Vineet; Ell, Peter J; Bomanji, Jamshed B

2013-11-01

A three-dimensional model-based resolution recovery (RR) reconstruction algorithm that compensates for collimator-detector response, resulting in an improvement in reconstructed spatial resolution and signal-to-noise ratio of single-photon emission computed tomography (SPECT) images, was tested. The software is said to retain image quality even with reduced acquisition time. Clinically, any improvement in patient throughput without loss of quality is to be welcomed. Furthermore, future restrictions in radiotracer supplies may add value to this type of data analysis. The aims of this study were to assess improvement in image quality using the software and to evaluate the potential of performing reduced time acquisitions for bone and parathyroid SPECT applications. Data acquisition was performed using the local standard SPECT/CT protocols for 99mTc-hydroxymethylene diphosphonate bone and 99mTc-methoxyisobutylisonitrile parathyroid SPECT imaging. The principal modification applied was the acquisition of an eight-frame gated data set acquired using an ECG simulator with a fixed signal as the trigger. This had the effect of partitioning the data such that the effect of reduced time acquisitions could be assessed without conferring additional scanning time on the patient. The set of summed data sets was then independently reconstructed using the RR software to permit a blinded assessment of the effect of acquired counts upon reconstructed image quality as adjudged by three experienced observers. Data sets reconstructed with the RR software were compared with the local standard processing protocols; filtered back-projection and ordered-subset expectation-maximization. Thirty SPECT studies were assessed (20 bone and 10 parathyroid). The images reconstructed with the RR algorithm showed improved image quality for both full-time and half-time acquisitions over local current processing protocols (P<0.05). The RR algorithm improved image quality compared with local processing protocols and has been introduced into routine clinical use. SPECT acquisitions are now acquired at half of the time previously required. The method of binning the data can be applied to any other camera system to evaluate the reduction in acquisition time for similar processes. The potential for dose reduction is also inherent with this approach.

[Development of a Striatal and Skull Phantom for Quantitative 123I-FP-CIT SPECT].

PubMed

Ishiguro, Masanobu; Uno, Masaki; Miyazaki, Takuma; Kataoka, Yumi; Toyama, Hiroshi; Ichihara, Takashi

123 Iodine-labelled N-(3-fluoropropyl) -2β-carbomethoxy-3β-(4-iodophenyl) nortropane ( 123 I-FP-CIT) single photon emission computerized tomography (SPECT) images are used for differential diagnosis such as Parkinson's disease (PD). Specific binding ratio (SBR) is affected by scattering and attenuation in SPECT imaging, because gender and age lead to changes in skull density. It is necessary to clarify and correct the influence of the phantom simulating the the skull. The purpose of this study was to develop phantoms that can evaluate scattering and attenuation correction. Skull phantoms were prepared based on the measuring the results of the average computed tomography (CT) value, average skull thickness of 12 males and 16 females. 123 I-FP-CIT SPECT imaging of striatal phantom was performed with these skull phantoms, which reproduced normal and PD. SPECT images, were reconstructed with scattering and attenuation correction. SBR with partial volume effect corrected (SBR act ) and conventional SBR (SBR Bolt ) were measured and compared. The striatum and the skull phantoms along with 123 I-FP-CIT were able to reproduce the normal accumulation and disease state of PD and further those reproduced the influence of skull density on SPECT imaging. The error rate with the true SBR, SBR act was much smaller than SBR Bolt . The effect on SBR could be corrected by scattering and attenuation correction even if the skull density changes with 123 I-FP-CIT on SPECT imaging. The combination of triple energy window method and CT-attenuation correction method would be the best correction method for SBR act .

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siman, W.; Mikell, J. K.; Kappadath, S. C., E-mail

Purpose: To develop a practical background compensation (BC) technique to improve quantitative {sup 90}Y-bremsstrahlung single-photon emission computed tomography (SPECT)/computed tomography (CT) using a commercially available imaging system. Methods: All images were acquired using medium-energy collimation in six energy windows (EWs), ranging from 70 to 410 keV. The EWs were determined based on the signal-to-background ratio in planar images of an acrylic phantom of different thicknesses (2–16 cm) positioned below a {sup 90}Y source and set at different distances (15–35 cm) from a gamma camera. The authors adapted the widely used EW-based scatter-correction technique by modeling the BC as scaled images.more » The BC EW was determined empirically in SPECT/CT studies using an IEC phantom based on the sphere activity recovery and residual activity in the cold lung insert. The scaling factor was calculated from 20 clinical planar {sup 90}Y images. Reconstruction parameters were optimized in the same SPECT images for improved image quantification and contrast. A count-to-activity calibration factor was calculated from 30 clinical {sup 90}Y images. Results: The authors found that the most appropriate imaging EW range was 90–125 keV. BC was modeled as 0.53× images in the EW of 310–410 keV. The background-compensated clinical images had higher image contrast than uncompensated images. The maximum deviation of their SPECT calibration in clinical studies was lowest (<10%) for SPECT with attenuation correction (AC) and SPECT with AC + BC. Using the proposed SPECT-with-AC + BC reconstruction protocol, the authors found that the recovery coefficient of a 37-mm sphere (in a 10-mm volume of interest) increased from 39% to 90% and that the residual activity in the lung insert decreased from 44% to 14% over that of SPECT images with AC alone. Conclusions: The proposed EW-based BC model was developed for {sup 90}Y bremsstrahlung imaging. SPECT with AC + BC gave improved lesion detectability and activity quantification compared to SPECT with AC only. The proposed methodology can readily be used to tailor {sup 90}Y SPECT/CT acquisition and reconstruction protocols with different SPECT/CT systems for quantification and improved image quality in clinical settings.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leichner, P.K.

This report summarizes research in beta-particle dosimetry, quantitative single-photon emission computed tomography (SPECT), the clinical implementation of these two areas of research in radioimmunotherapy (RIT), and postgraduate training provided since the inception of this grant on July 15, 1989. To improve beta-particle dosimetry, a point source function was developed that is valid for a wide range of beta emitters. Analytical solutions for beta-particle dose rates within out outside slabs of finite thickness were validated in experimental tumors and are now being used in clinical RIT. Quantitative SPECT based on the circular harmonic transform (CHT) algorithm was validated in phantom, experimental,more » and clinical studies. This has led to improved macrodosimetry in clinical RIT. In dosimetry at the multi-cellular level studies were made of the HepG2 human hepatoblastoma grown subcutaneously in nude mice. Histologic sections and autoradiographs were prepared to quantitate activity distributions of radiolabeled antibodies. Absorbed-dose calculations are being carried out for {sup 131}I and {sup 90}Y beta particles for these antibody distributions.« less

Evaluation of a 125I-labelled benzazepinone derived voltage-gated sodium channel blocker for imaging with SPECT.

PubMed

Pérez-Medina, Carlos; Patel, Niral; Robson, Mathew; Badar, Adam; Lythgoe, Mark F; Årstad, Erik

2012-12-21

Voltage-gated sodium channels (VGSCs) are a family of transmembrane proteins that mediate fast neurotransmission, and are integral to sustain physiological conditions and higher cognitive functions. Imaging of VGSCs in vivo holds promise as a tool to elucidate operational functions in the brain and to aid the treatment of a wide range of neurological diseases. To assess the suitability of 1-benzazepin-2-one derived VGSC blockers for imaging, we have prepared a (125)I-labelled analogue of BNZA and evaluated the tracer in vivo. In an automated patch-clamp assay, a diastereomeric mixture of the non-radioactive compound blocked the Na(v)1.2 and Na(v)1.7 VGSC isoforms with IC(50) values of 4.1 ± 1.5 μM and 0.25 ± 0.07 μM, respectively. [(3)H]BTX displacement studies revealed a three-fold difference in affinity between the two diastereomers. Iodo-destannylation of a tin precursor with iodine-125 afforded the two diastereomerically pure tracers, which were used to assess binding to VGSCs in vivo by comparing their tissue distributions in mice. Whilst the results point to a lack of VGSC binding in vivo, SPECT imaging revealed highly localized uptake in the interscapular region, an area typically associated with brown adipose tissue, which in addition to high metabolic stability of the iodinated tracer, demonstrate the potential of 1-benzazepin-2-ones for in vivo imaging.

SPECT System Optimization Against A Discrete Parameter Space

PubMed Central

Meng, L. J.; Li, N.

2013-01-01

In this paper, we present an analytical approach for optimizing the design of a static SPECT system or optimizing the sampling strategy with a variable/adaptive SPECT imaging hardware against an arbitrarily given set of system parameters. This approach has three key aspects. First, it is designed to operate over a discretized system parameter space. Second, we have introduced an artificial concept of virtual detector as the basic building block of an imaging system. With a SPECT system described as a collection of the virtual detectors, one can convert the task of system optimization into a process of finding the optimum imaging time distribution (ITD) across all virtual detectors. Thirdly, the optimization problem (finding the optimum ITD) could be solved with a block-iterative approach or other non-linear optimization algorithms. In essence, the resultant optimum ITD could provide a quantitative measure of the relative importance (or effectiveness) of the virtual detectors and help to identify the system configuration or sampling strategy that leads to an optimum imaging performance. Although we are using SPECT imaging as a platform to demonstrate the system optimization strategy, this development also provides a useful framework for system optimization problems in other modalities, such as positron emission tomography (PET) and X-ray computed tomography (CT) [1, 2]. PMID:23587609

Simulating patient-specific heart shape and motion using SPECT perfusion images with the MCAT phantom

NASA Astrophysics Data System (ADS)

Faber, Tracy L.; Garcia, Ernest V.; Lalush, David S.; Segars, W. Paul; Tsui, Benjamin M.

2001-05-01

The spline-based Mathematical Cardiac Torso (MCAT) phantom is a realistic software simulation designed to simulate single photon emission computed tomographic (SPECT) data. It incorporates a heart model of known size and shape; thus, it is invaluable for measuring accuracy of acquisition, reconstruction, and post-processing routines. New functionality has been added by replacing the standard heart model with left ventricular (LV) epicaridal and endocardial surface points detected from actual patient SPECT perfusion studies. LV surfaces detected from standard post-processing quantitation programs are converted through interpolation in space and time into new B-spline models. Perfusion abnormalities are added to the model based on results of standard perfusion quantification. The new LV is translated and rotated to fit within existing atria and right ventricular models, which are scaled based on the size of the LV. Simulations were created for five different patients with myocardial infractions who had undergone SPECT perfusion imaging. Shape, size, and motion of the resulting activity map were compared visually to the original SPECT images. In all cases, size, shape and motion of simulated LVs matched well with the original images. Thus, realistic simulations with known physiologic and functional parameters can be created for evaluating efficacy of processing algorithms.

Comparison of an adaptive neuro-fuzzy inference system and an artificial neural network in the cross-talk correction of simultaneous 99 m Tc / 201Tl SPECT imaging using a GATE Monte-Carlo simulation

NASA Astrophysics Data System (ADS)

Heidary, Saeed; Setayeshi, Saeed; Ghannadi-Maragheh, Mohammad

2014-09-01

The aim of this study is to compare the adaptive neuro-fuzzy inference system (ANFIS) and the artificial neural network (ANN) to estimate the cross-talk contamination of 99 m Tc / 201 Tl image acquisition in the 201 Tl energy window (77 ± 15% keV). GATE (Geant4 Application in Emission and Tomography) is employed due to its ability to simulate multiple radioactive sources concurrently. Two kinds of phantoms, including two digital and one physical phantom, are used. In the real and the simulation studies, data acquisition is carried out using eight energy windows. The ANN and the ANFIS are prepared in MATLAB, and the GATE results are used as a training data set. Three indications are evaluated and compared. The ANFIS method yields better outcomes for two indications (Spearman's rank correlation coefficient and contrast) and the two phantom results in each category. The maximum image biasing, which is the third indication, is found to be 6% more than that for the ANN.

Quantification of the spatial distribution of rectally applied surrogates for microbicide and semen in colon with SPECT and magnetic resonance imaging.

PubMed

Cao, Ying J; Caffo, Brian S; Fuchs, Edward J; Lee, Linda A; Du, Yong; Li, Liye; Bakshi, Rahul P; Macura, Katarzyna; Khan, Wasif A; Wahl, Richard L; Grohskopf, Lisa A; Hendrix, Craig W

2012-12-01

We sought to describe quantitatively the distribution of rectally administered gels and seminal fluid surrogates using novel concentration-distance parameters that could be repeated over time. These methods are needed to develop rationally rectal microbicides to target and prevent HIV infection. Eight subjects were dosed rectally with radiolabelled and gadolinium-labelled gels to simulate microbicide gel and seminal fluid. Rectal doses were given with and without simulated receptive anal intercourse. Twenty-four hour distribution was assessed with indirect single photon emission computed tomography (SPECT)/computed tomography (CT) and magnetic resonance imaging (MRI), and direct assessment via sigmoidoscopic brushes. Concentration-distance curves were generated using an algorithm for fitting SPECT data in three dimensions. Three novel concentration-distance parameters were defined to describe quantitatively the distribution of radiolabels: maximal distance (D(max) ), distance at maximal concentration (D(Cmax) ) and mean residence distance (D(ave) ). The SPECT/CT distribution of microbicide and semen surrogates was similar. Between 1 h and 24 h post dose, the surrogates migrated retrograde in all three parameters (relative to coccygeal level; geometric mean [95% confidence interval]): maximal distance (D(max) ), 10 cm (8.6-12) to 18 cm (13-26), distance at maximal concentration (D(Cmax) ), 3.8 cm (2.7-5.3) to 4.2 cm (2.8-6.3) and mean residence distance (D(ave) ), 4.3 cm (3.5-5.1) to 7.6 cm (5.3-11). Sigmoidoscopy and MRI correlated only roughly with SPECT/CT. Rectal microbicide surrogates migrated retrograde during the 24 h following dosing. Spatial kinetic parameters estimated using three dimensional curve fitting of distribution data should prove useful for evaluating rectal formulations of drugs for HIV prevention and other indications. © 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turkington, T.

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis

NASA Astrophysics Data System (ADS)

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Quantifying regional cerebral blood flow by N-isopropyl-P-[I-123]iodoamphetamine (IMP) using a ring type single-photon emission computed tomography system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, N.; Odano, I.; Ohkubo, M.

1994-05-01

We developed a more accurate quantitative measurement of regional cerebral blood flow (rCBF) with the microsphere model using N-isopropyl-p-[I-123] iodoamphetamine (IMP) and a ring type single photon emission computed tomography (SPECT) system. SPECT studies were performed in 17 patients with brain diseases. A dose of 222 MBq (6 mCi) of [I-123]IMP was injected i.v., at the same time a 5 min period of arterial blood withdrawal was begun. SPECT data were acquired from 25 min to 60 min after tracer injection. For obtaining the brain activity concentration at 5 min after IMP injection, total brain counts collections and one minutemore » period short time SPECT studies were performed at 5, 20, and 60 min. Measurement of the values of rCBF was calculated using short time SPECT images at 5 min (rCBF), static SPECT images corrected with total cerebral counts (rCBF{sub Ct}.) and those corrected with reconstructed counts on short time SPECT images (rCBF{sub Cb}). There was a good relationship (r=0.69) between rCBF and rCBF{sub Ct}, however, rCBF{sub Ct} tends to be underestimated in high flow areas and overestimated in low flow areas. There was better relationship between rCBF and rCBF{sub Cb}(r=0.92). The overestimation and underestimation shown in rCBF{sub Ct} was considered to be due to the correction of reconstructed counts using a total cerebral time activity curve, because of the kinetic behavior of [I-123]IMP was different in each region. We concluded that more accurate rCBF values could be obtained using the regional time activity curves.« less

Activity concentration measurements using a conjugate gradient (Siemens xSPECT) reconstruction algorithm in SPECT/CT.

PubMed

Armstrong, Ian S; Hoffmann, Sandra A

2016-11-01

The interest in quantitative single photon emission computer tomography (SPECT) shows potential in a number of clinical applications and now several vendors are providing software and hardware solutions to allow 'SUV-SPECT' to mirror metrics used in PET imaging. This brief technical report assesses the accuracy of activity concentration measurements using a new algorithm 'xSPECT' from Siemens Healthcare. SPECT/CT data were acquired from a uniform cylinder with 5, 10, 15 and 20 s/projection and NEMA image quality phantom with 25 s/projection. The NEMA phantom had hot spheres filled with an 8 : 1 activity concentration relative to the background compartment. Reconstructions were performed using parameters defined by manufacturer presets available with the algorithm. The accuracy of activity concentration measurements was assessed. A dose calibrator-camera cross-calibration factor (CCF) was derived from the uniform phantom data. In uniform phantom images, a positive bias was observed, ranging from ∼6% in the lower count images to ∼4% in the higher-count images. On the basis of the higher-count data, a CCF of 0.96 was derived. As expected, considerable negative bias was measured in the NEMA spheres using region mean values whereas positive bias was measured in the four largest NEMA spheres. Nonmonotonically increasing recovery curves for the hot spheres suggested the presence of Gibbs edge enhancement from resolution modelling. Sufficiently accurate activity concentration measurements can easily be measured on images reconstructed with the xSPECT algorithm without a CCF. However, the use of a CCF is likely to improve accuracy further. A manual conversion of voxel values into SUV should be possible, provided that the patient weight, injected activity and time between injection and imaging are all known accurately.

Performance index: A method for quantitative evaluation of filters used in clinical SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Contino, J.; Touya, J.J.; Corbus, H.F.

1984-01-01

The purpose of this study was to design a method for optimal filter selection during the reconstruction of clinical SPECT images. Hamming, Bartlett, Parzen and Butterworth filters were evaluated at different cutoff frequencies when applied to reconstruction of the Jaszczak phantom and liver SPECTs. The phantom filled with 6 mCi of Tc-99m was imaged following 4 different protocols which varied in matrix sizes (128 x 128 or 64 x 64) and in number of steps (128 or 64). Total imaging time in the 4 protocols was 24 minutes. A total of 160 reconstructions were analyzed. Liver SPECTs from 2 patientsmore » with small metastatic lesions from colon Ca were similarly studied. An ECT Performance Index (ECT PI) was defined as the product of the contrast efficiency function (ECT C) and uniformity (ECT U). ECT C as a function of the radius was measured following Rollo's approach. ECT U was measured as the ratio between min. and max. counts per pixel in a known uniform region. ECT PI was computed on a slice through the void spheres region of the phantom. In liver SPECTs the ECT U was measured over the spleen. The most favorable ECT PI (0.35, radius 7.9 mm) was obtained with images in 128 x 128 matrices, 128 steps, processed with a Butterworth cutoff frequency of 0.19, filter order 4. When images were acquired in 64 x 64 matrices using 64 steps the ECT PI was lower and influenced to a lesser degree by both choice of filter and cutoff frequency. Results in the two liver SPECT examinations were parallel to those found in the phantom studies confirming the clinical usefulness of the ECT PI in the evaluation of filters for reconstruction of SPECT images.« less

Radiotracer Imaging Allows for Noninvasive Detection and Quantification of Abnormalities in Angiosome Foot Perfusion in Diabetic Patients With Critical Limb Ischemia and Nonhealing Wounds

PubMed Central

Alvelo, Jessica L.; Papademetris, Xenophon; Mena-Hurtado, Carlos; Jeon, Sangchoon; Sumpio, Bauer E.; Sinusas, Albert J.

2018-01-01

Background: Single photon emission computed tomography (SPECT)/computed tomography (CT) imaging allows for assessment of skeletal muscle microvascular perfusion but has not been quantitatively assessed in angiosomes, or 3-dimensional vascular territories, of the foot. This study assessed and compared resting angiosome foot perfusion between healthy subjects and diabetic patients with critical limb ischemia (CLI). Additionally, the relationship between SPECT/CT imaging and the ankle–brachial index—a standard tool for evaluating peripheral artery disease—was assessed. Methods and Results: Healthy subjects (n=9) and diabetic patients with CLI and nonhealing ulcers (n=42) underwent SPECT/CT perfusion imaging of the feet. CT images were segmented into angiosomes for quantification of relative radiotracer uptake, expressed as standardized uptake values. Standardized uptake values were assessed in ulcerated angiosomes of patients with CLI and compared with whole-foot standardized uptake values in healthy subjects. Serial SPECT/CT imaging was performed to assess uptake kinetics of technetium-99m-tetrofosmin. The relationship between angiosome perfusion and ankle–brachial index was assessed via correlational analysis. Resting perfusion was significantly lower in CLI versus healthy subjects (P=0.0007). Intraclass correlation coefficients of 0.95 (healthy) and 0.93 (CLI) demonstrated excellent agreement between serial perfusion measurements. Correlational analysis, including healthy and CLI subjects, demonstrated a significant relationship between ankle–brachial index and SPECT/CT (P=0.01); however, this relationship was not significant for diabetic CLI patients only (P=0.2). Conclusions: SPECT/CT imaging assesses regional foot perfusion and detects abnormalities in microvascular perfusion that may be undetectable by conventional ankle–brachial index in patients with diabetes mellitus. SPECT/CT may provide a novel approach for evaluating responses to targeted therapies. PMID:29748311

High-Resolution 4D Imaging of Technetium Transport in Porous Media using Preclinical SPECT-CT

NASA Astrophysics Data System (ADS)

Dogan, M.; DeVol, T. A.; Groen, H.; Moysey, S. M.; Ramakers, R.; Powell, B. A.

2015-12-01

Preclinical SPECT-CT (single-photon emission computed tomography with integrated X-ray computed tomography) offers the potential to quantitatively image the dynamic three-dimensional distribution of radioisotopes with sub-millimeter resolution, overlaid with structural CT images (20-200 micron resolution), making this an attractive method for studying transport in porous media. A preclinical SPECT-CT system (U-SPECT4CT, MILabs BV. Utrecht, The Netherlands) was evaluated for imaging flow and transport of 99mTc (t1/2=6hrs) using a 46,5mm by 156,4mm column packed with individual layers consisting of <0.2mm diameter silica gel, 0.2-0.25, 0.5, 1.0, 2.0, 3.0, and 4.0mm diameter glass beads, and a natural soil sample obtained from the Savannah River Site. The column was saturated with water prior to injecting the 99mTc solution. During the injection the flow was interrupted intermittently for 10 minute periods to allow for the acquisition of a SPECT image of the transport front. Non-uniformity of the front was clearly observed in the images as well as the retarded movement of 99mTc in the soil layer. The latter is suggesting good potential for monitoring transport processes occurring on the timescale of hours. After breakthrough of 99mTc was achieved, the flow was stopped and SPECT data were collected in one hour increments to evaluate the sensitivity of the instrument as the isotope decayed. Fused SPECT- CT images allowed for improved interpretation of 99mTc distributions within individual pore spaces. With ~3 MBq remaining in the column, the lowest activity imaged, it was not possible to clearly discriminate any of the pore spaces.

Measurement of acute Q-wave myocardial infarct size with single photon emission computed tomography imaging of indium-111 antimyosin.

PubMed

Antunes, M L; Seldin, D W; Wall, R M; Johnson, L L

1989-04-01

Myocardial infarct size was measured by single photon emission computed tomography (SPECT) following injection of indium-111 antimyosin in 27 patients (18 male and 9 female; mean age 57.4 +/- 10.5 years, range 37 to 75) who had acute transmural myocardial infarction (MI). These 27 patients represent 27 of 35 (77%) consecutive patients with acute Q-wave infarctions who were injected with indium-111 antimyosin. In the remaining 8 patients either tracer uptake was too faint or the scans were technically inadequate to permit infarct sizing from SPECT reconstructions. In the 27 patients studied, infarct location by electrocardiogram was anterior in 15 and inferoposterior in 12. Nine patients had a history of prior infarction. Each patient received 2 mCi of indium-111 antimyosin followed by SPECT imaging 48 hours later. Infarct mass was determined from coronal slices using a threshold value obtained from a human torso/cardiac phantom. Infarct size ranged from 11 to 87 g mean 48.5 +/- 24). Anterior infarcts were significantly (p less than 0.01) larger (60 +/- 20 g) than inferoposterior infarcts (34 +/- 21 g). For patients without prior MI, there were significant inverse correlations between infarct size and ejection fraction (r = 0.71, p less than 0.01) and wall motion score (r = 0.58, p less than 0.01) obtained from predischarge gated blood pool scans. Peak creatine kinase-MB correlated significantly with infarct size for patients without either reperfusion or right ventricular infarction (r = 0.66). Seven patients without prior infarcts had additional simultaneous indium-111/thallium-201 SPECT studies using dual energy windows.(ABSTRACT TRUNCATED AT 250 WORDS)

The WOMEN study: what is the optimal method for ischemia evaluation in women? A multi-center, prospective, randomized study to establish the optimal method for detection of coronary artery disease (CAD) risk in women at an intermediate-high pretest likelihood of CAD: study design.

PubMed

Mieres, Jennifer H; Shaw, Leslee J; Hendel, Robert C; Heller, Gary V

2009-01-01

Coronary artery disease remains the leading cause of morbidity and mortality in women. The optimal non-invasive test for evaluation of ischemic heart disease in women is unknown. Although current guidelines support the choice of the exercise tolerance test (ETT) as a first line test for women with a normal baseline ECG and adequate exercise capabilities, supportive data for this recommendation are controversial. The what is the optimal method for ischemia evaluation in women? (WOMEN) study was designed to determine the optimal non-invasive strategy for CAD risk detection of intermediate and high risk women presenting with chest pain or equivalent symptoms suggestive of ischemic heart disease. The study will prospectively compare the 2-year event rates in women capable of performing exercise treadmill testing or Tc-99 m tetrofosmin SPECT myocardial perfusion imaging (MPI). The study will enroll women presenting for the evaluation of chest pain or anginal equivalent symptoms who are capable of performing >5 METs of exercise while at intermediate-high pretest risk for ischemic heart disease who will be randomized to either ETT testing alone or with Tc-99 m tetrofosmin SPECT MPI. The null hypothesis for this project is that the exercise ECG has the same negative predictive value for risk detection as gated myocardial perfusion SPECT in women. The primary aim is to compare 2-year cardiac event rates in women randomized to SPECT MPI to those randomized to ETT. The WOMEN study seeks to provide objective information for guidelines for the evaluation of symptomatic women with an intermediate-high likelihood for CAD.

Myocardial Perfusion SPECT 2015 in Germany

PubMed Central

Burchert, Wolfgang; Schäfer, Wolfgang; Hacker, Marcus

2016-01-01

Summary Aim The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 7th survey of myocardial perfusion SPECT (MPS) of the reporting year 2015. Method 268 questionnaires (173 practices [PR], 67 hospitals [HO], 28 university hospitals [UH]) were evaluated. Results of the last survey from 2012 are set in squared brackets. Results MPS of 121 939 [105 941] patients were reported. 98 % [95 %] of all MPS were performed with Tc-99m radiopharmaceuticals and 2 % [5 %] with Tl-201. 78 % [79 %] of all patients were studied in PR, 14 % [15 %] in HO, and 8 % [6 %] in UH. A pharmacological stress test was performed in 43 % [39 %] (22 % [24 %] adenosine, 20 % [9 %] regadenoson, 1% [6 %] dipyridamole or dobutamine). Attenuation correction was applied in 25 % [2009: 10 %] of MPS. Gated SPECT was performed in 78 % [70 %] of all rest MPS, in 80 % [73 %] of all stress and in 76 % [67 %] of all stress and rest MPS. 53 % [33 %] of all nuclear medicine departments performed MPS scoring by default, whereas 24 % [41 %] did not apply any quantification. 31 % [26 %] of all departments noticed an increase in their counted MPS and 29 % [29 %] no changes. Data from 89 departments which participated in all surveys showed an increase in MPS count of 11.1 % (PR: 12.2 %, HO: 4.8 %, UH: 18.4 %). 70 % [60 %] of the MPS were requested by ambulatory care cardiologists. Conclusion The 2015 MPS survey reveals a high-grade adherence of routine MPS practice to current guidelines. The positive trend in MPS performance and number of MPS already observed in 2012 continues. Educational training remains necessary in the field of SPECT scoring. PMID:27909712

Time-Gated Raman Spectroscopy for Quantitative Determination of Solid-State Forms of Fluorescent Pharmaceuticals.

PubMed

Lipiäinen, Tiina; Pessi, Jenni; Movahedi, Parisa; Koivistoinen, Juha; Kurki, Lauri; Tenhunen, Mari; Yliruusi, Jouko; Juppo, Anne M; Heikkonen, Jukka; Pahikkala, Tapio; Strachan, Clare J

2018-04-03

Raman spectroscopy is widely used for quantitative pharmaceutical analysis, but a common obstacle to its use is sample fluorescence masking the Raman signal. Time-gating provides an instrument-based method for rejecting fluorescence through temporal resolution of the spectral signal and allows Raman spectra of fluorescent materials to be obtained. An additional practical advantage is that analysis is possible in ambient lighting. This study assesses the efficacy of time-gated Raman spectroscopy for the quantitative measurement of fluorescent pharmaceuticals. Time-gated Raman spectroscopy with a 128 × (2) × 4 CMOS SPAD detector was applied for quantitative analysis of ternary mixtures of solid-state forms of the model drug, piroxicam (PRX). Partial least-squares (PLS) regression allowed quantification, with Raman-active time domain selection (based on visual inspection) improving performance. Model performance was further improved by using kernel-based regularized least-squares (RLS) regression with greedy feature selection in which the data use in both the Raman shift and time dimensions was statistically optimized. Overall, time-gated Raman spectroscopy, especially with optimized data analysis in both the spectral and time dimensions, shows potential for sensitive and relatively routine quantitative analysis of photoluminescent pharmaceuticals during drug development and manufacturing.

Left ventricular eccentricity index measured with SPECT myocardial perfusion imaging: An additional parameter of adverse cardiac remodeling.

PubMed

Gimelli, Alessia; Liga, Riccardo; Clemente, Alberto; Marras, Gavino; Kusch, Annette; Marzullo, Paolo

2017-01-12

Single-photon emission computed-tomography (SPECT) allows the quantification of LV eccentricity index (EI), a measure of cardiac remodeling. We sought to evaluate the feasibility of EI measurement with SPECT myocardial perfusion imaging and its interactions with relevant LV functional and structural parameters. Four-hundred and fifty-six patients underwent myocardial perfusion imaging on a Cadmium-Zinc-Telluride (CZT) camera. The summed rest, stress, and difference scores were calculated. From rest images, the LV end-diastolic (EDV) and end-systolic volumes, ejection fraction (EF), and peak filling rate (PFR) were calculated. In every patient, the EI, ranging from 0 (sphere) to 1 (line), was computed using a dedicated software (QGS/QPS; Cedars-Sinai Medical Center). Three-hundred and thirty-eight/456 (74%) patients showed a normal EF (>50%), while 26% had LV systolic dysfunction. The EI was computed from CZT images with excellent reproducibility (interclass correlation coefficient: 0.99, 95% CI 0.98-0.99). More impaired EI values correlated with the presence of a more abnormal LV perfusion (P < .001), function (EF and PFR, P < .001), and structure (EDV, P < .001). On multivariate analysis, higher EDV (P < .001) and depressed EF (P = .014) values were independent predictors of abnormal EI. The evaluation of LV eccentricity is feasible on gated CZT images. Abnormal EI associates with significant cardiac structural and functional abnormalities.

Monte Carlo evaluation of accuracy and noise properties of two scatter correction methods for /sup 201/Tl cardiac SPECT

NASA Astrophysics Data System (ADS)

Narita, Y.; Iida, H.; Ebert, S.; Nakamura, T.

1997-12-01

Two independent scatter correction techniques, transmission dependent convolution subtraction (TDCS) and triple-energy window (TEW) method, were evaluated in terms of quantitative accuracy and noise properties using Monte Carlo simulation (EGS4). Emission projections (primary, scatter and scatter plus primary) were simulated for three numerical phantoms for /sup 201/Tl. Data were reconstructed with ordered-subset EM algorithm including noise-less transmission data based attenuation correction. Accuracy of TDCS and TEW scatter corrections were assessed by comparison with simulated true primary data. The uniform cylindrical phantom simulation demonstrated better quantitative accuracy with TDCS than with TEW (-2.0% vs. 16.7%) and better S/N (6.48 vs. 5.05). A uniform ring myocardial phantom simulation demonstrated better homogeneity with TDCS than TEW in the myocardium; i.e., anterior-to-posterior wall count ratios were 0.99 and 0.76 with TDCS and TEW, respectively. For the MCAT phantom, TDCS provided good visual and quantitative agreement with simulated true primary image without noticeably increasing the noise after scatter correction. Overall TDCS proved to be more accurate and less noisy than TEW, facilitating quantitative assessment of physiological functions with SPECT.

A method for energy window optimization for quantitative tasks that includes the effects of model-mismatch on bias: application to Y-90 bremsstrahlung SPECT imaging.

PubMed

Rong, Xing; Du, Yong; Frey, Eric C

2012-06-21

Quantitative Yttrium-90 ((90)Y) bremsstrahlung single photon emission computed tomography (SPECT) imaging has shown great potential to provide reliable estimates of (90)Y activity distribution for targeted radionuclide therapy dosimetry applications. One factor that potentially affects the reliability of the activity estimates is the choice of the acquisition energy window. In contrast to imaging conventional gamma photon emitters where the acquisition energy windows are usually placed around photopeaks, there has been great variation in the choice of the acquisition energy window for (90)Y imaging due to the continuous and broad energy distribution of the bremsstrahlung photons. In quantitative imaging of conventional gamma photon emitters, previous methods for optimizing the acquisition energy window assumed unbiased estimators and used the variance in the estimates as a figure of merit (FOM). However, for situations, such as (90)Y imaging, where there are errors in the modeling of the image formation process used in the reconstruction there will be bias in the activity estimates. In (90)Y bremsstrahlung imaging this will be especially important due to the high levels of scatter, multiple scatter, and collimator septal penetration and scatter. Thus variance will not be a complete measure of reliability of the estimates and thus is not a complete FOM. To address this, we first aimed to develop a new method to optimize the energy window that accounts for both the bias due to model-mismatch and the variance of the activity estimates. We applied this method to optimize the acquisition energy window for quantitative (90)Y bremsstrahlung SPECT imaging in microsphere brachytherapy. Since absorbed dose is defined as the absorbed energy from the radiation per unit mass of tissues in this new method we proposed a mass-weighted root mean squared error of the volume of interest (VOI) activity estimates as the FOM. To calculate this FOM, two analytical expressions were derived for calculating the bias due to model-mismatch and the variance of the VOI activity estimates, respectively. To obtain the optimal acquisition energy window for general situations of interest in clinical (90)Y microsphere imaging, we generated phantoms with multiple tumors of various sizes and various tumor-to-normal activity concentration ratios using a digital phantom that realistically simulates human anatomy, simulated (90)Y microsphere imaging with a clinical SPECT system and typical imaging parameters using a previously validated Monte Carlo simulation code, and used a previously proposed method for modeling the image degrading effects in quantitative SPECT reconstruction. The obtained optimal acquisition energy window was 100-160 keV. The values of the proposed FOM were much larger than the FOM taking into account only the variance of the activity estimates, thus demonstrating in our experiment that the bias of the activity estimates due to model-mismatch was a more important factor than the variance in terms of limiting the reliability of activity estimates.

Imaging of gene expression in live pancreatic islet cell lines using dual-isotope SPECT.

PubMed

Tai, Joo Ho; Nguyen, Binh; Wells, R Glenn; Kovacs, Michael S; McGirr, Rebecca; Prato, Frank S; Morgan, Timothy G; Dhanvantari, Savita

2008-01-01

We are combining nuclear medicine with molecular biology to establish a sensitive, quantitative, and tomographic method with which to detect gene expression in pancreatic islet cells in vivo. Dual-isotope SPECT can be used to image multiple molecular events simultaneously, and coregistration of SPECT and CT images enables visualization of reporter gene expression in the correct anatomic context. We have engineered pancreatic islet cell lines for imaging with SPECT/CT after transplantation under the kidney capsule. INS-1 832/13 and alphaTC1-6 cells were stably transfected with a herpes simplex virus type 1-thymidine kinase-green fluorescent protein (HSV1-thymidine kinase-GFP) fusion construct (tkgfp). After clonal selection, radiolabel uptake was determined by incubation with 5-(131)I-iodo-1-(2-deoxy-2-fluoro-beta-d-arabinofuranosyl)uracil ((131)I-FIAU) (alphaTC1-6 cells) or (123)I-FIAU (INS-1 832/13 cells). For the first set of in vivo experiments, SPECT was conducted after alphaTC1-6/tkgfp cells had been labeled with either (131)I-FIAU or (111)In-tropolone and transplanted under the left kidney capsule of CD1 mice. Reconstructed SPECT images were coregistered to CT. In a second study using simultaneous acquisition dual-isotope SPECT, INS-1 832/13 clone 9 cells were labeled with (111)In-tropolone before transplantation. Mice were then systemically administered (123)I-FIAU and data for both (131)I and (111)In were acquired simultaneously. alphaTC1-6/tkgfp cells showed a 15-fold greater uptake of (131)I-FIAU, and INS-1/tkgfp cells showed a 12-fold greater uptake of (123)I-FIAU, compared with that of wild-type cells. After transplantation under the kidney capsule, both reporter gene expression and location of cells could be visualized in vivo with dual-isotope SPECT. Immunohistochemistry confirmed the presence of glucagon- and insulin-positive cells at the site of transplantation. Dual-isotope SPECT is a promising method to detect gene expression in and location of transplanted pancreatic cells in vivo.

Brain single-photon emission CT physics principles.

PubMed

Accorsi, R

2008-08-01

The basic principles of scintigraphy are reviewed and extended to 3D imaging. Single-photon emission computed tomography (SPECT) is a sensitive and specific 3D technique to monitor in vivo functional processes in both clinical and preclinical studies. SPECT/CT systems are becoming increasingly common and can provide accurately registered anatomic information as well. In general, SPECT is affected by low photon-collection efficiency, but in brain imaging, not all of the large FOV of clinical gamma cameras is needed: The use of fan- and cone-beam collimation trades off the unused FOV for increased sensitivity and resolution. The design of dedicated cameras aims at increased angular coverage and resolution by minimizing the distance from the patient. The corrections needed for quantitative imaging are challenging but can take advantage of the relative spatial uniformity of attenuation and scatter. Preclinical systems can provide submillimeter resolution in small animal brain imaging with workable sensitivity.

A comparative study of brain perfusion single-photon emission computed tomography and magnetic resonance imaging in patients with post-traumatic anosmia.

PubMed

Atighechi, Saeid; Salari, Hadi; Baradarantar, Mohammad Hossein; Jafari, Rozita; Karimi, Ghasem; Mirjali, Mehdi

2009-01-01

Loss of smell is a problem that can occur in up to 30% of patients with head trauma. The olfactory function investigation methods so far in use have mostly relied on subjective responses given by patients. Recently, some studies have used magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) to evaluate patients with post-traumatic anosmia. The present study seeks to detect post-traumatic anosmia and the areas in the brain that are related to olfactory impairment by using SPECT and MRI as imaging techniques. The study was conducted on 21 patients suffering from head injury and consequently anosmia as defined by an olfactory identification test. Two control groups (traumatic normosmic and nontraumatic healthy individuals) were selected. Brain MRI, qualitative and semiquantitative SPECT with 99mtc-ethyl-cysteinate-dimer were taken from all the patients. Then the brain SPECT and MRI were compared with each other. Semi-quantitative assessment of the brain perfusion SPECT revealed frontal, left parietal, and left temporal hypoperfusion as compared with the two control groups. Eighty-five percent of the anosmic patients had abnormal brain MRI. Regarding the MRI, the main abnormality proved to be in the anterior inferior region of the frontal lobes and olfactory bulbs. The findings of this study suggest that damage to the frontal lobes and olfactory bulbs as shown in the brain MRI and hypoperfusion in the frontal, left parietal, and left temporal lobes in the semiquantitative SPECT corresponds to post-traumatic anosmia. Further neurophysiological and imaging studies are definitely needed to set the idea completely.

Extension of the International Atomic Energy Agency phantom study in image quantification: results of multicentre evaluation in Croatia.

PubMed

Grošev, Darko; Gregov, Marin; Wolfl, Miroslava Radić; Krstonošić, Branislav; Debeljuh, Dea Dundara

2018-06-07

To make quantitative methods of nuclear medicine more available, four centres in Croatia participated in the national intercomparison study, following the materials and methods used in the previous international study organized by the International Atomic Energy Agency (IAEA). The study task was to calculate the activities of four Ba sources (T1/2=10.54 years; Eγ=356 keV) using planar and single-photon emission computed tomography (SPECT) or SPECT/CT acquisitions of the sources inside a water-filled cylindrical phantom. The sources were previously calibrated by the US National Institute of Standards and Technology. Triple-energy window was utilized for scatter correction. Planar studies were corrected for attenuation correction (AC) using the conjugate-view method. For SPECT/CT studies, data from X-ray computed tomography were used for attenuation correction (CT-AC), whereas for SPECT-only acquisition, the Chang-AC method was applied. Using the lessons learned from the IAEA study, data were acquired according to the harmonized data acquisition protocol, and the acquired images were then processed using centralized data analysis. The accuracy of the activity quantification was evaluated as the ratio R between the calculated activity and the value obtained from National Institute of Standards and Technology. For planar studies, R=1.06±0.08; for SPECT/CT study using CT-AC, R=1.00±0.08; and for Chang-AC, R=0.89±0.12. The results are in accordance with those obtained within the larger IAEA study and confirm that SPECT/CT method is the most appropriate for accurate activity quantification.

TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kida, S; University of Tokyo Hospital, Bunkyo, Tokyo; Bal, M

Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (amore » surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation image-based plans, providing evidence to use 4D-CT ventilation imaging for clinical applications. Supported in part by Free to Breathe Young Investigator Research Grant and NIH/NCI R01 CA 093626. The authors thank Philips Radiation Oncology Systems for the Pinnacle3 treatment planning systems.« less

Development of Realistic Striatal Digital Brain (SDB) Phantom for 123I-FP-CIT SPECT and Effect on Ventricle in the Brain for Semi-quantitative Index of Specific Binding Ratio.

PubMed

Furuta, Akihiro; Onishi, Hideo; Nakamoto, Kenta

This study aimed at developing the realistic striatal digital brain (SDB) phantom and to assess specific binding ratio (SBR) for ventricular effect in the 123 I-FP-CIT SPECT imaging. SDB phantom was constructed in to four segments (striatum, ventricle, brain parenchyma, and skull bone) using Percentile method and other image processing in the T2-weighted MR images. The reference image was converted into 128×128 matrixes to align MR images with SPECT images. The process image was reconstructed with projection data sets generated from reference images additive blurring, attenuation, scatter, and statically noise. The SDB phantom was evaluated to find the accuracy of calculated SBR and to find the effect of SBR with/without ventricular counts with the reference and process images. We developed and investigated the utility of the SDB phantom in the 123 I-FP-CIT SPECT clinical study. The true value of SBR was just marched to calculate SBR from reference and process images. The SBR was underestimated 58.0% with ventricular counts in reference image, however, was underestimated 162% with ventricular counts in process images. The SDB phantom provides an extremely convenient tool for discovering basic properties of 123 I-FP-CIT SPECT clinical study image. It was suggested that the SBR was susceptible to ventricle.

Simulation of realistic abnormal SPECT brain perfusion images: application in semi-quantitative analysis

NASA Astrophysics Data System (ADS)

Ward, T.; Fleming, J. S.; Hoffmann, S. M. A.; Kemp, P. M.

2005-11-01

Simulation is useful in the validation of functional image analysis methods, particularly when considering the number of analysis techniques currently available lacking thorough validation. Problems exist with current simulation methods due to long run times or unrealistic results making it problematic to generate complete datasets. A method is presented for simulating known abnormalities within normal brain SPECT images using a measured point spread function (PSF), and incorporating a stereotactic atlas of the brain for anatomical positioning. This allows for the simulation of realistic images through the use of prior information regarding disease progression. SPECT images of cerebral perfusion have been generated consisting of a control database and a group of simulated abnormal subjects that are to be used in a UK audit of analysis methods. The abnormality is defined in the stereotactic space, then transformed to the individual subject space, convolved with a measured PSF and removed from the normal subject image. The dataset was analysed using SPM99 (Wellcome Department of Imaging Neuroscience, University College, London) and the MarsBaR volume of interest (VOI) analysis toolbox. The results were evaluated by comparison with the known ground truth. The analysis showed improvement when using a smoothing kernel equal to system resolution over the slightly larger kernel used routinely. Significant correlation was found between effective volume of a simulated abnormality and the detected size using SPM99. Improvements in VOI analysis sensitivity were found when using the region median over the region mean. The method and dataset provide an efficient methodology for use in the comparison and cross validation of semi-quantitative analysis methods in brain SPECT, and allow the optimization of analysis parameters.

Quantitative accuracy of the closed-form least-squares solution for targeted SPECT.

PubMed

Shcherbinin, S; Celler, A

2010-10-07

The aim of this study is to investigate the quantitative accuracy of the closed-form least-squares solution (LSS) for single photon emission computed tomography (SPECT). The main limitation for employing this method in actual clinical reconstructions is the computational cost related to operations with a large-sized system matrix. However, in some clinical situations, the size of the system matrix can be decreased using targeted reconstruction. For example, some oncology SPECT studies are characterized by intense tracer uptakes that are localized in relatively small areas, while the remaining parts of the patient body have only a low activity background. Conventional procedures reconstruct the activity distribution in the whole object, which leads to relatively poor image accuracy/resolution for tumors while computer resources are wasted, trying to rebuild diagnostically useless background. In this study, we apply a concept of targeted reconstruction to SPECT phantom experiments imitating such oncology scans. Our approach includes two major components: (i) disconnection of the entire imaging system of equations and extraction of only those parts that correspond to the targets, i.e., regions of interest (ROI) encompassing active containers/tumors and (ii) generation of the closed-form LSS for each target ROI. We compared these ROI-based LSS with those reconstructed by the conventional MLEM approach. The analysis of the five processed cases from two phantom experiments demonstrated that the LSS approach outperformed MLEM in terms of the noise level inside ROI. On the other hand, MLEM better recovered total activity if the number of iterations was large enough. For the experiment without background activity, the ROI-based LSS led to noticeably better spatial activity distribution inside ROI. However, the distributions pertaining to both approaches were practically identical for the experiment with the concentration ratio 7:1 between the containers and the background.

Optimisation of quantitative lung SPECT applied to mild COPD: a software phantom simulation study.

PubMed

Norberg, Pernilla; Olsson, Anna; Alm Carlsson, Gudrun; Sandborg, Michael; Gustafsson, Agnetha

2015-01-01

The amount of inhomogeneities in a (99m)Tc Technegas single-photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT method, measuring these inhomogeneities was proposed in earlier work. To detect mild COPD, which is a difficult task, optimised parameter values are needed. In this work, the CVT method was optimised with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximisation (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung software phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%. The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq (99m)Tc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm(-1). Sixty-four reconstruction updates and a small kernel size should be used when the whole lung is analysed, and for the reduced lung a greater number of updates and a larger kernel size are needed. A LEHR collimator and 125 (99m)Tc MBq together with an optimal combination of cutoff frequency, number of updates and kernel size, gave the best result. Suboptimal selections of either cutoff frequency, number of updates and kernel size will reduce the imaging system's ability to detect mild COPD in the lung phantom.

SPECT and PET in ischemic heart failure.

PubMed

Angelidis, George; Giamouzis, Gregory; Karagiannis, Georgios; Butler, Javed; Tsougos, Ioannis; Valotassiou, Varvara; Giannakoulas, George; Dimakopoulos, Nikolaos; Xanthopoulos, Andrew; Skoularigis, John; Triposkiadis, Filippos; Georgoulias, Panagiotis

2017-03-01

Heart failure is a common clinical syndrome associated with significant morbidity and mortality worldwide. Ischemic heart disease is the leading cause of heart failure, at least in the industrialized countries. Proper diagnosis of the syndrome and management of patients with heart failure require anatomical and functional information obtained through various imaging modalities. Nuclear cardiology techniques play a main role in the evaluation of heart failure. Myocardial single photon emission computed tomography (SPECT) with thallium-201 or technetium-99 m labelled tracers offer valuable data regarding ventricular function, myocardial perfusion, viability, and intraventricular synchronism. Moreover, positron emission tomography (PET) permits accurate evaluation of myocardial perfusion, metabolism, and viability, providing high-quality images and the ability of quantitative analysis. As these imaging techniques assess different parameters of cardiac structure and function, variations of sensitivity and specificity have been reported among them. In addition, the role of SPECT and PET guided therapy remains controversial. In this comprehensive review, we address these controversies and report the advances in patient's investigation with SPECT and PET in ischemic heart failure. Furthermore, we present the innovations in technology that are expected to strengthen the role of nuclear cardiology modalities in the investigation of heart failure.

Pulmonary Ventilation Imaging Based on 4-Dimensional Computed Tomography: Comparison With Pulmonary Function Tests and SPECT Ventilation Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Tokihiro, E-mail: toyamamoto@ucdavis.edu; Department of Radiation Oncology, University of California Davis School of Medicine, Sacramento, California; Kabus, Sven

Purpose: 4-dimensional computed tomography (4D-CT)-based pulmonary ventilation imaging is an emerging functional imaging modality. The purpose of this study was to investigate the physiological significance of 4D-CT ventilation imaging by comparison with pulmonary function test (PFT) measurements and single-photon emission CT (SPECT) ventilation images, which are the clinical references for global and regional lung function, respectively. Methods and Materials: In an institutional review board–approved prospective clinical trial, 4D-CT imaging and PFT and/or SPECT ventilation imaging were performed in thoracic cancer patients. Regional ventilation (V{sub 4DCT}) was calculated by deformable image registration of 4D-CT images and quantitative analysis for regional volumemore » change. V{sub 4DCT} defect parameters were compared with the PFT measurements (forced expiratory volume in 1 second (FEV{sub 1}; % predicted) and FEV{sub 1}/forced vital capacity (FVC; %). V{sub 4DCT} was also compared with SPECT ventilation (V{sub SPECT}) to (1) test whether V{sub 4DCT} in V{sub SPECT} defect regions is significantly lower than in nondefect regions by using the 2-tailed t test; (2) to quantify the spatial overlap between V{sub 4DCT} and V{sub SPECT} defect regions with Dice similarity coefficient (DSC); and (3) to test ventral-to-dorsal gradients by using the 2-tailed t test. Results: Of 21 patients enrolled in the study, 18 patients for whom 4D-CT and either PFT or SPECT were acquired were included in the analysis. V{sub 4DCT} defect parameters were found to have significant, moderate correlations with PFT measurements. For example, V{sub 4DCT}{sup HU} defect volume increased significantly with decreasing FEV{sub 1}/FVC (R=−0.65, P<.01). V{sub 4DCT} in V{sub SPECT} defect regions was significantly lower than in nondefect regions (mean V{sub 4DCT}{sup HU} 0.049 vs 0.076, P<.01). The average DSCs for the spatial overlap with SPECT ventilation defect regions were only moderate (V{sub 4DCT}{sup HU}0.39 ± 0.11). Furthermore, ventral-to-dorsal gradients of V{sub 4DCT} were strong (V{sub 4DCT}{sup HU} R{sup 2} = 0.69, P=.08), which was similar to V{sub SPECT} (R{sup 2} = 0.96, P<.01). Conclusions: An 18-patient study demonstrated significant correlations between 4D-CT ventilation and PFT measurements as well as SPECT ventilation, providing evidence toward the validation of 4D-CT ventilation imaging.« less

Quantitative Determination on Ionic-Liquid-Gating Control of Interfacial Magnetism

DOE PAGES

Zhao, Shishun; Zhou, Ziyao; Peng, Bin; ...

2017-03-03

Ionic-liquid gating on a functional thin film with a low voltage has drawn a lot of attention due to rich chemical, electronic, and magnetic phenomena at the interface. A key challenge in quantitative determination of voltage-controlled magnetic anisotropy (VCMA) in Au/[DEME] +[TFSI] -/Co field-effect transistor heterostructures is addressed. The magnetic anisotropy change as response to the gating voltage is precisely detected by in situ electron spin resonance measurements. Furthermore, a reversible change of magnetic anisotropy up to 219 Oe is achieved with a low gating voltage of 1.5 V at room temperature, corresponding to a record high VCMA coefficient ofmore » ≈146 Oe V -1. Two gating effects, the electrostatic doping and electrochemical reaction, are distinguished at various gating voltage regions, as confirmed by X-ray photoelectron spectroscopy and atomic force microscopy experiments. Our work shows a unique ionic-liquid-gating system for strong interfacial magnetoelectric coupling with many practical advantages, paving the way toward ion-liquid-gating spintronic/electronic devices.« less

Quantitative Determination on Ionic-Liquid-Gating Control of Interfacial Magnetism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Shishun; Zhou, Ziyao; Peng, Bin

Ionic-liquid gating on a functional thin film with a low voltage has drawn a lot of attention due to rich chemical, electronic, and magnetic phenomena at the interface. A key challenge in quantitative determination of voltage-controlled magnetic anisotropy (VCMA) in Au/[DEME] +[TFSI] -/Co field-effect transistor heterostructures is addressed. The magnetic anisotropy change as response to the gating voltage is precisely detected by in situ electron spin resonance measurements. Furthermore, a reversible change of magnetic anisotropy up to 219 Oe is achieved with a low gating voltage of 1.5 V at room temperature, corresponding to a record high VCMA coefficient ofmore » ≈146 Oe V -1. Two gating effects, the electrostatic doping and electrochemical reaction, are distinguished at various gating voltage regions, as confirmed by X-ray photoelectron spectroscopy and atomic force microscopy experiments. Our work shows a unique ionic-liquid-gating system for strong interfacial magnetoelectric coupling with many practical advantages, paving the way toward ion-liquid-gating spintronic/electronic devices.« less

Database of normal human cerebral blood flow measured by SPECT: II. Quantification of I-123-IMP studies with ARG method and effects of partial volume correction.

PubMed

Inoue, Kentaro; Ito, Hiroshi; Shidahara, Miho; Goto, Ryoi; Kinomura, Shigeo; Sato, Kazunori; Taki, Yasuyuki; Okada, Ken; Kaneta, Tomohiro; Fukuda, Hiroshi

2006-02-01

The limited spatial resolution of SPECT causes a partial volume effect (PVE) and can lead to the significant underestimation of regional tracer concentration in the small structures surrounded by a low tracer concentration, such as the cortical gray matter of an atrophied brain. The aim of the present study was to determine, using 123I-IMP and SPECT, normal CBF of elderly subjects with and without PVE correction (PVC), and to determine regional differences in the effect of PVC and their association with the regional tissue fraction of the brain. Quantitative CBF SPECT using 123I-IMP was performed in 33 healthy elderly subjects (18 males, 15 females, 54-74 years old) using the autoradiographic method. We corrected CBF for PVE using segmented MR images, and analyzed quantitative CBF and regional differences in the effect of PVC using tissue fractions of gray matter (GM) and white matter (WM) in regions of interest (ROIs) placed on the cortical and subcortical GM regions and deep WM regions. The mean CBF in GM-ROIs were 31.7 +/- 6.6 and 41.0 +/- 8.1 ml/100 g/min for males and females, and in WM-ROIs, 18.2 +/- 0.7 and 22.9 +/- 0.8 ml/100 g/min for males and females, respectively. The mean CBF in GM-ROIs after PVC were 50.9 +/- 12.8 and 65.8 +/- 16.1 ml/100 g/min for males and females, respectively. There were statistically significant differences in the effect of PVC among ROIs, but not between genders. The effect of PVC was small in the cerebellum and parahippocampal gyrus, and it was large in the superior frontal gyrus, superior parietal lobule and precentral gyrus. Quantitative CBF in GM recovered significantly, but did not reach values as high as those obtained by invasive methods or in the H2(15)O PET study that used PVC. There were significant regional differences in the effect of PVC, which were considered to result from regional differences in GM tissue fraction, which is more reduced in the frontoparietal regions in the atrophied brain of the elderly.

SPECT/CT tracer uptake is influenced by tunnel orientation and position of the femoral and tibial ACL graft insertion site.

PubMed

Hirschmann, Michael T; Mathis, Dominic; Rasch, Helmut; Amsler, Felix; Friederich, Niklaus F; Arnold, Markus P

2013-02-01

SPECT/CT is a hybrid imaging modality, which combines a 3D scintigraphy (SPECT) and a conventional computerised tomography (CT). SPECT/CT allows accurate anatomical localisation of metabolic tracer activity. It allows the correlation of surgical factors such as tunnel position and orientation with mechanical alignment, clinical outcome and biological factors. The purpose of this study was to investigate whether the SPECT/CT tracer uptake (intensity and distribution) correlates with the stability and laxity of the knee joint and the position and orientation of the tibial and femoral tunnels in patients after anterior cruciate ligament (ACL) reconstruction. A consecutive series of knees (n=66), with symptoms of pain and/or instability after ACL reconstruction were prospectively evaluated using clinical examination and 99mTc-HDP-SPECT/CT. Clinical laxity testing was performed using the Rolimeter (Ormed, Freiburg, Germany) including Lachman testing (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), anterior drawer test (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), pivot shift test (positive versus negative) and patient-based subjective instability (yes versus no). For analysis of SPECT/CT tracer uptake a previously validated SPECT/CT localisation scheme consisting of 17 tibial, nine femoral and four patellar regions on standardised axial, coronal, and sagittal slices was used. The tracer activity on SPECT/CT was localised and recorded using a 3D volumetric and quantitative analysis software. Mean, standard deviation, minimum and maximum of grading for each area of the localisation scheme were recorded. The position and orientation of the tibial and femoral tunnel was assessed using a previously published method on 3D-CT. Correlation of instability, pivot shift as well as clinical laxity testing with 99mTc-HDP-SPECT/CT tracer uptake intensity and distribution showed no significant correlation. 99mTc-HDP-SPECT/CT tracer uptake correlated significantly with the position and orientation of the ACL graft. A more horizontal femoral graft position showed significantly increased tracer uptake within the superior and posterior femoral regions. A more posteriorly-placed femoral insertion site showed significantly more tracer uptake within the femoral and tibial tunnel regions. A more vertical or a less medial tibial tunnel orientation showed significant increased uptake within the tibial and femoral tunnel regions. A more anterior tibial tunnel position showed significantly more tracer uptake in the femoral and tibial tunnel regions as well as the entire tibiofemoral joint. SPECT/CT tracer uptake intensity and distribution showed a significant correlation with the femoral and tibial tunnel position and orientation in patients with symptomatic knees after ACL reconstruction. No correlation was found with stability or clinical laxity. SPECT/CT tracer uptake distribution has the potential to give us important information on joint homeostasis and remodelling after ACL reconstruction. It might help to predict ACL graft failure and improve our surgical ACL reconstruction technique in finding the optimal tunnel and graft position and orientation.

Technetium-99m-HMPAO labeled leukocyte single photon emission computerized tomography (SPECT) for assessing Crohn's disease extent and intestinal infiltration.

PubMed

Biancone, L; Schillaci, O; Capoccetti, F; Bozzi, R M; Fina, D; Petruzziello, C; Geremia, A; Simonetti, G; Pallone, F

2005-02-01

Scintigraphy using radiolabeled leukocytes is a useful technique for assessing intestinal infiltration in Crohn's disease (CD). However, limits of planar images include overlapping activity in other organs and low specificity. To investigate the usefulness of (99m)Tc-HMPAO (hexametyl propylene amine oxime) labeled leukocyte single photon emission computerized tomography (SPECT) for assessing CD lesions, in comparison with planar images. Twenty-two inflammatory bowel disease patients (19 CD; 2 ulcerative colitis, UC; 1 ileal pouch) assessed by conventional endoscopy or radiology were enrolled. Leukocytes were labeled with (99m)Tc-HMPAO. SPECT images were acquired at 2 h and planar images at 30 min and 2 h. Bowel uptake was quantitated in nine regions (score 0-3). Both SPECT and planar images detected a negative scintigraphy (score 0) in the UC patient with no pouchitis and a positive scintigraphy (score 1-3) in the 21 patients showing active inflammation by conventional techniques. SPECT showed a higher global score than planar images (0.71 +/- 0.09 vs 0.30 +/- 0.05; p < 0.001), and in particular in the right iliac fossa (p= 0.003), right and left flank (p < 0.001; p= 0.02), hypogastrium (p= 0.002), and mesogastrium (p < 0.001). SPECT provided a better visualization and a higher uptake than planar images in patients with ileal and ileocolonic CD (6.45 +/- 0.82 vs 2.8 +/- 0.55, p < 0.001; 5.5 +/- 1.6 vs 2.6 +/- 0.7, p= 0.03), and with perianal CD (6.6 +/- 1.6 vs 3.4 +/- 1.2; p= 0.03). (99m)Tc-HMPAO labeled leukocyte SPECT provides a more detailed visualization of CD lesions than planar images. This technique may better discriminate between intestinal and bone marrow uptake, thus being useful for assessing CD lesions within the pelvis, including perianal disease.

Liver perfusion imaging in patients with primary and metastatic liver malignancy: prospective comparison between 99mTc-MAA spect and dynamic CT perfusion.

PubMed

Reiner, Caecilia S; Goetti, Robert; Burger, Irene A; Fischer, Michael A; Frauenfelder, Thomas; Knuth, Alexander; Pfammatter, Thomas; Schaefer, Niklaus; Alkadhi, Hatem

2012-05-01

To prospectively analyze the correlation between parameters of liver perfusion from technetium99m-macroaggregates of albumin (99mTc-MAA) single photon emission computed tomography (SPECT) with those obtained from dynamic CT perfusion in patients with primary or metastatic liver malignancy. Twenty-five consecutive patients (11 women, 14 men; mean age 60.9 ± 10.8; range: 32-78 years) with primary (n = 5) or metastatic (n = 20) liver malignancy planned to undergo selective internal radiotherapy underwent dynamic contrast-enhanced CT liver perfusion imaging (four-dimensional spiral mode, scan range 14.8 cm, 15 scans, cycle time 3 seconds) and 99m)Tc-MAA SPECT after intraarterial injection of 180 MBq 99mTc-MAA on the same day. Data were evaluated by two blinded and independent readers for the parameters arterial liver perfusion (ALP), portal venous perfusion (PVP), and total liver perfusion (TLP) from CT, and the 99mTc-MAA uptake-ratio of tumors in relation to normal liver parenchyma from SPECT. Interreader agreements for quantitative perfusion parameters were high for dynamic CT (r = 0.90-0.98, each P < .01) and 99mTc -MAA SPECT (r = 0.91, P < .01). Significant correlation was found between 99mTc-MAA uptake ratio and ALP (r = 0.7, P < .01) in liver tumors. No significant correlation was found between 99mTc-MAA uptake ratio, PVP (r = -0.381, P = .081), and TLP (r = 0.039, P = .862). This study indicates that in patients with primary and metastatic liver malignancy, ALP obtained by dynamic CT liver perfusion significantly correlates with the 99mTc-MAA uptake ratio obtained by SPECT. Copyright © 2012 AUR. Published by Elsevier Inc. All rights reserved.

Impact of basal inferolateral scar burden determined by automatic analysis of 99mTc-MIBI myocardial perfusion SPECT on the long-term prognosis of cardiac resynchronization therapy.

PubMed

Morishima, Itsuro; Okumura, Kenji; Tsuboi, Hideyuki; Morita, Yasuhiro; Takagi, Kensuke; Yoshida, Ruka; Nagai, Hiroaki; Tomomatsu, Toshiro; Ikai, Yoshihiro; Terada, Kazushi; Sone, Takahito; Murohara, Toyoaki

2017-04-01

Left-ventricular (LV) scarring may be associated with a poor response to cardiac resynchronization therapy (CRT). The automatic analysis of myocardial perfusion single-photon emission computed tomography (MP-SPECT) may provide objective quantification of LV scarring. We investigated the impact of LV scarring determined by an automatic analysis of MP-SPECT on short-term LV volume response as well as long-term outcome. We studied consecutive 51 patients who were eligible to undergo 99mTc-MIBI MP-SPECT both at baseline and 6 months after CRT (ischaemic cardiomyopathies 31%). Quantitative perfusion SPECT was used to evaluate the defect extent (an index of global scarring) and the LV 17-segment regional uptake ratio (an inverse index of regional scar burden). The primary outcome was the composite of overall mortality or first hospitalization for worsening heart failure. A high global scar burden and a low mid/basal inferolateral regional uptake ratio were associated with volume non-responders to CRT at 6 months. The basal inferolateral regional uptake ratio remained as a predictor of volume non-response after adjusting for the type of cardiomyopathy. During a median follow-up of 36.1 months, the outcome occurred in 28 patients. The patients with a low basal inferolateral regional uptake ratio with a cutoff value of 57% showed poor prognosis (log-rank P= 0.006). The scarring determined by automatic analysis of MP-SPECT images may predict a poor response to CRT regardless of the pathogenesis of cardiomyopathy. The basal inferolateral scar burden in particular may have an adverse impact on long-term prognosis. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Usefulness of the convexity apparent hyperperfusion sign in 123I-iodoamphetamine brain perfusion SPECT for the diagnosis of idiopathic normal pressure hydrocephalus.

PubMed

Ohmichi, Takuma; Kondo, Masaki; Itsukage, Masahiro; Koizumi, Hidetaka; Matsushima, Shigenori; Kuriyama, Nagato; Ishii, Kazunari; Mori, Etsuro; Yamada, Kei; Mizuno, Toshiki; Tokuda, Takahiko

2018-03-16

OBJECTIVE The gold standard for the diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is the CSF removal test. For elderly patients, however, a less invasive diagnostic method is required. On MRI, high-convexity tightness was reported to be an important finding for the diagnosis of iNPH. On SPECT, patients with iNPH often show hyperperfusion of the high-convexity area. The authors tested 2 hypotheses regarding the SPECT finding: 1) it is relative hyperperfusion reflecting the increased gray matter density of the convexity, and 2) it is useful for the diagnosis of iNPH. The authors termed the SPECT finding the convexity apparent hyperperfusion (CAPPAH) sign. METHODS Two clinical studies were conducted. In study 1, SPECT was performed for 20 patients suspected of having iNPH, and regional cerebral blood flow (rCBF) of the high-convexity area was examined using quantitative analysis. Clinical differences between patients with the CAPPAH sign (CAP) and those without it (NCAP) were also compared. In study 2, the CAPPAH sign was retrospectively assessed in 30 patients with iNPH and 19 healthy controls using SPECT images and 3D stereotactic surface projection. RESULTS In study 1, rCBF of the high-convexity area of the CAP group was calculated as 35.2-43.7 ml/min/100 g, which is not higher than normal values of rCBF determined by SPECT. The NCAP group showed lower cognitive function and weaker responses to the removal of CSF than the CAP group. In study 2, the CAPPAH sign was positive only in patients with iNPH (24/30) and not in controls (sensitivity 80%, specificity 100%). The coincidence rate between tight high convexity on MRI and the CAPPAH sign was very high (28/30). CONCLUSIONS Patients with iNPH showed hyperperfusion of the high-convexity area on SPECT; however, the presence of the CAPPAH sign did not indicate real hyperperfusion of rCBF in the high-convexity area. The authors speculated that patients with iNPH without the CAPPAH sign, despite showing tight high convexity on MRI, might have comorbidities such as Alzheimer's disease.

MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halama, J.

2016-06-15

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Development of a Spect-Based Three-Dimensional Treatment Planner for Radionuclide Therapy with Iodine -131.

NASA Astrophysics Data System (ADS)

Giap, Huan Bosco

Accurate calculation of absorbed dose to target tumors and normal tissues in the body is an important requirement for establishing fundamental dose-response relationships for radioimmunotherapy. Two major obstacles have been the difficulty in obtaining an accurate patient-specific 3-D activity map in-vivo and calculating the resulting absorbed dose. This study investigated a methodology for 3-D internal dosimetry, which integrates the 3-D biodistribution of the radionuclide acquired from SPECT with a dose-point kernel convolution technique to provide the 3-D distribution of absorbed dose. Accurate SPECT images were reconstructed with appropriate methods for noise filtering, attenuation correction, and Compton scatter correction. The SPECT images were converted into activity maps using a calibration phantom. The activity map was convolved with an ^{131}I dose-point kernel using a 3-D fast Fourier transform to yield a 3-D distribution of absorbed dose. The 3-D absorbed dose map was then processed to provide the absorbed dose distribution in regions of interest. This methodology can provide heterogeneous distributions of absorbed dose in volumes of any size and shape with nonuniform distributions of activity. Comparison of the activities quantitated by our SPECT methodology to true activities in an Alderson abdominal phantom (with spleen, liver, and spherical tumor) yielded errors of -16.3% to 4.4%. Volume quantitation errors ranged from -4.0 to 5.9% for volumes greater than 88 ml. The percentage differences of the average absorbed dose rates calculated by this methodology and the MIRD S-values were 9.1% for liver, 13.7% for spleen, and 0.9% for the tumor. Good agreement (percent differences were less than 8%) was found between the absorbed dose due to penetrating radiation calculated from this methodology and TLD measurement. More accurate estimates of the 3 -D distribution of absorbed dose can be used as a guide in specifying the minimum activity to be administered to patients to deliver a prescribed absorbed dose to tumor without exceeding the toxicity limits of normal tissues.

MO-AB-206-00: Nuclear Medicine Physics and Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Fuzzy C-mean clustering on kinetic parameter estimation with generalized linear least square algorithm in SPECT

NASA Astrophysics Data System (ADS)

Choi, Hon-Chit; Wen, Lingfeng; Eberl, Stefan; Feng, Dagan

2006-03-01

Dynamic Single Photon Emission Computed Tomography (SPECT) has the potential to quantitatively estimate physiological parameters by fitting compartment models to the tracer kinetics. The generalized linear least square method (GLLS) is an efficient method to estimate unbiased kinetic parameters and parametric images. However, due to the low sensitivity of SPECT, noisy data can cause voxel-wise parameter estimation by GLLS to fail. Fuzzy C-Mean (FCM) clustering and modified FCM, which also utilizes information from the immediate neighboring voxels, are proposed to improve the voxel-wise parameter estimation of GLLS. Monte Carlo simulations were performed to generate dynamic SPECT data with different noise levels and processed by general and modified FCM clustering. Parametric images were estimated by Logan and Yokoi graphical analysis and GLLS. The influx rate (K I), volume of distribution (V d) were estimated for the cerebellum, thalamus and frontal cortex. Our results show that (1) FCM reduces the bias and improves the reliability of parameter estimates for noisy data, (2) GLLS provides estimates of micro parameters (K I-k 4) as well as macro parameters, such as volume of distribution (Vd) and binding potential (BP I & BP II) and (3) FCM clustering incorporating neighboring voxel information does not improve the parameter estimates, but improves noise in the parametric images. These findings indicated that it is desirable for pre-segmentation with traditional FCM clustering to generate voxel-wise parametric images with GLLS from dynamic SPECT data.

Quantitation of specific binding ratio in 123I-FP-CIT SPECT: accurate processing strategy for cerebral ventricular enlargement with use of 3D-striatal digital brain phantom.

PubMed

Furuta, Akihiro; Onishi, Hideo; Amijima, Hizuru

2018-06-01

This study aimed to evaluate the effect of ventricular enlargement on the specific binding ratio (SBR) and to validate the cerebrospinal fluid (CSF)-Mask algorithm for quantitative SBR assessment of 123 I-FP-CIT single-photon emission computed tomography (SPECT) images with the use of a 3D-striatum digital brain (SDB) phantom. Ventricular enlargement was simulated by three-dimensional extensions in a 3D-SDB phantom comprising segments representing the striatum, ventricle, brain parenchyma, and skull bone. The Evans Index (EI) was measured in 3D-SDB phantom images of an enlarged ventricle. Projection data sets were generated from the 3D-SDB phantoms with blurring, scatter, and attenuation. Images were reconstructed using the ordered subset expectation maximization (OSEM) algorithm and corrected for attenuation, scatter, and resolution recovery. We bundled DaTView (Southampton method) with the CSF-Mask processing software for SBR. We assessed SBR with the use of various coefficients (f factor) of the CSF-Mask. Specific binding ratios of 1, 2, 3, 4, and 5 corresponded to SDB phantom simulations with true values. Measured SBRs > 50% that were underestimated with EI increased compared with the true SBR and this trend was outstanding at low SBR. The CSF-Mask improved 20% underestimates and brought the measured SBR closer to the true values at an f factor of 1.0 despite an increase in EI. We connected the linear regression function (y = - 3.53x + 1.95; r = 0.95) with the EI and f factor using root-mean-square error. Processing with CSF-Mask generates accurate quantitative SBR from dopamine transporter SPECT images of patients with ventricular enlargement.

Longitudinal Evaluation of Fatty Acid Metabolism in Normal and Spontaneously Hypertensive Rat Hearts with Dynamic MicroSPECT Imaging

DOE PAGES

Reutter, Bryan W.; Huesman, Ronald H.; Brennan, Kathleen M.; ...

2011-01-01

The goal of this project is to develop radionuclide molecular imaging technologies using a clinical pinhole SPECT/CT scanner to quantify changes in cardiac metabolism using the spontaneously hypertensive rat (SHR) as a model of hypertensive-related pathophysiology. This paper quantitatively compares fatty acid metabolism in hearts of SHR and Wistar-Kyoto normal rats as a function of age and thereby tracks physiological changes associated with the onset and progression of heart failure in the SHR model. The fatty acid analog, 123 I-labeled BMIPP, was used in longitudinal metabolic pinhole SPECT imaging studies performed every seven months for 21 months. The uniqueness ofmore » this project is the development of techniques for estimating the blood input function from projection data acquired by a slowly rotating camera that is imaging fast circulation and the quantification of the kinetics of 123 I-BMIPP by fitting compartmental models to the blood and tissue time-activity curves.« less

Receiver-operating-characteristic analysis of an automated program for analyzing striatal uptake of 123I-ioflupane SPECT images: calibration using visual reads.

PubMed

Kuo, Phillip Hsin; Avery, Ryan; Krupinski, Elizabeth; Lei, Hong; Bauer, Adam; Sherman, Scott; McMillan, Natalie; Seibyl, John; Zubal, George

2013-03-01

A fully automated objective striatal analysis (OSA) program that quantitates dopamine transporter uptake in subjects with suspected Parkinson's disease was applied to images from clinical (123)I-ioflupane studies. The striatal binding ratios or alternatively the specific binding ratio (SBR) of the lowest putamen uptake was computed, and receiver-operating-characteristic (ROC) analysis was applied to 94 subjects to determine the best discriminator using this quantitative method. Ninety-four (123)I-ioflupane SPECT scans were analyzed from patients referred to our clinical imaging department and were reconstructed using the manufacturer-supplied reconstruction and filtering parameters for the radiotracer. Three trained readers conducted independent visual interpretations and reported each case as either normal or showing dopaminergic deficit (abnormal). The same images were analyzed using the OSA software, which locates the striatal and occipital structures and places regions of interest on the caudate and putamen. Additionally, the OSA places a region of interest on the occipital region that is used to calculate the background-subtracted SBR. The lower SBR of the 2 putamen regions was taken as the quantitative report. The 33 normal (bilateral comma-shaped striata) and 61 abnormal (unilateral or bilateral dopaminergic deficit) studies were analyzed to generate ROC curves. Twenty-nine of the scans were interpreted as normal and 59 as abnormal by all 3 readers. For 12 scans, the 3 readers did not unanimously agree in their interpretations (discordant). The ROC analysis, which used the visual-majority-consensus interpretation from the readers as the gold standard, yielded an area under the curve of 0.958 when using 1.08 as the threshold SBR for the lowest putamen. The sensitivity and specificity of the automated quantitative analysis were 95% and 89%, respectively. The OSA program delivers SBR quantitative values that have a high sensitivity and specificity, compared with visual interpretations by trained nuclear medicine readers. Such a program could be a helpful aid for readers not yet experienced with (123)I-ioflupane SPECT images and if further adapted and validated may be useful to assess disease progression during pharmaceutical testing of therapies.

Effect of Ranolazine on Left Ventricular Dyssynchrony in Patients with Coronary Artery Disease

PubMed Central

Venkataraman, Rajesh; Chen, Ji; Garcia, Ernest V.; Belardinelli, Luiz; Hage, Fadi G.; Heo, Jaekyeong; Iskandrian, Ami E.

2012-01-01

We previously reported that ranolazine improved exercise myocardial perfusion. Ranolazine ameliorates myocardial ischemia by augmenting myocardial blood flow; likely due to a reduction in extra-vascular compression of small vessels. We hypothesized that ranolazine could improve left ventricular (LV) dyssynchrony as assessed by phase analysis of gated SPECT myocardial perfusion imaging (MPI). Patients (n=32) with known or suspected coronary artery disease and reversible perfusion defects on a clinically indicated stress MPI were re-studied 4 weeks after ranolazine (500–1000 mg orally twice daily) was added to their conventional treatment in an open-label trial (data previously reported). The LV systolic and diastolic dyssynchrony indices were obtained using automated phase analysis before and after ranolazine. There were no significant changes in heart rate and blood pressure (at rest or during stress) after treatment. The perfusion pattern improved in 13 of 18 patients who had exercise testing but in only 3 of 14 patients who had vasodilator stress testing. There were no significant changes in LV ejection fraction or volumes after treatment. The systolic and diastolic LV dyssynchrony improved after ranolazine therapy; there was a significant decrease in systolic phase standard deviation (SD) (21±17 vs. 18±13, P=0.04), systolic bandwidth (BW) (69±60 vs. 53±38, P=0.03), diastolic SD (29±18 vs. 24±15, P=0.047) and diastolic BW (91±61 vs. 72±45, P=0.02). In conclusion, this is the first study to show improvement in diastolic and systolic LV synchrony with ranolazine as measured by automated phase analysis of gated SPECT MPI. PMID:22884560

Exercise induced left bundle branch block in isotopic exercise test. Findings and prognostic value.

PubMed

Gomez, M V; Lorente Castro, B C; Jané, P; García-Zoghby, L; Martínez-Lorca, A; Pérez, J A

2018-04-18

Exercise-induced left bundle branch block (EI-LBBB) is a rare circumstance of unknown significance. The purpose of this paper is to describe the scintigraphic features and the prognostic value of this finding. We reviewed the features of 1,885 patients who had visited our department to undergo GATED-SPECT ergometry to diagnose ischaemic heart disease. Seven patients showed EI-LBBB throughout the exercise testing. Coronary angiography was performed in 4 of them. Patients were followed-up over an average period of time of 30±8 months. The onset of major cardiovascular events was recorded during the follow-up period. The prevalence of EI-LBBB was 0.37%. Six out of 7 patients were women. Myocardial function and perfusion were normal in 3 patients. Three patients had fixed perfusion defects and one patient had a reversible defect. Two out of the 4 patients showing perfusion defects presented a moderate-severe decrease of the left ventricular ejection fraction. None of the 4 patients with perfusion defects were found to have coronary disease on coronary angiography. The prevalence of EI-LBBB among the patients that came to undergo GATED-SPECT ergometry was very low. The finding was more frequent in women. In our series, 2 patients presented non-ischaemic structural heart disease, but no patient was diagnosed with coronary artery disease. In our patients the presence of EI-LBBB did not relate to a greater risk of experiencing a major cardiovascular event. Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.

Clinical application of arterial spin-labeling MR imaging in patients with carotid stenosis: quantitative comparative study with single-photon emission CT.

PubMed

Uchihashi, Y; Hosoda, K; Zimine, I; Fujita, A; Fujii, M; Sugimura, K; Kohmura, E

2011-09-01

Arterial spin-labeling is an emerging technique for noninvasive measurement of cerebral perfusion, but concerns remain regarding the reliability of CBF quantification and clinical applications. Recently, an ASL implementation called QUASAR was proposed, and it was shown to have good reproducibility of CBF assessment in healthy volunteers. This study aimed to determine the utility of QUASAR for CBF assessment in patients with cerebrovascular diseases. Twenty patients with carotid stenosis underwent CBF quantification by ASL (QUASAR) within 3 days of performance of (123)I-iodoamphetamine-SPECT. CVR to acetazolamide also was assessed by ASL and SPECT. In surgically treated patients, the respective scans before and after the procedures were compared. Regional CBF and CVR values measured by ASL were significantly correlated and agreed with those measured by SPECT (r(s) = 0.92 and 0.88, respectively). A Bland-Altman plot demonstrated good agreement between 2 methods in terms of CBF quantification. Furthermore, ASL could detect pathologic states such as hypoperfusion, impaired vasoreactivity, and postoperative hyperperfusion, equivalent to SPECT. However, ASL tended to overestimate CBF values especially in high-perfusion regions. ASL perfusion MR imaging is clinically applicable and can be an alternative method for CBF assessment in patients with cerebrovascular diseases.

Simultaneous Tc-99m and I-123 dual-radionuclide imaging with a solid-state detector-based brain-SPECT system and energy-based scatter correction.

PubMed

Takeuchi, Wataru; Suzuki, Atsuro; Shiga, Tohru; Kubo, Naoki; Morimoto, Yuichi; Ueno, Yuichiro; Kobashi, Keiji; Umegaki, Kikuo; Tamaki, Nagara

2016-12-01

A brain single-photon emission computed tomography (SPECT) system using cadmium telluride (CdTe) solid-state detectors was previously developed. This CdTe-SPECT system is suitable for simultaneous dual-radionuclide imaging due to its fine energy resolution (6.6 %). However, the problems of down-scatter and low-energy tail due to the spectral characteristics of a pixelated solid-state detector should be addressed. The objective of this work was to develop a system for simultaneous Tc-99m and I-123 brain studies and evaluate its accuracy. A scatter correction method using five energy windows (FiveEWs) was developed. The windows are Tc-lower, Tc-main, shared sub-window of Tc-upper and I-lower, I-main, and I-upper. This FiveEW method uses pre-measured responses for primary gamma rays from each radionuclide to compensate for the overestimation of scatter by the triple-energy window method that is used. Two phantom experiments and a healthy volunteer experiment were conducted using the CdTe-SPECT system. A cylindrical phantom and a six-compartment phantom with five different mixtures of Tc-99m and I-123 and a cold one were scanned. The quantitative accuracy was evaluated using 18 regions of interest for each phantom. In the volunteer study, five healthy volunteers were injected with Tc-99m human serum albumin diethylene triamine pentaacetic acid (HSA-D) and scanned (single acquisition). They were then injected with I-123 N-isopropyl-4-iodoamphetamine hydrochloride (IMP) and scanned again (dual acquisition). The counts of the Tc-99m images for the single and dual acquisitions were compared. In the cylindrical phantom experiments, the percentage difference (PD) between the single and dual acquisitions was 5.7 ± 4.0 % (mean ± standard deviation). In the six-compartment phantom experiment, the PDs between measured and injected activity for Tc-99m and I-123 were 14.4 ± 11.0 and 2.3 ± 1.8 %, respectively. In the volunteer study, the PD between the single and dual acquisitions was 4.5 ± 3.4 %. This CdTe-SPECT system using the FiveEW method can provide accurate simultaneous dual-radionuclide imaging. A solid-state detector SPECT system using the FiveEW method will permit quantitative simultaneous Tc-99m and I-123 study to become clinically applicable.

Fractional flow reserve and myocardial viability as assessed by SPECT perfusion scintigraphy in patients with prior myocardial infarction.

PubMed

Beleslin, Branko; Dobric, Milan; Sobic-Saranovic, Dragana; Giga, Vojislav; Stepanovic, Jelena; Djordjevic-Dikic, Ana; Nedeljkovic, Milan; Stojkovic, Sinisa; Vukcevic, Vladan; Stankovic, Goran; Orlic, Dejan; Petrasinovic, Zorica; Pavlovic, Smiljana; Obradovic, Vladimir; Ostojic, Miodrag

2010-10-01

In patients with previous myocardial infarction (MI), assessment of myocardial viability and physiological significance of coronary artery stenoses are essential for appropriate guidance of revascularization. The aim of the study was to evaluate the relation between fractional flow reserve (FFR) and myocardial viability as assessed by gated SPECT MIBI perfusion scintigraphy in patients with previous MI undergoing elective PCI. The study population consisted of 26 patients (mean age 55 ± 7 years; 21 male) with a previous MI and a significant coronary stenosis in a single infarct-related coronary vessel for which PCI was being performed. In all patients, FFR was evaluated before and immediately after PCI. SPECT imaging was done before and 3 ± 1 months after PCI. A region representing the MI was considered viable if MIBI uptake was ≥55% of the normal region. Improvement in perfusion after revascularization was considered achieved if perfusion abnormalities decreased by 5% or more and there was a decrease in segmental score of ≥1 in three segments in PCI-related vascular territory. Extent of perfusion abnormalities decreased from 32 ± 16% to 27 ± 19% after PCI (P < .001). In patients with myocardial viability in comparison to patients with no viability, there was significant difference in FFR before PCI (.57 ± .14 vs .76 ± .12, P = .002), despite almost the same values of diameter stenosis of infarct-related artery (63 ± 8% vs 64 ± 3%, respectively, P = .572). In addition, FFR prior to PCI was related to improvement in perfusion abnormalities after revascularization (P = .047), as well as with peak activity of creatine-kinase measured during previous MI (r = .56, P = .005). Lower values of FFR before angioplasty are associated with myocardial viability and functional improvement as assessed by SPECT perfusion scintigraphy.

Myocardial perfusion SPECT 2015 in Germany. Results of the 7th survey.

PubMed

Lindner, Oliver; Burchert, Wolfgang; Schäfer, Wolfgang; Hacker, Marcus

2017-02-14

The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 7th survey of myocardial perfusion SPECT (MPS) of the reporting year 2015. 268 questionnaires (173 practices [PR], 67 hospitals [HO], 28 university hospitals [UH]) were evaluated. Results of the last survey from 2012 are set in squared brackets. MPS of 121 939 [105 941] patients were reported. 98 % [95 %] of all MPS were performed with Tc-99m radiopharmaceuticals and 2 % [5 %] with Tl-201. 78 % [79 %] of all patients were studied in PR, 14 % [15 %] in HO, and 8 % [6 %] in UH. A pharmacological stress test was performed in 43 % [39 %] (22 % [24 %] adenosine, 20 % [9 %] regadenoson, 1 % [6 %] dipyridamole or dobutamine). Attenuation correction was applied in 25 % [2009: 10 %] of MPS. Gated SPECT was performed in 78 % [70 %] of all rest MPS, in 80 % [73 %] of all stress and in 76 % [67 %] of all stress and rest MPS. 53 % [33 %] of all nuclear medicine departments performed MPS scoring by default, whereas 24 % [41 %] did not apply any quantification. 31 % [26 %] of all departments noticed an increase in their counted MPS and 29 % [29 %] no changes. Data from 89 departments which participated in all surveys showed an increase in MPS count of 11.1 % (PR: 12.2 %, HO: 4.8 %, UH: 18.4 %). 70 % [60 %] of the MPS were requested by ambulatory care cardiologists. The 2015 MPS survey reveals a high-grade adherence of routine MPS practice to current guidelines. The positive trend in MPS performance and number of MPS already observed in 2012 continues. Educational training remains necessary in the field of SPECT scoring.

Current status of nuclear cardiology practice in Latin America and the Caribbean.

PubMed

Paez, Diana; Peix, Amalia; Orellana, Pilar; Vitola, Joao; Mut, Fernando; Gutiérrez, Claudia; Plaza, Crosby; Becic, Tarik; Dondi, Maurizio; Estrada, Enrique

2017-02-01

The burden of cardiovascular diseases (CVDs) in the world is ever growing. They represent the first cause of death worldwide and in Latin America. Nuclear cardiology has a well-established role in the management of patient with CVDs and is being increasingly integrated into the healthcare systems in the region. However, there remains variability as to the infrastructure available across the countries, in terms of existing technology, radiopharmaceuticals, and human resources. The approximate number of gamma (γ) cameras in the region is 1348, with an average of 2.25 per million population; Argentina and Brazil having the largest number. Nearly 80% of the existing cameras are single-photon emission tomography (SPECT), of which 8% are hybrid SPECT-CT systems. Positron emission tomography technology is steadily increasing, and currently, there is an average of 0.25 scanners per million inhabitants, indicating that there is a potential to expand the capacities in order to cover the needs. Four countries have nuclear reactors for research purposes, which allow the production of technetium-99 m (Argentina, Chile, Mexico and Peru), while four (Argentina, Brazil, Cuba, and Mexico) assemble 99 Mo- 99m Tc generators. As for the nuclear cardiology studies, about 80% of studies performed are gated SPECT myocardial perfusion imaging; less than 10% are multi-gated acquisition (mainly for evaluation of cardiac toxicity in cancer patients), and the other 10% correspond to other types of studies, such as viability detection, and adrenergic innervation studies with 123 I-MIBG. Physical stress is preferred, when possible, based on the clinical condition of the patient. Regarding human resources, there is an average of 1.1 physicians and 1.3 technologists per γ camera, with 0.1 medical physicists and 0.1 radiopharmacists per center in the region. The future of nuclear cardiology in Latin America and the Caribbean is encouraging, with great potential and possibilities for growth. National, regional, and international cooperation including support from scientific societies and organizations such as International Atomic Energy Agency, American Society of Nuclear Cardiology, and Latin American Association of Biology and Nuclear Medicine Societies, as well as governmental commitment are key factors for the development of the specialty. A multimodality approach in cardiac imaging will contribute to a better management of patients with CVDs.

Image reconstruction from cone-beam projections with attenuation correction

NASA Astrophysics Data System (ADS)

Weng, Yi

1997-07-01

In single photon emission computered tomography (SPECT) imaging, photon attenuation within the body is a major factor contributing to the quantitative inaccuracy in measuring the distribution of radioactivity. Cone-beam SPECT provides improved sensitivity for imaging small organs. This thesis extends the results for 2D parallel- beam and fan-beam geometry to 3D parallel-beam and cone- beam geometries in order to derive filtered backprojection reconstruction algorithms for the 3D exponential parallel-beam transform and for the exponential cone-beam transform with sampling on a sphere. An exact inversion formula for the 3D exponential parallel-beam transform is obtained and is extended to the 3D exponential cone-beam transform. Sampling on a sphere is not useful clinically and current cone-beam tomography, with the focal point traversing a planar orbit, does not acquire sufficient data to give an accurate reconstruction. Thus a data acquisition method that obtains complete data for cone-beam SPECT by simultaneously rotating the gamma camera and translating the patient bed, so that cone-beam projections can be obtained with the focal point traversing a helix that surrounds the patient was developed. First, an implementation of Grangeat's algorithm for helical cone- beam projections was developed without attenuation correction. A fast new rebinning scheme was developed that uses all of the detected data to reconstruct the image and properly normalizes any multiply scanned data. In the case of attenuation no theorem analogous to Tuy's has been proven. We hypothesized that an artifact-free reconstruction could be obtained even if the cone-beam data are attenuated, provided the imaging orbit satisfies Tuy's condition and the exact attenuation map is known. Cone-beam emission data were acquired by using a circle- and-line and a helix orbit on a clinical SPECT system. An iterative conjugate gradient reconstruction algorithm was used to reconstruct projection data with a known attenuation map. The quantitative accuracy of the attenuation-corrected emission reconstruction was significantly improved.

SU-F-J-08: Quantitative SPECT Imaging of Ra-223 in a Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yue, J; Hobbs, R; Sgouros, G

Purpose: Ra-223 therapy of prostate cancer bone metastases is being used to treat patients routinely. However, the absorbed dose distribution at the macroscopic and microscopic scales remains elusive, due to the inability to image the small activities injected. Accurate activity quantification through imaging is essential to calculate the absorbed dose in organs and sub-units in radiopharmaceutical therapy, enabling personalized absorbed dose-based treatment planning methodologies and more effective and optimal treatments. Methods: A 22 cm diameter by 20 cm long cylindrical phantom, containing a 3.52 cm diameter sphere, was used. A total of 2.01 MBq of Ra-223 was placed in themore » phantom with 177.6 kBq in the sphere. Images were acquired on a dual-head Siemens Symbia T16 gamma camera using three 20% full-width energy windows and centered at 84, 154, and 269 keV (120 projections, 360° rotation, 45 s per view). We have implemented reconstruction of Ra-223 SPECT projections using OS-EM (up to 20 iterations of 10 subsets) with compensation for attenuation using CT-based attenuation maps, collimator-detector response (CDR) (including septal penetration, scatter and Pb x-ray modeling), and scatter in the patient using the effective source scatter estimation (ESSE) method. The CDR functions and scatter kernels required for ESSE were computed using the SIMIND MC simulation code. All Ra-223 photon emissions as well as gamma rays from the daughters Rn-219 and Bi-211 were modeled. Results: The sensitivity of the camera in the three combined windows was 107.3 cps/MBq. The visual quality of the SPECT images was reasonably good and the activity in the sphere was 27% smaller than the true activity. This underestimation is likely due to partial volume effect. Conclusion: Absolute quantitative Ra-223 SPECT imaging is achievable with careful attention to compensate for image degrading factors and system calibration.« less

Engineering modular and orthogonal genetic logic gates for robust digital-like synthetic biology.

PubMed

Wang, Baojun; Kitney, Richard I; Joly, Nicolas; Buck, Martin

2011-10-18

Modular and orthogonal genetic logic gates are essential for building robust biologically based digital devices to customize cell signalling in synthetic biology. Here we constructed an orthogonal AND gate in Escherichia coli using a novel hetero-regulation module from Pseudomonas syringae. The device comprises two co-activating genes hrpR and hrpS controlled by separate promoter inputs, and a σ(54)-dependent hrpL promoter driving the output. The hrpL promoter is activated only when both genes are expressed, generating digital-like AND integration behaviour. The AND gate is demonstrated to be modular by applying new regulated promoters to the inputs, and connecting the output to a NOT gate module to produce a combinatorial NAND gate. The circuits were assembled using a parts-based engineering approach of quantitative characterization, modelling, followed by construction and testing. The results show that new genetic logic devices can be engineered predictably from novel native orthogonal biological control elements using quantitatively in-context characterized parts. © 2011 Macmillan Publishers Limited. All rights reserved.

Semi-Quantitative Analysis of Post-Transarterial Radioembolization (90)Y Microsphere Positron Emission Tomography Combined with Computed Tomography (PET/CT) Images in Advanced Liver Malignancy: Comparison With (99m)Tc Macroaggregated Albumin (MAA) Single Photon Emission Computed Tomography (SPECT).

PubMed

Rhee, Seunghong; Kim, Sungeun; Cho, Jaehyuk; Park, Jukyung; Eo, Jae Seon; Park, Soyeon; Lee, Eunsub; Kim, Yun Hwan; Choe, Jae-Gol

2016-03-01

The purpose of this study is to evaluate the correlation between pretreatment planning technetium-99m ((99m)Tc) macroaggregated albumin (MAA) SPECT images and posttreatment transarterial radioembolization (TARE) yttirum-90 ((90)Y) PET/CT images by comparing the ratios of tumor-to-normal liver counts. Fifty-two patients with advanced hepatic malignancy who underwent (90)Y microsphere radioembolization from January 2010 to December 2012 were retrospectively reviewed. Patients had undergone (99m)Tc MAA intraarterial injection SPECT for a pretreatment evaluation of microsphere distribution and therapy planning. After the administration of (90)Y microspheres, the patients underwent posttreatment (90)Y PET/CT within 24 h. For semiquantitative analysis, the tumor-to-normal uptake ratios in (90)Y PET/CT (TNR-yp) and (99m)Tc MAA SPECT (TNR-ms) as well as the tumor volumes measured in angiographic CT were obtained and analyzed. The relationship of TNR-yp and TNR-ms was evaluated by Spearman's rank correlation and Wilcoxon's matched pairs test. In a total of 79 lesions of 52 patients, the distribution of microspheres was well demonstrated in both the SPECT and PET/CT images. A good correlation was observed of between TNR-ms and TNR-yp (rho value = 0.648, p < 0.001). The TNR-yp (median 2.78, interquartile range 2.43) tend to show significantly higher values than TNR-ms (median 2.49, interquartile range of 1.55) (p = 0.012). The TNR-yp showed weak correlation with tumor volume (rho = 0.230, p = 0.041). The (99m)Tc MAA SPECT showed a good correlation with (90)Y PET/CT in TNR values, suggesting that (99m)Tc MAA can be used as an adequate pretreatment evaluation method. However, the (99m)Tc MAA SPECT image consistently shows lower TNR values compared to (90)Y PET/CT, which means the possibility of underestimation of tumorous uptake in the partition dosimetry model using (99m)Tc MAA SPECT. Considering that (99m)Tc MAA is the only clinically available surrogate marker for distribution of microsphere, we recommend measurement of tumorous uptake using (90)Y PET/CT should be included routinely in the posttherapeutic evaluation.

Motion-gated acquisition for in vivo optical imaging

PubMed Central

Gioux, Sylvain; Ashitate, Yoshitomo; Hutteman, Merlijn; Frangioni, John V.

2009-01-01

Wide-field continuous wave fluorescence imaging, fluorescence lifetime imaging, frequency domain photon migration, and spatially modulated imaging have the potential to provide quantitative measurements in vivo. However, most of these techniques have not yet been successfully translated to the clinic due to challenging environmental constraints. In many circumstances, cardiac and respiratory motion greatly impair image quality and∕or quantitative processing. To address this fundamental problem, we have developed a low-cost, field-programmable gate array–based, hardware-only gating device that delivers a phase-locked acquisition window of arbitrary delay and width that is derived from an unlimited number of pseudo-periodic and nonperiodic input signals. All device features can be controlled manually or via USB serial commands. The working range of the device spans the extremes of mouse electrocardiogram (1000 beats per minute) to human respiration (4 breaths per minute), with timing resolution ⩽0.06%, and jitter ⩽0.008%, of the input signal period. We demonstrate the performance of the gating device, including dramatic improvements in quantitative measurements, in vitro using a motion simulator and in vivo using near-infrared fluorescence angiography of beating pig heart. This gating device should help to enable the clinical translation of promising new optical imaging technologies. PMID:20059276

Segmentation and Visual Analysis of Whole-Body Mouse Skeleton microSPECT

PubMed Central

Khmelinskii, Artem; Groen, Harald C.; Baiker, Martin; de Jong, Marion; Lelieveldt, Boudewijn P. F.

2012-01-01

Whole-body SPECT small animal imaging is used to study cancer, and plays an important role in the development of new drugs. Comparing and exploring whole-body datasets can be a difficult and time-consuming task due to the inherent heterogeneity of the data (high volume/throughput, multi-modality, postural and positioning variability). The goal of this study was to provide a method to align and compare side-by-side multiple whole-body skeleton SPECT datasets in a common reference, thus eliminating acquisition variability that exists between the subjects in cross-sectional and multi-modal studies. Six whole-body SPECT/CT datasets of BALB/c mice injected with bone targeting tracers 99mTc-methylene diphosphonate (99mTc-MDP) and 99mTc-hydroxymethane diphosphonate (99mTc-HDP) were used to evaluate the proposed method. An articulated version of the MOBY whole-body mouse atlas was used as a common reference. Its individual bones were registered one-by-one to the skeleton extracted from the acquired SPECT data following an anatomical hierarchical tree. Sequential registration was used while constraining the local degrees of freedom (DoFs) of each bone in accordance to the type of joint and its range of motion. The Articulated Planar Reformation (APR) algorithm was applied to the segmented data for side-by-side change visualization and comparison of data. To quantitatively evaluate the proposed algorithm, bone segmentations of extracted skeletons from the correspondent CT datasets were used. Euclidean point to surface distances between each dataset and the MOBY atlas were calculated. The obtained results indicate that after registration, the mean Euclidean distance decreased from 11.5±12.1 to 2.6±2.1 voxels. The proposed approach yielded satisfactory segmentation results with minimal user intervention. It proved to be robust for “incomplete” data (large chunks of skeleton missing) and for an intuitive exploration and comparison of multi-modal SPECT/CT cross-sectional mouse data. PMID:23152834

SPECT myocardial perfusion imaging as an adjunct to coronary calcium score for the detection of hemodynamically significant coronary artery stenosis

PubMed Central

2012-01-01

Background Coronary artery calcifications (CAC) are markers of coronary atherosclerosis, but do not correlate well with stenosis severity. This study intended to evaluate clinical situations where a combined approach of coronary calcium scoring (CS) and nuclear stress test (SPECT-MPI) is useful for the detection of relevant CAD. Methods Patients with clinical indication for invasive coronary angiography (ICA) were included into our study during 08/2005-09/2008. At first all patients underwent CS procedure as part of the study protocol performed by either using a multidetector computed tomography (CT) scanner or a dual-source CT imager. CAC were automatically defined by dedicated software and the Agatston score was semi-automatically calculated. A stress-rest SPECT-MPI study was performed afterwards and scintigraphic images were evaluated quantitatively. Then all patients underwent ICA. Thereby significant CAD was defined as luminal stenosis ≥75% in quantitative coronary analysis (QCA) in ≥1 epicardial vessel. To compare data lacking Gaussian distribution an unpaired Wilcoxon-Test (Mann–Whitney) was used. Otherwise a Students t-test for unpaired samples was applied. Calculations were considered to be significant at a p-value of <0.05. Results We consecutively included 351 symptomatic patients (mean age: 61.2±12.3 years; range: 18–94 years; male: n=240) with a mean Agatston score of 258.5±512.2 (range: 0–4214). ICA verified exclusion of significant CAD in 66/67 (98.5%) patients without CAC. CAC was detected in remaining 284 patients. In 132/284 patients (46.5%) with CS>0 significant CAD was confirmed by ICA, and excluded in 152/284 (53.5%) patients. Sensitivity for CAD detection by CS alone was calculated as 99.2%, specificity was 30.3%, and negative predictive value was 98.5%. An additional SPECT in patients with CS>0 increased specificity to 80.9% while reducing sensitivity to 87.9%. Diagnostic accuracy was 84.2%. Conclusions In patients without CS=0 significant CAD can be excluded with a high negative predictive value by CS alone. An additional SPECT-MPI in those patients with CS>0 leads to a high diagnostic accuracy for the detection of CAD while reducing the number of patients needing invasive diagnostic procedure. PMID:23206557

GATE Monte Carlo simulation in a cloud computing environment

NASA Astrophysics Data System (ADS)

Rowedder, Blake Austin

The GEANT4-based GATE is a unique and powerful Monte Carlo (MC) platform, which provides a single code library allowing the simulation of specific medical physics applications, e.g. PET, SPECT, CT, radiotherapy, and hadron therapy. However, this rigorous yet flexible platform is used only sparingly in the clinic due to its lengthy calculation time. By accessing the powerful computational resources of a cloud computing environment, GATE's runtime can be significantly reduced to clinically feasible levels without the sizable investment of a local high performance cluster. This study investigated a reliable and efficient execution of GATE MC simulations using a commercial cloud computing services. Amazon's Elastic Compute Cloud was used to launch several nodes equipped with GATE. Job data was initially broken up on the local computer, then uploaded to the worker nodes on the cloud. The results were automatically downloaded and aggregated on the local computer for display and analysis. Five simulations were repeated for every cluster size between 1 and 20 nodes. Ultimately, increasing cluster size resulted in a decrease in calculation time that could be expressed with an inverse power model. Comparing the benchmark results to the published values and error margins indicated that the simulation results were not affected by the cluster size and thus that integrity of a calculation is preserved in a cloud computing environment. The runtime of a 53 minute long simulation was decreased to 3.11 minutes when run on a 20-node cluster. The ability to improve the speed of simulation suggests that fast MC simulations are viable for imaging and radiotherapy applications. With high power computing continuing to lower in price and accessibility, implementing Monte Carlo techniques with cloud computing for clinical applications will continue to become more attractive.

SPECT Perfusion Imaging Demonstrates Improvement of Traumatic Brain Injury With Transcranial Near-infrared Laser Phototherapy.

PubMed

Henderson, Theodore A; Morries, Larry D

2015-01-01

Traumatic brain injury (TBI) is a growing health concern affecting civilians and military personnel. Near-infrared (NIR) light has shown benefits in animal models and human trials for stroke and in animal models for TBI. Diodes emitting low-level NIR often have lacked therapeutic efficacy, perhaps failing to deliver sufficient radiant energy to the necessary depth. In this case report, a patient with moderate TBI documented in anatomical magnetic resonance imaging (MRI) and perfusion single-photon emission computed tomography (SPECT) received 20 NIR treatments in the course of 2 mo using a high-power NIR laser. Symptoms were monitored by clinical examination and a novel patient diary system specifically designed for this patient population. Clinical application of these levels of infrared energy for this patient with TBI yielded highly favorable outcomes with decreased depression, anxiety, headache, and insomnia, whereas cognition and quality of life improved. Neurological function appeared to improve based on changes in the SPECT by quantitative analysis. NIR in the power range of 10-15 W at 810 and 980 nm can safely and effectively treat chronic symptoms of TBI.

Automated Quantitative Nuclear Cardiology Methods

PubMed Central

Motwani, Manish; Berman, Daniel S.; Germano, Guido; Slomka, Piotr J.

2016-01-01

Quantitative analysis of SPECT and PET has become a major part of nuclear cardiology practice. Current software tools can automatically segment the left ventricle, quantify function, establish myocardial perfusion maps and estimate global and local measures of stress/rest perfusion – all with minimal user input. State-of-the-art automated techniques have been shown to offer high diagnostic accuracy for detecting coronary artery disease, as well as predict prognostic outcomes. This chapter briefly reviews these techniques, highlights several challenges and discusses the latest developments. PMID:26590779

Identification and Quantitation of Various Inositols and O-methylinositols Present in Plant Roots Using Gas Chromatograpghy/Mass Spectrometry

USDA-ARS?s Scientific Manuscript database

Many inositols and O-methylinositols serve important roles in medicine and plant biology. A simple method was developed for the identification of these compounds in plant roots by extracting with 80% ethanol, derivatizing with trimethylsilyl imidazole, and analyzing by gas chromatography/mass spect...

A QUANTITATIVE ASSESSMENT OF A COMBINED SPECTRAL AND GIS RULE-BASED LAND-COVER CLASSIFICATION IN THE NEUSE RIVER BASIN OF NORTH CAROLINA

EPA Science Inventory

The 14,582 km2 Neuse River Basin in North Carolina was characterized based on a user defined land-cover (LC) classification system developed specifically to support spatially explicit, non-point source nitrogen allocation modeling studies. Data processing incorporated both spect...

Clinical utility of indigenously formulated single-vial lyophilized HYNIC-TOC kit in evaluating Gastro-entero Pancreatic neuro endocrine tumours

PubMed Central

Shinto, Ajit S; Kamaleshwaran, K; Vyshak, K; Sudhakar, Natarajan; Banerjee, Sharmila; Korde, Aruna; Samuel, Grace; Mallia, Madhav

2014-01-01

Objective(s): The objective of this study was to evaluate the performance and utility of 99mTc HYNIC-TOC planar scintigraphy and SPECT/CT in the diagnosis, staging and management of gastroenteropancreatic neuroendocrine tumors (GPNETs). Methods: 22 patients (median age, 46 years) with histologically proven gastro- entero- pancreatic NETs underwent 99mTc HYNIC-TOC whole body scintigraphy and regional SPECT/CT as indicated. Scanning was performed after injection of 370-550 MBq (10-15 mCi) of 99mTc HYNIC-TOC intravenously. Images were evaluated by two experienced nuclear medicine physicians both qualitatively as well as semi quantitatively (tumor to background and tumor to normal liver ratios on SPECT -CT images). Results of SPECT/CT were compared with the results of conventional imaging. Histopathology results and follow-up somatostatin receptor scintigraphy with 99mTc HYNIC TOC or conventional imaging with biochemical markers were considered to be the reference standards. Results: 99mTc HYNIC TOC showed sensitivity and specificity of 87.5% and 85.7%, respectively, for primary tumor and 100% and 86% for metastases. It was better than conventional imaging modalities for the detection of both primary tumor (P<0.001) and metastases (P<0.0001). It changed the management strategy in 6 patients (31.8%) and supported management decisions in 8 patients (36.3%). Conclusion: 99mTc HYNIC TOC SPECT/CT appears to be a highly sensitive and specific modality for the detection and staging of GPNETs. It is better than conventional imaging for the evaluation of GPNETs and can have a significant impact on patient management and planning further therapeutic options. PMID:27408857

Clinical utility of indigenously formulated single-vial lyophilized HYNIC-TOC kit in evaluating Gastro-entero Pancreatic neuro endocrine tumours.

PubMed

Shinto, Ajit S; Kamaleshwaran, K; Vyshak, K; Sudhakar, Natarajan; Banerjee, Sharmila; Korde, Aruna; Samuel, Grace; Mallia, Madhav

2014-01-01

The objective of this study was to evaluate the performance and utility of (99m)Tc HYNIC-TOC planar scintigraphy and SPECT/CT in the diagnosis, staging and management of gastroenteropancreatic neuroendocrine tumors (GPNETs). 22 patients (median age, 46 years) with histologically proven gastro- entero- pancreatic NETs underwent (99m)Tc HYNIC-TOC whole body scintigraphy and regional SPECT/CT as indicated. Scanning was performed after injection of 370-550 MBq (10-15 mCi) of (99m)Tc HYNIC-TOC intravenously. Images were evaluated by two experienced nuclear medicine physicians both qualitatively as well as semi quantitatively (tumor to background and tumor to normal liver ratios on SPECT -CT images). Results of SPECT/CT were compared with the results of conventional imaging. Histopathology results and follow-up somatostatin receptor scintigraphy with (99m)Tc HYNIC TOC or conventional imaging with biochemical markers were considered to be the reference standards. (99m)Tc HYNIC TOC showed sensitivity and specificity of 87.5% and 85.7%, respectively, for primary tumor and 100% and 86% for metastases. It was better than conventional imaging modalities for the detection of both primary tumor (P<0.001) and metastases (P<0.0001). It changed the management strategy in 6 patients (31.8%) and supported management decisions in 8 patients (36.3%). (99m)Tc HYNIC TOC SPECT/CT appears to be a highly sensitive and specific modality for the detection and staging of GPNETs. It is better than conventional imaging for the evaluation of GPNETs and can have a significant impact on patient management and planning further therapeutic options.

Design of a short nonuniform acquisition protocol for quantitative analysis in dynamic cardiac SPECT imaging - a retrospective 123 I-MIBG animal study.

PubMed

Zan, Yunlong; Long, Yong; Chen, Kewei; Li, Biao; Huang, Qiu; Gullberg, Grant T

2017-07-01

Our previous works have found that quantitative analysis of 123 I-MIBG kinetics in the rat heart with dynamic single-photon emission computed tomography (SPECT) offers the potential to quantify the innervation integrity at an early stage of left ventricular hypertrophy. However, conventional protocols involving a long acquisition time for dynamic imaging reduce the animal survival rate and thus make longitudinal analysis difficult. The goal of this work was to develop a procedure to reduce the total acquisition time by selecting nonuniform acquisition times for projection views while maintaining the accuracy and precision of estimated physiologic parameters. Taking dynamic cardiac imaging with 123 I-MIBG in rats as an example, we generated time activity curves (TACs) of regions of interest (ROIs) as ground truths based on a direct four-dimensional reconstruction of experimental data acquired from a rotating SPECT camera, where TACs represented as the coefficients of B-spline basis functions were used to estimate compartmental model parameters. By iteratively adjusting the knots (i.e., control points) of B-spline basis functions, new TACs were created according to two rules: accuracy and precision. The accuracy criterion allocates the knots to achieve low relative entropy between the estimated left ventricular blood pool TAC and its ground truth so that the estimated input function approximates its real value and thus the procedure yields an accurate estimate of model parameters. The precision criterion, via the D-optimal method, forces the estimated parameters to be as precise as possible, with minimum variances. Based on the final knots obtained, a new protocol of 30 min was built with a shorter acquisition time that maintained a 5% error in estimating rate constants of the compartment model. This was evaluated through digital simulations. The simulation results showed that our method was able to reduce the acquisition time from 100 to 30 min for the cardiac study of rats with 123 I-MIBG. Compared to a uniform interval dynamic SPECT protocol (1 s acquisition interval, 30 min acquisition time), the newly proposed protocol with nonuniform interval achieved comparable (K1 and k2, P = 0.5745 for K1 and P = 0.0604 for k2) or better (Distribution Volume, DV, P = 0.0004) performance for parameter estimates with less storage and shorter computational time. In this study, a procedure was devised to shorten the acquisition time while maintaining the accuracy and precision of estimated physiologic parameters in dynamic SPECT imaging. The procedure was designed for 123 I-MIBG cardiac imaging in rat studies; however, it has the potential to be extended to other applications, including patient studies involving the acquisition of dynamic SPECT data. © 2017 American Association of Physicists in Medicine.

Diagnostic accuracy of semi-automatic quantitative metrics as an alternative to expert reading of CT myocardial perfusion in the CORE320 study.

PubMed

Ostovaneh, Mohammad R; Vavere, Andrea L; Mehra, Vishal C; Kofoed, Klaus F; Matheson, Matthew B; Arbab-Zadeh, Armin; Fujisawa, Yasuko; Schuijf, Joanne D; Rochitte, Carlos E; Scholte, Arthur J; Kitagawa, Kakuya; Dewey, Marc; Cox, Christopher; DiCarli, Marcelo F; George, Richard T; Lima, Joao A C

To determine the diagnostic accuracy of semi-automatic quantitative metrics compared to expert reading for interpretation of computed tomography perfusion (CTP) imaging. The CORE320 multicenter diagnostic accuracy clinical study enrolled patients between 45 and 85 years of age who were clinically referred for invasive coronary angiography (ICA). Computed tomography angiography (CTA), CTP, single photon emission computed tomography (SPECT), and ICA images were interpreted manually in blinded core laboratories by two experienced readers. Additionally, eight quantitative CTP metrics as continuous values were computed semi-automatically from myocardial and blood attenuation and were combined using logistic regression to derive a final quantitative CTP metric score. For the reference standard, hemodynamically significant coronary artery disease (CAD) was defined as a quantitative ICA stenosis of 50% or greater and a corresponding perfusion defect by SPECT. Diagnostic accuracy was determined by area under the receiver operating characteristic curve (AUC). Of the total 377 included patients, 66% were male, median age was 62 (IQR: 56, 68) years, and 27% had prior myocardial infarction. In patient based analysis, the AUC (95% CI) for combined CTA-CTP expert reading and combined CTA-CTP semi-automatic quantitative metrics was 0.87(0.84-0.91) and 0.86 (0.83-0.9), respectively. In vessel based analyses the AUC's were 0.85 (0.82-0.88) and 0.84 (0.81-0.87), respectively. No significant difference in AUC was found between combined CTA-CTP expert reading and CTA-CTP semi-automatic quantitative metrics in patient based or vessel based analyses(p > 0.05 for all). Combined CTA-CTP semi-automatic quantitative metrics is as accurate as CTA-CTP expert reading to detect hemodynamically significant CAD. Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

The purpose of the computer program is to generate system matrices that model data acquisition process in dynamic single photon emission computed tomography (SPECT). The application is for the reconstruction of dynamic data from projection measurements that provide the time evolution of activity uptake and wash out in an organ of interest. The measurement of the time activity in the blood and organ tissue provide time-activity curves (TACs) that are used to estimate kinetic parameters. The program provides a correct model of the in vivo spatial and temporal distribution of radioactive in organs. The model accounts for the attenuation ofmore » the internal emitting radioactivity, it accounts for the vary point response of the collimators, and correctly models the time variation of the activity in the organs. One important application where the software is being used in a measuring the arterial input function (AIF) in a dynamic SPECT study where the data are acquired from a slow camera rotation. Measurement of the arterial input function (AIF) is essential to deriving quantitative estimates of regional myocardial blood flow using kinetic models. A study was performed to evaluate whether a slowly rotating SPECT system could provide accurate AIF's for myocardial perfusion imaging (MPI). Methods: Dynamic cardiac SPECT was first performed in human subjects at rest using a Phillips Precedence SPECT/CT scanner. Dynamic measurements of Tc-99m-tetrofosmin in the myocardium were obtained using an infusion time of 2 minutes. Blood input, myocardium tissue and liver TACs were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. Results: The spatiotemporal 4D ML-EM reconstructions gave more accurate reconstructions that did standard frame-by-frame 3D ML-EM reconstructions. From additional computer simulations and phantom studies, it was determined that a 1 minute infusion with a SPECT system rotation speed providing 180 degrees of projection data every 54s can produce measurements of blood pool and myocardial TACs. This has important application in the circulation of coronary flow reserve using rest/stress dynamic cardiac SPECT. They system matrices are used in maximum likelihood and maximum a posterior formulations in estimation theory where through iterative algorithms (conjugate gradient, expectation maximization, or maximum a posteriori probability algorithms) the solution is determined that maximizes a likelihood or a posteriori probability function.« less

Fast simulation of yttrium-90 bremsstrahlung photons with GATE.

PubMed

Rault, Erwann; Staelens, Steven; Van Holen, Roel; De Beenhouwer, Jan; Vandenberghe, Stefaan

2010-06-01

Multiple investigators have recently reported the use of yttrium-90 (90Y) bremsstrahlung single photon emission computed tomography (SPECT) imaging for the dosimetry of targeted radionuclide therapies. Because Monte Carlo (MC) simulations are useful for studying SPECT imaging, this study investigates the MC simulation of 90Y bremsstrahlung photons in SPECT. To overcome the computationally expensive simulation of electrons, the authors propose a fast way to simulate the emission of 90Y bremsstrahlung photons based on prerecorded bremsstrahlung photon probability density functions (PDFs). The accuracy of bremsstrahlung photon simulation is evaluated in two steps. First, the validity of the fast bremsstrahlung photon generator is checked. To that end, fast and analog simulations of photons emitted from a 90Y point source in a water phantom are compared. The same setup is then used to verify the accuracy of the bremsstrahlung photon simulations, comparing the results obtained with PDFs generated from both simulated and measured data to measurements. In both cases, the energy spectra and point spread functions of the photons detected in a scintillation camera are used. Results show that the fast simulation method is responsible for a 5% overestimation of the low-energy fluence (below 75 keV) of the bremsstrahlung photons detected using a scintillation camera. The spatial distribution of the detected photons is, however, accurately reproduced with the fast method and a computational acceleration of approximately 17-fold is achieved. When measured PDFs are used in the simulations, the simulated energy spectrum of photons emitted from a point source of 90Y in a water phantom and detected in a scintillation camera closely approximates the measured spectrum. The PSF of the photons imaged in the 50-300 keV energy window is also accurately estimated with a 12.4% underestimation of the full width at half maximum and 4.5% underestimation of the full width at tenth maximum. Despite its limited accuracy, the fast bremsstrahlung photon generator is well suited for the simulation of bremsstrahlung photons emitted in large homogeneous organs, such as the liver, and detected in a scintillation camera. The computational acceleration makes it very useful for future investigations of 90Y bremsstrahlung SPECT imaging.

3D SPECT/CT fusion using image data projection of bone SPECT onto 3D volume-rendered CT images: feasibility and clinical impact in the diagnosis of bone metastasis.

PubMed

Ogata, Yuji; Nakahara, Tadaki; Ode, Kenichi; Matsusaka, Yohji; Katagiri, Mari; Iwabuchi, Yu; Itoh, Kazunari; Ichimura, Akira; Jinzaki, Masahiro

2017-05-01

We developed a method of image data projection of bone SPECT into 3D volume-rendered CT images for 3D SPECT/CT fusion. The aims of our study were to evaluate its feasibility and clinical usefulness. Whole-body bone scintigraphy (WB) and SPECT/CT scans were performed in 318 cancer patients using a dedicated SPECT/CT systems. Volume data of bone SPECT and CT were fused to obtain 2D SPECT/CT images. To generate our 3D SPECT/CT images, colored voxel data of bone SPECT were projected onto the corresponding location of the volume-rendered CT data after a semi-automatic bone extraction. Then, the resultant 3D images were blended with conventional volume-rendered CT images, allowing to grasp the three-dimensional relationship between bone metabolism and anatomy. WB and SPECT (WB + SPECT), 2D SPECT/CT fusion, and 3D SPECT/CT fusion were evaluated by two independent reviewers in the diagnosis of bone metastasis. The inter-observer variability and diagnostic accuracy in these three image sets were investigated using a four-point diagnostic scale. Increased bone metabolism was found in 744 metastatic sites and 1002 benign changes. On a per-lesion basis, inter-observer agreements in the diagnosis of bone metastasis were 0.72 for WB + SPECT, 0.90 for 2D SPECT/CT, and 0.89 for 3D SPECT/CT. Receiver operating characteristic analyses for the diagnostic accuracy of bone metastasis showed that WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT had an area under the curve of 0.800, 0.983, and 0.983 for reader 1, 0.865, 0.992, and 0.993 for reader 2, respectively (WB + SPECT vs. 2D or 3D SPECT/CT, p < 0.001; 2D vs. 3D SPECT/CT, n.s.). The durations of interpretation of WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT images were 241 ± 75, 225 ± 73, and 182 ± 71 s for reader 1 and 207 ± 72, 190 ± 73, and 179 ± 73 s for reader 2, respectively. As a result, it took shorter time to read 3D SPECT/CT images than 2D SPECT/CT (p < 0.0001) or WB + SPECT images (p < 0.0001). 3D SPECT/CT fusion offers comparable diagnostic accuracy to 2D SPECT/CT fusion. The visual effect of 3D SPECT/CT fusion facilitates reduction of reading time compared to 2D SPECT/CT fusion.

Comparison of SSS and SRS calculated from normal databases provided by QPS and 4D-MSPECT manufacturers and from identical institutional normals.

PubMed

Knollmann, Daniela; Knebel, Ingrid; Koch, Karl-Christian; Gebhard, Michael; Krohn, Thomas; Buell, Ulrich; Schaefer, Wolfgang M

2008-02-01

There is proven evidence for the importance of myocardial perfusion-single-photon emission computed tomography (SPECT) with computerised determination of summed stress and rest scores (SSS/SRS) for the diagnosis of coronary artery disease (CAD). SSS and SRS can thereby be calculated semi-quantitatively using a 20-segment model by comparing tracer-uptake with values from normal databases (NDB). Four severity-degrees for SSS and SRS are normally used: <4, 4-8, 9-13, and > or =14. Manufacturers' NDBs (M-NDBs) often do not fit the institutional (I) settings. Therefore, this study compared SSS and SRS obtained with the algorithms Quantitative Perfusion SPECT (QPS) and 4D-MSPECT using M-NDB and I-NDB. I-NDBs were obtained using QPS and 4D-MSPECT from exercise stress data (450 MBq (99m)Tc-tetrofosmin, triple-head-camera, 30 s/view, 20 views/head) from 36 men with a low post-stress test CAD probability and visually normal SPECT findings. Patient group was 60 men showing the entire CAD-spectrum referred for routine perfusion-SPECT. Stress/rest results of automatic quantification of the 60 patients were compared to M-NDB and I-NDB. After reclassifying SSS/SRS into the four severity degrees, kappa values were calculated to objectify agreement. Mean values (vs M-NDB) were 9.4 +/- 10.3 (SSS) and 5.8 +/- 9.7 (SRS) for QPS and 8.2 +/- 8.7 (SSS) and 6.2 +/- 7.8 (SRS) for 4D-MSPECT. Thirty seven of sixty SSS classifications (kappa = 0.462) and 40/60 SRS classifications (kappa = 0.457) agreed. Compared to I-NDB, mean values were 10.2 +/- 11.6 (SSS) and 6.5 +/- 10.4 (SRS) for QPS and 9.2 +/- 9.3 (SSS) and 7.2 +/- 8.6 (SRS) for 4D-MSPECT. Forty four of sixty patients agreed in SSS and SRS (kappa = 0.621 resp. 0.58). Considerable differences between SSS/SRS obtained with QPS and 4D-MSPECT were found when using M-NDB. Even using identical patients and identical I-NDB, the algorithms still gave substantial different results.

Design and assessment of a novel SPECT system for desktop open-gantry imaging of small animals: A simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeraatkar, Navid; Farahani, Mohammad Hossein; Rahmim, Arman

Purpose: Given increasing efforts in biomedical research utilizing molecular imaging methods, development of dedicated high-performance small-animal SPECT systems has been growing rapidly in the last decade. In the present work, we propose and assess an alternative concept for SPECT imaging enabling desktop open-gantry imaging of small animals. Methods: The system, PERSPECT, consists of an imaging desk, with a set of tilted detector and pinhole collimator placed beneath it. The object to be imaged is simply placed on the desk. Monte Carlo (MC) and analytical simulations were utilized to accurately model and evaluate the proposed concept and design. Furthermore, a dedicatedmore » image reconstruction algorithm, finite-aperture-based circular projections (FABCP), was developed and validated for the system, enabling more accurate modeling of the system and higher quality reconstructed images. Image quality was quantified as a function of different tilt angles in the acquisition and number of iterations in the reconstruction algorithm. Furthermore, more complex phantoms including Derenzo, Defrise, and mouse whole body were simulated and studied. Results: The sensitivity of the PERSPECT was 207 cps/MBq. It was quantitatively demonstrated that for a tilt angle of 30°, comparable image qualities were obtained in terms of normalized squared error, contrast, uniformity, noise, and spatial resolution measurements, the latter at ∼0.6 mm. Furthermore, quantitative analyses demonstrated that 3 iterations of FABCP image reconstruction (16 subsets/iteration) led to optimally reconstructed images. Conclusions: The PERSPECT, using a novel imaging protocol, can achieve comparable image quality performance in comparison with a conventional pinhole SPECT with the same configuration. The dedicated FABCP algorithm, which was developed for reconstruction of data from the PERSPECT system, can produce high quality images for small-animal imaging via accurate modeling of the system as incorporated in the forward- and back-projection steps. Meanwhile, the developed MC model and the analytical simulator of the system can be applied for further studies on development and evaluation of the system.« less

Regional Cerebral Blood Flow Analysis in Patients with Multiple Sclerosis Using TC-99M Hmpao and a Three - Spect System.

NASA Astrophysics Data System (ADS)

D'Souza, Maximian Felix

1995-01-01

The purpose of the present study was to determine the changes in regional cerebral blood flow (rCBF) with a cognitive task of semantic word retrieval (verbal fluency) in patients with multiple sclerosis (MS) and compare with the rCBF distribution of normal controls. Two groups of patients with low and high verbal fluency scores and two groups of normal controls were selected to determine a relationship between rCBF and verbal performance. A three-detector gamma camera (TRIAD 88) was used with radiotracer Tc-99m HMPAO and single photon emission computed tomography (SPECT) to obtain 3D rCBF maps. The performance characteristics of the camera was comprehensively studied before being utilized for clinical studies. In addition, technical improvements were implemented in the form of scatter correction and MRI-SPECT coregistration to potentially enhance the quantitative accuracy of the rCBF data. The performance analysis of the gamma camera showed remarkable consistency among the three-detector heads and yielded results that were consistent with the manufacturer's specification. Measurements of physical objects also showed excellent image quality. The coregistration of SPECT and MRI images allowed more accurate anatomical localization for extraction of regional blood flow information. The validation of the scatter correction technique with physical phantoms indicated marked improvements in quantitative accuracy. There was marked difference in activation patterns between patients and normals. In normals, individually subjects showed either an increase or a decrease in blood flow to left frontal and temporal, however, on average, there was not a statistically significant change. The lack of significant change may suggest large variability among subjects chosen or that the individual changes are not large enough to be significant. The results from MS patients showed several left cortical areas with statistically significant change in blood flow after cognitive activation, especially in the low fluent group, with decreased flow. Scatter corrected data yielded mostly right sided significant increases in blood flow. Further studies must be conducted to further evaluate the scatter correction technique. Additional studies on MS patients must focus on correlating lesion volume, location and number to the rCBF distribution.

Coronary Artery Disease: Analysis of Diagnostic Performance of CT Perfusion and MR Perfusion Imaging in Comparison with Quantitative Coronary Angiography and SPECT-Multicenter Prospective Trial.

PubMed

Rief, Matthias; Chen, Marcus Y; Vavere, Andrea L; Kendziora, Benjamin; Miller, Julie M; Bandettini, W Patricia; Cox, Christopher; George, Richard T; Lima, João; Di Carli, Marcelo; Plotkin, Michail; Zimmermann, Elke; Laule, Michael; Schlattmann, Peter; Arai, Andrew E; Dewey, Marc

2018-02-01

Purpose To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). Materials and Methods All patients gave written informed consent prior to inclusion in this institutional review board-approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. Results The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P < .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P < .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). Conclusion This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. © RSNA, 2017 Online supplemental material is available for this article.

99m Tc-MIP-1404-SPECT/CT for the detection of PSMA-positive lesions in 225 patients with biochemical recurrence of prostate cancer.

PubMed

Schmidkonz, Christian; Hollweg, Claudia; Beck, Michael; Reinfelder, Julia; Goetz, Theresa I; Sanders, James C; Schmidt, Daniela; Prante, Olaf; Bäuerle, Tobias; Cavallaro, Alexander; Uder, Michael; Wullich, Bernd; Goebell, Peter; Kuwert, Torsten; Ritt, Philipp

2018-01-01

99m Tc-MIP-1404 (Progenics Pharmaceuticals, Inc., New York, NY) is a novel, SPECT-compatible 99m Tc-labeled PSMA inhibitor for the detection of prostate cancer. We present results of its clinical use in a cohort of 225 men with histologically confirmed prostate cancer referred for workup of biochemical relapse. From April 2013 to April 2017, 99m Tc-MIP1404-scintigraphy was performed in 225 patients for workup of PSA biochemical relapse of prostate cancer. Whole-body planar and SPECT/CT images of the lower abdomen and thorax were obtained 3-4 h p.i. of 710 ± 64 MBq 99m Tc-MIP-1404. Images were visually analyzed for presence and location of abnormal uptake. In addition, quantitative analysis of the SPECT/CT data was carried out on a subset of 125 patients. Follow-up reports of subsequent therapeutic interventions were available for 59% (139) of all patients. Tracer-positive lesions were detected in 77% (174/225) of all patients. Detections occurred at the area of local recurrence in the prostate in 25% of patients (or a total of 56), with metastases in lymph nodes in 47% (105), bone in 27% (60), lung in 5% (12), and other locations in 2% (4) of patients. Detection rates were 90% at PSA levels ≥2 ng/mL and 54% below that threshold. Lesional SUVmax values were, on average, 32.2 ± 29.6 (0.8-142.2), and tumor-to-normal ratios 146.6 ± 160.5 (1.9-1482.4). The PSA level correlated significantly with total uptake of MIP-1404 in tumors (P < 0.001). Furthermore, total tumor uptake was significantly higher in patients with Gleason scores ≥8 compared to those with Gleason scores ≤7 (P < 0.05). In patients with androgen deprivation therapy, the detection rate was significantly higher compared to patients without androgen deprivation therapy (86% vs 71%, P < 0.001). Based on 99m Tc-MIP-1404-imaging and other information, an interdisciplinary tumor board review recommended changes to treatment plans in 74% (104/139) of those patients for whom the necessary documentation was available. SPECT/CT with 99m Tc-labeled MIP-1404 has a high probability in detecting PSMA-positive lesions in patients with elevated PSA. Statistical analysis disclosed significant relationship between quantitative 99m Tc-MIP-1404 uptake, PSA level, and Gleason score. © 2017 Wiley Periodicals, Inc.

MO-DE-303-03: Session on quantitative imaging for assessment of tumor response to radiation therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, S.

This session will focus on quantitative imaging for assessment of tumor response to radiation therapy. This is a technically challenging method to translate to practice in radiation therapy. In the new era of precision medicine, however, delivering the right treatment, to the right patient, and at the right time, can positively impact treatment choices and patient outcomes. Quantitative imaging provides the spatial sensitivity required by radiation therapy for precision medicine that is not available by other means. In this Joint ESTRO -AAPM Symposium, three leading-edge investigators will present specific motivations for quantitative imaging biomarkers in radiation therapy of esophageal, headmore » and neck, locally advanced non-small cell lung cancer, and hepatocellular carcinoma. Experiences with the use of dynamic contrast enhanced (DCE) MRI, diffusion- weighted (DW) MRI, PET/CT, and SPECT/CT will be presented. Issues covered will include: response prediction, dose-painting, timing between therapy and imaging, within-therapy biomarkers, confounding effects, normal tissue sparing, dose-response modeling, and association with clinical biomarkers and outcomes. Current information will be presented from investigational studies and clinical practice. Learning Objectives: Learn motivations for the use of quantitative imaging biomarkers for assessment of response to radiation therapy Review the potential areas of application in cancer therapy Examine the challenges for translation, including imaging confounds and paucity of evidence to date Compare exemplary examples of the current state of the art in DCE-MRI, DW-MRI, PET/CT and SPECT/CT imaging for assessment of response to radiation therapy Van der Heide: Research grants from the Dutch Cancer Society and the European Union (FP7) Bowen: RSNA Scholar grant.« less

Evaluation of dead-time corrections for post-radionuclide-therapy (177)Lu quantitative imaging with low-energy high-resolution collimators.

PubMed

Celler, Anna; Piwowarska-Bilska, Hanna; Shcherbinin, Sergey; Uribe, Carlos; Mikolajczak, Renata; Birkenfeld, Bozena

2014-01-01

Dead-time (DT) effects rarely cause problems in diagnostic single-photon emission computed tomography (SPECT) studies; however, in post-radionuclide-therapy imaging, DT can be substantial. Therefore, corrections may be necessary if quantitative images are used in image-based dosimetry or for evaluation of therapy outcomes. This task is particularly challenging if low-energy collimators are used. Our goal was to design a simple method to determine the dead-time correction factor (DTCF) without the need for phantom experiments and complex calculations. Planar and SPECT/CT scans of a water phantom containing a 70 ml bottle filled with lutetium-177 (Lu) were acquired over 60 days. Two small Lu markers were used in all scans. The DTCF based on the ratio of observed to true count rates measured over the entire spectrum and using photopeak primary photons only was estimated for phantom (DT present) and marker (no DT) scans. In addition, variations in counts in SPECT projections (potentially caused by varying bremsstrahlung and scatter) were investigated. For count rates that were about two-fold higher than typically seen in post-therapy Lu scans, the maximum DTCF reached a level of about 17%. The DTCF values determined directly from the phantom experiments using the total energy spectrum and photopeak counts only were equal to 13 and 16%, respectively. They were closely matched by those from the proposed marker-based method, which uses only two energy windows and measures photopeak primary photons (15-17%). A simple, marker-based method allowing for determination of the DTCF in high-activity Lu imaging studies has been proposed and validated using phantom experiments.

Imaging Transgene Expression with Radionuclide Imaging Technologies1

PubMed Central

Gambhir, SS; Herschman, HR; Cherry, SR; Barrio, JR; Satyamurthy, N; Toyokuni, T; Phelps, ME; Larson, SM; Balaton, J; Finn, R; Sadelain, M; Tjuvajev, J

2000-01-01

Abstract A variety of imaging technologies are being investigated as tools for studying gene expression in living subjects. Noninvasive, repetitive and quantitative imaging of gene expression will help both to facilitate human gene therapy trials and to allow for the study of animal models of molecular and cellular therapy. Radionuclide approaches using single photon emission computed tomography (SPECT) and positron emission tomography (PET) are the most mature of the current imaging technologies and offer many advantages for imaging gene expression compared to optical and magnetic resonance imaging (MRI)-based approaches. These advantages include relatively high sensitivity, full quantitative capability (for PET), and the ability to extend small animal assays directly into clinical human applications. We describe a PET scanner (micro PET) designed specifically for studies of small animals. We review “marker/reporter gene” imaging approaches using the herpes simplex type 1 virus thymidine kinase (HSV1-tk) and the dopamine type 2 receptor (D2R) genes. We describe and contrast several radiolabeled probes that can be used with the HSV1-tk reporter gene both for SPECT and for PET imaging. We also describe the advantages/disadvantages of each of the assays developed and discuss future animal and human applications. PMID:10933072

Dual-radiolabeled nanoparticle probes for depth-independent in vivo imaging of enzyme activation

NASA Astrophysics Data System (ADS)

Black, Kvar C. L.; Zhou, Mingzhou; Sarder, Pinaki; Kuchuk, Maryna; Al-Yasiri, Amal Y.; Gunsten, Sean P.; Liang, Kexian; Hennkens, Heather M.; Akers, Walter J.; Laforest, Richard; Brody, Steven L.; Cutler, Cathy S.; Achilefu, Samuel

2018-02-01

Quantitative and noninvasive measurement of protease activities has remained an imaging challenge in deep tissues such as the lungs. Here, we designed a dual-radiolabeled probe for reporting the activities of proteases such as matrix metalloproteinases (MMPs) with multispectral single photon emission computed tomography (SPECT) imaging. A gold nanoparticle (NP) was radiolabeled with 125I and 111In and functionalized with an MMP9-cleavable peptide to form a multispectral SPECT imaging contrast agent. In another design, incorporation of 199Au radionuclide into the metal crystal structure of gold NPs provided a superior and stable reference signal in lungs, and 111In was linked to the NP surface via a protease-cleavable substrate, which can serve as an enzyme activity reporter. This work reveals strategies to correlate protease activities with diverse pathologies in a tissue-depth independent manner.

Tc-99m Radiolabeled Peptide p5 + 14 is an Effective Probe for SPECT Imaging of Systemic Amyloidosis.

PubMed

Kennel, Stephen J; Stuckey, Alan; McWilliams-Koeppen, Helen P; Richey, Tina; Wall, Jonathan S

2016-08-01

Systemic peripheral amyloidosis is a rare disease in which misfolded proteins deposit in various organs. We have previously developed I-124 labeled peptide p5 + 14 as a tracer for positron emission tomography imaging of amyloid in patients. In this report, we now document the labeling efficiency, bioactivity, and stability of Tc-99m labeled p5 + 14 for single-photon emission computed tomography (SPECT) imaging of amyloidosis, validated in a mouse model of systemic amyloidosis. Radiochemical yield, purity, and biological activity of [(99m)Tc]p5 + 14 were documented by instant thin-layer chromatography (ITLC), SDS-PAGE and a quantitative amyloid fibril pulldown assay. The efficacy and stability were documented in serum amyloid protein A (AA) amyloid-bearing or wild-type (WT) control mice imaged with SPECT/X-ray computed tomography (CT) at two time points. The uptake and retention of [(99m)Tc]p5 + 14 in hepatosplenic amyloid was evaluated using region of interest (ROI) and tissue counting measurements. Tc-99m p5 + 14 was produced with a radiochemical yield of 75 % with greater than 90 % purity and biological activity comparable to that of radioiodinated peptide. AA amyloid was visualized by SPECT/CT imaging with specific uptake seen in amyloid-laden organs at levels ∼5 folds higher than in healthy mice. ROI analyses of decay-corrected SPECT/CT images showed <20 % loss of radiolabel from the 1 to 4 h imaging time points. Biodistribution data confirmed the specificity of the probe accumulation by amyloid-laden organs as compared to non-diseased tissues. [(99m)Tc]p5 + 14 is a specific and stable radiotracer for systemic amyloid in mice and may provide a convenient and inexpensive alternative to imaging of peripheral amyloidosis in patients.

Incremental value of 99mTc-HYNIC-TOC SPECT/CT over whole-body planar scintigraphy and SPECT in patients with neuroendocrine tumours.

PubMed

Trogrlic, Mate; Težak, Stanko

2017-06-12

The aim of this study was to evaluate the additional value of 99m Tc-HYNIC-TOC SPECT/CT over planar whole-body (WB) scintigraphy and SPECT alone in the detection and accurate localisation of neuroendocrine tumour (NET) lesions. This study included 65 patients with a definitive histological diagnosis of NET prior to scintigraphy. Planar WB scintigraphy, SPECT, and SPECT/CT images were acquired at 4 h post-administration of 670 MBq 99m Tc-HYNIC-TOC. Additional SPECT images at 10 min after tracer administration were also acquired. Clinical and imaging follow-up findings were considered as the reference standards (minimum follow-up period, 15 months). Patient and lesion-based analyses of the efficacies of the imaging modalities were performed. While 38 patients exhibited metastasis of NETs, 27 presented no evidence of metastasis. Upon patient-based analysis, the sensitivity and specificity of SPECT/CT were found to be 88.9 and 79.3 %, respectively. The diagnostic accuracies of WB scintigraphy, 4h-SPECT, and SPECT/CT were 72.3, 73.8, and 84.6 %, respectively. The area under curve (AUC) value for SPECT/CT (0.84) was the highest, followed by those for 4h-SPECT (0.75) and WB scintigraphy (0.74). The accuracy and AUC values of SPECT/CT were significantly better compared to those of WB scintigraphy (p < 0.001), 10 min-SPECT (p < 0.001), and 4 h-SPECT (p = 0.001). The findings of SPECT/CT led to the change in treatment plan of 11 patients (16.9 %). The sensitivity and diagnostic accuracy of SPECT/CT in the evaluation of NET lesions outperforms planar WB imaging or SPECT alone.

Brain SPECT scans in students with specific learning disability: Preliminary results.

PubMed

Karande, S; Deshmukh, N; Rangarajan, V; Agrawal, A; Sholapurwala, R

2018-06-08

Brain single-photon emission computed tomography (SPECT) assesses brain function through measurement of regional cerebral blood flow. This study was conducted to assess whether students with newly diagnosed specific learning disability (SpLD) show any abnormalities in cerebral cortex perfusion. Cross-sectional single-arm pilot study in two tertiary care hospitals. Nine students with SpLD were enrolled. Brain SPECT scan was done twice in each student. For the first or "baseline" scan, the student was first made to sit with eyes open in a quiet, dimly lit room for a period of 30-40 min and then injected intravenously with 20 mCi of 99mTc-ECD. An hour later, "baseline scan" was conducted. After a minimum gap of 4 days, a second or "test scan" was conducted, wherein the student performed an age-appropriate curriculum-based test for a period of 30-40 min to activate the areas in central nervous system related to learning before being injected with 20 mCi of 99mTc-ECD. Cerebral cortex perfusion at rest and after activation in each student was compared qualitatively by visual analysis and quantitatively using NeuroGam TM software. Visual analysis showed reduction in regional blood flow in temporoparietal areas in both "baseline" and "test" scans. However, when normalization was attempted and comparison done by Talairach analysis using NeuroGam software, no statistically significant change in regional perfusion in temporoparietal areas was appreciated. Brain SPECT scan may serve as a robust tool to identify changes in regional brain perfusion in students with SpLD.

Experimental validation of absolute SPECT/CT quantification for response monitoring in breast cancer.

PubMed

Collarino, Angela; Pereira Arias-Bouda, Lenka M; Valdés Olmos, Renato A; van der Tol, Pieternel; Dibbets-Schneider, Petra; de Geus-Oei, Lioe-Fee; van Velden, Floris H P

2018-05-01

Recent developments in iterative image reconstruction enable absolute quantification of SPECT/CT studies by incorporating compensation for collimator-detector response, attenuation, and scatter as well as resolution recovery into the reconstruction process (Evolution; Q.Metrix package; GE Healthcare, Little Chalfont, UK). The aim of this experimental study is to assess its quantitative accuracy for potential clinical 99m Tc-sestamibi (MIBI)-related SPECT/CT application in neoadjuvant chemotherapy response studies in breast cancer. Two phantoms were filled with MIBI and acquired on a SPECT/CT gamma camera (Discovery 670 Pro; GE Healthcare), that is, a water cylinder and a NEMA body phantom containing six spheres that were filled with an activity concentration reflecting clinical MIBI uptake. Subsequently, volumes-of-interest (VOI) of each sphere were drawn (semi)automatically on SPECT using various isocontour methods or manually on CT. Finally, prone MIBI SPECT/CT scans were acquired 5 and 90 min p.i. in a locally advanced breast cancer patient. Activity concentration in the four largest spheres converged after nine iterations of evolution. Depending on the count statistics, the accuracy of the reconstructed activity concentration varied between -4.7 and -0.16% (VOI covering the entire phantom) and from 6.9% to 10% (8.8 cm ⌀ cylinder VOI placed in the center of the phantom). Recovery coefficients of SUV max were 1.89 ± 0.18, 1.76 ± 0.17, 2.00 ± 0.38, 1.89 ± 0.35, and 0.90 ± 0.26 for spheres with 37, 28, 22, 17, and 13 mm ⌀, respectively. Recovery coefficients of SUV mean were 1.07 ± 0.06, 1.03 ± 0.09, 1.17 ± 0.21, 1.10 ± 0.20, and 0.52 ± 0.14 (42% isocontour); 1.10 ± 0.07, 1.02 ± 0.09, 1.13 ± 0.19, 1.06 ± 0.19, and 0.51 ± 0.13 (36% isocontour with local background correction); and 0.96, 1.09, 1.03, 1.03, and 0.29 (CT). Patient study results were concordant with the phantom validation. Absolute SPECT/CT quantification of breast studies using MIBI seems feasible (<17% deviation) when a 42% isocontour is used for delineation for tumors of at least 17 mm diameter. However, with tumor shrinkage, response evaluation should be handled with caution, especially when using SUV max . © 2018 American Association of Physicists in Medicine.

SPECT/CT in patients with lower back pain after lumbar fusion surgery.

PubMed

Sumer, Johannes; Schmidt, Daniela; Ritt, Philipp; Lell, Michael; Forst, Raimund; Kuwert, Torsten; Richter, Richard

2013-10-01

The aim of the study was to investigate the incremental diagnostic value of skeletal hybrid imaging with single-photon emission computed tomography and X-ray computed tomography (SPECT/CT) over conventional nuclear medical imaging in patients with lower back pain after lumbar fusion surgery (LFS). This retrospective study comprised 37 patients suffering from lower back pain after LFS in whom three-phase planar bone scintigraphies of the lumbar spine including SPECT/CT of that region had been performed. The findings visible on these imaging data sets were classified into the following five diagnostic categories: (a) metal loosening; (b) insufficient stabilizing function of the metal implants indicated by metabolically active facet joint arthritis and/or intervertebral osteochondrosis in the instrumented region; (c) adjacent instability defined as metabolically active degenerative disease in the segments adjacent to the instrumented region; (d) indeterminate; and (e) normal. In the case of eight patients no lesions were visible on their planar scintigraphy and SPECT (planar/SPECT) or SPECT/CT images. In the remaining 29 patients, planar/SPECT disclosed 62 pathological foci of uptake within the graft region and SPECT/CT revealed 55. The rate of reclassification by SPECT/CT compared with planar/SPECT was 5/12 for lesions categorized as metal loosening by planar/SPECT, 16/29 for foci with a planar/SPECT diagnosis of insufficient stabilizing function, 7/20 when the planar/SPECT diagnosis had been adjacent instability, and 1/1 for the lesions indeterminate on planar/SPECT. Two lesions had been detected on SPECT/CT only. The overall rate of reclassification was 45.2% (28/62) (95% confidence interval, 33.4-57.5%). Because of its significantly higher accuracy compared with planar/SPECT, SPECT/CT should be the conventional nuclear medical procedure of choice for patients with lower back pain after LFS.

Improved dose-volume histogram estimates for radiopharmaceutical therapy by optimizing quantitative SPECT reconstruction parameters

NASA Astrophysics Data System (ADS)

Cheng, Lishui; Hobbs, Robert F.; Segars, Paul W.; Sgouros, George; Frey, Eric C.

2013-06-01

In radiopharmaceutical therapy, an understanding of the dose distribution in normal and target tissues is important for optimizing treatment. Three-dimensional (3D) dosimetry takes into account patient anatomy and the nonuniform uptake of radiopharmaceuticals in tissues. Dose-volume histograms (DVHs) provide a useful summary representation of the 3D dose distribution and have been widely used for external beam treatment planning. Reliable 3D dosimetry requires an accurate 3D radioactivity distribution as the input. However, activity distribution estimates from SPECT are corrupted by noise and partial volume effects (PVEs). In this work, we systematically investigated OS-EM based quantitative SPECT (QSPECT) image reconstruction in terms of its effect on DVHs estimates. A modified 3D NURBS-based Cardiac-Torso (NCAT) phantom that incorporated a non-uniform kidney model and clinically realistic organ activities and biokinetics was used. Projections were generated using a Monte Carlo (MC) simulation; noise effects were studied using 50 noise realizations with clinical count levels. Activity images were reconstructed using QSPECT with compensation for attenuation, scatter and collimator-detector response (CDR). Dose rate distributions were estimated by convolution of the activity image with a voxel S kernel. Cumulative DVHs were calculated from the phantom and QSPECT images and compared both qualitatively and quantitatively. We found that noise, PVEs, and ringing artifacts due to CDR compensation all degraded histogram estimates. Low-pass filtering and early termination of the iterative process were needed to reduce the effects of noise and ringing artifacts on DVHs, but resulted in increased degradations due to PVEs. Large objects with few features, such as the liver, had more accurate histogram estimates and required fewer iterations and more smoothing for optimal results. Smaller objects with fine details, such as the kidneys, required more iterations and less smoothing at early time points post-radiopharmaceutical administration but more smoothing and fewer iterations at later time points when the total organ activity was lower. The results of this study demonstrate the importance of using optimal reconstruction and regularization parameters. Optimal results were obtained with different parameters at each time point, but using a single set of parameters for all time points produced near-optimal dose-volume histograms.

Diagnostic role of (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging for early and atypical bone metastases.

PubMed

Chen, Xiao-Liang; Li, Qian; Cao, Lin; Jiang, Shi-Xi

2014-01-01

The bone metastasis appeared early before the bone imaging for most of the above patients. (99)Tc(m)-MDP ((99)Tc(m) marked methylene diphosphonate) bone imaging could diagnosis the bone metastasis with highly sensitivity, but with lower specificity. The aim of this study is to explore the diagnostic value of (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging for the early period atypical bone metastases. 15 to 30 mCi (99)Tc(m)-MDP was intravenously injected to the 34 malignant patients diagnosed as doubtful early bone metastases. SPECT, CT and SPECT/CT images were captured and analyzed consequently. For the patients diagnosed as early period atypical bone metastases by SPECT/CT, combining the SPECT/CT and MRI together as the SPECT/MRI integrated image. The obtained SPECT/MRI image was analyzed and compared with the pathogenic results of patients. The results indicated that 34 early period doubtful metastatic focus, including 34 SPECT positive focus, 17 focus without special changes by using CT method, 11 bone metastases focus by using SPECT/CT method, 23 doubtful bone metastases focus, 8 doubtful bone metastases focus, 14 doubtful bone metastases focus and 2 focus without clear image. Totally, SPECT/CT combined with SPECT/MRI method diagnosed 30 bone metastatic focus and 4 doubtfully metastatic focus. In conclusion, (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging shows a higher diagnostic value for the early period bone metastases, which also enhances the diagnostic accuracy rate.

IQ-SPECT for thallium-201 myocardial perfusion imaging: effect of normal databases on quantification.

PubMed

Konishi, Takahiro; Nakajima, Kenichi; Okuda, Koichi; Yoneyama, Hiroto; Matsuo, Shinro; Shibutani, Takayuki; Onoguchi, Masahisa; Kinuya, Seigo

2017-07-01

Although IQ-single-photon emission computed tomography (SPECT) provides rapid acquisition and attenuation-corrected images, the unique technology may create characteristic distribution different from the conventional imaging. This study aimed to compare the diagnostic performance of IQ-SPECT using Japanese normal databases (NDBs) with that of the conventional SPECT for thallium-201 ( 201 Tl) myocardial perfusion imaging (MPI). A total of 36 patients underwent 1-day 201 Tl adenosine stress-rest MPI. Images were acquired with IQ-SPECT at approximately one-quarter of the standard time of conventional SPECT. Projection data acquired with the IQ-SPECT system were reconstructed via an ordered subset conjugate gradient minimizer method with or without scatter and attenuation correction (SCAC). Projection data obtained using the conventional SPECT were reconstructed via a filtered back projection method without SCAC. The summed stress score (SSS) was calculated using NDBs created by the Japanese Society of Nuclear Medicine working group, and scores were compared between IQ-SPECT and conventional SPECT using the acquisition condition-matched NDBs. The diagnostic performance of the methods for the detection of coronary artery disease was also compared. SSSs were 6.6 ± 8.2 for the conventional SPECT, 6.6 ± 9.4 for IQ-SPECT without SCAC, and 6.5 ± 9.7 for IQ-SPECT with SCAC (p = n.s. for each comparison). The SSS showed a strong positive correlation between conventional SPECT and IQ-SPECT (r = 0.921 and p < 0.0001), and the correlation between IQ-SPECT with and without SCAC was also good (r = 0.907 and p < 0.0001). Regarding diagnostic performance, the sensitivity, specificity, and accuracy were 80.8, 78.9, and 79.4%, respectively, for the conventional SPECT; 80.8, 80.3, and 82.0%, respectively, for IQ-SPECT without SCAC; and 88.5, 86.8, and 87.3%, respectively, for IQ-SPECT with SCAC, respectively. The area under the curve obtained via receiver operating characteristic analysis were 0.77, 0.80, and 0.86 for conventional SPECT, IQ-SPECT without SCAC, and IQ-SPECT with SCAC, respectively (p = n.s. for each comparison). When appropriate NDBs were used, the diagnostic performance of 201 Tl IQ-SPECT was comparable with that of the conventional system regardless of different characteristics of myocardial accumulation in the conventional system.

SU-E-J-126: Respiratory Gating Quality Assurance: A Simple Method to Achieve Millisecond Temporal Resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCabe, B; Wiersma, R

Purpose: Low temporal latency between a gating on/off signal and a linac beam on/off during respiratory gating is critical for patient safety. Although, a measurement of temporal lag is recommended by AAPM Task Group 142 for commissioning and annual quality assurance, there currently exists no published method. Here we describe a simple, inexpensive, and reliable method to precisely measure gating lag at millisecond resolutions. Methods: A Varian Real-time Position Management™ (RPM) gating simulator with rotating disk was modified with a resistive flex sensor (Spectra Symbol) attached to the gating box platform. A photon diode was placed at machine isocenter. Outputmore » signals of the flex sensor and diode were monitored with a multichannel oscilloscope (Tektronix™ DPO3014). Qualitative inspection of the gating window/beam on synchronicity were made by setting the linac to beam on/off at end-expiration, and the oscilloscope's temporal window to 100 ms to visually examine if the on/off timing was within the recommended 100-ms tolerance. Quantitative measurements were made by saving the signal traces and analyzing in MatLab™. The on and off of the beam signal were located and compared to the expected gating window (e.g. 40% to 60%). Four gating cycles were measured and compared. Results: On a Varian TrueBeam™ STx linac with RPM gating software, the average difference in synchronicity at beam on and off for four cycles was 14 ms (3 to 30 ms) and 11 ms (2 to 32 ms), respectively. For a Varian Clinac™ 21EX the average difference at beam on and off was 127 ms (122 to 133 ms) and 46 ms (42 to 49 ms), respectively. The uncertainty in the synchrony difference was estimated at ±6 ms. Conclusion: This new gating QA method is easy to implement and allows for fast qualitative inspection and quantitative measurements for commissioning and TG-142 annual QA measurements.« less

Experience with single photon emission computerized tomography (SPECT) in follow-up of sternotomy healing.

PubMed

Harjula, A; Järvinen, A; Mattila, S; Porkka, L

1985-01-01

Single photon emission computerized tomography (SPECT) was performed thrice in ten patients undergoing open-heart surgery--preoperatively and 2 and 12 weeks postoperatively. The operations were done for ischemic heart disease (5), aortic valvular stenosis (2), aortic valvular insufficiency (1), leaking mitral prosthetic valve (1) and combined aortic and mitral valvular stenosis and insufficiency (1). The healing process in the longitudinally divided sternum was evaluated from the SPECT study. Four conventional static images in two dimensions were registered in anteroposterior, posteroanterior and left and right lateral projections. A tomographic study was done. Quantitative analyses were performed. The ratio of the sternal counts to the counts from a thoracic vertebra was calculated for use as a reference. The activity ratios showed a similar pattern in six cases, with initial increases and at 12 weeks slight decrease compared with the preoperative values. In two cases the activity was still increasing after 12 postoperative weeks. One patient, with sternotomy also one year previously, showed only slightly increased activity. The activity at the areas of the sternal wires was increased in six cases. The study thus revealed differing patterns of isotope uptake, although recovery was uneventful in all patients. The differences may reflect the possibility that the operative course and the preoperative clinical status can influence the healing mechanisms.

Correction of Hysteretic Respiratory Motion in SPECT Myocardial Perfusion Imaging: Simulation and Patient Studies

PubMed Central

Dasari, Paul K. R.; Könik, Arda; Pretorius, P. Hendrik; Johnson, Karen L.; Segars, William P.; Shazeeb, Mohammed. S.; King, Michael A.

2017-01-01

Purpose Amplitude based respiratory gating is known to capture the extent of respiratory motion (RM) accurately but results in residual motion in the presence of respiratory hysteresis. In our previous study, we proposed and developed a novel approach to account for respiratory hysteresis by applying the Bouc-Wen (BW) model of hysteresis to external surrogate signals of anterior / posterior motion of the abdomen and chest with respiration. In this work using simulated and clinical SPECT myocardial perfusion imaging (MPI) studies, we investigate the effects of respiratory hysteresis and evaluate the benefit of correcting it using the proposed BW model in comparison with the abdomen signal typically employed clinically. Methods The MRI navigator data acquired in free breathing human volunteers were used in the specially modified 4-D NCAT phantoms to allow simulating three types of respiratory patterns: monotonic, mild-hysteresis, and strong-hysteresis with normal myocardial uptake, and perfusion defects in the anterior, lateral, inferior, and septal locations of the mid-ventricular wall. Clinical scans were performed using a 99mTc-Sestamibi MPI protocol while recording respiratory signals from thoracic and abdomen regions using a Visual Tracking System (VTS). The performance of the correction using the respiratory signals was assessed through polar map analysis in phantom and ten clinical studies selected on the basis of having substantial RM. Results In phantom studies, simulations illustrating normal myocardial uptake showed significant differences (p<0.001) in the uniformity of the polar maps between the RM uncorrected and corrected. No significant differences were seen in the polar map uniformity across the RM corrections. Studies simulating perfusion defects showed significantly decreased errors (p<0.001) in defect severity and extent for the RM corrected compared to the uncorrected. Only for the strong-hysteretic pattern was there a significant difference (p<0.001) among the RM corrections. The errors in defect severity and extent for the RM correction using abdomen signal were significantly higher compared to that of the BW (severity=-4.0%, p<0.001; extent=-65.4%, p<0.01) and chest (severity=-4.1%, p<0.001; extent=-52.5%, p<0.01) signals. In clinical studies, the quantitative analysis of the polar maps demonstrated qualitative and quantitative but not statistically significant differences (p=0.73) between the correction methods that used the BW signal and the abdominal signal. Conclusions This study shows that hysteresis in respiration affects the extent of residual motion left in the RM binned data, which can impact wall uniformity and the visualization of defects. Thus there appears to be the potential for improved accuracy in reconstruction in the presence of hysteretic RM with the BW model method providing a possible step in the direction of improvement. PMID:28032913

Significance of the gate voltage-dependent mobility in the electrical characterization of organic field effect transistors

NASA Astrophysics Data System (ADS)

Kim, Jong Beom; Lee, Dong Ryeol

2018-04-01

We studied the effect of the addition of free hole- and electron-rich organic molecules to organic semiconductors (OSCs) in organic field effect transistors (OFETs) on the gate voltage-dependent mobility. The drain current versus gate voltage characteristics were quantitatively analyzed using an OFET mobility model of power law behavior based on hopping transport in an OSC. This analysis distinguished the threshold voltage shifts, depending on the materials and structures of the OFET device, and properly estimated the hopping transport of the charge carriers induced by the gate bias within the OSC from the power law exponent parameter. The addition of pentacene or C60 molecules to a one-monolayer pentacene-based OFET shifted the threshold voltages negatively or positively, respectively, due to the structural changes that occurred in the OFET device. On the other hand, the power law parameters revealed that the addition of charge carriers of the same or opposite polarity enhanced or hindered hopping transport, respectively. This study revealed the need for a quantitative analysis of the gate voltage-dependent mobility while distinguishing this effect from the threshold voltage effect in order to understand OSC hopping transport in OFETs.

Absolute activity quantitation from projections using an analytical approach: comparison with iterative methods in Tc-99m and I-123 brain SPECT

NASA Astrophysics Data System (ADS)

Fakhri, G. El; Kijewski, M. F.; Moore, S. C.

2001-06-01

Estimates of SPECT activity within certain deep brain structures could be useful for clinical tasks such as early prediction of Alzheimer's disease with Tc-99m or Parkinson's disease with I-123; however, such estimates are biased by poor spatial resolution and inaccurate scatter and attenuation corrections. We compared an analytical approach (AA) of more accurate quantitation to a slower iterative approach (IA). Monte Carlo simulated projections of 12 normal and 12 pathologic Tc-99m perfusion studies, as well as 12, normal and 12 pathologic I-123 neurotransmission studies, were generated using a digital brain phantom and corrected for scatter by a multispectral fitting procedure. The AA included attenuation correction by a modified Metz-Fan algorithm and activity estimation by a technique that incorporated Metz filtering to compensate for variable collimator response (VCR), IA-modeled attenuation, and VCR in the projector/backprojector of an ordered subsets-expectation maximization (OSEM) algorithm. Bias and standard deviation over the 12 normal and 12 pathologic patients were calculated with respect to the reference values in the corpus callosum, caudate nucleus, and putamen. The IA and AA yielded similar quantitation results in both Tc-99m and I-123 studies in all brain structures considered in both normal and pathologic patients. The bias with respect to the reference activity distributions was less than 7% for Tc-99m studies, but greater than 30% for I-123 studies, due to partial volume effect in the striata. Our results were validated using I-123 physical acquisitions of an anthropomorphic brain phantom. The IA yielded quantitation accuracy comparable to that obtained with IA, while requiring much less processing time. However, in most conditions, IA yielded lower noise for the same bias than did AA.

(⁹⁹m)Tc-MAA overestimates the absorbed dose to the lungs in radioembolization: a quantitative evaluation in patients treated with ¹⁶⁶Ho-microspheres.

PubMed

Elschot, Mattijs; Nijsen, Johannes F W; Lam, Marnix G E H; Smits, Maarten L J; Prince, Jip F; Viergever, Max A; van den Bosch, Maurice A A J; Zonnenberg, Bernard A; de Jong, Hugo W A M

2014-10-01

Radiation pneumonitis is a rare but serious complication of radioembolic therapy of liver tumours. Estimation of the mean absorbed dose to the lungs based on pretreatment diagnostic (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) imaging should prevent this, with administered activities adjusted accordingly. The accuracy of (99m)Tc-MAA-based lung absorbed dose estimates was evaluated and compared to absorbed dose estimates based on pretreatment diagnostic (166)Ho-microsphere imaging and to the actual lung absorbed doses after (166)Ho radioembolization. This prospective clinical study included 14 patients with chemorefractory, unresectable liver metastases treated with (166)Ho radioembolization. (99m)Tc-MAA-based and (166)Ho-microsphere-based estimation of lung absorbed doses was performed on pretreatment diagnostic planar scintigraphic and SPECT/CT images. The clinical analysis was preceded by an anthropomorphic torso phantom study with simulated lung shunt fractions of 0 to 30 % to determine the accuracy of the image-based lung absorbed dose estimates after (166)Ho radioembolization. In the phantom study, (166)Ho SPECT/CT-based lung absorbed dose estimates were more accurate (absolute error range 0.1 to -4.4 Gy) than (166)Ho planar scintigraphy-based lung absorbed dose estimates (absolute error range 9.5 to 12.1 Gy). Clinically, the actual median lung absorbed dose was 0.02 Gy (range 0.0 to 0.7 Gy) based on posttreatment (166)Ho-microsphere SPECT/CT imaging. Lung absorbed doses estimated on the basis of pretreatment diagnostic (166)Ho-microsphere SPECT/CT imaging (median 0.02 Gy, range 0.0 to 0.4 Gy) were significantly better predictors of the actual lung absorbed doses than doses estimated on the basis of (166)Ho-microsphere planar scintigraphy (median 10.4 Gy, range 4.0 to 17.3 Gy; p < 0.001), (99m)Tc-MAA SPECT/CT imaging (median 2.5 Gy, range 1.2 to 12.3 Gy; p < 0.001), and (99m)Tc-MAA planar scintigraphy (median 5.5 Gy, range 2.3 to 18.2 Gy; p < 0.001). In clinical practice, lung absorbed doses are significantly overestimated by pretreatment diagnostic (99m)Tc-MAA imaging. Pretreatment diagnostic (166)Ho-microsphere SPECT/CT imaging accurately predicts lung absorbed doses after (166)Ho radioembolization.

The Use of Quantitative SPECT/CT Imaging to Assess Residual Limb Health

DTIC Science & Technology

2017-10-01

loss in 2020.4 BACKGROUND The integrity of the vasculature, nerves, and soft tissue within the extremities is of high importance, as an impairment or...formation, and vascular abnormalities .6 Therefore, effective diagnosis can be critical in directing the medical treatment of patients. Standard noninva...and identify damage to their nor- mal fasicular pattern, nerve swelling or thickening, loss of nerve bundle integrity , and development of neuromas

Use Case Analysis: The Ambulatory EEG in Navy Medicine for Traumatic Brain Injuries

DTIC Science & Technology

2016-12-01

best uses of the device for naval medicine. 14. SUBJECT TERMS traumatic brain injuries, electroencephalography, EEG, use case study 15. NUMBER OF...Traumatic Brain Injury NCS Non-Convulsive Seizures PD Parkinson’s Disease QEEG Quantitative EEG SPECT Single-Photon Emission Computerized Tomography...INTENTIONALLY LEFT BLANK 1 I. INTRODUCTION This study examines the diagnosis of traumatic brain injuries (TBI). Early detection and diagnosis is

Flow-gated radial phase-contrast imaging in the presence of weak flow.

PubMed

Peng, Hsu-Hsia; Huang, Teng-Yi; Wang, Fu-Nien; Chung, Hsiao-Wen

2013-01-01

To implement a flow-gating method to acquire phase-contrast (PC) images of carotid arteries without use of an electrocardiography (ECG) signal to synchronize the acquisition of imaging data with pulsatile arterial flow. The flow-gating method was realized through radial scanning and sophisticated post-processing methods including downsampling, complex difference, and correlation analysis to improve the evaluation of flow-gating times in radial phase-contrast scans. Quantitatively comparable results (R = 0.92-0.96, n = 9) of flow-related parameters, including mean velocity, mean flow rate, and flow volume, with conventional ECG-gated imaging demonstrated that the proposed method is highly feasible. The radial flow-gating PC imaging method is applicable in carotid arteries. The proposed flow-gating method can potentially avoid the setting up of ECG-related equipment for brain imaging. This technique has potential use in patients with arrhythmia or weak ECG signals.

Imaging and modeling of flow in porous media using clinical nuclear emission tomography systems and computational fluid dynamics

NASA Astrophysics Data System (ADS)

Boutchko, Rostyslav; Rayz, Vitaliy L.; Vandehey, Nicholas T.; O'Neil, James P.; Budinger, Thomas F.; Nico, Peter S.; Druhan, Jennifer L.; Saloner, David A.; Gullberg, Grant T.; Moses, William W.

2012-01-01

This paper presents experimental and modeling aspects of applying nuclear emission tomography to study fluid flow in laboratory packed porous media columns of the type frequently used in geophysics, geochemistry and hydrology research. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are used as non-invasive tools to obtain dynamic 3D images of radioactive tracer concentrations. Dynamic sequences obtained using 18F-FDG PET are used to trace flow through a 5 cm diameter × 20 cm tall sand packed column with and without an impermeable obstacle. In addition, a custom-made rotating column setup placed in a clinical two-headed SPECT camera is used to image 99mTc-DTPA tracer propagation in a through-flowing column (10 cm diameter × 30 cm tall) packed with recovered aquifer sediments. A computational fluid dynamics software package FLUENT is used to model the observed flow dynamics. Tracer distributions obtained in the simulations in the smaller column uniformly packed with sand and in the column with an obstacle are remarkably similar to the reconstructed images in the PET experiments. SPECT results demonstrate strongly non-uniform flow patterns for the larger column slurry-packed with sub-surface sediment and slow upward flow. In the numerical simulation of the SPECT study, two symmetric channels with increased permeability are prescribed along the column walls, which result in the emergence of two well-defined preferential flow paths. Methods and results of this work provide new opportunities in hydrologic and biogeochemical research. The primary target application for developed technologies is non-destructive, non-perturbing, quantitative imaging of flow dynamics within laboratory scale porous media systems.

Imaging and modeling of flow in porous media using clinical nuclear emission tomography systems and computational fluid dynamics.

PubMed

Boutchko, Rostyslav; Rayz, Vitaliy L; Vandehey, Nicholas T; O'Neil, James P; Budinger, Thomas F; Nico, Peter S; Druhan, Jennifer L; Saloner, David A; Gullberg, Grant T; Moses, William W

2012-01-01

This paper presents experimental and modeling aspects of applying nuclear emission tomography to study fluid flow in laboratory packed porous media columns of the type frequently used in geophysics, geochemistry and hydrology research. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are used as non-invasive tools to obtain dynamic 3D images of radioactive tracer concentrations. Dynamic sequences obtained using 18 F-FDG PET are used to trace flow through a 5 cm diameter × 20 cm tall sand packed column with and without an impermeable obstacle. In addition, a custom-made rotating column setup placed in a clinical two-headed SPECT camera is used to image 99m Tc-DTPA tracer propagation in a through-flowing column (10 cm diameter × 30 cm tall) packed with recovered aquifer sediments. A computational fluid dynamics software package FLUENT is used to model the observed flow dynamics. Tracer distributions obtained in the simulations in the smaller column uniformly packed with sand and in the column with an obstacle are remarkably similar to the reconstructed images in the PET experiments. SPECT results demonstrate strongly non-uniform flow patterns for the larger column slurry-packed with sub-surface sediment and slow upward flow. In the numerical simulation of the SPECT study, two symmetric channels with increased permeability are prescribed along the column walls, which result in the emergence of two well-defined preferential flow paths. Methods and results of this work provide new opportunities in hydrologic and biogeochemical research. The primary target application for developed technologies is non-destructive, non-perturbing, quantitative imaging of flow dynamics within laboratory scale porous media systems.

Radionuclide bone scan SPECT-CT: lowering the dose of CT significantly reduces radiation dose without impacting CT image quality

PubMed Central

Gupta, Sandeep Kumar; Trethewey, Scott; Brooker, Bree; Rutherford, Natalie; Diffey, Jenny; Viswanathan, Suresh; Attia, John

2017-01-01

The CT component of SPECT-CT is required for attenuation correction and anatomical localization of the uptake on SPECT but there is no guideline about the optimal CT acquisition parameters. In our department, a standard CT acquisition protocol was changed in 2013 to give lower radiation dose to the patient. In this study, we retrospectively compared the effects on patient dose as well as the CT image quality with current versus older CT protocols. Ninety nine consecutive patients [n=51 Standard dose ‘old’ protocol (SDP); n=48 lower dose ‘new’ protocol (LDP)] with lumbar spine SPECT-CT for bone scan were examined. The main differences between the two protocols were that SDP used 130 kVp tube voltage and reference current-time product of 70 mAs whereas the LDP used 110 kVp and 40 mAs respectively. Various quantitative parameters from the CT images were obtained and the images were also rated blindly by two experienced nuclear medicine physicians for bony definition and noise. The mean calculated dose length product of the LDP group (121.5±39.6 mGy.cm) was significantly lower compared to the SDP group patients (266.9±96.9 mGy.cm; P<0.0001). This translated into a significant reduction in the mean effective dose to 1.8 mSv from 4.0 mSv. The physicians reported better CT image quality for the bony structures in LDP group although for soft tissue structures, the SDP group had better image quality. The optimized new CT acquisition protocol significantly reduced the radiation dose to the patient and in-fact improved CT image quality for the assessment of bony structures. PMID:28533938

PubMed Central

DI NARDO, W.; GIANNANTONIO, S.; DI GIUDA, D.; DE CORSO, E.; SCHINAIA, L.; PALUDETTI, G.

2013-01-01

SUMMARY Pre-surgery evaluation, indications for cochlear implantation and expectations in terms of post-operative functional results remain challenging topics in pre-lingually deaf adults. Our study has the purpose of determining the benefits of Single Photon Emission Tomography (SPECT) assessment in pre-surgical evaluation of pre-lingually deaf adults who are candidates for cochlear implantation. In 7 pre-lingually profoundly deaf patients, brain SPECT was performed at baseline conditions and in bilateral simultaneous multi-frequency acoustic stimulation. Six sagittal tomograms of both temporal cortices were used for semi-quantitative analysis in each patient. Percentage increases in cortical perfusion resulting from auditory stimulation were calculated. The results showed an inter-hemispherical asymmetry of the activation extension and intensity in the stimulated temporal areas. Consistent with the obtained brain activation data, patients were implanted preferring the side that showed higher activation after acoustic stimulus. Considering the increment in auditory perception performances, it was possible to point out a relationship between cortical brain activity shown by SPECT and hearing performances, and, even more significant, a correlation between post-operative functional performances and the activation of the most medial part of the sagittal temporal tomograms, corresponding to medium-high frequencies. In light of these findings, we believe that brain SPECT could be considered in the evaluation of deaf patients candidate for cochlear implantation, and that it plays a major role in functional assessment of the auditory cortex of pre-lingually deaf subjects, even if further studies are necessary to conclusively establish its utility. Further developments of this technique are possible by using trans-tympanic electrical stimulation of the cochlear promontory, which could give the opportunity to study completely deaf patients, whose evaluation is objectively difficult with current audiological methods. PMID:23620636

Estimating Lymphodynamic Conditions and Lymphovenous Anastomosis Efficacy Using 99mTc-phytate Lymphoscintigraphy with SPECT-CT in Patients with Lower-limb Lymphedema

PubMed Central

Fukushima, Yoshimitsu; Kumita, Shinichiro; Ogawa, Rei; Hyakusoku, Hiko

2015-01-01

Background: Diagnostic and therapeutic strategies for lower-limb lymphedema have not yet been established. The purpose of this study was to estimate the lymphodynamic condition and therapeutic efficacy of lymphovenous anastomosis (LVA) in lower-limb lymphedema patients using 2-phase 99mTc-phytate lymphoscintigraphy with single-photon emission computed tomography-computed tomography (SPECT-CT). Methods: In this study, consecutive patients with lower-limb lymphedema who underwent 2-phase lymphoscintigraphy using 99mTc-phytate were enrolled between June 2013 and June 2014. SPECT-CT was also performed to clarify the relationships between functional and morphological information. In both the early and delayed images, inguinal lymph node accumulation, dermal backflow, and their sequential alternations were evaluated, and liver-to-blood ratio and inguinal lymph node-to-blood ratio were calculated. All participants were classified into 6 types of lymphodynamic conditions based on the image findings. Patients with both dermal backflow and associated normal lymphatic vessel accumulation proceeded to LVA and underwent a second lymphoscintigraphy after the operation. Results: Of all 30 participants, the largest population was categorized as type 4, which had consistent inguinal lymph node accumulation defect with dermal backflow. In 12 operated cases, dermal backflow was degraded in 10 cases by LVA. Liver-to-blood ratio in both early and delayed images and inguinal lymph node-to-blood ratio in delayed image significantly increased after LVA. Conclusions: Lymphoscintigraphy with SPECT-CT can provide both functional and morphological information simultaneously in patients with lower-limb lymphedema. Using these procedures, a type categorization for the patients was devised, which reflects their lymphodynamic conditions. The therapeutic efficacy of LVA could also be estimated quantitatively by the derived findings. PMID:26090294

SPECT Analysis of Cardiac Perfusion Changes After Whole-Breast/Chest Wall Radiation Therapy With or Without Active Breathing Coordinator: Results of a Randomized Phase 3 Trial

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zellars, Richard, E-mail: zellari@jhmi.edu; Bravo, Paco E.; Tryggestad, Erik

2014-03-15

Purpose: Cardiac muscle perfusion, as determined by single-photon emission computed tomography (SPECT), decreases after breast and/or chest wall (BCW) irradiation. The active breathing coordinator (ABC) enables radiation delivery when the BCW is farther from the heart, thereby decreasing cardiac exposure. We hypothesized that ABC would prevent radiation-induced cardiac toxicity and conducted a randomized controlled trial evaluating myocardial perfusion changes after radiation for left-sided breast cancer with or without ABC. Methods and Materials: Stages I to III left breast cancer patients requiring adjuvant radiation therapy (XRT) were randomized to ABC or No-ABC. Myocardial perfusion was evaluated by SPECT scans (before andmore » 6 months after BCW radiation) using 2 methods: (1) fully automated quantitative polar mapping; and (2) semiquantitative visual assessment. The left ventricle was divided into 20 segments for the polar map and 17 segments for the visual method. Segments were grouped by anatomical rings (apical, mid, basal) or by coronary artery distribution. For the visual method, 2 nuclear medicine physicians, blinded to treatment groups, scored each segment's perfusion. Scores were analyzed with nonparametric tests and linear regression. Results: Between 2006 and 2010, 57 patients were enrolled and 43 were available for analysis. The cohorts were well matched. The apical and left anterior descending coronary artery segments had significant decreases in perfusion on SPECT scans in both ABC and No-ABC cohorts. In unadjusted and adjusted analyses, controlling for pretreatment perfusion score, age, and chemotherapy, ABC was not significantly associated with prevention of perfusion deficits. Conclusions: In this randomized controlled trial, ABC does not appear to prevent radiation-induced cardiac perfusion deficits.« less

Regional radiation dose-response modeling of functional liver in hepatocellular carcinoma patients with longitudinal sulfur colloid SPECT/CT: a proof of concept.

PubMed

Price, Ryan G; Apisarnthanarax, Smith; Schaub, Stephanie K; Nyflot, Matthew J; Chapman, Tobias R; Matesan, Manuela; Vesselle, Hubert J; Bowen, Stephen R

2018-06-19

We report on patient-specific quantitative changes in longitudinal sulfur colloid SPECT/CT as a function of regional radiation dose distributions to normal liver in a cohort of hepatocellular carcinoma patients. Dose-response thresholds and slopes varied with baseline liver function metrics, and extreme values were found in patients with fatal hepatotoxicity. Dose-response modeling of normal liver in individual HCC patients has potential to characterize in vivo radiosensitivity, identify high risk subgroups, and personalize treatment planning dose constraints. Hepatotoxicity risk in hepatocellular carcinoma (HCC) patients is modulated by radiation dose delivered to normal liver tissue, but reported dose-response data are limited. Our prior work established baseline [ 99m Tc]sulfur colloid (SC) SPECT/CT liver function imaging biomarkers that predict clinical outcomes. We conducted a proof-of-concept investigation with longitudinal SC SPECT/CT to characterize patient-specific radiation dose-response relationships as surrogates for liver radiosensitivity. SC SPECT/CT images of 15 HCC patients with variable Child-Pugh status (8 CP-A, 7 CP-B/C) were acquired in treatment position prior to and 1 month (nominal) after SBRT (n=6) or proton therapy (n=9). Localized rigid registrations between pre/post-treatment CT to planning CT scans were performed, and transformations were applied to pre/post-treatment SC SPECT images. Radiotherapy doses were converted to EQD2 α/β=3 and Gy (RBE), and binned in 5 GyEQD2 increments within tumor-subtracted livers. Mean dose and percent change (%ΔSC) between pre- and post-treatment SPECT uptake, normalized to regions receiving < 5 GyEQD2, were calculated in each binned dose region. Dose-response data were parameterized by sigmoid functions (double exponential) consisting of maximum reduction (%ΔSC max ), dose midpoint (D mid ), and dose-response slope (α mid ) parameters. Individual patient sigmoid dose-response curves had high goodness-of-fit (median R 2 = 0.96, range 0.76-0.99). Large inter-patient variability was observed, with median (range) in %ΔSC max of 44% (20-75%), D mid of 13 Gy (4-27 GyEQD2), and α mid of 0.11 GyEQD2 -1 (0.04-0.29 GyEQD2 -1 ), respectively. Eight of 15 patients had %ΔSC max = 20-45%, while 7/15 had %ΔSC max = 60-75%, with subgroups made up of variable baseline liver function status and radiation treatment modality. Fatal hepatotoxicity occurred in patients (2/15) with low TLF (< 0.12) and low D mid (< 7 GyEQD2). Longitudinal SC SPECT/CT imaging revealed patient-specific variations in dose-response, and may identify patients with poor baseline liver function and increased sensitivity to radiation therapy. Validation of this regional liver dose-response modeling concept as a surrogate for patient-specific radiosensitivity has potential to guide HCC therapy regimen selection and planning constraints. Copyright © 2018 Elsevier Inc. All rights reserved.

WE-H-207A-07: Image-Based Versus Atlas-Based Internal Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fallahpoor, M; Abbasi, M; Parach, A

Purpose: Monte Carlo (MC) simulation is known as the gold standard method for internal dosimetry. It requires radionuclide distribution from PET or SPECT and body structure from CT for accurate dose calculation. The manual or semi-automatic segmentation of organs from CT images is a major obstacle. The aim of this study is to compare the dosimetry results based on patient’s own CT and a digital humanoid phantom as an atlas with pre-specified organs. Methods: SPECT-CT images of a 50 year old woman who underwent bone pain palliation with Samarium-153 EDTMP for osseous metastases from breast cancer were used. The anatomicalmore » date and attenuation map were extracted from SPECT/CT and three XCAT digital phantoms with different BMIs (i.e. matched (38.8) and unmatched (35.5 and 36.7) with patient’s BMI that was 38.3). Segmentation of patient’s organs in CT image was performed using itk-SNAP software. GATE MC Simulator was used for dose calculation. Specific absorbed fractions (SAFs) and S-values were calculated for the segmented organs. Results: The differences between SAFs and S-values are high using different anatomical data and range from −13% to 39% for SAF values and −109% to 79% for S-values in different organs. In the spine, the clinically important target organ for Samarium Therapy, the differences in the S-values and SAF values are higher between XCAT phantom and CT when the phantom with identical BMI is employed (53.8% relative difference in S-value and 26.8% difference in SAF). However, the whole body dose values were the same between the calculations based on the CT and XCAT with different BMIs. Conclusion: The results indicated that atlas-based dosimetry using XCAT phantom even with matched BMI for patient leads to considerable errors as compared to image-based dosimetry that uses the patient’s own CT Patient-specific dosimetry using CT image is essential for accurate results.« less

Monte Carlo Optimization of Crystal Configuration for Pixelated Molecular SPECT Scanners

NASA Astrophysics Data System (ADS)

Mahani, Hojjat; Raisali, Gholamreza; Kamali-Asl, Alireza; Ay, Mohammad Reza

2017-02-01

Resolution-sensitivity-PDA tradeoff is the most challenging problem in design and optimization of pixelated preclinical SPECT scanners. In this work, we addressed such a challenge from a crystal point-of-view by looking for an optimal pixelated scintillator using GATE Monte Carlo simulation. Various crystal configurations have been investigated and the influence of different pixel sizes, pixel gaps, and three scintillators on tomographic resolution, sensitivity, and PDA of the camera were evaluated. The crystal configuration was then optimized using two objective functions: the weighted-sum and the figure-of-merit methods. The CsI(Na) reveals the highest sensitivity of the order of 43.47 cps/MBq in comparison to the NaI(Tl) and the YAP(Ce), for a 1.5×1.5 mm2 pixel size and 0.1 mm gap. The results show that the spatial resolution, in terms of FWHM, improves from 3.38 to 2.21 mm while the sensitivity simultaneously deteriorates from 42.39 cps/MBq to 27.81 cps/MBq when pixel size varies from 2×2 mm2 to 0.5×0.5 mm2 for a 0.2 mm gap, respectively. The PDA worsens from 0.91 to 0.42 when pixel size decreases from 0.5×0.5 mm2 to 1×1 mm2 for a 0.2 mm gap at 15° incident-angle. The two objective functions agree that the 1.5×1.5 mm2 pixel size and 0.1 mm Epoxy gap CsI(Na) configuration provides the best compromise for small-animal imaging, using the HiReSPECT scanner. Our study highlights that crystal configuration can significantly affect the performance of the camera, and thereby Monte Carlo optimization of pixelated detectors is mandatory in order to achieve an optimal quality tomogram.

Cost-effectiveness of initial stress cardiovascular MR, stress SPECT or stress echocardiography as a gate-keeper test, compared with upfront invasive coronary angiography in the investigation and management of patients with stable chest pain: mid-term outcomes from the CECaT randomised controlled trial

PubMed Central

Thom, Howard; West, Nicholas E J; Hughes, Vikki; Dyer, Matthew; Buxton, Martin; Sharples, Linda D; Jackson, Christopher H; Crean, Andrew M

2014-01-01

Objectives To compare outcomes and cost-effectiveness of various initial imaging strategies in the management of stable chest pain in a long-term prospective randomised trial. Setting Regional cardiothoracic referral centre in the east of England. Participants 898 patients (69% man) entered the study with 869 alive at 2 years of follow-up. Patients were included if they presented for assessment of stable chest pain with a positive exercise test and no prior history of ischaemic heart disease. Exclusion criteria were recent infarction, unstable symptoms or any contraindication to stress MRI. Primary outcome measures The primary outcomes of this follow-up study were survival up to a minimum of 2 years post-treatment, quality-adjusted survival and cost-utility of each strategy. Results 898 patients were randomised. Compared with angiography, mortality was marginally higher in the groups randomised to cardiac MR (HR 2.6, 95% CI 1.1 to 6.2), but similar in the single photon emission CT-methoxyisobutylisonitrile (SPECT-MIBI; HR 1.0, 95% CI 0.4 to 2.9) and ECHO groups (HR 1.6, 95% CI 0.6 to 4.0). Although SPECT-MIBI was marginally superior to other non-invasive tests there were no other significant differences between the groups in mortality, quality-adjusted survival or costs. Conclusions Non-invasive cardiac imaging can be used safely as the initial diagnostic test to diagnose coronary artery disease without adverse effects on patient outcomes or increased costs, relative to angiography. These results should be interpreted in the context of recent advances in imaging technology. Trial registration ISRCTN 47108462, UKCRN 3696. PMID:24508847

A Multimodal Imaging Protocol, (123)I/(99)Tc-Sestamibi, SPECT, and SPECT/CT, in Primary Hyperparathyroidism Adds Limited Benefit for Preoperative Localization.

PubMed

Lee, Grace S; McKenzie, Travis J; Mullan, Brian P; Farley, David R; Thompson, Geoffrey B; Richards, Melanie L

2016-03-01

Focused parathyroidectomy in primary hyperparathyroidism (1°HPT) is possible with accurate preoperative localization and intraoperative PTH monitoring (IOPTH). The added benefit of multimodal imaging techniques for operative success is unknown. Patients with 1°HPT, who underwent parathyroidectomy in 2012-2014 at a single institution, were retrospectively reviewed. Only the patients who underwent the standardized multimodal imaging workup consisting of (123)I/(99)Tc-sestamibi subtraction scintigraphy, SPECT, and SPECT/CT were assessed. Of 360 patients who were identified, a curative operation was performed in 96%, using pre-operative imaging and IOPTH. Imaging analysis showed that (123)I/(99)Tc-sestamibi had a sensitivity of 86% (95% CI 82-90%), positive predictive value (PPV) 93%, and accuracy 81%, based on correct lateralization. SPECT had a sensitivity of 77% (95% CI 72-82%), PPV 92% and accuracy 72%. SPECT/CT had a sensitivity of 75% (95% CI 70-80%), PPV of 94%, and accuracy 71%. There were 3 of 45 (7%) patients with negative sestamibi imaging that had an accurate SPECT and SPECT/CT. Of 312 patients (87%) with positive uptake on sestamibi (93% true positive, 7% false positive), concordant findings were present in 86% SPECT and 84% SPECT/CT. In cases where imaging modalities were discordant, but at least one method was true-positive, (123)I/(99)Tc-sestamibi was significantly better than both SPECT and SPECT/CT (p < 0.001). The inclusion of SPECT and SPECT/CT in 1°HPT imaging protocol increases patient cost up to 2.4-fold. (123)I/(99)Tc-sestamibi subtraction imaging is highly sensitive for preoperative localization in 1°HPT. SPECT and SPECT/CT are commonly concordant with (123)I/(99)Tc-sestamibi and rarely increase the sensitivity. Routine inclusion of multimodality imaging technique adds minimal clinical benefit but increases cost to patient in high-volume setting.

A guide to SPECT equipment for brain imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffer, P.B.; Zubal, G.

1991-12-31

Single photon emission computed tomography (SPECT) was started by Kuhl and Edwards about 30 years ago. Their original instrument consisted of four focused Nal probes mounted on a moving gantry. During the 1980s, clinical SPECT imaging was most frequently performed using single-headed Anger-type cameras which were modified for rotational as well as static imaging. Such instruments are still available and may be useful in settings where there are few patients and SPECT is used only occasionally. More frequently, however, dedicated SPECT devices are purchased which optimize equipment potential while being user-friendly. Modern SPECT instrumentation incorporates improvements in the detector, computers,more » mathematical formulations, electronics and display systems. A comprehensive discussion of all aspects of SPECT is beyond the scope of this article. The authors, however, discuss general concepts of SPECT, the current state-of-the-art in clinical SPECT instrumentation, and areas of common misunderstanding. 9 refs.« less

Global quantitative analysis of phosphorylation underlying phencyclidine signaling and sensorimotor gating in the prefrontal cortex.

PubMed

McClatchy, D B; Savas, J N; Martínez-Bartolomé, S; Park, S K; Maher, P; Powell, S B; Yates, J R

2016-02-01

Prepulse inhibition (PPI) is an example of sensorimotor gating and deficits in PPI have been demonstrated in schizophrenia patients. Phencyclidine (PCP) suppression of PPI in animals has been studied to elucidate the pathological elements of schizophrenia. However, the molecular mechanisms underlying PCP treatment or PPI in the brain are still poorly understood. In this study, quantitative phosphoproteomic analysis was performed on the prefrontal cortex from rats that were subjected to PPI after being systemically injected with PCP or saline. PCP downregulated phosphorylation events were significantly enriched in proteins associated with long-term potentiation (LTP). Importantly, this data set identifies functionally novel phosphorylation sites on known LTP-associated signaling molecules. In addition, mutagenesis of a significantly altered phosphorylation site on xCT (SLC7A11), the light chain of system xc-, the cystine/glutamate antiporter, suggests that PCP also regulates the activity of this protein. Finally, new insights were also derived on PPI signaling independent of PCP treatment. This is the first quantitative phosphorylation proteomic analysis providing new molecular insights into sensorimotor gating.

The origin and reduction of spurious extrahepatic counts observed in 90Y non-TOF PET imaging post radioembolization

NASA Astrophysics Data System (ADS)

Walrand, Stephan; Hesse, Michel; Jamar, François; Lhommel, Renaud

2018-04-01

Our literature survey revealed a physical effect unknown to the nuclear medicine community, i.e. internal bremsstrahlung emission, and also the existence of long energy resolution tails in crystal scintillation. None of these effects has ever been modelled in PET Monte Carlo (MC) simulations. This study investigates whether these two effects could be at the origin of two unexplained observations in 90Y imaging by PET: the increasing tails in the radial profile of true coincidences, and the presence of spurious extrahepatic counts post radioembolization in non-TOF PET and their absence in TOF PET. These spurious extrahepatic counts hamper the microsphere delivery check in liver radioembolization. An acquisition of a 32P vial was performed on a GSO PET system. This is the ideal setup to study the impact of bremsstrahlung x-rays on the true coincidence rate when no positron emission and no crystal radioactivity are present. A MC simulation of the acquisition was performed using Gate-Geant4. MC simulations of non-TOF PET and TOF-PET imaging of a synthetic 90Y human liver radioembolization phantom were also performed. Internal bremsstrahlung and long energy resolution tails inclusion in MC simulations quantitatively predict the increasing tails in the radial profile. In addition, internal bremsstrahlung explains the discrepancy previously observed in bremsstrahlung SPECT between the measure of the 90Y bremsstrahlung spectrum and its simulation with Gate-Geant4. However the spurious extrahepatic counts in non-TOF PET mainly result from the failure of conventional random correction methods in such low count rate studies and poor robustness versus emission-transmission inconsistency. A novel proposed random correction method succeeds in cleaning the spurious extrahepatic counts in non-TOF PET. Two physical effects not considered up to now in nuclear medicine were identified to be at the origin of the unusual 90Y true coincidences radial profile. TOF reconstruction removing of the spurious extrahepatic counts was theoretically explained by a better robustness against emission-transmission inconsistency. A novel random correction method was proposed to overcome the issue in non-TOF PET. Further studies are needed to assess the novel random correction method robustness.

Quantitatively accurate activity measurements with a dedicated cardiac SPECT camera: Physical phantom experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pourmoghaddas, Amir, E-mail: apour@ottawaheart.ca; Wells, R. Glenn

Purpose: Recently, there has been increased interest in dedicated cardiac single photon emission computed tomography (SPECT) scanners with pinhole collimation and improved detector technology due to their improved count sensitivity and resolution over traditional parallel-hole cameras. With traditional cameras, energy-based approaches are often used in the clinic for scatter compensation because they are fast and easily implemented. Some of the cardiac cameras use cadmium-zinc-telluride (CZT) detectors which can complicate the use of energy-based scatter correction (SC) due to the low-energy tail—an increased number of unscattered photons detected with reduced energy. Modified energy-based scatter correction methods can be implemented, but theirmore » level of accuracy is unclear. In this study, the authors validated by physical phantom experiments the quantitative accuracy and reproducibility of easily implemented correction techniques applied to {sup 99m}Tc myocardial imaging with a CZT-detector-based gamma camera with multiple heads, each with a single-pinhole collimator. Methods: Activity in the cardiac compartment of an Anthropomorphic Torso phantom (Data Spectrum Corporation) was measured through 15 {sup 99m}Tc-SPECT acquisitions. The ratio of activity concentrations in organ compartments resembled a clinical {sup 99m}Tc-sestamibi scan and was kept consistent across all experiments (1.2:1 heart to liver and 1.5:1 heart to lung). Two background activity levels were considered: no activity (cold) and an activity concentration 1/10th of the heart (hot). A plastic “lesion” was placed inside of the septal wall of the myocardial insert to simulate the presence of a region without tracer uptake and contrast in this lesion was calculated for all images. The true net activity in each compartment was measured with a dose calibrator (CRC-25R, Capintec, Inc.). A 10 min SPECT image was acquired using a dedicated cardiac camera with CZT detectors (Discovery NM530c, GE Healthcare), followed by a CT scan for attenuation correction (AC). For each experiment, separate images were created including reconstruction with no corrections (NC), with AC, with attenuation and dual-energy window (DEW) scatter correction (ACSC), with attenuation and partial volume correction (PVC) applied (ACPVC), and with attenuation, scatter, and PVC applied (ACSCPVC). The DEW SC method used was modified to account for the presence of the low-energy tail. Results: T-tests showed that the mean error in absolute activity measurement was reduced significantly for AC and ACSC compared to NC for both (hot and cold) datasets (p < 0.001) and that ACSC, ACPVC, and ACSCPVC show significant reductions in mean differences compared to AC (p ≤ 0.001) without increasing the uncertainty (p > 0.4). The effect of SC and PVC was significant in reducing errors over AC in both datasets (p < 0.001 and p < 0.01, respectively), resulting in a mean error of 5% ± 4%. Conclusions: Quantitative measurements of cardiac {sup 99m}Tc activity are achievable using attenuation and scatter corrections, with the authors’ dedicated cardiac SPECT camera. Partial volume corrections offer improvements in measurement accuracy in AC images and ACSC images with elevated background activity; however, these improvements are not significant in ACSC images with low background activity.« less

Added value of SPECT/spiral CT versus SPECT or CT alone in diagnosing solitary skeletal lesions.

PubMed

Zhang, Yiqiu; Li, Beilei; Shi, Hongcheng; Yu, Haojun; Gu, Yushen; Xiu, Yan

2017-08-14

The aim of this study was to investigate the added value of SPECT/spiral CT versus SPECT or CT alone in the differential diagnosis of solitary skeletal lesions. This was a retrospective study on a total of 69 patients who had a solitary skeletal "hot spot" that could not be definitively diagnosed using planar scintigraphy. Thus, SPECT/spiral CT was performed on the indeterminate lesions. SPECT, CT and SPECT/spiral CT images were independently interpreted by two experienced doctors who have both identification of CT and nuclear medicine. Each lesion was graded on a 4-point diagnostic scale (1: benign, 2: likely benign, 3: likely malignant, 4: malignant). The final diagnosis of each lesion was based on pathological confirmation after surgery within 3 weeks of the bone scan. Final diagnoses based on the pathological results revealed that 43 of the 69 patients were diagnosed with malignancy, and the remaining 26 patients were diagnosed as having benign lesions. For SPECT and CT scans, both of the reviewers rated 55.1 % (38/69) and 37.7 % (26/69) of lesions as equivocal, with the help of SPECT/CT, 33.3 % (23/69) of lesions were rated as equivocal. The diagnostic accuracies of SPECT, CT alone and SPECT/CT were 66.7 % (46/69) ,82.6 % (57/69) and 85.5 %(59/69), respectively. The kappa scores for the degree of agreement between SPECT, CT alone or SPECT/CT with pathological results were 0.185 (p = 0.054) , 0.612 (p < 0.001) and 0.671 (p < 0.001), respectively. Compared with SPECT or imaging alone, SPECT/spiral CT imaging was more accurate and valuable in the differential diagnosis of solitary skeletal lesions and resulted in significantly fewer equivocal findings.

A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen

2013-12-15

Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequencemore » is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using minimal external hardware and software modification through a single input channel, while still recording cardiac gating signals.« less

Phase analysis of gated blood pool SPECT for multiple stress testing assessments of ventricular mechanical dyssynchrony in a tachycardia-induced dilated cardiomyopathy canine model.

PubMed

Salimian, Samaneh; Thibault, Bernard; Finnerty, Vincent; Grégoire, Jean; Harel, François

2017-02-01

Stress-induced dyssynchrony has been shown to be independently correlated with clinical outcomes in patients with dilated cardiomyopathy (DCM) and narrow QRS complexes. However, the extent to which stress levels affect inter- and intraventricular dyssynchrony parameters remains unknown. Ten large dogs were submitted to tachycardia-induced DCM by pacing the right ventricular apex for 3-4 weeks to reach a target ejection fraction (EF) of 35% or less. Stress was then induced in DCM dogs by administering intravenous dobutamine up to a maximum of 20 μg·kg -1 ·min -1 . Hemodynamic and ventricular dyssynchrony data were analyzed by left ventricular (LV) pressure measurements and gated blood pool SPECT (GBPS) imaging. In order to assess mechanical dyssynchrony in DCM subjects and compare it with that of 8 normal counterparts, we extracted the following data: count-based indices of LV contraction homogeneity index (CHI), entropy and phase standard deviation, and interventricular dyssynchrony index. A significant LV intraventricular dyssynchrony (CHI: 96.4 ± 1.3% in control vs 78.6% ± 10.9% in DCM subjects) resulted in an intense LV dysfunction in DCM subjects (EF: 49.5% ± 8.4% in control vs 22.6% ± 6.0% in DCM), compared to control subjects. However, interventricular dyssynchrony did not vary significantly between the two groups. Under stress, DCM subjects showed a significant improvement in ventricular functional parameters at each level (EF: 22.6% ± 6.0% at rest vs 48.1% ± 5.8% at maximum stress). All intraventricular dyssynchrony indices showed a significant increase in magnitude of synchrony from baseline to stress levels of greater than or equal to 5 μg·kg -1 ·min -1 dobutamine. There were individual differences in the magnitude and pattern of change in interventricular dyssynchrony during the various levels of stress. Based on GBPS analyses, different levels of functional stress, even in close intervals, can have a significant impact on hemodynamic and intraventricular dyssynchrony parameters in a DCM model with narrow QRS complex.

The origins of SPECT and SPECT/CT.

PubMed

Hutton, Brian F

2014-05-01

Single photon emission computed tomography (SPECT) has a long history of development since its initial demonstration by Kuhl and Edwards in 1963. Although clinical utility has been dominated by the rotating gamma camera, there have been many technological innovations with the recent popularity of organ-specific dedicated SPECT systems. The combination of SPECT and CT evolved from early transmission techniques used for attenuation correction with the initial commercial systems predating the release of PET/CT. The development and acceptance of SPECT/CT has been relatively slow with continuing debate as to what cost/performance ratio is justified. Increasingly, fully diagnostic CT is combined with SPECT so as to facilitate optimal clinical utility.

Correlation-based perfusion mapping using time-resolved MR angiography: A feasibility study for patients with suspicions of steno-occlusive craniocervical arteries.

PubMed

Nam, Yoonho; Jang, Jinhee; Park, Sonya Youngju; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-Soo

2018-05-22

To explore the feasibility of using correlation-based time-delay (CTD) maps produced from time-resolved MR angiography (TRMRA) to diagnose perfusion abnormalities in patients suspected to have steno-occlusive lesions in the craniocervical arteries. Twenty-seven patients who were suspected to have steno-occlusive lesions in the craniocervical arteries underwent both TRMRA and brain single-photon emission computed tomography (SPECT). TRMRA was performed on the supra-aortic area after intravenous injection of a 0.03 mmol/kg gadolinium-based contrast agent. Time-to-peak (TTP) maps and CTD maps of the brain were automatically generated from TRMRA data, and their quality was assessed. Detection of perfusion abnormalities was compared between CTD maps and the time-series maximal intensity projection (MIP) images from TRMRA and TTP maps. Correlation coefficients between quantitative changes in SPECT and parametric maps for the abnormal perfusion areas were calculated. The CTD maps were of significantly superior quality than TTP maps (p < 0.01). For perfusion abnormality detection, CTD maps (kappa 0.84, 95% confidence interval [CI] 0.67-1.00) showed better agreement with SPECT than TTP maps (0.66, 0.46-0.85). For perfusion deficit detection, CTD maps showed higher accuracy (85.2%, 95% CI 66.3-95.8) than MIP images (66.7%, 46-83.5), with marginal significance (p = 0.07). In abnormal perfusion areas, correlation coefficients between SPECT and CTD (r = 0.74, 95% CI 0.34-0.91) were higher than those between SPECT and TTP (r = 0.66, 0.20-0.88). CTD maps generated from TRMRA were of high quality and offered good diagnostic performance for detecting perfusion abnormalities associated with steno-occlusive arterial lesions in the craniocervical area. • Generation of perfusion parametric maps from time-resolved MR angiography is clinically useful. • Correlation-based delay maps can be used to detect perfusion abnormalities associated with steno-occlusive craniocervical arteries. • Estimation of correlation-based delay is robust for low signal-to-noise 4D MR data.

SPECT/CT with 99mTc-MAA in radioembolization with 90Y microspheres in patients with hepatocellular cancer.

PubMed

Hamami, Monia E; Poeppel, Thorsten D; Müller, Stephan; Heusner, Till; Bockisch, Andreas; Hilgard, Philipp; Antoch, Gerald

2009-05-01

Radioembolization with (90)Y microspheres is a novel treatment for hepatic tumors. Generally, hepatic arteriography and (99m)Tc-macroaggregated albumin (MAA) scanning are performed before selective internal radiation therapy to detect extrahepatic shunting to the lung or the gastrointestinal tract. Whereas previous studies have used only planar or SPECT scans, the present study used (99m)Tc-MAA SPECT/CT scintigraphy (SPECT with integrated low-dose CT) to evaluate whether SPECT/CT and additional diagnostic contrast-enhanced CT before radioembolization with (90)Y microspheres are superior to SPECT or planar imaging alone for detection of gastrointestinal shunting. In a prospective study, we enrolled 58 patients (mean age, 66 y; SD, 12 y; 10 women and 48 men) with hepatocellular carcinoma who underwent hepatic arteriography and scintigraphy with (99m)Tc-MAA using planar imaging, SPECT, and SPECT with integrated low-dose CT of the upper abdomen (acquired with a hybrid SPECT/CT camera). The ability of the different imaging modalities to detect extrahepatic MAA shunting was compared. Patient follow-up of a mean of 180 d served as the standard of reference. Gastrointestinal shunting was revealed by planar imaging in 4, by SPECT in 9, and by SPECT/CT in 16 of the 68 examinations. For planar imaging, the sensitivity for detection of gastrointestinal shunting was 25%, the specificity 87%, and the accuracy 72%. For SPECT without CT, the sensitivity was 56%, the specificity 87%, and the accuracy 79%. SPECT with CT fusion had a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. In 3 patients, MAA deposits in the portal vein could accurately be attributed to tumor thrombus only with additional information from contrast-enhanced CT. The follow-up did not show any gastrointestinal complications. SPECT with integrated low-dose CT using (99m)Tc-MAA is beneficial in radioembolization with (90)Y microspheres because it increases the sensitivity and specificity of (99m)Tc-MAA SPECT when detecting extrahepatic arterial shunting. The overall low risk of gastrointestinal complications in radioembolization may therefore be further reduced by SPECT/CT.

Molecular Imaging and Quantitation of EphA2 Expression in Xenograft Models with 89Zr-DS-8895a.

PubMed

Burvenich, Ingrid J G; Parakh, Sagun; Gan, Hui K; Lee, Fook-Thean; Guo, Nancy; Rigopoulos, Angela; Lee, Sze-Ting; Gong, Sylvia; O'Keefe, Graeme J; Tochon-Danguy, Henri; Kotsuma, Masakatsu; Hasegawa, Jun; Senaldi, Giorgio; Scott, Andrew M

2016-06-01

Subtype A2 of the erythropoietin-producing hepatocellular tyrosine kinase (EphA2) cell surface receptor is expressed in a range of epithelial cancers. This study evaluated the molecular imaging of EphA2 expression in vivo in mouse tumor models using SPECT/MR and PET/MR and a humanized anti-EphA2 antibody, DS-8895a. DS-8895a was labeled with (111)In, (125)I, and (89)Zr and assessed for radiochemical purity, immunoreactivity (Lindmo analysis), antigen-binding affinity (Scatchard analysis), and serum stability in vitro. In vivo biodistribution, imaging, and pharmacokinetic studies were performed with SPECT/MR and PET/MR. A dose-escalation study was also performed to determine EphA2 receptor saturability through tissue and imaging quantitative analysis. All conjugates demonstrated good serum stability and specific binding to EphA2-expressing cells in vitro. In vivo biodistribution studies showed high uptake of (111)In-CHX-A″-DTPA-DS-8895a and (89)Zr-Df-Bz-NCS-DS-8895a in EphA2-expressing xenograft models, with no specific uptake in normal tissues. In comparison, retention of (125)I-DS-8895a in tumors was lower because of internalization of the radioconjugate and dehalogenation. These results were confirmed by SPECT/MR and PET/MR. EphA2 receptor saturation was observed at the 30 mg/kg dose. Molecular imaging of tumor uptake of DS-8895a allows noninvasive measurement of EphA2 expression in tumors in vivo and determination of receptor saturation. (89)Zr-Df-Bz-NCS-DS-8895a is suited for human bioimaging trials on the basis of superior imaging characteristics and will inform DS-8895a dose assessment and patient response evaluation in clinical trials. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

The influence of gravity on regional lung blood flow in humans: SPECT in the upright and head-down posture.

PubMed

Ax, M; Sanchez-Crespo, A; Lindahl, S G E; Mure, M; Petersson, J

2017-06-01

Previous studies in humans have shown that gravity has little influence on the distribution of lung blood flow while changing posture from supine to prone. This study aimed to evaluate the maximal influence of posture by comparison of regional lung blood flow in the upright and head-down posture in 8 healthy volunteers, using a tilt table. Regional lung blood flow was marked by intravenous injection of macroaggregates of human albumin labeled with 99m Tc or 113m In, in the upright and head-down posture, respectively, during tidal breathing. Both radiotracers remain fixed in the lung after administration. The distribution of radioactivity was mapped using quantitative single photon emission computed tomography (SPECT) corrected for attenuation and scatter. All images were obtained supine during tidal breathing. A shift from upright to the head-down posture caused a clear redistribution of blood flow from basal to apical regions. We conclude that posture plays a role for the distribution of lung blood flow in upright humans, and that the influence of posture, and thereby gravity, is much greater in the upright and head-down posture than in horizontal postures. However, the results of the study demonstrate that lung structure is the main determinant of regional blood flow and gravity is a secondary contributor to the distribution of lung blood flow in the upright and head-down positions. NEW & NOTEWORTHY Using a dual-isotope quantitative SPECT method, we demonstrated that although a shift in posture redistributes blood flow in the direction of gravity, the results are also consistent with lung structure being a greater determinant of regional blood flow than gravity. To our knowledge, this is the first study to use modern imaging methods to quantify the shift in regional lung blood flow in humans at a change between the upright and head-down postures. Copyright © 2017 the American Physiological Society.

SU-C-9A-05: A Medical Physics Approach to the Evaluation of a New Anti-Reflux Catheter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pasciak, A; McElmurray, J

2014-06-01

Purpose: The Surefire Infusion System (SIS) is a coaxial microcatheter system with a pliant expanding tip designed to limit retrograde flow of administered intra-arterial embolic agents and resultant non-target embolization (NTE). A recent study suggests that the SIS may achieve relative arterial hypotension downstream to the catheter tip when compared to an end-hole catheter, potentially altering microsphere distribution. We have used a physics based approach to evaluate particulate distribution using both the SIS and standard end-hole microcatheter via a two-step same-day injection of Tc-99m MAA as a microsphere surrogate. Methods: Informed patient consent and IRB approval were obtained. Four patientsmore » with primary or secondary liver cancer underwent two sequential low-particulate infusions of Tc-99m MAA on the same day using both the SIS and a conventional end-hole catheter. Radiopharmaceutical dosages of approximately 1:8 were utilized in the first infusion relative to the second to eliminate the effect of residual activity on the images acquired after each step. SPECT imaging was obtained following each infusion, and MAA distribution was analyzed and compared. Archived fluoroscopic images confirmed near-identical catheter position for both infusions. Results: SPECT images from all four patients demonstrate qualitatively increased penetration of MAA distal to the site of infusion using the SIS when compared to a standard end-hole catheter. Quantitative evaluations corroborate these findings with some distal regions receiving between 33% to more than 200% greater relative activity when SIS was used. No appreciable NTE was identified in either patient subset. Conclusion: These preliminary data demonstrate the validity of this dual-infusion technique. Both qualitative and quantitative assessment of SPECT images and comparison with baseline contrast enhanced CT and PET/CT images indicate an improvement in MAA penetration into the target lesion with the SIS. However, the degree of improvement is highly dependent on tumor type and size. Financial support provided by Surefire Medical.« less

Quantitative multimodality imaging in cancer research and therapy.

PubMed

Yankeelov, Thomas E; Abramson, Richard G; Quarles, C Chad

2014-11-01

Advances in hardware and software have enabled the realization of clinically feasible, quantitative multimodality imaging of tissue pathophysiology. Earlier efforts relating to multimodality imaging of cancer have focused on the integration of anatomical and functional characteristics, such as PET-CT and single-photon emission CT (SPECT-CT), whereas more-recent advances and applications have involved the integration of multiple quantitative, functional measurements (for example, multiple PET tracers, varied MRI contrast mechanisms, and PET-MRI), thereby providing a more-comprehensive characterization of the tumour phenotype. The enormous amount of complementary quantitative data generated by such studies is beginning to offer unique insights into opportunities to optimize care for individual patients. Although important technical optimization and improved biological interpretation of multimodality imaging findings are needed, this approach can already be applied informatively in clinical trials of cancer therapeutics using existing tools. These concepts are discussed herein.

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

DOE PAGES

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.; ...

2015-10-09

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variationmore » of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. We find these results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Finally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.« less

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

NASA Astrophysics Data System (ADS)

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.; Gullberg, Grant T.

2015-11-01

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variation of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. These results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Additionally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variationmore » of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. We find these results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Finally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.« less

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration.

PubMed

Shrestha, Uttam M; Seo, Youngho; Botvinick, Elias H; Gullberg, Grant T

2015-11-07

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variation of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. These results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Additionally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.

The significance of 99mTc-MAA SPECT/CT liver perfusion imaging in treatment planning for 90Y-microsphere selective internal radiation treatment.

PubMed

Ahmadzadehfar, Hojjat; Sabet, Amir; Biermann, Kim; Muckle, Marianne; Brockmann, Holger; Kuhl, Christiane; Wilhelm, Kai; Biersack, Hans-Jürgen; Ezziddin, Samer

2010-08-01

Selective internal radiation therapy (SIRT), a catheter-based liver-directed modality for treating primary and metastatic liver cancer, requires appropriate planning to maximize its therapeutic response and minimize its side effects. (99m)Tc-macroaggregated albumin (MAA) scanning should precede the therapy to detect any extrahepatic shunting to the lung or gastrointestinal tract. Our aim was to compare the ability of SPECT/CT with that of planar imaging and SPECT in the detection and localization of extrahepatic (99m)Tc-MAA accumulation and to evaluate the impact of SPECT/CT on SIRT treatment planning and its added value to angiography in this setting. Ninety diagnostic hepatic angiograms with (99m)Tc-MAA were obtained for 76 patients with different types of cancer. All images were reviewed retrospectively for extrahepatic MAA deposition in the following order: planar, non-attenuation-corrected SPECT, and SPECT/CT. Review of angiograms and follow-up of patients with abdominal shunting served as reference standards. Extrahepatic accumulation was detected by planar imaging, SPECT, and SPECT/CT in 12%, 17%, and 42% of examinations, respectively. The sensitivity for detecting extrahepatic shunting with planar imaging, SPECT, and SPECT/CT was 32%, 41%, and 100%, respectively; specificity was 98%, 98%, and 93%, respectively. The respective positive predictive values were 92%, 93%, and 89%, and the respective negative predictive values were 71%, 73%, and 100%. The therapy plan was changed according to the results of planar imaging, SPECT, and SPECT/CT in 7.8%, 8.9%, and 29% of patients, respectively. In pre-SIRT planning, (99m)Tc-MAA SPECT/CT is valuable for identifying extrahepatic visceral sites at risk for postradioembolization complications.

Incremental diagnostic accuracy of hybrid SPECT/CT coronary angiography in a population with an intermediate to high pre-test likelihood of coronary artery disease.

PubMed

Schaap, Jeroen; Kauling, Robert M; Boekholdt, S Matthijs; Nieman, Koen; Meijboom, W Bob; Post, Martijn C; Van der Heyden, Jan A; de Kroon, Thom L; van Es, H Wouter; Rensing, Benno J; Verzijlbergen, J Fred

2013-07-01

Hybrid myocardial perfusion imaging with single photon emission computed tomography (SPECT) and CT coronary angiography (CCTA) has the potential to play a major role in patients with non-conclusive SPECT or CCTA results. We evaluated the performance of hybrid SPECT/CCTA vs. standalone SPECT and CCTA for the diagnosis of significant coronary artery disease (CAD) in patients with an intermediate to high pre-test likelihood of CAD. In total, 98 patients (mean age 62.5 ± 10.1 years, 68.4% male) with stable anginal complaints and a median pre-test likelihood of 87% (range 22-95%) were prospectively included in this study. Hybrid SPECT/CCTA was performed prior to conventional coronary angiography (CA) including fractional flow reserve (FFR) measurements. Hybrid analysis was performed by combined interpretation of SPECT and CCTA images. The sensitivity, specificity, positive (PPV), and negative (NPV) predictive values were calculated for standalone SPECT, CCTA, and hybrid SPECT/CCTA on per patient level, using an FFR <0.80 as a reference for significant CAD. Significant CAD was demonstrated in 56 patients (57.9%). Non-conclusive SPECT or CCTA results were found in 32 (32.7%) patients. SPECT had a sensitivity of 93%, specificity 79%, PPV 85%, and NPV 89%. CCTA had a sensitivity of 98%, specificity 62%, PPV 77%, and NPV 96%. Hybrid analysis of SPECT and CCTA improved the overall performance: sensitivity, specificity, PPV, and NPV for the presence of significant CAD to 96, 95, 96, and 95%, respectively. In > 40% of the patients with a high pre-test likelihood no significant CAD was demonstrated, emphasizing the value of accurate pre-treatment cardiovascular imaging. Hybrid SPECT/CCTA was able to accurately diagnose and exclude significant CAD surpassing standalone myocardial SPECT and CCTA, vs. a reference standard of FFR measurements.

Comparison between stress myocardial perfusion SPECT recorded with cadmium-zinc-telluride and Anger cameras in various study protocols.

PubMed

Verger, Antoine; Djaballah, Wassila; Fourquet, Nicolas; Rouzet, François; Koehl, Grégoire; Imbert, Laetitia; Poussier, Sylvain; Fay, Renaud; Roch, Véronique; Le Guludec, Dominique; Karcher, Gilles; Marie, Pierre-Yves

2013-02-01

The results of stress myocardial perfusion SPECT could be enhanced by new cadmium-zinc-telluride (CZT) cameras, although differences compared to the results with conventional Anger cameras remain poorly known for most study protocols. This study was aimed at comparing the results of CZT and Anger SPECT according to various study protocols while taking into account the influence of obesity. The study population, which was from three different institutions equipped with identical CZT cameras, comprised 276 patients referred for study using protocols involving (201)Tl (n = 120) or (99m)Tc-sestamibi injected at low dose at stress ((99m)Tc-Low; stress/rest 1-day protocol; n = 110) or at high dose at stress ((99m)Tc-High; rest/stress 1-day or 2-day protocol; n = 46). Each Anger SPECT scan was followed by a high-speed CZT SPECT scan (2 to 4 min). Agreement rates between CZT and Anger SPECT were good irrespective of the study protocol (for abnormal SPECT, (201)Tl 92 %, (99m)Tc-Low 86 %, (99m)Tc-High 98 %), although quality scores were much higher for CZT SPECT with all study protocols. Overall correlations were high for the extent of myocardial infarction (r = 0.80) and a little lower for ischaemic areas (r = 0.72), the latter being larger on Anger SPECT (p < 0.001). This larger extent was mainly observed in 50 obese patients who were in the (201)Tl or (99m)Tc-Low group and in whom stress myocardial counts were particularly low with Anger SPECT (228 ± 101 kcounts) and dramatically enhanced with CZT SPECT (+279 ± 251 %). Concordance between the results of CZT and Anger SPECT is good regardless of study protocol and especially when excluding obese patients who have low-count Anger SPECT and for whom myocardial counts are dramatically enhanced on CZT SPECT.

99mTc-HMPAO SPECT of the brain in mild to moderate traumatic brain injury patients: compared with CT--a prospective study.

PubMed

Nedd, K; Sfakianakis, G; Ganz, W; Uricchio, B; Vernberg, D; Villanueva, P; Jabir, A M; Bartlett, J; Keena, J

1993-01-01

Single photon emission computed tomography (SPECT) with Technetium-99m hexamethyl propylenamine oxime (Tc-99m-HMPAO) was used in 20 patients with mild to moderate traumatic brain injury (TBI) to evaluate the effects of brain trauma on regional cerebral blood flow (rCBF). SPECT scan was compared with CT scan in 16 patients. SPECT showed intraparenchymal differences in rCBF more often than lesions diagnosed with CT scans (87.5% vs. 37.5%). In five of six patients with lesions in both modalities, the area of involvement was relatively larger on SPECT scans than on CT scans. Contrecoup changes were seen in five patients on SPECT alone, two patients with CT alone and one patient had contrecoup lesions on CT and SPECT. Of the eight patients (50%) with skull fractures, seven (43.7%) had rCBF findings on SPECT scan and five (31.3%) demonstrated decrease in rCBF in brain underlying the fracture. All these patients with fractures had normal brain on CT scans. Conversely, extra-axial lesions and fractures evident on CT did not visualize on SPECT, but SPECT demonstrated associated changes in rCBF. Although there is still lack of clinical and pathological correlation, SPECT appears to be a promising method for a more sensitive evaluation of axial lesions in patients with mild to moderate TBI.

Dual respiratory and cardiac motion estimation in PET imaging: Methods design and quantitative evaluation.

PubMed

Feng, Tao; Wang, Jizhe; Tsui, Benjamin M W

2018-04-01

The goal of this study was to develop and evaluate four post-reconstruction respiratory and cardiac (R&C) motion vector field (MVF) estimation methods for cardiac 4D PET data. In Method 1, the dual R&C motions were estimated directly from the dual R&C gated images. In Method 2, respiratory motion (RM) and cardiac motion (CM) were separately estimated from the respiratory gated only and cardiac gated only images. The effects of RM on CM estimation were modeled in Method 3 by applying an image-based RM correction on the cardiac gated images before CM estimation, the effects of CM on RM estimation were neglected. Method 4 iteratively models the mutual effects of RM and CM during dual R&C motion estimations. Realistic simulation data were generated for quantitative evaluation of four methods. Almost noise-free PET projection data were generated from the 4D XCAT phantom with realistic R&C MVF using Monte Carlo simulation. Poisson noise was added to the scaled projection data to generate additional datasets of two more different noise levels. All the projection data were reconstructed using a 4D image reconstruction method to obtain dual R&C gated images. The four dual R&C MVF estimation methods were applied to the dual R&C gated images and the accuracy of motion estimation was quantitatively evaluated using the root mean square error (RMSE) of the estimated MVFs. Results show that among the four estimation methods, Methods 2 performed the worst for noise-free case while Method 1 performed the worst for noisy cases in terms of quantitative accuracy of the estimated MVF. Methods 4 and 3 showed comparable results and achieved RMSE lower by up to 35% than that in Method 1 for noisy cases. In conclusion, we have developed and evaluated 4 different post-reconstruction R&C MVF estimation methods for use in 4D PET imaging. Comparison of the performance of four methods on simulated data indicates separate R&C estimation with modeling of RM before CM estimation (Method 3) to be the best option for accurate estimation of dual R&C motion in clinical situation. © 2018 American Association of Physicists in Medicine.

Simulation study of the second-generation MR-compatible SPECT system based on the inverted compound-eye gamma camera design

NASA Astrophysics Data System (ADS)

Lai, Xiaochun; Meng, Ling-Jian

2018-02-01

In this paper, we present simulation studies for the second-generation MRI compatible SPECT system, MRC-SPECT-II, based on an inverted compound eye (ICE) gamma camera concept. The MRC-SPECT-II system consists of a total of 1536 independent micro-pinhole-camera-elements (MCEs) distributed in a ring with an inner diameter of 6 cm. This system provides a FOV of 1 cm diameter and a peak geometrical efficiency of approximately 1.3% (the typical levels of 0.1%-0.01% found in modern pre-clinical SPECT instrumentations), while maintaining a sub-500 μm spatial resolution. Compared to the first-generation MRC-SPECT system (MRC-SPECT-I) (Cai 2014 Nucl. Instrum. Methods Phys. Res. A 734 147-51) developed in our lab, the MRC-SPECT-II system offers a similar resolution with dramatically improved sensitivity and greatly reduced physical dimension. The latter should allow the system to be placed inside most clinical and pre-clinical MRI scanners for high-performance simultaneous MRI and SPECT imaging.

PET AND SPECT STUDIES IN CHILDREN WITH HEMISPHERIC LOW-GRADE GLIOMAS

PubMed Central

Juhász, Csaba; Bosnyák, Edit

2016-01-01

Molecular imaging is playing an increasing role in the pre-treatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting and improved detection of tumor recurrence. This review provides a brief overview of single photon emission computed tomography (SPECT) studies followed by a more detailed review of clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pre- and post-treatment evaluation of pediatric brain tumors. PMID:27659825

PET and SPECT studies in children with hemispheric low-grade gliomas.

PubMed

Juhász, Csaba; Bosnyák, Edit

2016-10-01

Molecular imaging is playing an increasing role in the pretreatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting, and improved detection of tumor recurrence. This review provides a brief overview of single-photon emission computed tomography (SPECT) studies followed by a more detailed review of the clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity, and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pretreatment and post-treatment evaluation of pediatric brain tumors.

Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

NASA Astrophysics Data System (ADS)

Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin; Chi, Li-Feng; Wang, Sui-Dong

2015-03-01

Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

MR-based keyhole SPECT for small animal imaging

PubMed Central

Lee, Keum Sil; Roeck, Werner W; Gullberg, Grant T; Nalcioglu, Orhan

2011-01-01

The rationale for multi-modality imaging is to integrate the strengths of different imaging technologies while reducing the shortcomings of an individual modality. The work presented here proposes a limited-field-of-view (LFOV) SPECT reconstruction technique that can be implemented on a multi-modality MR/SPECT system that can be used to obtain simultaneous MRI and SPECT images for small animal imaging. The reason for using a combined MR/SPECT system in this work is to eliminate any possible misregistration between the two sets of images when MR images are used as a priori information for SPECT. In nuclear imaging the target area is usually smaller than the entire object; thus, focusing the detector on the LFOV results in various advantages including the use of a smaller nuclear detector (less cost), smaller reconstruction region (faster reconstruction) and higher spatial resolution when used in conjunction with pinhole collimators with magnification. The MR/SPECT system can be used to choose a region of interest (ROI) for SPECT. A priori information obtained by the full field-of-view (FOV) MRI combined with the preliminary SPECT image can be used to reduce the dimensions of the SPECT reconstruction by limiting the computation to the smaller FOV while reducing artifacts resulting from the truncated data. Since the technique is based on SPECT imaging within the LFOV it will be called the keyhole SPECT (K-SPECT) method. At first MRI images of the entire object using a larger FOV are obtained to determine the location of the ROI covering the target organ. Once the ROI is determined, the animal is moved inside the radiofrequency (rf) coil to bring the target area inside the LFOV and then simultaneous MRI and SPECT are performed. The spatial resolution of the SPECT image is improved by employing a pinhole collimator with magnification >1 by having carefully calculated acceptance angles for each pinhole to avoid multiplexing. In our design all the pinholes are focused to the center of the LFOV. K-SPECT reconstruction is accomplished by generating an adaptive weighting matrix using a priori information obtained by simultaneously acquired MR images and the radioactivity distribution obtained from the ROI region of the SPECT image that is reconstructed without any a priori input. Preliminary results using simulations with numerical phantoms show that the image resolution of the SPECT image within the LFOV is improved while minimizing artifacts arising from parts of the object outside the LFOV due to the chosen magnification and the new reconstruction technique. The root-mean-square-error (RMSE) in the out-of-field artifacts was reduced by 60% for spherical phantoms using the K-SPECT reconstruction technique and by 48.5–52.6% for the heart in the case with the MOBY phantom. The KSPECT reconstruction technique significantly improved the spatial resolution and quantification while reducing artifacts from the contributions outside the LFOV as well as reducing the dimension of the reconstruction matrix. PMID:21220840

Distinguished Neuropsychologist Award Lecture 1999. The lesion(s) in traumatic brain injury: implications for clinical neuropsychology.

PubMed

Bigler, E D

2001-02-01

This paper overviews the current status of neuroimaging in neuropsychological outcome in traumatic brain injury (TBI). The pathophysiology of TBI is reviewed and integrated with expected neuroimaging and neuropsychological findings. The integration of clinical and quantitative magnetic resonance (QMR) imaging is the main topic of review, but these findings are integrated with single photon emission computed tomography (SPECT) and magnetoencephalography (MEG). Various clinical caveats are offered for the clinician.

The AdaptiSPECT Imaging Aperture

PubMed Central

Chaix, Cécile; Moore, Jared W.; Van Holen, Roel; Barrett, Harrison H.; Furenlid, Lars R.

2015-01-01

In this paper, we present the imaging aperture of an adaptive SPECT imaging system being developed at the Center for Gamma Ray Imaging (AdaptiSPECT). AdaptiSPECT is designed to automatically change its configuration in response to preliminary data, in order to improve image quality for a particular task. In a traditional pinhole SPECT imaging system, the characteristics (magnification, resolution, field of view) are set by the geometry of the system, and any modification can be accomplished only by manually changing the collimator and the distance of the detector to the center of the field of view. Optimization of the imaging system for a specific task on a specific individual is therefore difficult. In an adaptive SPECT imaging system, on the other hand, the configuration can be conveniently changed under computer control. A key component of an adaptive SPECT system is its aperture. In this paper, we present the design, specifications, and fabrication of the adaptive pinhole aperture that will be used for AdaptiSPECT, as well as the controls that enable autonomous adaptation. PMID:27019577

Experimental fault-tolerant universal quantum gates with solid-state spins under ambient conditions

PubMed Central

Rong, Xing; Geng, Jianpei; Shi, Fazhan; Liu, Ying; Xu, Kebiao; Ma, Wenchao; Kong, Fei; Jiang, Zhen; Wu, Yang; Du, Jiangfeng

2015-01-01

Quantum computation provides great speedup over its classical counterpart for certain problems. One of the key challenges for quantum computation is to realize precise control of the quantum system in the presence of noise. Control of the spin-qubits in solids with the accuracy required by fault-tolerant quantum computation under ambient conditions remains elusive. Here, we quantitatively characterize the source of noise during quantum gate operation and demonstrate strategies to suppress the effect of these. A universal set of logic gates in a nitrogen-vacancy centre in diamond are reported with an average single-qubit gate fidelity of 0.999952 and two-qubit gate fidelity of 0.992. These high control fidelities have been achieved at room temperature in naturally abundant 13C diamond via composite pulses and an optimized control method. PMID:26602456

A novel dual gating approach using joint inertial sensors: implications for cardiac PET imaging

NASA Astrophysics Data System (ADS)

Jafari Tadi, Mojtaba; Teuho, Jarmo; Lehtonen, Eero; Saraste, Antti; Pänkäälä, Mikko; Koivisto, Tero; Teräs, Mika

2017-10-01

Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i.e. tri-axial accelerometer and gyroscope. This approach can be used for optimized selection of quiescent phases of cardiac and respiratory cycles. Cardiomechanical activity according to echocardiography observations was investigated to confirm whether this dual sensor solution can provide accurate trigger timings for cardiac gating. Additionally, longitudinal chest motions originating from breathing were measured by accelerometric- and gyroscopic-derived respiratory (ADR and GDR) tracking. The ADR and GDR signals were evaluated against Varian real-time position management (RPM) signals in terms of amplitude and phase. Accordingly, high linear correlation and agreement were achieved between the reference electrocardiography, RPM, and measured MEMS signals. We also performed a Ge-68 phantom study to evaluate possible metal artifacts caused by the integrated read-out electronics including mechanical sensors and semiconductors. The reconstructed phantom images did not reveal any image artifacts. Thus, it was concluded that MEMS-driven dual gating can be used in PET studies without an effect on the quantitative or visual accuracy of the PET images. Finally, the applicability of MEMS dual gating for cardiac PET imaging was investigated with two atherosclerosis patients. Dual gated PET images were successfully reconstructed using only MEMS signals and both qualitative and quantitative assessments revealed encouraging results that warrant further investigation of this method.

Design and evaluation of two multi-pinhole collimators for brain SPECT.

PubMed

Chen, Ling; Tsui, Benjamin M W; Mok, Greta S P

2017-10-01

SPECT is a powerful tool for diagnosing or staging brain diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) but is limited by its inferior resolution and sensitivity. At the same time, pinhole SPECT provides superior resolution and detection efficiency trade-off as compared to the conventional parallel-hole collimator for imaging small field-of-view (FOV), which fits for the case of brain imaging. In this study, we propose to develop and evaluate two multi-pinhole (MPH) collimator designs to improve the imaging of cerebral blood flow and striatum. We set the target resolutions to be 12 and 8 mm, respectively, and the FOV at 200 mm which is large enough to cover the whole brain. The constraints for system optimization include maximum and minimum detector-to-center-of-FOV (CFOV) distances of 344 and 294 mm, respectively, and minimal radius-of-rotation (ROR) of 135 mm to accommodate patients' shoulder. According to the targeted FOV, resolutions, and constraints, we determined the pinhole number, ROR, focal length, aperture acceptance angle, and aperture diameter which maximized the system sensitivity. We then assessed the imaging performance of the proposed MPH and standard low-energy high-resolution (LEHR) collimators using analytical simulations of a digital NCAT brain phantom with 99m Tc-HMPAO/ 99m Tc-TRODAT-1 distributions; Monte Carlo simulations of a hot-rod phantom; and a Defrise phantom using GATE v6.1. Projections were generated over 360° and reconstructed using the 3D MPH/LEHR OS-EM methods with up to 720 updates. The normalized mean square error (NMSE) was calculated over the cerebral and striatal regions extracted from the reconstructed images for 99m Tc-HMPAO and 99m Tc-TRODAT-1 simulations, respectively, and average normalized standard deviation (NSD) based on 20 noise realizations was assessed on selected uniform 3D regions as the noise index. Visual assessment and image profiles were applied to the results of Monte Carlo simulations. The optimized design parameters of the MPH collimators were 9 pinholes with 4.7 and 2.8 mm pinhole diameter, 73° acceptance angle, 127 mm focal length, 167 mm ROR for 12 mm and 8 mm target resolution, respectively. According to the optimization results, the detection efficiencies of the proposed collimators were 270 and 40% more as compared to LEHR. The Monte Carlo simulations showed that 7.9 and 6.4 mm rods can be discriminated for the MPH collimators with target resolutions of 12 and 8 mm, respectively. The eight 12 mm-thick discs of the Defrise phantom can also be resolved clearly in the axial plane as demonstrated by the image profiles generated with the MPH collimators. The two collimator designs provide superior image quality as compared to the conventional LEHR, and shows potential to improve current brain SPECT imaging based on a conventional SPECT scanner.

2D Quantum Transport Modeling in Nanoscale MOSFETs

NASA Technical Reports Server (NTRS)

Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan

2001-01-01

With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density- gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions, oxide tunneling and phase-breaking scattering are treated on equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. Quantum simulations are focused on MIT 25, 50 and 90 nm "well- tempered" MOSFETs and compared to classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. These results are quantitatively consistent with I D Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and sub-threshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.

System Integration of FastSPECT III, a Dedicated SPECT Rodent-Brain Imager Based on BazookaSPECT Detector Technology

PubMed Central

Miller, Brian W.; Furenlid, Lars R.; Moore, Stephen K.; Barber, H. Bradford; Nagarkar, Vivek V.; Barrett, Harrison H.

2010-01-01

FastSPECT III is a stationary, single-photon emission computed tomography (SPECT) imager designed specifically for imaging and studying neurological pathologies in rodent brain, including Alzheimer’s and Parkinsons’s disease. Twenty independent BazookaSPECT [1] gamma-ray detectors acquire projections of a spherical field of view with pinholes selected for desired resolution and sensitivity. Each BazookaSPECT detector comprises a columnar CsI(Tl) scintillator, image-intensifier, optical lens, and fast-frame-rate CCD camera. Data stream back to processing computers via firewire interfaces, and heavy use of graphics processing units (GPUs) ensures that each frame of data is processed in real time to extract the images of individual gamma-ray events. Details of the system design, imaging aperture fabrication methods, and preliminary projection images are presented. PMID:21218137

Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

NASA Astrophysics Data System (ADS)

Winant, Celeste D.; Aparici, Carina Mari; Zelnik, Yuval R.; Reutter, Bryan W.; Sitek, Arkadiusz; Bacharach, Stephen L.; Gullberg, Grant T.

2012-01-01

Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94Tc-methoxyisobutylisonitrile (94Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99mTc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal maximum-likelihood expectation-maximization (4D ML-EM) reconstructions gave more accurate reconstructions than did standard frame-by-frame static 3D ML-EM reconstructions. The SPECT/P results showed that 4D ML-EM reconstruction gave higher and more accurate estimates of K1 than did 3D ML-EM, yielding anywhere from a 44% underestimation to 24% overestimation for the three patients. The SPECT/D results showed that 4D ML-EM reconstruction gave an overestimation of 28% and 3D ML-EM gave an underestimation of 1% for K1. For the patient study the 4D ML-EM reconstruction provided continuous images as a function of time of the concentration in both ventricular cavities and myocardium during the 2 min infusion. It is demonstrated that a 2 min infusion with a two-headed SPECT system rotating 180° every 54 s can produce measurements of blood pool and myocardial TACs, though the SPECT simulation studies showed that one must sample at least every 30 s to capture a 1 min infusion input function.

Blood-pool SPECT in addition to bone SPECT in the viability assessment in mandibular reconstruction.

PubMed

Aydogan, F; Akbay, E; Cevik, C; Kalender, E

2014-01-01

The assessment of the postoperative viability of vascularized and non-vascularized grafts used in the reconstruction of mandibular defects due to trauma and surgical reasons is a major problem in maxillofacial surgery. In the present study, we evaluated the feasibility and image quality of blood-pool SPECT, which is used for the first time in the literature here in the assessment of mandibular reconstruction, in addition to non-invasive bone scintigraphy and bone SPECT. We also evaluated whether it would be useful in clinical prediction. Micro-vascularized and non-vascularized bone grafts were used in 12 Syrian men with maxillofacial trauma. Between days 5-7 after surgery, three-phase bone scintigraphy, blood-pool SPECT and delayed bone SPECT scans were performed. After month 6, the patients were assessed by control CT scans. Of the non-vascularized grafts, one graft was reported as non-viable at week one. At month 6, graft resorption was demonstrated on the CT images. The remaining non-vascularized grafts and all of the micro-vascularized grafts were considered to be viable according to delayed bone SPECT and blood-pool SPECT images. However, only the anterior and posterior ends could be clearly assessed on delayed SPECT images, while blood-pool SPECT images allowed the clear assessment of the entire graft. The combined use of blood-pool and delayed SPECT scans could allow for better assessment of graft viability in the early period, and can provide more detailed information to clinicians about prognosis in the follow-up of patients undergoing mandibular graft reconstruction.

A 3D-printed anatomical pancreas and kidney phantom for optimizing SPECT/CT reconstruction settings in beta cell imaging using 111In-exendin.

PubMed

Woliner-van der Weg, Wietske; Deden, Laura N; Meeuwis, Antoi P W; Koenrades, Maaike; Peeters, Laura H C; Kuipers, Henny; Laanstra, Geert Jan; Gotthardt, Martin; Slump, Cornelis H; Visser, Eric P

2016-12-01

Quantitative single photon emission computed tomography (SPECT) is challenging, especially for pancreatic beta cell imaging with 111 In-exendin due to high uptake in the kidneys versus much lower uptake in the nearby pancreas. Therefore, we designed a three-dimensionally (3D) printed phantom representing the pancreas and kidneys to mimic the human situation in beta cell imaging. The phantom was used to assess the effect of different reconstruction settings on the quantification of the pancreas uptake for two different, commercially available software packages. 3D-printed, hollow pancreas and kidney compartments were inserted into the National Electrical Manufacturers Association (NEMA) NU2 image quality phantom casing. These organs and the background compartment were filled with activities simulating relatively high and low pancreatic 111 In-exendin uptake for, respectively, healthy humans and type 1 diabetes patients. Images were reconstructed using Siemens Flash 3D and Hermes Hybrid Recon, with varying numbers of iterations and subsets and corrections. Images were visually assessed on homogeneity and artefacts, and quantitatively by the pancreas-to-kidney activity concentration ratio. Phantom images were similar to clinical images and showed comparable artefacts. All corrections were required to clearly visualize the pancreas. Increased numbers of subsets and iterations improved the quantitative performance but decreased homogeneity both in the pancreas and the background. Based on the phantom analyses, the Hybrid Recon reconstruction with 6 iterations and 16 subsets was found to be most suitable for clinical use. This work strongly contributed to quantification of pancreatic 111 In-exendin uptake. It showed how clinical images of 111 In-exendin can be interpreted and enabled selection of the most appropriate protocol for clinical use.

A solid dielectric gated graphene nanosensor in electrolyte solutions.

PubMed

Zhu, Yibo; Wang, Cheng; Petrone, Nicholas; Yu, Jaeeun; Nuckolls, Colin; Hone, James; Lin, Qiao

2015-03-23

This letter presents a graphene field effect transistor (GFET) nanosensor that, with a solid gate provided by a high- κ dielectric, allows analyte detection in liquid media at low gate voltages. The gate is embedded within the sensor and thus is isolated from a sample solution, offering a high level of integration and miniaturization and eliminating errors caused by the liquid disturbance, desirable for both in vitro and in vivo applications. We demonstrate that the GFET nanosensor can be used to measure pH changes in a range of 5.3-9.3. Based on the experimental observations and quantitative analysis, the charging of an electrical double layer capacitor is found to be the major mechanism of pH sensing.

[Analysis of single-photon emission computed tomography in patients with hypertensive encephalopathy complicated with previous hypertensive crisis].

PubMed

Kustkova, H S

2012-01-01

In cerebrovascular diseases pefuzionnaya single photon emission computed tomography with lipophilic amines used for the diagnosis of functional disorders of cerebral blood flow. Quantitative calculations helps clarify the nature of vascular disease and clarify the adequacy and effectiveness of the treatment. In this modern program for SPECT ensure conduct not only as to the calculation of blood flow, but also make it possible to compute also the absolute values of cerebral blood flow.

Evaluation of Rigid-Body Motion Compensation in Cardiac Perfusion SPECT Employing Polar-Map Quantification

PubMed Central

Pretorius, P. Hendrik; Johnson, Karen L.; King, Michael A.

2016-01-01

We have recently been successful in the development and testing of rigid-body motion tracking, estimation and compensation for cardiac perfusion SPECT based on a visual tracking system (VTS). The goal of this study was to evaluate in patients the effectiveness of our rigid-body motion compensation strategy. Sixty-four patient volunteers were asked to remain motionless or execute some predefined body motion during an additional second stress perfusion acquisition. Acquisitions were performed using the standard clinical protocol with 64 projections acquired through 180 degrees. All data were reconstructed with an ordered-subsets expectation-maximization (OSEM) algorithm using 4 projections per subset and 5 iterations. All physical degradation factors were addressed (attenuation, scatter, and distance dependent resolution), while a 3-dimensional Gaussian rotator was used during reconstruction to correct for six-degree-of-freedom (6-DOF) rigid-body motion estimated by the VTS. Polar map quantification was employed to evaluate compensation techniques. In 54.7% of the uncorrected second stress studies there was a statistically significant difference in the polar maps, and in 45.3% this made a difference in the interpretation of segmental perfusion. Motion correction reduced the impact of motion such that with it 32.8 % of the polar maps were statistically significantly different, and in 14.1% this difference changed the interpretation of segmental perfusion. The improvement shown in polar map quantitation translated to visually improved uniformity of the SPECT slices. PMID:28042170

Reproducibility Between Brain Uptake Ratio Using Anatomic Standardization and Patlak-Plot Methods.

PubMed

Shibutani, Takayuki; Onoguchi, Masahisa; Noguchi, Atsushi; Yamada, Tomoki; Tsuchihashi, Hiroko; Nakajima, Tadashi; Kinuya, Seigo

2015-12-01

The Patlak-plot and conventional methods of determining brain uptake ratio (BUR) have some problems with reproducibility. We formulated a method of determining BUR using anatomic standardization (BUR-AS) in a statistical parametric mapping algorithm to improve reproducibility. The objective of this study was to demonstrate the inter- and intraoperator reproducibility of mean cerebral blood flow as determined using BUR-AS in comparison to the conventional-BUR (BUR-C) and Patlak-plot methods. The images of 30 patients who underwent brain perfusion SPECT were retrospectively used in this study. The images were reconstructed using ordered-subset expectation maximization and processed using an automatic quantitative analysis for cerebral blood flow of ECD tool. The mean SPECT count was calculated from axial basal ganglia slices of the normal side (slices 31-40) drawn using a 3-dimensional stereotactic region-of-interest template after anatomic standardization. The mean cerebral blood flow was calculated from the mean SPECT count. Reproducibility was evaluated using coefficient of variation and Bland-Altman plotting. For both inter- and intraoperator reproducibility, the BUR-AS method had the lowest coefficient of variation and smallest error range about the Bland-Altman plot. Mean CBF obtained using the BUR-AS method had the highest reproducibility. Compared with the Patlak-plot and BUR-C methods, the BUR-AS method provides greater inter- and intraoperator reproducibility of cerebral blood flow measurement. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Dipyridamole stress myocardial perfusion by computed tomography in patients with left bundle branch block.

PubMed

Cabeda, Estêvan Vieira; Falcão, Andréa Maria Gomes; Soares, José; Rochitte, Carlos Eduardo; Nomura, César Higa; Ávila, Luiz Francisco Rodrigues; Parga, José Rodrigues

2015-12-01

Functional tests have limited accuracy for identifying myocardial ischemia in patients with left bundle branch block (LBBB). To assess the diagnostic accuracy of dipyridamole-stress myocardial computed tomography perfusion (CTP) by 320-detector CT in patients with LBBB using invasive quantitative coronary angiography (QCA) (stenosis ≥ 70%) as reference; to investigate the advantage of adding CTP to coronary computed tomography angiography (CTA) and compare the results with those of single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy. Thirty patients with LBBB who had undergone SPECT for the investigation of coronary artery disease were referred for stress tomography. Independent examiners performed per-patient and per-coronary territory assessments. All patients gave written informed consent to participate in the study that was approved by the institution's ethics committee. The patients' mean age was 62 ± 10 years. The mean dose of radiation for the tomography protocol was 9.3 ± 4.6 mSv. With regard to CTP, the per-patient values for sensitivity, specificity, positive and negative predictive values, and accuracy were 86%, 81%, 80%, 87%, and 83%, respectively (p = 0.001). The per-territory values were 63%, 86%, 65%, 84%, and 79%, respectively (p < 0.001). In both analyses, the addition of CTP to CTA achieved higher diagnostic accuracy for detecting myocardial ischemia than SPECT (p < 0.001). The use of the stress tomography protocol is feasible and has good diagnostic accuracy for assessing myocardial ischemia in patients with LBBB.

A new era for Nuclear Medicine neuroimaging in Spain: Where do we start from in Spain?

PubMed

Balsa, M A; Camacho, V; Garrastachu, P; García-Solís, D; Gómez-Río, M; Rubí, S; Setoain, X; Arbizu, J

To determine the status of neuroimaging studies of Nuclear Medicine in Spain during 2013 and first quarter of 2014, in order to define the activities of the neuroimaging group of the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM). A questionnaire of 14 questions was designed, divided into 3 parts: characteristics of the departments (equipment and professionals involved); type of scans and clinical indications; and evaluation methods. The questionnaire was sent to 166 Nuclear Medicine departments. A total of 54 departments distributed among all regions completed the questionnaire. Most departments performed between 300 and 800 neuroimaging examinations per year, representing more than 25 scans per month. The average pieces of equipment were three; half of the departments had a PET/CT scanner and SPECT/CT equipment. Scans performed more frequently were brain SPECT with 123 I-FP-CIT, followed by brain perfusion SPECT and PET with 18 F-FDG. The most frequent clinical indications were cognitive impairment followed by movement disorders. For evaluation of the images most sites used only visual assessment, and for the quantitative assessment the most used was quantification by region of interest. These results reflect the clinical activity of 2013 and first quarter of 2014. The main indications of the studies were cognitive impairment and movement disorders. Variability in the evaluation of the studies is among the challenges that will be faced in the coming years. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Imaging Lung Function in Mice Using SPECT/CT and Per-Voxel Analysis

PubMed Central

Jobse, Brian N.; Rhem, Rod G.; McCurry, Cory A. J. R.; Wang, Iris Q.; Labiris, N. Renée

2012-01-01

Chronic lung disease is a major worldwide health concern but better tools are required to understand the underlying pathologies. Ventilation/perfusion (V/Q) single photon emission computed tomography (SPECT) with per-voxel analysis allows for non-invasive measurement of regional lung function. A clinically adapted V/Q methodology was used in healthy mice to investigate V/Q relationships. Twelve week-old mice were imaged to describe normal lung function while 36 week-old mice were imaged to determine how age affects V/Q. Mice were ventilated with Technegas™ and injected with 99mTc-macroaggregated albumin to trace ventilation and perfusion, respectively. For both processes, SPECT and CT images were acquired, co-registered, and quantitatively analyzed. On a per-voxel basis, ventilation and perfusion were moderately correlated (R = 0.58±0.03) in 12 week old animals and a mean log(V/Q) ratio of −0.07±0.01 and standard deviation of 0.36±0.02 were found, defining the extent of V/Q matching. In contrast, 36 week old animals had significantly increased levels of V/Q mismatching throughout the periphery of the lung. Measures of V/Q were consistent across healthy animals and differences were observed with age demonstrating the capability of this technique in quantifying lung function. Per-voxel analysis and the ability to non-invasively assess lung function will aid in the investigation of chronic lung disease models and drug efficacy studies. PMID:22870297

Three-dimensional fractal analysis of 99mTc-MAA SPECT images in chronic thromboembolic pulmonary hypertension for evaluation of response to balloon pulmonary angioplasty: association with pulmonary arterial pressure.

PubMed

Maruoka, Yasuhiro; Nagao, Michinobu; Baba, Shingo; Isoda, Takuro; Kitamura, Yoshiyuki; Yamazaki, Yuzo; Abe, Koichiro; Sasaki, Masayuki; Abe, Kohtaro; Honda, Hiroshi

2017-06-01

Balloon pulmonary angioplasty (BPA) is used for inoperable chronic thromboembolic pulmonary hypertension (CTEPH), but its effect cannot be evaluated noninvasively. We devised a noninvasive quantitative index of response to BPA using three-dimensional fractal analysis (3D-FA) of technetium-99m-macroaggregated albumin (Tc-MAA) single-photon emission computed tomography (SPECT). Forty CTEPH patients who underwent pulmonary perfusion scintigraphy and mean pulmonary arterial pressure (mPAP) measurement by right heart catheterization before and after BPA were studied. The total uptake volume (TUV) in bilateral lungs was determined from maximum intensity projection Tc-MAA SPECT images. Fractal dimension was assessed by 3D-FA. Parameters were compared before and after BPA, and between patients with post-BPA mPAP more than 30 mmHg and less than or equal to 30 mmHg. Receiver operating characteristic analysis was carried out. BPA significantly improved TUV (595±204-885±214 ml, P<0.001) and reduced the laterality of uptake (238±147-135±131 ml, P<0.001). Patients with poor therapeutic response (post-BPA mPAP≥30 mmHg, n=16) showed a significantly smaller TUV increase (P=0.044) and a significantly greater post-BPA fractal dimension (P<0.001) than the low-mPAP group. Fractal dimension correlated with mPAP values before and after BPA (P=0.013 and 0.001, respectively). A post-BPA fractal dimension threshold of 2.4 distinguished between BPA success and failure with 75% sensitivity, 79% specificity, 78% accuracy, and area under the curve of 0.85. 3D-FA using Tc-MAA SPECT pulmonary perfusion scintigraphy enables a noninvasive evaluation of the response of CTEPH patients to BPA.

Longitudinal Assessment of Lung Cancer Progression in Mice Using the Sodium Iodide Symporter Reporter Gene and SPECT/CT Imaging.

PubMed

Price, Dominique N; McBride, Amber A; Anton, Martina; Kusewitt, Donna F; Norenberg, Jeffrey P; MacKenzie, Debra A; Thompson, Todd A; Muttil, Pavan

2016-01-01

Lung cancer has the highest mortality rate of any tissue-specific cancer in both men and women. Research continues to investigate novel drugs and therapies to mitigate poor treatment efficacy, but the lack of a good descriptive lung cancer animal model for preclinical drug evaluation remains an obstacle. Here we describe the development of an orthotopic lung cancer animal model which utilizes the human sodium iodide symporter gene (hNIS; SLC5A5) as an imaging reporter gene for the purpose of non-invasive, longitudinal tumor quantification. hNIS is a glycoprotein that naturally transports iodide (I-) into thyroid cells and has the ability to symport the radiotracer 99mTc-pertechnetate (99mTcO4-). A549 lung adenocarcinoma cells were genetically modified with plasmid or lentiviral vectors to express hNIS. Modified cells were implanted into athymic nude mice to develop two tumor models: a subcutaneous and an orthotopic xenograft tumor model. Tumor progression was longitudinally imaged using SPECT/CT and quantified by SPECT voxel analysis. hNIS expression in lung tumors was analyzed by quantitative real-time PCR. Additionally, hematoxylin and eosin staining and visual inspection of pulmonary tumors was performed. We observed that lentiviral transduction provided enhanced and stable hNIS expression in A549 cells. Furthermore, 99mTcO4- uptake and accumulation was observed within lung tumors allowing for imaging and quantification of tumor mass at two-time points. This study illustrates the development of an orthotopic lung cancer model that can be longitudinally imaged throughout the experimental timeline thus avoiding inter-animal variability and leading to a reduction in total animal numbers. Furthermore, our orthotopic lung cancer animal model is clinically relevant and the genetic modification of cells for SPECT/CT imaging can be translated to other tissue-specific tumor animal models.

Longitudinal Assessment of Lung Cancer Progression in Mice Using the Sodium Iodide Symporter Reporter Gene and SPECT/CT Imaging

PubMed Central

Anton, Martina; Kusewitt, Donna F.; Norenberg, Jeffrey P.; MacKenzie, Debra A.; Thompson, Todd A.; Muttil, Pavan

2016-01-01

Lung cancer has the highest mortality rate of any tissue-specific cancer in both men and women. Research continues to investigate novel drugs and therapies to mitigate poor treatment efficacy, but the lack of a good descriptive lung cancer animal model for preclinical drug evaluation remains an obstacle. Here we describe the development of an orthotopic lung cancer animal model which utilizes the human sodium iodide symporter gene (hNIS; SLC5A5) as an imaging reporter gene for the purpose of non-invasive, longitudinal tumor quantification. hNIS is a glycoprotein that naturally transports iodide (I-) into thyroid cells and has the ability to symport the radiotracer 99mTc-pertechnetate (99mTcO4-). A549 lung adenocarcinoma cells were genetically modified with plasmid or lentiviral vectors to express hNIS. Modified cells were implanted into athymic nude mice to develop two tumor models: a subcutaneous and an orthotopic xenograft tumor model. Tumor progression was longitudinally imaged using SPECT/CT and quantified by SPECT voxel analysis. hNIS expression in lung tumors was analyzed by quantitative real-time PCR. Additionally, hematoxylin and eosin staining and visual inspection of pulmonary tumors was performed. We observed that lentiviral transduction provided enhanced and stable hNIS expression in A549 cells. Furthermore, 99mTcO4- uptake and accumulation was observed within lung tumors allowing for imaging and quantification of tumor mass at two-time points. This study illustrates the development of an orthotopic lung cancer model that can be longitudinally imaged throughout the experimental timeline thus avoiding inter-animal variability and leading to a reduction in total animal numbers. Furthermore, our orthotopic lung cancer animal model is clinically relevant and the genetic modification of cells for SPECT/CT imaging can be translated to other tissue-specific tumor animal models. PMID:28036366

Estimation of myocardial flow reserve utilizing an ultrafast cardiac SPECT: Comparison with coronary angiography, fractional flow reserve, and the SYNTAX score.

PubMed

Miyagawa, Masao; Nishiyama, Yoshiko; Uetani, Teruyoshi; Ogimoto, Akiyoshi; Ikeda, Shuntaro; Ishimura, Hayato; Watanabe, Emiri; Tashiro, Rami; Tanabe, Yuki; Kido, Teruhito; Kurata, Akira; Mochizuki, Teruhito

2017-10-01

Quantitative assessment of myocardial flow reserve (MFR) by single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is challenging but may facilitate evaluation of multi-vessel coronary artery disease (CAD). We enrolled 153 patients with suspected or known CAD, referred for pharmacological stress MPI. They underwent a 99m Tc-perfusion stress/rest SPECT with an ultrafast cadmium-zinc-telluride (CZT) camera. Dynamic data were acquired and time-activity curves fitted to a 1-tissue compartment analysis with input function. K1 was assigned for stress and rest data. The MFR index (MFRi) was calculated as K1 stress/K1 at-rest. The findings were validated by invasive coronary angiography in 69 consecutive patients. The global MFRi was 1.46 (1.16-1.76), 1.33 (1.12-1.54), and 1.18 (1.01-1.35), for 1-vessel disease (VD), 2-VD, and 3-VD, respectively. In the 3-VD, global MFRi was lower than that in 0-VD (1.63 [1.22-2.04], P<0.0001) and 1-VD (P=0.003). Multivariate logistic regression analysis for 3-VD showed significant associations with smoking history (odds ratio [OR]: 4.4 [0.4-8.4]), left ventricular ejection fraction (OR: 61.6 [57.5-66.0]), and global MFRi (OR: 119.6 [111.5-127.7], P=0.002). A cut-off value of 1.3 yielded 93.3% sensitivity and 75.9% specificity for diagnosing 3-VD. Fractional flow reserve positively correlated with regional MFRi (r=0.62, P=0.008), and the SYNTAX score correlated negatively with global MFRi (r=0.567, P=0.0003). We developed and validated a clinically available method for MFR quantification by dynamic 99m Tc-perfusion SPECT utilizing a CZT camera, which improves the detectability of multi-vessel CAD. Copyright © 2017 Elsevier B.V. All rights reserved.

Radiosynthesis and evaluation of novel acetylcholine receptor radioligands

NASA Astrophysics Data System (ADS)

Pimlott, Sally L.

Neuroreceptor single photon emission computed tomography (SPECT) imaging provides a powerful tool for the evaluation of the function of a neurotransmitter system in normal and or disease states in the living human brain. The cholinergic system is involved in the control of a variety of complex functions including learning, memory and modulation of behaviour. Deficits in the cholinergic system have been found in a number of neurological diseases, such as Alzheimer's disease, dementia with Lewy bodies, Parkinson's disease and Epilepsy. Acetylcholine receptors (AChRs) are divided into two classes, muscarinic and nicotinic. The aim of this project was to develop two novel SPECT AChR ligands: (R,R)[123I]I-QNB, a M1 subtype selective muscarinic acetylcholine receptor (mAChR) ligand, and 5-[123I]-A-85380, a alpha4beta2 subtype selective nicotinic receptor (nAChR) ligand, for use in human SPECT imaging studies. The calculation of the binding potential of a ligand can be used to obtain quantitative information from a SPECT scan, enabling comparisons to be made between studies. Methodological issues involved in the calculation of binding potential are therefore crucial for the accuracy of results. A particularly important parameter is the amount of authentic radioligand available to cross the blood brain barrier. This was characterised in the research performed for this thesis. The radiosynthesis of two novel neuroreceptor radioligands has been optimised for use in humans. (R, R)[123I]I-QNB has been used in human studies to provide useful information on the human mAChR function in disease. Pre-clinical evaluation of 5-[123I]-A-85380 provided useful information for in vivo human studies. Both radioligands are concluded to successfully provide novel information on the function of the acetylcholine system. Methodological issues involved in the blood metabolite analysis and measurement of plasma protein binding have been investigated and discussed, with particular reference made to the factors that must be taken into account when designing these experiments. (Abstract shortened by ProQuest.).

Voxel-based statistical analysis of cerebral blood flow using Tc-99m ECD brain SPECT in patients with traumatic brain injury: group and individual analyses.

PubMed

Shin, Yong Beom; Kim, Seong-Jang; Kim, In-Ju; Kim, Yong-Ki; Kim, Dong-Soo; Park, Jae Heung; Yeom, Seok-Ran

2006-06-01

Statistical parametric mapping (SPM) was applied to brain perfusion single photon emission computed tomography (SPECT) images in patients with traumatic brain injury (TBI) to investigate regional cerebral abnormalities compared to age-matched normal controls. Thirteen patients with TBI underwent brain perfusion SPECT were included in this study (10 males, three females, mean age 39.8 +/- 18.2, range 21 - 74). SPM2 software implemented in MATLAB 5.3 was used for spatial pre-processing and analysis and to determine the quantitative differences between TBI patients and age-matched normal controls. Three large voxel clusters of significantly decreased cerebral blood perfusion were found in patients with TBI. The largest clusters were area including medial frontal gyrus (voxel number 3642, peak Z-value = 4.31, 4.27, p = 0.000) in both hemispheres. The second largest clusters were areas including cingulated gyrus and anterior cingulate gyrus of left hemisphere (voxel number 381, peak Z-value = 3.67, 3.62, p = 0.000). Other clusters were parahippocampal gyrus (voxel number 173, peak Z-value = 3.40, p = 0.000) and hippocampus (voxel number 173, peak Z-value = 3.23, p = 0.001) in the left hemisphere. The false discovery rate (FDR) was less than 0.04. From this study, group and individual analyses of SPM2 could clearly identify the perfusion abnormalities of brain SPECT in patients with TBI. Group analysis of SPM2 showed hypoperfusion pattern in the areas including medial frontal gyrus of both hemispheres, cingulate gyrus, anterior cingulate gyrus, parahippocampal gyrus and hippocampus in the left hemisphere compared to age-matched normal controls. Also, left parahippocampal gyrus and left hippocampus were additional hypoperfusion areas. However, these findings deserve further investigation on a larger number of patients to be performed to allow a better validation of objective SPM analysis in patients with TBI.

Improved Quantification of the Beta Cell Mass after Pancreas Visualization with 99mTc-demobesin-4 and Beta Cell Imaging with 111In-exendin-3 in Rodents.

PubMed

van der Kroon, Inge; Joosten, Lieke; Nock, Berthold A; Maina, Theodosia; Boerman, Otto C; Brom, Maarten; Gotthardt, Martin

2016-10-03

Accurate assessment of the 111 In-exendin-3 uptake within the pancreas requires exact delineation of the pancreas, which is highly challenging by MRI and CT in rodents. In this study, the pancreatic tracer 99m Tc-demobesin-4 was evaluated for accurate delineation of the pancreas to be able to accurately quantify 111 In-exendin-3 uptake within the pancreas. Healthy and alloxan-induced diabetic Brown Norway rats were injected with the pancreatic tracer 99m Tc-demobesin-4 ([ 99m Tc-N 4 -Pro 1 ,Tyr 4 ,Nle 14 ]bombesin) and the beta cell tracer 111 In-exendin-3 ([ 111 In-DTPA-Lys 40 ]exendin-3). After dual isotope acquisition of SPECT images, 99m Tc-demobesin-4 was used to define a volume of interest for the pancreas in SPECT images subsequently the 111 In-exendin-3 uptake within this region was quantified. Furthermore, biodistribution and autoradiography were performed in order to gain insight in the distribution of both tracers in the animals. 99m Tc-demobesin-4 showed high accumulation in the pancreas. The uptake was highly homogeneous throughout the pancreas, independent of diabetic status, as demonstrated by autoradiography, whereas 111 In-exendin-3 only accumulates in the islets of Langerhans. Quantification of both ex vivo and in vivo SPECT images resulted in an excellent linear correlation between the pancreatic uptake, determined with ex vivo counting and 111 In-exendin-3 uptake, determined from the quantitative analysis of the SPECT images (Pearson r = 0.97, Pearson r = 0.92). 99m Tc-demobesin-4 shows high accumulation in the pancreas of rats. It is a suitable tracer for accurate delineation of the pancreas and can be conveniently used for simultaneous acquisition with 111 In labeled exendin-3. This method provides a straightforward, reliable, and objective method for preclinical beta cell mass (BCM) quantification with 111 In-exendin-3.

Realistic simulated MRI and SPECT databases. Application to SPECT/MRI registration evaluation.

PubMed

Aubert-Broche, Berengere; Grova, Christophe; Reilhac, Anthonin; Evans, Alan C; Collins, D Louis

2006-01-01

This paper describes the construction of simulated SPECT and MRI databases that account for realistic anatomical and functional variability. The data is used as a gold-standard to evaluate four SPECT/MRI similarity-based registration methods. Simulation realism was accounted for using accurate physical models of data generation and acquisition. MRI and SPECT simulations were generated from three subjects to take into account inter-subject anatomical variability. Functional SPECT data were computed from six functional models of brain perfusion. Previous models of normal perfusion and ictal perfusion observed in Mesial Temporal Lobe Epilepsy (MTLE) were considered to generate functional variability. We studied the impact noise and intensity non-uniformity in MRI simulations and SPECT scatter correction may have on registration accuracy. We quantified the amount of registration error caused by anatomical and functional variability. Registration involving ictal data was less accurate than registration involving normal data. MR intensity nonuniformity was the main factor decreasing registration accuracy. The proposed simulated database is promising to evaluate many functional neuroimaging methods, involving MRI and SPECT data.

Molecular imaging of angiogenesis with SPECT

PubMed Central

Boerman, Otto C.

2010-01-01

Single-photon emission computed tomography (SPECT) and position emission tomography (PET) are the two main imaging modalities in nuclear medicine. SPECT imaging is more widely available than PET imaging and the radionuclides used for SPECT are easier to prepare and usually have a longer half-life than those used for PET. In addition, SPECT is a less expensive technique than PET. Commonly used gamma emitters are: 99mTc (Emax 141 keV, T1/2 6.02 h), 123I (Emax 529 keV, T1/2 13.0 h) and 111In (Emax 245 keV, T1/2 67.2 h). Compared to clinical SPECT, PET has a higher spatial resolution and the possibility to more accurately estimate the in vivo concentration of a tracer. In preclinical imaging, the situation is quite different. The resolution of microSPECT cameras (<0.5 mm) is higher than that of microPET cameras (>1.5 mm). In this report, studies on new radiolabelled tracers for SPECT imaging of angiogenesis in tumours are reviewed. PMID:20617435

Ventilation/perfusion SPECT or SPECT/CT for lung function imaging in patients with pulmonary emphysema?

PubMed

Froeling, Vera; Heimann, Uwe; Huebner, Ralf-Harto; Kroencke, Thomas J; Maurer, Martin H; Doellinger, Felix; Geisel, Dominik; Hamm, Bernd; Brenner, Winfried; Schreiter, Nils F

2015-07-01

To evaluate the utility of attenuation correction (AC) of V/P SPECT images for patients with pulmonary emphysema. Twenty-one patients (mean age 67.6 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. AC/non-AC V/P SPECT images were compared visually and semiquantitatively. Visual comparison of AC/non-AC images was based on a 5-point likert scale. Semiquantitative comparison assessed absolute counts per lung (aCpLu) and lung lobe (aCpLo) for AC/non-AC images using software-based analysis; percentage counts (PC = (aCpLo/aCpLu) × 100) were calculated. Correlation between AC/non-AC V/P SPECT images was analyzed using Spearman's rho correlation coefficient; differences were tested for significance with the Wilcoxon rank sum test. Visual analysis revealed high conformity for AC and non-AC V/P SPECT images. Semiquantitative analysis of PC in AC/non-AC images had an excellent correlation and showed no significant differences in perfusion (ρ = 0.986) or ventilation (ρ = 0.979, p = 0.809) SPECT/CT images. AC of V/P SPECT images for lung lobe-based function imaging in patients with pulmonary emphysema do not improve visual or semiquantitative image analysis.

Double match of 18F-fluorodeoxyglucose-PET and iomazenil-SPECT improves outcomes of focus resection surgery.

PubMed

Fujimoto, Ayataka; Okanishi, Tohru; Kanai, Sotaro; Sato, Keishiro; Itamura, Shinji; Baba, Shimpei; Nishimura, Mitsuyo; Masui, Takayuki; Enoki, Hideo

2018-06-01

When the results of electroencephalography (EEG), magnetic resonance imaging (MRI), and seizure semiology are discordant or no structural lesion is evident on MRI, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are important examinations for lateralization or localization of epileptic regions. We hypothesized that the concordance between interictal 2-[ 18 F]fluoro-2-deoxy-D-glucose ( 18 FDG)-PET and iomazenil (IMZ)-SPECT could suggest the epileptogenic lobe in patients with non-lesional findings on MRI. Fifty-nine patients (31 females, 28 males; mean age, 29 years; median age, 27 years; range, 7-56 years) underwent subdural electrode implantation followed by focus resection. All patients underwent 18 FDG-PET, IMZ-SPECT, and focus resection surgery. Follow-up was continued for ≥ 2 years. We evaluated surgical outcomes as seizure-free or not and analyzed correlations between outcomes and concordances of low-uptake lobes on PET, SPECT, or both PET and SPECT to the resection lobes. We used uni- and multivariate logistic regression analyses. In univariate analyses, all three concordances correlated significantly with seizure-free outcomes (PET, p = 0.017; SPECT, p = 0.030; both PET and SPECT, p = 0.006). In multivariate analysis, concordance between resection and low-uptake lobes in both PET and SPECT correlated significantly with seizure-free outcomes (p = 0.004). The odds ratio was 6.0. Concordance between interictal 18 FDG-PET and IMZ-SPECT suggested that the epileptogenic lobe is six times better than each examination alone among patients with non-lesional findings on MRI. IMZ-SPECT and 18 FDG-PET are complementary examinations in the assessment of localization-related epilepsy.

Design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals

NASA Astrophysics Data System (ADS)

Tsui, Benjamin M. W.; Hugg, James W.; Xu, Jingyan; Chen, Si; Meier, Dirk; Edelstein, William; El-Sharkawy, Abdel; Wagenaar, Douglas J.; Patt, Bradley E.

2011-03-01

We describe a continuing design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals. A first generation prototype SPECT system was designed and constructed to fit inside a MRI system with a gradient bore inner diameter of 12 cm. It consists of 3 angularly offset rings of 8 detectors (1"x1", 16x16 pixels MR-compatible solid-state CZT). A matching 24-pinhole collimator sleeve, made of a tungsten-compound, provides projections from a common FOV of ~25 mm. A birdcage RF coil for MRI data acquisition surrounds the collimator. The SPECT system was tested inside a clinical 3T MRI system. Minimal interference was observed on the simultaneously acquired SPECT and MR images. We developed a sparse-view image reconstruction method based on accurate modeling of the point response function (PRF) of each of the 24 pinholes to provide artifact-free SPECT images. The stationary SPECT system provides relatively low resolution of 3-5 mm but high geometric efficiency of 0.5- 1.2% for fast dynamic acquisition, demonstrated in a SPECT renal kinetics study using Tc-99m DTPA. Based on these results, a second generation prototype MR-compatible SPECT system with an outer diameter of 20 cm that fits inside a mid-sized preclinical MRI system is being developed. It consists of 5 rings of 19 CZT detectors. The larger ring diameter allows the use of optimized multi-pinhole collimator designs, such as high system resolution up to ~1 mm, high geometric efficiency, or lower system resolution without collimator rotation. The anticipated performance of the new system is supported by simulation data.

SPECT-CT in routine clinical practice: increase in patient radiation dose compared with SPECT alone.

PubMed

Sharma, Punit; Sharma, Shekhar; Ballal, Sanjana; Bal, Chandrasekhar; Malhotra, Arun; Kumar, Rakesh

2012-09-01

To assess the patient radiation dose during routine clinical single-photon emission computed tomography-computed tomography (SPECT-CT) and measure the increase as compared with SPECT alone. Data pertaining to 357 consecutive patients who had undergone radioisotope imaging along with SPECT-CT of a selected volume were retrospectively evaluated. Dose of the injected radiopharmaceutical (MBq) was noted, and the effective dose (mSv) was calculated as per International Commission on Radiological Protection (ICRP) guidelines. The volume-weighted computed tomography dose index (CTDIvol) and dose length product of the CT were also assessed using standard phantoms. The effective dose (mSv) due to CT was calculated as the product of dose length product and a conversion factor depending on the region of investigation, using ICRP guidelines. The dose due to CT was compared among different investigations. The increase in effective dose was calculated as CT dose expressed as a percentage of radiopharmaceutical dose. The per-patient CT effective dose for different studies varied between 0.06 and 11.9 mSv. The mean CT effective dose was lowest for 99mTc-ethylene cysteine dimer brain SPECT-CT (0.9 ± 0.7) and highest for 99mTc-methylene diphosphonate bone SPECT-CT (4.2 ± 2.8). The increase in radiation dose (SPECT-CT vs. SPECT) varied widely (2.3-666.4% for 99mTc-tracers and 0.02-96.2% for 131I-tracers). However, the effective dose of CT in SPECT-CT was less than the values reported for conventional CT examinations of the same regions. Addition of CT to nuclear medicine imaging in the form of SPECT-CT increases the radiation dose to the patient, with the effective dose due to CT exceeding the effective dose of RP in many instances. Hence, appropriate utilization and optimization of the protocols of SPECT-CT is needed to maximize benefit to patients.

The impact of system matrix dimension on small FOV SPECT reconstruction with truncated projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Chung, E-mail: Chung.Chan@yale.edu, E-mail: Chi.Liu@yale.edu; Wu, Jing; Liu, Chi, E-mail: Chung.Chan@yale.edu, E-mail: Chi.Liu@yale.edu

Purpose: A dedicated cardiac hybrid single photon emission computed tomography (SPECT)/CT scanner that uses cadmium zinc telluride detectors and multiple pinhole collimators for stationary acquisition offers many advantages. However, the impact of the reconstruction system matrix (SM) dimension on the reconstructed image quality from truncated projections and 19 angular samples acquired on this scanner has not been extensively investigated. In this study, the authors aimed to investigate the impact of the dimensions of SM and the use of body contour derived from adjunctive CT imaging as an object support in reconstruction on this scanner, in relation to background extracardiac activity.more » Methods: The authors first simulated a generic SPECT/CT system to image four NCAT phantoms with various levels of extracardiac activity and compared the reconstructions using SM in different dimensions and with/without body contour as a support for quantitative evaluations. The authors then compared the reconstructions of 18 patient studies, which were acquired on a GE Discovery NM570c scanner following injection of different radiotracers, including {sup 99m}Tc-Tetrofosmin and {sup 123}I-mIBG, comparing the scanner’s default SM that incompletely covers the body with a large SM that incorporates a patient specific full body contour. Results: The simulation studies showed that the reconstructions using a SM that only partially covers the body yielded artifacts on the edge of the field of view (FOV), overestimation of activity and increased nonuniformity in the blood pool for the phantoms with higher relative levels of extracardiac activity. However, the impact on the quantitative accuracy in the high activity region, such as the myocardium, was subtle. On the other hand, an excessively large SM that enclosed the entire body alleviated the artifacts and reduced overestimation in the blood pool, but yielded slight underestimation in myocardium and defect regions. The reconstruction using the larger SM with body contour yielded the most quantitatively accurate results in all the regions of interest for a range of uptake levels in the extracardiac regions. In patient studies, the SM incorporating patient specific body contour minimized extracardiac artifacts, yielded similar myocardial activity, lower blood pool activity, and subsequently improved myocardium-to-blood pool contrast (p < 0.0001) by an average of 7% (range 0%–18%) across all the patients, compared to the reconstructions using the scanner’s default SM. Conclusions: Their results demonstrate that using a large SM that incorporates a CT derived body contour in the reconstruction could improve quantitative accuracy within the FOV for clinical studies with high extracardiac activity.« less

Quantitative SIMS depth profiling of diffusion barrier gate-oxynitride structures in TFT-LCDs.

PubMed

Dreer, Sabine; Wilhartitz, Peter; Piplits, Kurt; Mayerhofer, Karl; Foisner, Johann; Hutter, Herbert

2004-06-01

Gate oxynitride structures of TFT-LCDs were investigated by SIMS, and successful solutions are demonstrated to overcome difficulties arising due to the charging effects of the multilayer systems, the matrix effect of the method, and the small pattern sizes of the samples. Because of the excellent reproducibility achieved by applying exponential relative sensitivity functions for quantitative analysis, minor differences in the barrier gate-oxynitride composition deposited on molybdenum capped aluminium-neodymium metallisation electrodes were determined between the centre and the edge of the TFT-LCD substrates. No differences were found for molybdenum-tungsten metallisations. Furthermore, at the edge of the glass substrates, aluminium, neodymium, and molybdenum SIMS depth profiles show an exponential trend. With TEM micrographs an inhomogeneous thickness of the molybdenum capping is revealed as the source of this effect, which influences the electrical behaviour of the device. The production process was improved after these results and the aging behaviour of TFT-LCDs was investigated in order to explain the change in control voltage occurring during the lifetime of the displays. SIMS and TEM show an enrichment of neodymium at the interface to the molybdenum layer, confirming good diffusion protection of the molybdenum barrier during accelerated aging. The reason for the shift of the control voltage was finally located by semi-quantitative depth profiling of the sodium diffusion originating from the glass substrate. Molybdenum-tungsten was a much better buffer for the highly-mobile charge carriers than aluminium-neodymium. Best results were achieved with PVD silicon oxynitride as diffusion barrier and gate insulator deposited on aluminium-neodymium metallisation layers.

[Acute stent thrombosis and reverse transient left ventricular dilatation after performing a single-photon emission computed tomography myocardial perfusion].

PubMed

Miranda, B; Pizzi, M N; Aguadé-Bruix, S; Domingo, E; Candell-Riera, J

2015-01-01

A 63-year-old male patient with a history of stent implantation in the left anterior descending three months before. Due to the presentation of vegetative symptoms, he was referred for gated-SPECT myocardial perfusion. During acquisition of the resting images he presented chest pain and ST segment elevation, so that urgent cardiac catheterization was performed, showing stent thrombosis. Rest perfusion imaging showed a defect in anterior and apical perfusion, more severe and extensive than in the stress images, with striking left ventricular dilatation and a fall in the ejection fraction related to the acute ischemia phenomenon. Intense exercise is associated with a transient activation of the coagulation system and hemodynamic changes that might induce thrombosis, especially in recently implanted coronary stents that probably still have not become completely endothelialized. Copyright © 2014 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Investigation of attenuation correction in SPECT using textural features, Monte Carlo simulations, and computational anthropomorphic models.

PubMed

Spirou, Spiridon V; Papadimitroulas, Panagiotis; Liakou, Paraskevi; Georgoulias, Panagiotis; Loudos, George

2015-09-01

To present and evaluate a new methodology to investigate the effect of attenuation correction (AC) in single-photon emission computed tomography (SPECT) using textural features analysis, Monte Carlo techniques, and a computational anthropomorphic model. The GATE Monte Carlo toolkit was used to simulate SPECT experiments using the XCAT computational anthropomorphic model, filled with a realistic biodistribution of (99m)Tc-N-DBODC. The simulated gamma camera was the Siemens ECAM Dual-Head, equipped with a parallel hole lead collimator, with an image resolution of 3.54 × 3.54 mm(2). Thirty-six equispaced camera positions, spanning a full 360° arc, were simulated. Projections were calculated after applying a ± 20% energy window or after eliminating all scattered photons. The activity of the radioisotope was reconstructed using the MLEM algorithm. Photon attenuation was accounted for by calculating the radiological pathlength in a perpendicular line from the center of each voxel to the gamma camera. Twenty-two textural features were calculated on each slice, with and without AC, using 16 and 64 gray levels. A mask was used to identify only those pixels that belonged to each organ. Twelve of the 22 features showed almost no dependence on AC, irrespective of the organ involved. In both the heart and the liver, the mean and SD were the features most affected by AC. In the liver, six features were affected by AC only on some slices. Depending on the slice, skewness decreased by 22-34% with AC, kurtosis by 35-50%, long-run emphasis mean by 71-91%, and long-run emphasis range by 62-95%. In contrast, gray-level non-uniformity mean increased by 78-218% compared with the value without AC and run percentage mean by 51-159%. These results were not affected by the number of gray levels (16 vs. 64) or the data used for reconstruction: with the energy window or without scattered photons. The mean and SD were the main features affected by AC. In the heart, no other feature was affected. In the liver, other features were affected, but the effect was slice dependent. The number of gray levels did not affect the results.

Changes in the planning target volume and liver volume dose based on the selected respiratory phase in respiratory-gated radiation therapy for a hepatocellular carcinoma

NASA Astrophysics Data System (ADS)

Lee, Jae-Seung; Im, In-Chul; Kang, Su-Man; Goo, Eun-Hoe; Baek, Seong-Min

2013-11-01

The aim of this study was to quantitatively analyze the changes in the planning target volume (PTV) and liver volume dose based on the respiratory phase to identify the optimal respiratory phase for respiratory-gated radiation therapy for a hepatocellular carcinoma (HCC). Based on the standardized procedure for respiratory-gated radiation therapy, we performed a 4-dimensional computed tomography simulation for 0 ˜ 90%, 30 ˜ 70%, and 40 ˜ 60% respiratory phases to assess the respiratory stability (S R ) and the defined PTV i for each respiratory phase i. A treatment plan was established, and the changes in the PTV i and dose volume of the liver were quantitatively analyzed. Most patients (91.5%) passed the respiratory stability test (S R = 0.111 ± 0.015). With standardized respiration training exercises, we were able to minimize the overall systematic error caused by irregular respiration. Furthermore, a quantitative analysis to identify the optimal respiratory phase revealed that when a short respiratory phase (40 ˜ 60%) was used, the changes in the PTV were concentrated inside the center line; thus, we were able to obtain both a PTV margin accounting for respiration and a uniform radiation dose within the PTV.

Voxel-based correlation between coregistered single-photon emission computed tomography and dynamic susceptibility contrast magnetic resonance imaging in subjects with suspected Alzheimer disease.

PubMed

Cavallin, L; Axelsson, R; Wahlund, L O; Oksengard, A R; Svensson, L; Juhlin, P; Wiberg, M Kristoffersen; Frank, A

2008-12-01

Current diagnosis of Alzheimer disease is made by clinical, neuropsychologic, and neuroimaging assessments. Neuroimaging techniques such as magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) could be valuable in the differential diagnosis of Alzheimer disease, as well as in assessing prognosis. To compare SPECT and MRI in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer disease (AD). 24 patients, eight with AD, 10 with MCI, and six controls, were investigated with SPECT using (99m)Tc-hexamethylpropyleneamine oxime (HMPAO, Ceretec; GE Healthcare Ltd., Little Chalsont UK) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with a contrast-enhancing gadobutrol formula (Gadovist; Bayer Schering Pharma, Berlin, Germany). Voxel-based correlation between coregistered SPECT and DSC-MR images was calculated. Region-of-interest (ROI) analyses were then performed in 24 different brain areas using brain registration and analysis of SPECT studies (BRASS; Nuclear Diagnostics AB, Stockholm, Sweden) on both SPECT and DSC-MRI. Voxel-based correlation between coregistered SPECT and DSC-MR showed a high correlation, with a mean correlation coefficient of 0.94. ROI analyses of 24 regions showed significant differences between the control group and AD patients in 10 regions using SPECT and five regions in DSC-MR. SPECT remains superior to DSC-MRI in differentiating normal from pathological perfusion, and DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer disease.

Detection of Sentinel Lymph Nodes in Gynecologic Tumours by Planar Scintigraphy and SPECT/CT

PubMed Central

Kraft, Otakar; Havel, Martin

2012-01-01

Objective: Assess the role of planar lymphoscintigraphy and fusion imaging of SPECT/CT in sentinel lymph node (SLN) detection in patients with gynecologic tumours. Material and Methods: Planar scintigraphy and hybrid modality SPECT/CT were performed in 64 consecutive women with gynecologic tumours (mean age 53.6 with range 30-77 years): 36 pts with cervical cancer (Group A), 21 pts with endometrial cancer (Group B), 7 pts with vulvar carcinoma (Group C). Planar and SPECT/CT images were interpreted separately by two nuclear medicine physicians. Efficacy of these two techniques to image SLN were compared. Results: Planar scintigraphy did not image SLN in 7 patients (10.9%), SPECT/CT was negative in 4 patients (6.3%). In 35 (54.7%) patients the number of SLNs captured on SPECT/CT was higher than on planar imaging. Differences in detection of SLN between planar and SPECT/CT imaging in the group of all 64 patients are statistically significant (p<0.05). Three foci of uptake (1.7% from totally visible 177 foci on planar images) in 2 patients interpreted on planar images as hot LNs were found to be false positive non-nodal sites of uptake when further assessed on SPECT/CT. SPECT/CT showed the exact anatomical location of all visualised sentinel nodes. Conclusion: In some patients with gynecologic cancers SPECT/CT improves detection of sentinel lymph nodes. It can image nodes not visible on planar scintigrams, exclude false positive uptake and exactly localise pelvic and paraaortal SLNs. It improves anatomic localization of SLNs. Conflict of interest:None declared. PMID:23486989

Direct comparison of rest and adenosine stress myocardial perfusion CT with rest and stress SPECT

PubMed Central

Okada, David R.; Ghoshhajra, Brian B.; Blankstein, Ron; Rocha-Filho, Jose A.; Shturman, Leonid D.; Rogers, Ian S.; Bezerra, Hiram G.; Sarwar, Ammar; Gewirtz, Henry; Hoffmann, Udo; Mamuya, Wilfred S.; Brady, Thomas J.; Cury, Ricardo C.

2010-01-01

Introduction We have recently described a technique for assessing myocardial perfusion using adenosine-mediated stress imaging (CTP) with dual source computed tomography. SPECT myocardial perfusion imaging (SPECT-MPI) is a widely utilized and extensively validated method for assessing myocardial perfusion. The aim of this study was to determine the level of agreement between CTP and SPECT-MPI at rest and under stress on a per-segment, per-vessel, and per-patient basis. Methods Forty-seven consecutive patients underwent CTP and SPECT-MPI. Perfusion images were interpreted using the 17 segment AHA model and were scored on a 0 (normal) to 3 (abnormal) scale. Summed rest and stress scores were calculated for each vascular territory and patient by adding corresponding segmental scores. Results On a per-segment basis (n = 799), CTP and SPECT-MPI demonstrated excellent correlation: Goodman-Kruskall γ = .59 (P < .0001) for stress and .75 (P < .0001) for rest. On a per-vessel basis (n = 141), CTP and SPECT-MPI summed scores demonstrated good correlation: Pearson r = .56 (P < .0001) for stress and .66 (P < .0001) for rest. On a per-patient basis (n = 47), CTP and SPECT-MPI demonstrated good correlation: Pearson r = .60 (P < .0001) for stress and .76 (P < .0001) for rest. Conclusions CTP compares favorably with SPECT-MPI for detection, extent, and severity of myocardial perfusion defects at rest and stress. PMID:19936863

Influence of the Pixel Sizes of Reference Computed Tomography on Single-photon Emission Computed Tomography Image Reconstruction Using Conjugate-gradient Algorithm.

PubMed

Okuda, Kyohei; Sakimoto, Shota; Fujii, Susumu; Ida, Tomonobu; Moriyama, Shigeru

The frame-of-reference using computed-tomography (CT) coordinate system on single-photon emission computed tomography (SPECT) reconstruction is one of the advanced characteristics of the xSPECT reconstruction system. The aim of this study was to reveal the influence of the high-resolution frame-of-reference on the xSPECT reconstruction. 99m Tc line-source phantom and National Electrical Manufacturers Association (NEMA) image quality phantom were scanned using the SPECT/CT system. xSPECT reconstructions were performed with the reference CT images in different sizes of the display field-of-view (DFOV) and pixel. The pixel sizes of the reconstructed xSPECT images were close to 2.4 mm, which is acquired as originally projection data, even if the reference CT resolution was varied. The full width at half maximum (FWHM) of the line-source, absolute recovery coefficient, and background variability of image quality phantom were independent on the sizes of DFOV in the reference CT images. The results of this study revealed that the image quality of the reconstructed xSPECT images is not influenced by the resolution of frame-of-reference on SPECT reconstruction.

Assessment of functional liver reserve: old and new in 99mTc-sulfur colloid scintigraphy.

PubMed

Matesan, Manuela M; Bowen, Stephen R; Chapman, Tobias R; Miyaoka, Robert S; Velez, James W; Wanner, Michele F; Nyflot, Matthew J; Apisarnthanarax, Smith; Vesselle, Hubert J

2017-07-01

A semiquantitative assessment of hepatic reticuloendothelial system function using colloidal particles scintigraphy has been proposed previously as a surrogate for liver function evaluation. In this article, we present an updated method for the overall assessment of technetium-99m (Tc)-sulfur colloid (SC) biodistribution that combines information from planar and attenuation-corrected Tc-SC single-photon emission computed tomography (SPECT) images. The imaging protocol described here was developed as an easy-to-implement method to assess overall and regional liver function changes associated with chronic liver disease. Thirty patients with chronic liver disease and primary liver cancers underwent Tc-SC whole-body planar imaging and upper-abdomen SPECT/computed tomography (CT) imaging before external beam radiation therapy. Liver plus spleen and bone marrow counts as a fraction of whole-body total counts were calculated from SC planar imaging. Attenuation correction Tc-SC images were rigidly coregistered with treatment planning CT images that contained liver and spleen regions-of-interest. Ratios of total liver counts to total spleen counts were obtained from the aligned Tc-SC SPECT and CT images, and were subsequently used to separate liver plus spleen counts obtained on the planar images. This hybrid SPECT/CT and planar scintigraphy approach yielded an updated estimation of whole-body SC distribution. These biodistribution estimates were compared with historical data for reference. Statistical associations of Tc-SC biodistribution to liver function parameters and liver disease scoring systems (Child-Pugh) were evaluated by Spearman rank correlation. Percentages of Tc-SC uptake ranged from 19.3 to 77.3% for the liver; 3.4 to 40.7% for the spleen; and 19.0 to 56.7% for the bone marrow. Spearman's correlation coefficient showed a significant statistical association between Child-Pugh score and bone marrow uptake at 0.55 (P≤0.05), liver uptake at 0.71 (P≤0.001), spleen uptake at 0.56 (P≤0.05), and spleen plus bone marrow uptake at 0.71 (P≤0.001). There was also a good correlation of SC uptake percentages with individual quantitative liver function components such as albumin and total bilirubin, and qualitative liver function components (varices, portal hypertension, ascites). For albumin: r=0.64 (P<0.001) compared with liver uptake percentage from the whole-body counts, r=0.49 (P<0.001) compared with splenic uptake percentage, and r=0.45 (P≤0.05) compared with bone marrow uptake percentage. We describe a novel liver function quantitative assessment method that combines whole-body planar images and SPECT/CT attenuation-corrected images of Tc-SC distribution. Attenuation-corrected SC images provide valuable regional liver function information, which is a unique feature compared with other imaging methods available. The results of our study indicate that the Tc-SC uptake by the liver, spleen, and bone marrow correlates with liver function parameters in patients with diffuse liver disease and the correlation with liver disease severity is slightly better for liver uptake percentages than for individual values of bone marrow and spleen uptake percentages.

Partition Model-Based 99mTc-MAA SPECT/CT Predictive Dosimetry Compared with 90Y TOF PET/CT Posttreatment Dosimetry in Radioembolization of Hepatocellular Carcinoma: A Quantitative Agreement Comparison.

PubMed

Gnesin, Silvano; Canetti, Laurent; Adib, Salim; Cherbuin, Nicolas; Silva Monteiro, Marina; Bize, Pierre; Denys, Alban; Prior, John O; Baechler, Sebastien; Boubaker, Ariane

2016-11-01

90 Y-microsphere selective internal radiation therapy (SIRT) is a valuable treatment in unresectable hepatocellular carcinoma (HCC). Partition-model predictive dosimetry relies on differential tumor-to-nontumor perfusion evaluated on pretreatment 99m Tc-macroaggregated albumin (MAA) SPECT/CT. The aim of this study was to evaluate agreement between the predictive dosimetry of 99m Tc-MAA SPECT/CT and posttreatment dosimetry based on 90 Y time-of-flight (TOF) PET/CT. We compared the 99m Tc-MAA SPECT/CT results for 27 treatment sessions (25 HCC patients, 41 tumors) with 90 Y SIRT (7 glass spheres, 20 resin spheres) and the posttreatment 90 Y TOF PET/CT results. Three-dimensional voxelized dose maps were computed from the 99m Tc-MAA SPECT/CT and 90 Y TOF PET/CT data. Mean absorbed dose ([Formula: see text]) was evaluated to compute the predicted-to-actual dose ratio ([Formula: see text]) in tumor volumes (TVs) and nontumor volumes (NTVs) for glass and resin spheres. The Lin concordance ([Formula: see text]) was used to measure accuracy ([Formula: see text]) and precision (ρ). Administered activity ranged from 0.8 to 1.9 GBq for glass spheres and from 0.6 to 3.4 GBq for resin spheres, and the respective TVs ranged from 2 to 125 mL and from 6 to 1,828 mL. The mean dose [Formula: see text] was 240 Gy for glass and 122 Gy for resin in TVs and 72 Gy for glass and 47 Gy for resin in NTVs. [Formula: see text] was 1.46 ± 0.58 (0.65-2.53) for glass and 1.16 ± 0.41 (0.54-2.54) for resin, and the respective values for [Formula: see text] were 0.88 ± 0.15 (0.56-1.00) and 0.86 ± 0.2 (0.58-1.35). DR variability was substantially lower in NTVs than in TVs. The Lin concordance between [Formula: see text] and [Formula: see text] (resin) was significantly better for tumors larger than 150 mL than for tumors 150 mL or smaller ([Formula: see text] = 0.93 and [Formula: see text] = 0.95 vs. [Formula: see text] = 0.57 and [Formula: see text] = 0.93; P < 0.05). In 90 Y radioembolization of HCC, predictive dosimetry based on 99m Tc-MAA SPECT/CT provided good estimates of absorbed doses calculated from posttreatment 90 Y TOF PET/CT for tumor and nontumor tissues. The low variability of [Formula: see text] demonstrates that pretreatment dosimetry is particularly suitable for minimizing radiation-induced hepatotoxicity. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

A randomization approach to handling data scaling in nuclear medicine.

PubMed

Bai, Chuanyong; Conwell, Richard; Kindem, Joel

2010-06-01

In medical imaging, data scaling is sometimes desired to handle the system complexity, such as uniformity calibration. Since the data are usually saved in short integer, conventional data scaling will first scale the data in floating point format and then truncate or round the floating point data to short integer data. For example, when using truncation, scaling of 9 by 1.1 results in 9 and scaling of 10 by 1.1 results in 11. When the count level is low, such scaling may change the local data distribution and affect the intended application of the data. In this work, the authors use an example gated cardiac SPECT study to illustrate the effect of conventional scaling by factors of 1.1 and 1.2. The authors then scaled the data with the same scaling factors using a randomization approach, in which a random number evenly distributed between 0 and 1 is generated to determine how the floating point data will be saved as short integer data. If the random number is between 0 and 0.9, then 9.9 will be saved as 10, otherwise 9. In other words, the floating point value 9.9 will be saved in short integer value as 10 with 90% probability or 9 with 10% probability. For statistical analysis of the performance, the authors applied the conventional approach with rounding and the randomization approach to 50 consecutive gated studies from a clinical site. For the example study, the image reconstructed from the original data showed an apparent perfusion defect at the apex of the myocardium. The defect size was noticeably changed by scaling with 1.1 and 1.2 using the conventional approaches with truncation and rounding. Using the randomization approach, in contrast, the images from the scaled data appeared identical to the original image. Line profile analysis of the scaled data showed that the randomization approach introduced the least change to the data as compared to the conventional approaches. For the 50 gated data sets, significantly more studies showed quantitative differences between the original images and the images from the data scaled by 1.2 using the rounding approach than the randomization approach [46/50 (92%) versus 3/50 (6%), p < 0.05]. Likewise, significantly more studies showed visually noticeable differences between the original images and the images from the data scaled by 1.2 using the rounding approach than randomization [29/50 (58%) versus 1/50 (2%), p < 0.05]. In conclusion, the proposed randomization approach minimizes the scaling-introduced local data change as compared to the conventional approaches. It is preferred for nuclear medicine data scaling.

Initial experience with SPECT imaging of the brain using I-123 p-iodoamphetamine in focal epilepsy

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaManna, M.M.; Sussman, N.M.; Harner, R.N.

1989-06-01

Nineteen patients with complex partial seizures refractory to medical treatment were examined with routine electroencephalography (EEG), video EEG monitoring, computed tomography or magnetic resonance imaging, neuropsychological tests and interictal single photon emission computed tomography (SPECT) with I-123 iodoamphetamine (INT). In 18 patients, SPECT identified areas of focal reduction in tracer uptake that correlated with the epileptogenic focus identified on the EEG. In addition, SPECT disclosed other areas of neurologic dysfunction as elicited on neuropsychological tests. Thus, IMP SPECT is a useful tool for localizing epileptogenic foci and their associated dynamic deficits.

An automated voxelized dosimetry tool for radionuclide therapy based on serial quantitative SPECT/CT imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, Price A.; Kron, Tomas; Beauregard, Jean-Mathieu

2013-11-15

Purpose: To create an accurate map of the distribution of radiation dose deposition in healthy and target tissues during radionuclide therapy.Methods: Serial quantitative SPECT/CT images were acquired at 4, 24, and 72 h for 28 {sup 177}Lu-octreotate peptide receptor radionuclide therapy (PRRT) administrations in 17 patients with advanced neuroendocrine tumors. Deformable image registration was combined with an in-house programming algorithm to interpolate pharmacokinetic uptake and clearance at a voxel level. The resultant cumulated activity image series are comprised of values representing the total number of decays within each voxel's volume. For PRRT, cumulated activity was translated to absorbed dose basedmore » on Monte Carlo-determined voxel S-values at a combination of long and short ranges. These dosimetric image sets were compared for mean radiation absorbed dose to at-risk organs using a conventional MIRD protocol (OLINDA 1.1).Results: Absorbed dose values to solid organs (liver, kidneys, and spleen) were within 10% using both techniques. Dose estimates to marrow were greater using the voxelized protocol, attributed to the software incorporating crossfire effect from nearby tumor volumes.Conclusions: The technique presented offers an efficient, automated tool for PRRT dosimetry based on serial post-therapy imaging. Following retrospective analysis, this method of high-resolution dosimetry may allow physicians to prescribe activity based on required dose to tumor volume or radiation limits to healthy tissue in individual patients.« less

Quantitative assessment of cerebral blood flow in genetically confirmed spinocerebellar ataxia type 6.

PubMed

Honjo, Kie; Ohshita, Tomohiko; Kawakami, Hideshi; Naka, Hiromitsu; Imon, Yukari; Maruyama, Hirofumi; Mimori, Yasuyo; Matsumoto, Masayasu

2004-06-01

Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant cerebellar ataxia caused by CAG trinucleotide expansion. The characteristics of regional cerebral blood flow (rCBF) in SCA6 patients have not been established, whereas it has been reported that decreased rCBF in the cerebrum seems to be a remote effect of cerebellar impairment in other cerebellar disorders. To clarify the characteristics of rCBF, including cerebro-cerebellar relationship, and its correlation with clinical manifestations in patients with genetically confirmed SCA6 using quantitative assessment of rCBF by brain single-photon emission computed tomography (SPECT). Technetium Tc 99m ethyl cysteinate dimer SPECT study using a Patlak plot. Patients Hiroshima University Hospital, Hiroshima, Japan. Ten patients with SCA6 and 9 healthy controls. Main Outcome Measure The rCBF of the cerebellar vermis, cerebellar hemisphere, and frontal lobes. In SCA6 patients, rCBF was decreased only in the cerebellar vermis and hemisphere compared with healthy controls, and this was inversely correlated with duration of illness. The rCBF in the frontal lobes was slightly correlated with duration of illness without statistical significance. The rCBF in the vermis was inversely correlated with severity of dysarthria, but there was no significant correlation with CAG repeated expansions. Decrease in rCBF was found only in the cerebellum and was associated with duration of illness, dysarthria and ataxia, and cerebellar atrophy. No remote effect of cerebellar hypoperfusion was found in the SCA6 patients.

Monte Carlo simulation of PET and SPECT imaging of {sup 90}Y

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Akihiko, E-mail: takahsr@hs.med.kyushu-u.ac.jp; Sasaki, Masayuki; Himuro, Kazuhiko

2015-04-15

Purpose: Yittrium-90 ({sup 90}Y) is traditionally thought of as a pure beta emitter, and is used in targeted radionuclide therapy, with imaging performed using bremsstrahlung single-photon emission computed tomography (SPECT). However, because {sup 90}Y also emits positrons through internal pair production with a very small branching ratio, positron emission tomography (PET) imaging is also available. Because of the insufficient image quality of {sup 90}Y bremsstrahlung SPECT, PET imaging has been suggested as an alternative. In this paper, the authors present the Monte Carlo-based simulation–reconstruction framework for {sup 90}Y to comprehensively analyze the PET and SPECT imaging techniques and to quantitativelymore » consider the disadvantages associated with them. Methods: Our PET and SPECT simulation modules were developed using Monte Carlo simulation of Electrons and Photons (MCEP), developed by Dr. S. Uehara. PET code (MCEP-PET) generates a sinogram, and reconstructs the tomography image using a time-of-flight ordered subset expectation maximization (TOF-OSEM) algorithm with attenuation compensation. To evaluate MCEP-PET, simulated results of {sup 18}F PET imaging were compared with the experimental results. The results confirmed that MCEP-PET can simulate the experimental results very well. The SPECT code (MCEP-SPECT) models the collimator and NaI detector system, and generates the projection images and projection data. To save the computational time, the authors adopt the prerecorded {sup 90}Y bremsstrahlung photon data calculated by MCEP. The projection data are also reconstructed using the OSEM algorithm. The authors simulated PET and SPECT images of a water phantom containing six hot spheres filled with different concentrations of {sup 90}Y without background activity. The amount of activity was 163 MBq, with an acquisition time of 40 min. Results: The simulated {sup 90}Y-PET image accurately simulated the experimental results. PET image is visually superior to SPECT image because of the low background noise. The simulation reveals that the detected photon number in SPECT is comparable to that of PET, but the large fraction (approximately 75%) of scattered and penetration photons contaminates SPECT image. The lower limit of {sup 90}Y detection in SPECT image was approximately 200 kBq/ml, while that in PET image was approximately 100 kBq/ml. Conclusions: By comparing the background noise level and the image concentration profile of both the techniques, PET image quality was determined to be superior to that of bremsstrahlung SPECT. The developed simulation codes will be very useful in the future investigations of PET and bremsstrahlung SPECT imaging of {sup 90}Y.« less

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads.

PubMed

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Morimoto, Yuichi; Kobashi, Keiji; Ueno, Yuichiro

2015-10-01

To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. PT-SPECT provides improved image resolution at not only upper but also at central slices of the cerebrum.

I-123 iomazenil single photon emission computed tomography for detecting loss of neuronal integrity in patients with traumatic brain injury.

PubMed

Abiko, Kagari; Ikoma, Katsunori; Shiga, Tohru; Katoh, Chietsugu; Hirata, Kenji; Kuge, Yuji; Kobayashi, Kentaro; Tamaki, Nagara

2017-12-01

Traumatic brain injury (TBI) causes brain dysfunction in many patients. Using C-11 flumazenil (FMZ) positron emission tomography (PET), we have detected and reported the loss of neuronal integrity, leading to brain dysfunction in TBI patients. Similarly to FMZ PET, I-123 iomazenil (IMZ) single photon emission computed tomography (SPECT) is widely used to determine the distribution of the benzodiazepine receptor (BZR) in the brain cortex. The purpose of this study is to examine whether IMZ SPECT is as useful as FMZ PET for evaluating the loss of neuronal integrity in TBI patients. The subjects of this study were seven patients who suffered from neurobehavioral disability. They underwent IMZ SPECT and FMZ PET. Nondisplaceable binding potential (BP ND ) was calculated from FMZ PET images. The uptake of IMZ was evaluated on the basis of lesion-to-pons ratio (LPR). The locations of low uptake levels were visually evaluated both in IMZ SPECT and FMZ PET images. We compared FMZ BP ND and (LPR-1) of IMZ SPECT. In the visual assessment, FMZ BP ND decreased in 11 regions. In IMZ SPECT, low uptake levels were observed in eight of the 11 regions. The rate of concordance between FMZ PET and IMZ SPECT was 72.7%. The mean values IMZ (LPR-1) (1.95 ± 1.01) was significantly lower than that of FMZ BP ND (2.95 ± 0.80 mL/mL). There was good correlation between FMZ BP ND and IMZ (LPR-1) (r = 0.80). IMZ SPECT findings were almost the same as FMZ PET findings in TBI patients. The results indicated that IMZ SPECT is useful for evaluating the loss of neuronal integrity. Because IMZ SPECT can be performed in various facilities, IMZ SPECT may become widely adopted for evaluating the loss of neuronal integrity.

Usefulness of coronary calcium scoring to myocardial perfusion SPECT in the diagnosis of coronary artery disease in a predominantly high risk population.

PubMed

Schaap, Jeroen; Kauling, Robert M; Boekholdt, S Matthijs; Post, Martijn C; Van der Heyden, Jan A; de Kroon, Thom L; van Es, H Wouter; Rensing, Benno J W M; Verzijlbergen, J Fred

2013-03-01

Coronary calcium scoring (CCS) adds to the diagnostic performance of myocardial perfusion single-photon emission computed tomography (SPECT) to assess the presence of significant coronary artery disease (CAD). Patients with a high pre-test likelihood are expected to have a high CCS which potentially could enhance the diagnostic performance of myocardial perfusion SPECT in this specific patient group. We evaluated the added value of CCS to SPECT in the diagnosis of significant CAD in patients with an intermediate to high pre-test likelihood. In total, 129 patients (mean age 62.7 ± 9.7 years, 65 % male) with stable anginal complaints and intermediate to high pre-test likelihood of CAD (median 87 %, range 22-95) were prospectively included in this study. All patients received SPECT and CCS imaging preceding invasive coronary angiography (CA). Fractional flow reserve (FFR) measurements were acquired from patients with angiographically estimated 50-95 % obstructive CAD. For SPECT a SSS > 3 was defined significant CAD. For CCS the optimal cut-off value for significant CAD was determined by ROC curve analysis. The reference standard for significant CAD was a FFR of <0.80 acquired by CA. Significant CAD was demonstrated in 64 patients (49.6 %). Optimal CCS cut-off value for significant CAD was >182.5. ROC curve analysis for prediction of the presence of significant CAD for SPECT, CCS and the combination of CCS and SPECT resulted in an area under the curve (AUC) of 0.88 (95 % CI 81-94), 0.75 (95 % CI 66-83 %) and 0.92 (95 % CI 87-97 %) respectively. The difference of the AUC between SPECT and the combination of CCS and SPECT was 0.05 (P = 0.12). The addition of CCS did not significantly improve the diagnostic performance of SPECT in the evaluation of patients with a predominantly high pre-test likelihood of CAD.

Neurobehavioral and neurometabolic (SPECT) correlates of paranormal information: involvement of the right hemisphere and its sensitivity to weak complex magnetic fields.

PubMed

Roll, W G; Persinger, M A; Webster, D L; Tiller, S G; Cook, C M

2002-02-01

Experiments were designed to help elucidate the neurophysiological correlates for the experiences reported by Sean Harribance. For most of his life he has routinely experienced "flashes of images" of objects that were hidden and of accurate personal information concerning people with whom he was not familiar. The specificity of details for target pictures of people was correlated positively with the proportion of occipital alpha activity. Results from a complete neuropsychological assessment, Single Photon Emission Computed Tomography (SPECT), and screening electroencephalography suggested that his experiences were associated with increased activity within the parietal lobe and occipital regions of the right hemisphere. Sensed presences (subjectively localized to his left side) were evoked when weak, magnetic fields, whose temporal structure simulated long-term potentiation in the hippocampus, were applied over his right temporoparietal lobes. These results suggest that the phenomena attributed to paranormal or "extrasensory" processes are correlated quantitatively with morphological and functional anomalies involving the right parietotemporal cortices (or its thalamic inputs) and the hippocampal formation.

Vasodilator Stress Single-Photon Emission Computed Tomography or Contrast Stress Echocardiography Association with Hard Cardiac Events in Suspected Coronary Artery Disease.

PubMed

Gaibazzi, Nicola; Siniscalchi, Carmine; Porter, Thomas R; Crocamo, Antonio; Basaglia, Manuela; Boffetti, Francesca; Lorenzoni, Valentina

2018-06-01

We compared the long-term outcome of subjects without prior cardiac disease who underwent either vasodilator single-photon emission computed tomography (SPECT) or contrast stress-echocardiography (cSE) for suspected coronary artery disease (CAD). Subjects who underwent vasodilator SPECT or cSE between 2008 and 2012 for suspected CAD but no history of cardiac disease were included. We retrospectively compared the association of each method with combined all-cause death and nonfatal myocardial infarction and their positive predictive value (PPV) for angiographically obstructive CAD. A total of 1,387 subjects were selected: 497 who underwent SPECT and 890 who underwent cSE. During 4 years of mean follow-up there were 78 hard events in the cSE group and 51 in the SPECT group. Event-free survival in subjects testing positive for ischemia, either with SPECT or cSE, was significantly worse both in the overall population and after propensity matching patients. In multivariable analyses, vasodilator SPECT or cSE demonstrated significant stratification capability with an ischemic test doubling (SPECT) or more than doubling (cSE) the risk of future hard events independently from other variables. PPV of vasodilator SPECT for the diagnosis of obstructive CAD was inferior to vasodilator cSE (PPV = 63% vs 89%, respectively; P < .001). Our study suggests that the associations of vasodilator SPECT or cSE with outcome are comparable, with cSE demonstrating better diagnostic PPV for CAD. The absence of ionizing radiation and anticipated lower costs from higher PPV suggest that vasodilator cSE is a valid alternative to vasodilator SPECT as a gatekeeper in subjects without a prior history of CAD. Copyright © 2018 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Myocardial scintigraphy using a fatty acid analogue detects coronary artery disease in hemodialysis patients.

PubMed

Nishimura, Masato; Hashimoto, Tetsuya; Kobayashi, Hiroyuki; Fukuda, Toyofumi; Okino, Koji; Yamamoto, Noriyuki; Fujita, Hiroshi; Inoue Tsunehiko Nishimura, Naoto; Ono, Toshihiko

2004-08-01

Coronary artery disease contributes significantly to mortality in end-stage renal disease (ESRD) patients. Single-photon emission computed tomography (SPECT) using an iodinated fatty acid analogue, iodine-123-methyl iodophenylpentadecanoic acid (123I-BMIPP), can assess fatty acid metabolism in the myocardium. We investigated the ability of 123I-BMIPP SPECT to detect coronary artery disease in hemodialysis patients compared with 201thallium chloride (201Tl) SPECT. We prospectively studied 130 ESRD patients undergoing hemodialysis for a mean of 88.6 months (male/female, 77/53; mean age, 63.8 years). Dual SPECT using 123I-BMIPP and 201Tl was performed, followed by coronary angiography. SPECT findings were graded in 17 segments on a five-point scale (0, normal uptake; 4, none) and assessed as a summed score. By coronary angiography, 71.5% of patients (93/130) had significant coronary stenosis (> or =75%), and five patients showed coronary spasm without coronary stenosis. When a BMIPP summed score of 6 or more was defined as abnormal, sensitivity, specificity, and accuracy for detecting coronary artery disease by BMIPP SPECT were 98.0%, 65.6%, and 90.0%, respectively; in contrast, these parameters for detecting coronary artery disease by Tl SPECT were 84.7%, 46.9%, and 75.0%, respectively, when a Tl summed score of 1 or more was defined as abnormal. In receiver operating characteristic analysis, the area under the curve was 0.895 in BMIPP and 0.727 in Tl SPECT, respectively. Resting BMIPP SPECT is superior to Tl SPECT for detecting coronary lesions, and provides safe screening for coronary artery disease among maintenance hemodialysis patients.

Irradiation induced modest changes in murine cardiac function despite progressive structural damage to the myocardium and microvasculature.

PubMed

Seemann, Ingar; Gabriels, Karen; Visser, Nils L; Hoving, Saske; te Poele, Johannes A; Pol, Jeffrey F; Gijbels, Marion J; Janssen, Ben J; van Leeuwen, Fijs W; Daemen, Mat J; Heeneman, Sylvia; Stewart, Fiona A

2012-05-01

Radiotherapy of thoracic and chest wall tumors increases the long-term risk of cardiotoxicity, but the underlying mechanisms are unclear. Single doses of 2, 8, or 16 Gy were delivered to the hearts of mice and damage was evaluated at 20, 40, and 60 weeks, relative to age matched controls. Single photon emission computed tomography (SPECT/CT) and ultrasound were used to measure cardiac geometry and function, which was related to histo-morphology and microvascular damage. Gated SPECT/CT and ultrasound demonstrated decreases in end diastolic and systolic volumes, while the ejection fraction was increased at 20 and 40 weeks after 2, 8, and 16 Gy. Cardiac blood volume was decreased at 20 and 60 weeks after irradiation. Histological examination revealed inflammatory changes at 20 and 40 weeks after 8 and 16 Gy. Microvascular density in the left ventricle was decreased at 40 and 60 weeks after 8 and 16 Gy, with functional damage to remaining microvasculature manifest as decreased alkaline phosphatase (2, 8, and 16 Gy), increased von Willebrand Factor and albumin leakage from vessels (8 and 16 Gy), and amyloidosis (16 Gy). 16 Gy lead to sudden death between 30 and 40 weeks in 38% of mice. Irradiation with 2 and 8 Gy induced modest changes in murine cardiac function within 20 weeks but this did not deteriorate further, despite progressive structural and microvascular damage. This indicates that heart function can compensate for significant structural damage, although higher doses, eventually lead to sudden death. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging.

PubMed

Iskandrian, A S; Powers, J; Cave, V; Wasserleben, V; Cassell, D; Heo, J

1995-01-01

This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease. Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075). 123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

123I-BMIPP fatty acid analogue imaging is a novel diagnostic and prognostic approach following acute myocardial infarction.

PubMed

Biswas, S K; Sarai, M; Hishida, H; Ozaki, Y

2009-10-01

Fatty acid oxidation is the most efficient mode of myocardial energy production which requires a large amount of oxygen. Thus, alteration of fatty acid oxidation is considered to be a sensitive marker of ischaemia and myocardial damage. (123)I-BMIPP ([123]I-beta-methyl-p-iodophenylpentadecanoic acid) is a newly-investigated single-photon branching free fatty acid radiopharmaceutical with slow metabolism; thus, it is well-suited for single-photon emission computed tomography (SPECT). Assessment of fatty acid metabolism by radionuclide techniques has a potential role for the early detection of myocardial ischaemia and the assessment of the severity of ischaemic heart disease. Although stable patients with a healed myocardial infarction may have a relatively good prognosis, risk stratification in the predischarge period should be valuable for deciding upon appropriate management. In this respect, the presence of discordant BMIPP uptake relative to (201)Tl perfusion appears to be the best predictor of future cardiac events among all other cardiovascular imaging modalities. Since discordant BMIPP uptake correlates well with redistribution on stress (201)Tl imaging and perfusion-metabolism mismatch on positron emission tomography, it is considered that such BMIPP and (201)Tl discordance may identify a high-risk subgroup among patients with acute myocardial infarction. A BMIPP scan may reflect prior severe ischaemia after recovery of perfusion, the so-called "ischaemic memory". Gated BMIPP SPECT has been recently introduced for simultaneous assessment of myocardial metabolism and ventricular function. Such a new technique seems to be valuable for a better understanding of the pathophysiological state of heart failure and cardiomyopathy.

SPECT (Single-Photon Emission Computerized Tomography) Scan

MedlinePlus

... can become damaged or even die. Reduced pumping efficiency. SPECT can show how completely your heart chambers ... radioactive tracer SPECT scans aren't safe for women who are pregnant or breast-feeding because the ...

Molecular SPECT Imaging: An Overview

PubMed Central

Khalil, Magdy M.; Tremoleda, Jordi L.; Bayomy, Tamer B.; Gsell, Willy

2011-01-01

Molecular imaging has witnessed a tremendous change over the last decade. Growing interest and emphasis are placed on this specialized technology represented by developing new scanners, pharmaceutical drugs, diagnostic agents, new therapeutic regimens, and ultimately, significant improvement of patient health care. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) have their signature on paving the way to molecular diagnostics and personalized medicine. The former will be the topic of the current paper where the authors address the current position of the molecular SPECT imaging among other imaging techniques, describing strengths and weaknesses, differences between SPECT and PET, and focusing on different SPECT designs and detection systems. Radiopharmaceutical compounds of clinical as well-preclinical interest have also been reviewed. Moreover, the last section covers several application, of μSPECT imaging in many areas of disease detection and diagnosis. PMID:21603240

Cell adhesion monitoring of human induced pluripotent stem cell based on intrinsic molecular charges

NASA Astrophysics Data System (ADS)

Sugimoto, Haruyo; Sakata, Toshiya

2014-01-01

We have shown a simple way for real-time, quantitative, non-invasive, and non-label monitoring of human induced pluripotent stem (iPS) cell adhesion by use of a biologically coupled-gate field effect transistor (bio-FET), which is based on detection of molecular charges at cell membrane. The electrical behavior revealed quantitatively the electrical contacts of integrin-receptor at the cell membrane with RGDS peptide immobilized at the gate sensing surface, because that binding site was based on cationic α chain of integrin. The platform based on the bio-FET would provide substantial information to evaluate cell/material bio-interface and elucidate biding mechanism of adhesion molecules, which could not be interpreted by microscopic observation.

Navigation of a robot-integrated fluorescence laparoscope in preoperative SPECT/CT and intraoperative freehand SPECT imaging data: a phantom study

NASA Astrophysics Data System (ADS)

van Oosterom, Matthias Nathanaël; Engelen, Myrthe Adriana; van den Berg, Nynke Sjoerdtje; KleinJan, Gijs Hendrik; van der Poel, Henk Gerrit; Wendler, Thomas; van de Velde, Cornelis Jan Hadde; Navab, Nassir; van Leeuwen, Fijs Willem Bernhard

2016-08-01

Robot-assisted laparoscopic surgery is becoming an established technique for prostatectomy and is increasingly being explored for other types of cancer. Linking intraoperative imaging techniques, such as fluorescence guidance, with the three-dimensional insights provided by preoperative imaging remains a challenge. Navigation technologies may provide a solution, especially when directly linked to both the robotic setup and the fluorescence laparoscope. We evaluated the feasibility of such a setup. Preoperative single-photon emission computed tomography/X-ray computed tomography (SPECT/CT) or intraoperative freehand SPECT (fhSPECT) scans were used to navigate an optically tracked robot-integrated fluorescence laparoscope via an augmented reality overlay in the laparoscopic video feed. The navigation accuracy was evaluated in soft tissue phantoms, followed by studies in a human-like torso phantom. Navigation accuracies found for SPECT/CT-based navigation were 2.25 mm (coronal) and 2.08 mm (sagittal). For fhSPECT-based navigation, these were 1.92 mm (coronal) and 2.83 mm (sagittal). All errors remained below the <1-cm detection limit for fluorescence imaging, allowing refinement of the navigation process using fluorescence findings. The phantom experiments performed suggest that SPECT-based navigation of the robot-integrated fluorescence laparoscope is feasible and may aid fluorescence-guided surgery procedures.

Brain single photon emission computed tomography in neonates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denays, R.; Van Pachterbeke, T.; Tondeur, M.

1989-08-01

This study was designed to rate the clinical value of ({sup 123}I)iodoamphetamine (IMP) or ({sup 99m}Tc) hexamethyl propylene amine oxyme (HM-PAO) brain single photon emission computed tomography (SPECT) in neonates, especially in those likely to develop cerebral palsy. The results showed that SPECT abnormalities were congruent in most cases with structural lesions demonstrated by ultrasonography. However, mild bilateral ventricular dilatation and bilateral subependymal porencephalic cysts diagnosed by ultrasound were not associated with an abnormal SPECT finding. In contrast, some cortical periventricular and sylvian lesions and all the parasagittal lesions well visualized in SPECT studies were not diagnosed by ultrasound scans.more » In neonates with subependymal and/or intraventricular hemorrhage the existence of a parenchymal abnormality was only diagnosed by SPECT. These results indicate that ({sup 123}I)IMP or ({sup 99m}Tc)HM-PAO brain SPECT shows a potential clinical value as the neurodevelopmental outcome is clearly related to the site, the extent, and the number of cerebral lesions. Long-term clinical follow-up is, however, mandatory in order to define which SPECT abnormality is associated with neurologic deficit.« less

Characteristics of Bremsstrahlung emissions of (177)Lu, (188)Re, and (90)Y for SPECT/CT quantification in radionuclide therapy.

PubMed

Uribe, Carlos F; Esquinas, Pedro L; Gonzalez, Marjorie; Celler, Anna

2016-05-01

Beta particles emitted by radioisotopes used in targeted radionuclide therapies (TRT) create Bremsstrahlung (BRS) which may affect SPECT quantification when imaging these isotopes. The purpose of the current study was to investigate the characteristics of Bremsstrahlung produced in tissue by three β-emitting radioisotopes used in TRT. Monte Carlo simulations of (177)Lu, (188)Re, and (90)Y sources placed in water filled cylinders were performed. BRS yields, mean energies and energy spectra for (a) all photons generated in the decays, (b) photons that were not absorbed and leave the cylinder, and (c) photons detected by the camera were analyzed. Next, the results of simulations were compared with those from experiments performed on a clinical SPECT camera using same acquisition conditions and phantom configurations as in simulations. Simulations reproduced relatively well the shapes of the measured spectra, except for (90)Y which showed an overestimation in the low energy range. Detailed analysis of the results allowed us to suggest best collimators and imaging conditions for each of the investigated isotopes. Finally, our simulations confirmed that the BRS contribution to the energy spectra in quantitative imaging of (177)Lu and (188)Re could be ignored. For (177)Lu and (188)Re, BRS contributes only marginally to the total spectra recorded by the camera. Our analysis shows that MELP and HE collimators are the best for imaging these two isotopes. For (90)Y, HE collimator should be used. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Optimizing Parkinson's disease diagnosis: the role of a dual nuclear imaging algorithm.

PubMed

Langston, J William; Wiley, Jesse C; Tagliati, Michele

2018-01-01

The diagnosis of Parkinson's disease (PD) currently relies almost exclusively on the clinical judgment of an experienced neurologist, ideally a specialist in movement disorders. However, such clinical diagnosis is often incorrect in a large percentage of patients, particularly in the early stages of the disease. A commercially available, objective and quantitative marker of nigrostriatal neurodegeneration was recently provided by 123-iodine 123 I-ioflupane SPECT imaging, which is however unable to differentiate PD from a variety of other parkinsonian syndromes associated with striatal dopamine deficiency. There is evidence to support an algorithm utilizing a dual neuroimaging strategy combining 123 I-ioflupane SPECT and the noradrenergic receptor ligand 123 I-metaiodobenzylguanidine (MIBG), which assesses the post-ganglion peripheral autonomic nervous system. Evolving concepts regarding the synucleinopathy affecting the central and peripheral autonomic nervous systems as part of a multisystem disease are reviewed to sustain such strategy. Data are presented to show how MIBG deficits are a common feature of multisystem Lewy body disease and can be used as a unique feature to distinguish PD from atypical parkinsonisms. We propose that the combination of cardiac (MIBG) and cerebral 123 I-ioflupane SPECT could satisfy one of the most significant unmet needs of current PD diagnosis and management, namely the early and accurate diagnosis of patients with typical Lewy body PD. Exemplary case scenarios will be described, highlighting how dual neuroimaging strategy can maximize diagnostic accuracy for patient care, clinical trials, pre-symptomatic PD screening, and special cases provided by specific genetic mutations associated with PD.

Clinical Usefulness of SPECT-CT in Patients with an Unexplained Pain in Metal on Metal (MOM) Total Hip Arthroplasty.

PubMed

Berber, Reshid; Henckel, Johann; Khoo, Michael; Wan, Simon; Hua, Jia; Skinner, John; Hart, Alister

2015-04-01

SPECT-CT is increasingly used to assess painful knee arthroplasties. The aim of this study was to evaluate the clinical usefulness of SPECT-CT in unexplained painful MOM hip arthroplasty. We compared the diagnosis and management plan for 19 prosthetic MOM hips in 15 subjects with unexplained pain before and after SPECT-CT. SPECT-CT changed the management decision in 13 (68%) subjects, Chi-Square=5.49, P=0.24. In 6 subjects (32%) pain remained unexplained however the result reassured the surgeon to continue with non-operative management. SPECT-CT should be reserved as a specialist test to help identify possible causes of pain where conventional investigations have failed. It can help reassure surgeons making management decisions for patients with unexplained pain following MOM hip arthroplasty. Copyright © 2014 Elsevier Inc. All rights reserved.

Diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT: a clinical follow up study.

PubMed

Menéndez-González, Manuel; Tavares, Francisco; Zeidan, Nahla; Salas-Pacheco, José M; Arias-Carrión, Oscar

2014-01-01

The [(123)I]ioflupane-a dopamine transporter radioligand-SPECT (DaT-SPECT) has proven to be useful in the differential diagnosis of tremor. Here, we investigate the diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT. Therefore, 30 patients with tremor and normal DaT-SPECT were followed up for 2 years. In 18 cases we were able to make a diagnosis. The residual 12 patients underwent a second DaT-SPECT, were then followed for additional 12 months and thereafter the diagnosis was reconsidered again. The final diagnoses included cases of essential tremor, dystonic tremor, multisystem atrophy, vascular parkinsonism, progressive supranuclear palsy, corticobasal degeneration, fragile X-associated tremor ataxia syndrome, psychogenic parkinsonism, iatrogenic parkinsonism and Parkinson's disease. However, for 6 patients the diagnosis remained uncertain. Larger series are needed to better establish the relative frequency of the different conditions behind these cases.

Cell-to-Cell Communication Circuits: Quantitative Analysis of Synthetic Logic Gates

PubMed Central

Hoffman-Sommer, Marta; Supady, Adriana; Klipp, Edda

2012-01-01

One of the goals in the field of synthetic biology is the construction of cellular computation devices that could function in a manner similar to electronic circuits. To this end, attempts are made to create biological systems that function as logic gates. In this work we present a theoretical quantitative analysis of a synthetic cellular logic-gates system, which has been implemented in cells of the yeast Saccharomyces cerevisiae (Regot et al., 2011). It exploits endogenous MAP kinase signaling pathways. The novelty of the system lies in the compartmentalization of the circuit where all basic logic gates are implemented in independent single cells that can then be cultured together to perform complex logic functions. We have constructed kinetic models of the multicellular IDENTITY, NOT, OR, and IMPLIES logic gates, using both deterministic and stochastic frameworks. All necessary model parameters are taken from literature or estimated based on published kinetic data, in such a way that the resulting models correctly capture important dynamic features of the included mitogen-activated protein kinase pathways. We analyze the models in terms of parameter sensitivity and we discuss possible ways of optimizing the system, e.g., by tuning the culture density. We apply a stochastic modeling approach, which simulates the behavior of whole populations of cells and allows us to investigate the noise generated in the system; we find that the gene expression units are the major sources of noise. Finally, the model is used for the design of system modifications: we show how the current system could be transformed to operate on three discrete values. PMID:22934039

Nuclear medicine and imaging research (quantitative studies in radiopharmaceutical science)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, M.; Beck, R.N.

1992-06-01

This report describes three studies aimed at using radiolabeled pharmaceuticals to explore brain function and anatomy. The first section describes the chemical preparation of (F18)fluorinated benzamides (dopamine D-2 receptor tracers), (F18)fluorinated benzazepines (dopamine D-1 receptor tracers), and tissue distribution of (F18)-fluoxetine (serotonin reuptake site tracer). The second section relates pharmacological and behavioral studies of amphetamines. The third section reports on progress made with processing of brain images from CT, MRI and PET/SPECT with regards to brain metabolism of glucose during mental tasks.

Comparison of 18F SPECT with PET in myocardial imaging: a realistic thorax-cardiac phantom study.

PubMed

Knešaurek, Karin; Machac, Josef

2006-10-31

Positron emission tomography (PET) imaging with fluorine-18 (18F) Fluorodeoxyglucose (FDG) and flow tracer such as Rubidium-82 (82Rb) is an established method for evaluating an ischemic but viable myocardium. However, the high cost of PET imaging restricts its wider clinical use. Therefore, less expensive 18F FDG single photon emission computed tomography (SPECT) imaging has been considered as an alternative to 18F FDG PET imaging. The purpose of the work is to compare SPECT with PET in myocardial perfusion/viability imaging. A nonuniform RH-2 thorax-heart phantom was used in the SPECT and PET acquisitions. Three inserts, 3 cm, 2 cm and 1 cm in diameter, were placed in the left ventricular (LV) wall to simulate infarcts. The phantom acquisition was performed sequentially with 7.4 MBq of 18F and 22.2 MBq of Technetium-99m (99mTc) in the SPECT study and with 7.4 MBq of 18F and 370 MBq of 82Rb in the PET study. SPECT and PET data were processed using standard reconstruction software provided by vendors. Circumferential profiles of the short-axis slices, the contrast and viability of the inserts were used to evaluate the SPECT and PET images. The contrast for 3 cm, 2 cm and 1 cm inserts were for 18F PET data, 1.0 +/- 0.01, 0.67 +/- 0.02 and 0.25 +/- 0.01, respectively. For 82Rb PET data, the corresponding contrast values were 0.61 +/- 0.02, 0.37 +/- 0.02 and 0.19 +/- 0.01, respectively. For 18F SPECT the contrast values were, 0.31 +/- 0.03 and 0.20 +/- 0.05 for 3 cm and 2 cm inserts, respectively. For 99mTc SPECT the contrast values were, 0.63 +/- 0.04 and 0.24 +/- 0.05 for 3 cm and 2 cm inserts respectively. In SPECT, the 1 cm insert was not detectable. In the SPECT study, all three inserts were falsely diagnosed as "viable", while in the PET study, only the 1 cm insert was diagnosed falsely "viable". For smaller defects the 99mTc/18F SPECT imaging cannot entirely replace the more expensive 82Rb/18F PET for myocardial perfusion/viability imaging, due to poorer image spatial resolution and poorer defect contrast.

Gender differences in the diagnostic accuracy of SPECT myocardial perfusion imaging: a bivariate meta-analysis.

PubMed

Iskandar, Aline; Limone, Brendan; Parker, Matthew W; Perugini, Andrew; Kim, Hyejin; Jones, Charles; Calamari, Brian; Coleman, Craig I; Heller, Gary V

2013-02-01

It remains controversial whether the diagnostic accuracy of single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) is different in men as compared to women. We performed a meta-analysis to investigate gender differences of SPECT MPI for the diagnosis of CAD (≥50% stenosis). Two investigators independently performed a systematic review of the MEDLINE and EMBASE databases from inception through January 2012 for English-language studies determining the diagnostic accuracy of SPECT MPI. We included prospective studies that compared SPECT MPI with conventional coronary angiography which provided sufficient data to calculate gender-specific true and false positives and negatives. Data from studies evaluating <20 patients of one gender were excluded. Bivariate meta-analysis was used to create summary receiver operating curves. Twenty-six studies met inclusion criteria, representing 1,148 women and 1,142 men. Bivariate meta-analysis yielded a mean sensitivity and specificity of 84.2% (95% confidence interval [CI] 78.7%-88.6%) and 78.7% (CI 70.0%-85.3%) for SPECT MPI in women and 89.1% (CI 84.0%-92.7%) and 71.2% (CI 60.8%-79.8%) for SPECT MPI in men. There was no significant difference in the sensitivity (P = .15) or specificity (P = .23) between male and female subjects. In a bivariate meta-analysis of the available literature, the diagnostic accuracy of SPECT MPI is similar for both men and women.

Performance evaluation of D-SPECT: a novel SPECT system for nuclear cardiology

NASA Astrophysics Data System (ADS)

Erlandsson, Kjell; Kacperski, Krzysztof; van Gramberg, Dean; Hutton, Brian F.

2009-05-01

D-SPECT (Spectrum Dynamics, Israel) is a novel SPECT system for cardiac perfusion studies. Based on CZT detectors, region-centric scanning, high-sensitivity collimators and resolution recovery, it offers potential advantages over conventional systems. A series of measurements were made on a β-version D-SPECT system in order to evaluate its performance in terms of energy resolution, scatter fraction, sensitivity, count rate capability and resolution. Corresponding measurements were also done on a conventional SPECT system (CS) for comparison. The energy resolution of the D-SPECT system at 140 keV was 5.5% (CS: 9.25%), the scatter fraction 30% (CS: 34%), the planar sensitivity 398 s-1 MBq-1 per head (99mTc, 10 cm) (CS: 72 s-1 MBq-1), and the tomographic sensitivity in the heart region was in the range 647-1107 s-1 MBq-1 (CS: 141 s-1 MBq-1). The count rate increased linearly with increasing activity up to 1.44 M s-1. The intrinsic resolution was equal to the pixel size, 2.46 mm (CS: 3.8 mm). The average reconstructed resolution using the standard clinical filter was 12.5 mm (CS: 13.7 mm). The D-SPECT has superior sensitivity to that of a conventional system with similar spatial resolution. It also has excellent energy resolution and count rate characteristics, which should prove useful in dynamic and dual radionuclide studies.

Automatic and remote controlled ictal SPECT injection for seizure focus localization by use of a commercial contrast agent application pump.

PubMed

Feichtinger, Michael; Eder, Hans; Holl, Alexander; Körner, Eva; Zmugg, Gerda; Aigner, Reingard; Fazekas, Franz; Ott, Erwin

2007-07-01

In the presurgical evaluation of patients with partial epilepsy, the ictal single photon emission computed tomography (SPECT) is a useful noninvasive diagnostic tool for seizure focus localization. To achieve optimal SPECT scan quality, ictal tracer injection should be carried out as quickly as possible after the seizure onset and under highest safety conditions possible. Compared to the commonly used manual injection, an automatic administration of the radioactive tracer may provide higher quality standards for this procedure. In this study, therefore, we retrospectively analyzed efficiency and safety of an automatic injection system for ictal SPECT tracer application. Over a 31-month period, 26 patients underwent ictal SPECT by use of an automatic remote-controlled injection pump originally designed for CT-contrast agent application. Various factors were reviewed, including latency of ictal injection, radiation safety parameters, and ictal seizure onset localizing value. Times between seizure onset and tracer injection ranged between 3 and 48 s. In 21 of 26 patients ictal SPECT supported the localization of the epileptogenic focus in the course of the presurgical evaluation. In all cases ictal SPECT tracer injection was performed with a high degree of safety to patients and staff. Ictal SPECT by use of a remote-controlled CT-contrast agent injection system provides a high scan quality and is a safe and confirmatory presurgical evaluation technique in the epilepsy-monitoring unit.

The promise of subtraction ictal SPECT co-registered to MRI for improved seizure localization in pediatric epilepsies: Affecting factors and relationship to the surgical outcome

PubMed Central

Stamoulis, Catherine; Verma, Nishant; Kaulas, Himanshu; Halford, Jonathan J.; Duffy, Frank H.; Pearl, Phillip L.; Treves, S. Ted

2016-01-01

Objective Ictal SPECT is promising for accurate non-invasive localization of the epileptogenic brain tissue in focal epilepsies. However, high quality ictal scans require meticulous attention to the seizure onset. In a relatively large cohort of pediatric patients, this study investigated the impact of the timing of radiotracer injection, MRI findings and seizure characteristics on ictal SPECT localizations, and the relationship between concordance of ictal SPECT, scalp EEG and resected area with seizure freedom following epilepsy surgery. Methods Scalp EEG and ictal SPECT studies from 95 patients (48 males and 47 females, median age = 11 years, (25th, 75th) quartiles = (6.0, 14.75) years) with pharmacoresistant focal epilepsy and no prior epilepsy surgery were reviewed. The ictal SPECT result was examined as a function of the radiotracer injection delay, seizure duration, epilepsy etiology, cerebral lobe of seizure onset identified by EEG and MRI findings. Thirty two patients who later underwent epilepsy surgery had postoperative seizure freedom data at <1, 6 and 12 months. Results Sixty patients (63.2%) had positive SPECT localizations - 51 with a hyperperfused region that was concordant with the cerebral lobe of seizure origin identified by EEG and 9 with discordant localizations. Of these, 35 patients (58.3%) had temporal and 25 (41.7%) had extratemporal seizures. The ictal SPECT result was significantly correlated with the injection delay (p<0.01) and cerebral lobe of seizure onset (specifically frontal versus temporal; p = 0.02) but not MRI findings (p = 0.33), epilepsy etiology (p ≥ 0.27) or seizure duration (p = 0.20). Concordance of SPECT, scalp EEG and resected area was significantly correlated with seizure freedom at 6 months after surgery (p=0.04). Significance Ictal SPECT holds promise as a powerful source imaging tool for presurgical planning in pediatric epilepsies. To optimize the SPECT result the radiotracer injection delay should be minimized to ≤ 25 s, although the origin of seizure onset (specifically temporal versus frontal) also significantly impacts the localization. PMID:27918961

The promise of subtraction ictal SPECT co-registered to MRI for improved seizure localization in pediatric epilepsies: Affecting factors and relationship to the surgical outcome.

PubMed

Stamoulis, Catherine; Verma, Nishant; Kaulas, Himanshu; Halford, Jonathan J; Duffy, Frank H; Pearl, Phillip L; Treves, S Ted

2017-01-01

Ictal SPECT is promising for accurate non-invasive localization of the epileptogenic brain tissue in focal epilepsies. However, high quality ictal scans require meticulous attention to the seizure onset. In a relatively large cohort of pediatric patients, this study investigated the impact of the timing of radiotracer injection, MRI findings and seizure characteristics on ictal SPECT localizations, and the relationship between concordance of ictal SPECT, scalp EEG and resected area with seizure freedom following epilepsy surgery. Scalp EEG and ictal SPECT studies from 95 patients (48 males and 47 females, median age=11years, (25th, 75th) quartiles=(6.0, 14.75) years) with pharmacoresistant focal epilepsy and no prior epilepsy surgery were reviewed. The ictal SPECT result was examined as a function of the radiotracer injection delay, seizure duration, epilepsy etiology, cerebral lobe of seizure onset identified by EEG and MRI findings. Thirty two patients who later underwent epilepsy surgery had postoperative seizure freedom data at <1, 6 and 12 months. Sixty patients (63.2%) had positive SPECT localizations - 51 with a hyperperfused region that was concordant with the cerebral lobe of seizure origin identified by EEG and 9 with discordant localizations. Of these, 35 patients (58.3%) had temporal and 25 (41.7%) had extratemporal seizures. The ictal SPECT result was significantly correlated with the injection delay (p<0.01) and cerebral lobe of seizure onset (specifically frontal versus temporal; p=0.02) but not MRI findings (p=0.33), epilepsy etiology (p≥0.27) or seizure duration (p=0.20). Concordance of SPECT, scalp EEG and resected area was significantly correlated with seizure freedom at 6 months after surgery (p=0.04). Ictal SPECT holds promise as a powerful source imaging tool for presurgical planning in pediatric epilepsies. To optimize the SPECT result the radiotracer injection delay should be minimized to≤25s, although the origin of seizure onset (specifically temporal versus frontal) also significantly impacts the localization. Copyright © 2016 Elsevier B.V. All rights reserved.

Five months' follow-up of patients with and without iodine-positive lymph node metastases of thyroid carcinoma as disclosed by (131)I-SPECT/CT at the first radioablation.

PubMed

Schmidt, Daniela; Linke, Rainer; Uder, Michael; Kuwert, Torsten

2010-04-01

In differentiated thyroid carcinoma (DTC), (131)I-SPECT/CT is more accurate in identifying radioiodine-positive lymph node metastases (LNM) than planar whole-body scans (WBS). The purpose of this study was to investigate the value of (131)I-SPECT/CT performed at the first radioablation to predict the occurrence and/or persistence of cervical radioiodine-positive LNM 5 months later. The study included 81 DTC patients that had had SPECT/ spiral CT after radioablation of thyroid remnants after thyroidectomy. The patients were re-examined 5 months later using (131)I-WBS performed at TSH stimulation. In addition, SPECT/CT of the neck was performed in patients with iodine-positive cervical foci to distinguish between thyroid remnant and LNM. The outcome variable of the study was the detection or exclusion of iodine-positive cervical LNM. Of 61 patients without a SPECT/CT diagnosis of (131)I-positive LNM at radioablation, 60 had no (131)I-positive LNM at follow-up. In the remaining patient of this group, a new radioiodine-positive LNM was detected. In 17 of 20 patients with a SPECT/CT diagnosis of (131)I-positive LNM (n = 19) or an indeterminate lesion (n = 1) at first radioablation, no (131)I-positive LNM were detected 5 months later. Radioiodine-positive LNM persisted in three patients of this group. (131)I-SPECT/CT has a high negative predictive value with regard to the occurrence of radioiodine-positive cervical LNM 5 months after initial therapy. The majority of iodine-positive LNM diagnosed by SPECT/CT at radioablation disappear within 5 months. These findings motivate further research into the value of (131)I-SPECT/CT of the neck for predicting recurrence and planning surgical reintervention in DTC.

SPECT data acquisition and image reconstruction in a stationary small animal SPECT/MRI system

NASA Astrophysics Data System (ADS)

Xu, Jingyan; Chen, Si; Yu, Jianhua; Meier, Dirk; Wagenaar, Douglas J.; Patt, Bradley E.; Tsui, Benjamin M. W.

2010-04-01

The goal of the study was to investigate data acquisition strategies and image reconstruction methods for a stationary SPECT insert that can operate inside an MRI scanner with a 12 cm bore diameter for simultaneous SPECT/MRI imaging of small animals. The SPECT insert consists of 3 octagonal rings of 8 MR-compatible CZT detectors per ring surrounding a multi-pinhole (MPH) collimator sleeve. Each pinhole is constructed to project the field-of-view (FOV) to one CZT detector. All 24 pinholes are focused to a cylindrical FOV of 25 mm in diameter and 34 mm in length. The data acquisition strategies we evaluated were optional collimator rotations to improve tomographic sampling; and the image reconstruction methods were iterative ML-EM with and without compensation for the geometric response function (GRF) of the MPH collimator. For this purpose, we developed an analytic simulator that calculates the system matrix with the GRF models of the MPH collimator. The simulator was used to generate projection data of a digital rod phantom with pinhole aperture sizes of 1 mm and 2 mm and with different collimator rotation patterns. Iterative ML-EM reconstruction with and without GRF compensation were used to reconstruct the projection data from the central ring of 8 detectors only, and from all 24 detectors. Our results indicated that without GRF compensation and at the default design of 24 projection views, the reconstructed images had significant artifacts. Accurate GRF compensation substantially improved the reconstructed image resolution and reduced image artifacts. With accurate GRF compensation, useful reconstructed images can be obtained using 24 projection views only. This last finding potentially enables dynamic SPECT (and/or MRI) studies in small animals, one of many possible application areas of the SPECT/MRI system. Further research efforts are warranted including experimentally measuring the system matrix for improved geometrical accuracy, incorporating the co-registered MRI image in SPECT reconstruction, and exploring potential applications of the simultaneous SPECT/MRI SA system including dynamic SPECT studies.

Clinical Utility of SPECT Neuroimaging in the Diagnosis and Treatment of Traumatic Brain Injury: A Systematic Review

PubMed Central

Raji, Cyrus A.; Tarzwell, Robert; Pavel, Dan; Schneider, Howard; Uszler, Michael; Thornton, John; van Lierop, Muriel; Cohen, Phil; Amen, Daniel G.; Henderson, Theodore

2014-01-01

Purpose This systematic review evaluated the clinical utility of single photon emission computed tomography (SPECT) in traumatic brain injury (TBI). Methods After defining a PICO Statement (Population, Intervention, Comparison and Outcome Statement), PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria were applied to identify 1600 articles. After screening, 374 articles were eligible for review. Inclusion for review was focus on SPECT in the setting of mild, moderate, or severe TBI with cerebral lobar specificity of SPECT findings. Other inclusion criteria were comparison modalities in the same subjects and articles in English. Foreign language articles, SPECT studies that did not include comparison modalities, and case reports were not included for review. Results We identified 19 longitudinal and 52 cross-sectional studies meeting inclusion criteria. Three longitudinal studies examined diagnostic predictive value. The first showed positive predictive value increases from initial SPECT scan shortly after trauma to one year follow up scans, from 59% to 95%. Subsequent work replicated these results in a larger cohort. Longitudinal and cross sectional studies demonstrated SPECT lesion localization not detected by CT or MRI. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value. Conclusions This review demonstrates Level IIA evidence (at least one non-randomized controlled trial) for the value of SPECT in TBI. Given its advantages over CT and MRI in the detection of mild TBI in numerous studies of adequate quality, and given its excellent negative predictive value, it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurological or psychiatric symptoms. PMID:24646878

Clinical utility of SPECT neuroimaging in the diagnosis and treatment of traumatic brain injury: a systematic review.

PubMed

Raji, Cyrus A; Tarzwell, Robert; Pavel, Dan; Schneider, Howard; Uszler, Michael; Thornton, John; van Lierop, Muriel; Cohen, Phil; Amen, Daniel G; Henderson, Theodore

2014-01-01

This systematic review evaluated the clinical utility of single photon emission computed tomography (SPECT) in traumatic brain injury (TBI). After defining a PICO Statement (Population, Intervention, Comparison and Outcome Statement), PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria were applied to identify 1600 articles. After screening, 374 articles were eligible for review. Inclusion for review was focus on SPECT in the setting of mild, moderate, or severe TBI with cerebral lobar specificity of SPECT findings. Other inclusion criteria were comparison modalities in the same subjects and articles in English. Foreign language articles, SPECT studies that did not include comparison modalities, and case reports were not included for review. We identified 19 longitudinal and 52 cross-sectional studies meeting inclusion criteria. Three longitudinal studies examined diagnostic predictive value. The first showed positive predictive value increases from initial SPECT scan shortly after trauma to one year follow up scans, from 59% to 95%. Subsequent work replicated these results in a larger cohort. Longitudinal and cross sectional studies demonstrated SPECT lesion localization not detected by CT or MRI. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value. This review demonstrates Level IIA evidence (at least one non-randomized controlled trial) for the value of SPECT in TBI. Given its advantages over CT and MRI in the detection of mild TBI in numerous studies of adequate quality, and given its excellent negative predictive value, it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurological or psychiatric symptoms.

Onboard functional and molecular imaging: A design investigation for robotic multipinhole SPECT

PubMed Central

Bowsher, James; Yan, Susu; Roper, Justin; Giles, William; Yin, Fang-Fang

2014-01-01

Purpose: Onboard imaging—currently performed primarily by x-ray transmission modalities—is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single photon emission computed tomography (SPECT), are premier modalities for molecular imaging. The purpose of this study is to investigate a robotic multipinhole approach to onboard SPECT. Methods: Computer-aided design (CAD) studies were performed to assess the feasibility of maneuvering a robotic SPECT system about a patient in position for radiation therapy. In order to obtain fast, high-quality SPECT images, a 49-pinhole SPECT camera was designed which provides high sensitivity to photons emitted from an imaging region of interest. This multipinhole system was investigated by computer-simulation studies. Seventeen hot spots 10 and 7 mm in diameter were placed in the breast region of a supine female phantom. Hot spot activity concentration was six times that of background. For the 49-pinhole camera and a reference, more conventional, broad field-of-view (FOV) SPECT system, projection data were computer simulated for 4-min scans and SPECT images were reconstructed. Hot-spot localization was evaluated using a nonprewhitening forced-choice numerical observer. Results: The CAD simulation studies found that robots could maneuver SPECT cameras about patients in position for radiation therapy. In the imaging studies, most hot spots were apparent in the 49-pinhole images. Average localization errors for 10-mm- and 7-mm-diameter hot spots were 0.4 and 1.7 mm, respectively, for the 49-pinhole system, and 3.1 and 5.7 mm, respectively, for the reference broad-FOV system. Conclusions: A robot could maneuver a multipinhole SPECT system about a patient in position for radiation therapy. The system could provide onboard functional and molecular imaging with 4-min scan times. PMID:24387490

Onboard functional and molecular imaging: A design investigation for robotic multipinhole SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowsher, James, E-mail: james.bowsher@duke.edu; Giles, William; Yin, Fang-Fang

2014-01-15

Purpose: Onboard imaging—currently performed primarily by x-ray transmission modalities—is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single photon emission computed tomography (SPECT), are premier modalities for molecular imaging. The purpose of this study is to investigate a robotic multipinhole approach to onboard SPECT. Methods: Computer-aided design (CAD) studies were performed to assess the feasibility of maneuvering a robotic SPECT system about a patient in position for radiation therapy. In order to obtain fast, high-quality SPECT images, a 49-pinholemore » SPECT camera was designed which provides high sensitivity to photons emitted from an imaging region of interest. This multipinhole system was investigated by computer-simulation studies. Seventeen hot spots 10 and 7 mm in diameter were placed in the breast region of a supine female phantom. Hot spot activity concentration was six times that of background. For the 49-pinhole camera and a reference, more conventional, broad field-of-view (FOV) SPECT system, projection data were computer simulated for 4-min scans and SPECT images were reconstructed. Hot-spot localization was evaluated using a nonprewhitening forced-choice numerical observer. Results: The CAD simulation studies found that robots could maneuver SPECT cameras about patients in position for radiation therapy. In the imaging studies, most hot spots were apparent in the 49-pinhole images. Average localization errors for 10-mm- and 7-mm-diameter hot spots were 0.4 and 1.7 mm, respectively, for the 49-pinhole system, and 3.1 and 5.7 mm, respectively, for the reference broad-FOV system. Conclusions: A robot could maneuver a multipinhole SPECT system about a patient in position for radiation therapy. The system could provide onboard functional and molecular imaging with 4-min scan times.« less

Identifying the heterogeneity of COPD by V/P SPECT: a new tool for improving the diagnosis of parenchymal defects and grading the severity of small airways disease.

PubMed

Bajc, M; Chen, Y; Wang, J; Li, X Y; Shen, W M; Wang, C Z; Huang, H; Lindqvist, A; He, X Y

2017-01-01

Airway obstruction and possible concomitant pulmonary diseases in COPD cannot be identified conventionally with any single diagnostic tool. We aimed to diagnose and grade COPD severity and identify pulmonary comorbidities associated with COPD with ventilation/perfusion single-photon emission computed tomography (V/P SPECT) using Technegas as the functional ventilation imaging agent. 94 COPD patients (aged 43-86 years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I-IV) were examined with V/P SPECT and spirometry. Ventilation and perfusion defects were analyzed blindly according to the European guidelines. Penetration grade of Technegas in V SPECT measured the degree of obstructive small airways disease. Total preserved lung function and penetration grade of Technegas in V SPECT were assessed by V/P SPECT and compared to GOLD stages and spirometry. Signs of small airway obstruction in the ventilation SPECT images were found in 92 patients. Emphysema was identified in 81 patients. Two patients had no signs of COPD, but both of them had a pulmonary embolism, and in one of them we also suspected a lung tumor. The penetration grade of Technegas in V SPECT and total preserved lung function correlated significantly to GOLD stages ( r =0.63 and -0.60, respectively, P <0.0001). V/P SPECT identified pulmonary embolism in 30 patients (32%). A pattern typical for heart failure was present in 26 patients (28%). Parenchymal changes typical for pneumonia or lung tumor were present in several cases. V/P SPECT, using Technegas as the functional ventilation imaging agent, is a new tool to diagnose COPD and to grade its severity. Additionally, it revealed heterogeneity of COPD caused by pulmonary comorbidities. The characteristics of these comorbidities suggest their significant impact in clarifying symptoms, and also their influence on the prognosis.

Development of an MR-compatible SPECT system (MRSPECT) for simultaneous data acquisition.

PubMed

Hamamura, Mark J; Ha, Seunghoon; Roeck, Werner W; Muftuler, L Tugan; Wagenaar, Douglas J; Meier, Dirk; Patt, Bradley E; Nalcioglu, Orhan

2010-03-21

In medical imaging, single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high spatial resolution anatomical information as well as complementary functional information. In this study, we developed a miniaturized dual-modality SPECT/MRI (MRSPECT) system and demonstrated the feasibility of simultaneous SPECT and MRI data acquisition, with the possibility of whole-body MRSPECT systems through suitable scaling of components. For our MRSPECT system, a cadmium-zinc-telluride (CZT) nuclear radiation detector was interfaced with a specialized radiofrequency (RF) coil and placed within a whole-body 4 T MRI system. Various phantom experiments characterized the interaction between the SPECT and MRI hardware components. The metallic components of the SPECT hardware altered the B(0) field and generated a non-uniform reduction in the signal-to-noise ratio (SNR) of the MR images. The presence of a magnetic field generated a position shift and resolution loss in the nuclear projection data. Various techniques were proposed to compensate for these adverse effects. Overall, our results demonstrate that accurate, simultaneous SPECT and MRI data acquisition is feasible, justifying the further development of MRSPECT for either small-animal imaging or whole-body human systems by using appropriate components.

Development of an MR-compatible SPECT system (MRSPECT) for simultaneous data acquisition

NASA Astrophysics Data System (ADS)

Hamamura, Mark J.; Ha, Seunghoon; Roeck, Werner W.; Tugan Muftuler, L.; Wagenaar, Douglas J.; Meier, Dirk; Patt, Bradley E.; Nalcioglu, Orhan

2010-03-01

In medical imaging, single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high spatial resolution anatomical information as well as complementary functional information. In this study, we developed a miniaturized dual-modality SPECT/MRI (MRSPECT) system and demonstrated the feasibility of simultaneous SPECT and MRI data acquisition, with the possibility of whole-body MRSPECT systems through suitable scaling of components. For our MRSPECT system, a cadmium-zinc-telluride (CZT) nuclear radiation detector was interfaced with a specialized radiofrequency (RF) coil and placed within a whole-body 4 T MRI system. Various phantom experiments characterized the interaction between the SPECT and MRI hardware components. The metallic components of the SPECT hardware altered the B0 field and generated a non-uniform reduction in the signal-to-noise ratio (SNR) of the MR images. The presence of a magnetic field generated a position shift and resolution loss in the nuclear projection data. Various techniques were proposed to compensate for these adverse effects. Overall, our results demonstrate that accurate, simultaneous SPECT and MRI data acquisition is feasible, justifying the further development of MRSPECT for either small-animal imaging or whole-body human systems by using appropriate components.

Forensic applications of cerebral single photon emission computed tomography in mild traumatic brain injury.

PubMed

Wortzel, Hal S; Filley, Christopher M; Anderson, C Alan; Oster, Timothy; Arciniegas, David B

2008-01-01

Traumatic brain injury (TBI) is a substantial source of mortality and morbidity world wide. Although most such injuries are relatively mild, accurate diagnosis and prognostication after mild TBI are challenging. These problems are complicated further when considered in medicolegal contexts, particularly civil litigation. Cerebral single photon emission computed tomography (SPECT) may contribute to the evaluation and treatment of persons with mild TBI. Cerebral SPECT is relatively sensitive to the metabolic changes produced by TBI. However, such changes are not specific to this condition, and their presence on cerebral SPECT imaging does not confirm a diagnosis of mild TBI. Conversely, the absence of abnormalities on cerebral SPECT imaging does not exclude a diagnosis of mild TBI, although such findings may be of prognostic value. The literature does not demonstrate consistent relationships between SPECT images and neuropsychological testing or neuropsychiatric symptoms. Using the rules of evidence shaped by Daubert v. Merrell Dow Pharmaceuticals, Inc., and its progeny to analyze the suitability of SPECT for forensic purposes, we suggest that expert testimony regarding SPECT findings should be admissible only as evidence to support clinical history, neuropsychological test results, and structural brain imaging findings and not as stand-alone diagnostic data.

Wireless Synchronization of a Multi-Pinhole Small Animal SPECT Collimation Device With a Clinical Scanner

NASA Astrophysics Data System (ADS)

DiFilippo, Frank P.; Patel, Sagar

2009-06-01

A multi-pinhole collimation device for small animal single photon emission computed tomography (SPECT) uses the gamma camera detectors of a standard clinical SPECT scanner. The collimator and animal bed move independently of the detectors, and therefore their motions must be synchronized. One approach is manual triggering of the SPECT acquisition simultaneously with a programmed motion sequence for the device. However, some data blurring and loss of image quality result, and true electronic synchronization is preferred. An off-the-shelf digital gyroscope with integrated Bluetooth interface provides a wireless solution to device synchronization. The sensor attaches to the SPECT gantry and reports its rotational speed to a notebook computer controlling the device. Software processes the rotation data in real-time, averaging the signal and issuing triggers while compensating for baseline drift. Motion commands are sent to the collimation device with minimal delay, within approximately 0.5 second of the start of SPECT gantry rotation. Test scans of a point source demonstrate an increase in true counts and a reduction in background counts compared to manual synchronization. The wireless rotation sensor provides robust synchronization of the collimation device with the clinical SPECT scanner and enhances image quality.

Effect of attenuation correction on image quality in emission tomography

NASA Astrophysics Data System (ADS)

Denisova, N. V.; Ondar, M. M.

2017-10-01

In this paper, mathematical modeling and computer simulations of myocardial perfusion SPECT imaging are performed. The main factors affecting the quality of reconstructed images in SPECT are anatomical structures, the diastolic volume of a myocardium and attenuation of gamma rays. The purpose of the present work is to study the effect of attenuation correction on image quality in emission tomography. The basic 2D model describing a Tc-99m distribution in a transaxial slice of the thoracic part of a patient body was designed. This model was used to construct four phantoms simulated various anatomical shapes: 2 male and 2 female patients with normal, obese and subtle physique were included in the study. Data acquisition model which includes the effect of non-uniform attenuation, collimator-detector response and Poisson statistics was developed. The projection data were calculated for 60 views in accordance with the standard myocardial perfusion SPECT imaging protocol. Reconstructions of images were performed using the OSEM algorithm which is widely used in modern SPECT systems. Two types of patient's examination procedures were simulated: SPECT without attenuation correction and SPECT/CT with attenuation correction. The obtained results indicate a significant effect of the attenuation correction on the SPECT images quality.

Brain SPECT Imaging in Complex Psychiatric Cases: An Evidence-Based, Underutilized Tool

PubMed Central

Amen, Daniel G; Trujillo, Manuel; Newberg, Andrew; Willeumier, Kristen; Tarzwell, Robert; Wu, Joseph C; Chaitin, Barry

2011-01-01

Over the past 20 years brain Single Photon Emission Computed Tomography (SPECT) imaging has developed a substantial, evidence-based foundation and is now recommended by professional societies for numerous indications relevant to psychiatric practice. Unfortunately, SPECT in clinical practice is utilized by only a handful of clinicians. This article presents a rationale for a more widespread use of SPECT in clinical practice for complex cases, and includes seven clinical applications where it may help optimize patient care. PMID:21863144

Comparison of SPECT/CT and Planar Lympho-scintigraphy in Sentinel Node Biopsies of Oral Cavity Squamous Cell Carcinomas.

PubMed

Chandra, Piyush; Dhake, Sanket; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu; Rangarajan, Venkatesh

2017-01-01

Evidence supporting the use of Sentinel node biopsy (SNB) for nodal staging of early oral squamous cell carcinomas (OSCC) appears to be very promising. Pre-operative lymphatic mapping using planar lymphoscinitigraphy (PL) with or without SPECT/CT in the SNB procedure is useful in sentinel node localization and for planning appropriate surgery. Recently, a large prospective multi-centric study evaluating SNB in cutaneous melanoma, breast and pelvic malignancies, demonstrated that adding SPECT to PL leads to surgical adjustments in a considerable number of patients. Our aim of this study was to evaluate the incremental value of additional SPECT/CT over PL alone in SNB for OSCC. This was a retrospective analysis of 44 patients (40- tongue, 4- buccal mucosa) with T1-T2, clinically N0 oral cavity SCC who underwent sentinel node biopsy procedure. PL and SPECT lymphoscinitigraphy images were compared for pre-operative mapping of sentinel nodes. Using a handheld gamma probe, a total of 179 sentinel nodes were harvested, with a mean of 4.06 per patient. PL revealed 75 hotspots with a mean of 1.70 per patient, and SPECT/CT revealed 92 hotspots with a mean of 2.09 per patient. Additional hotpots were identified in 14 patients on SPECT/CT, which included 4 patients, where PL did not detect any sentinel nodes. Pre-operative SPECT/CT in addition to planar lympho-scinitigraphy in sentinel node biopsies of oral cavity SCC detects more number of sentinel nodes compared to planar imaging alone. The higher sensitivity of SPECT combined with better anatomical localization using diagnostic CT may further improve the precision of SNB procedure.

Risk Stratification for Avascular Necrosis of the Femoral Head After Internal Fixation of Femoral Neck Fractures by Post-Operative Bone SPECT/CT.

PubMed

Han, Sangwon; Oh, Minyoung; Yoon, Seokho; Kim, Jinsoo; Kim, Ji-Wan; Chang, Jae-Suk; Ryu, Jin-Sook

2017-03-01

Avascular necrosis (AVN) of the femoral head is a major complication after internal fixation of a femoral neck fracture and determines the functional prognosis. We investigated postoperative bone single-photon emission computed tomography/computed tomography (SPECT/CT) for assessing the risk of femoral head AVN. We retrospectively reviewed 53 consecutive patients who underwent bone SPECT/CT within 2 weeks of internal fixation of a femoral neck fracture and follow-up serial hip radiographs over at least 12 months. Nine patients developed femoral head AVN. In 15 patients who showed normal uptake on immediate postoperative SPECT/CT, no AVN occurred, whereas 9 of 38 patients who showed cold defects of the femoral head later developed AVN. The negative predictive value of immediate postoperative SPECT/CT for AVN was 100 %, whereas the positive predictive value was 24 %. Among 38 patients with cold defects, 1 developed AVN 3 months postoperatively. A follow-up bone SPECT/CT was performed in the other 37 patients at 2-10 months postoperatively. The follow-up bone SPECT/CT revealed completely normalized femoral head uptake in 27, partially normalized uptake in 8, and persistent cold defects in 2 patients. AVN developed in 3.7 % (1/27), 62.5 % (5/8), and 100 % (2/2) of each group, respectively. According to the time point of imaging, radiotracer uptake patterns of the femoral head on postoperative bone SPECT/CT indicate the risk of AVN after internal fixation of femoral neck fractures differently. Postoperative bone SPECT/CT may help orthopedic surgeons determine the appropriate follow-up of these patients.

The predictive value of single-photon emission computed tomography/computed tomography for sentinel lymph node localization in head and neck cutaneous malignancy.

PubMed

Remenschneider, Aaron K; Dilger, Amanda E; Wang, Yingbing; Palmer, Edwin L; Scott, James A; Emerick, Kevin S

2015-04-01

Preoperative localization of sentinel lymph nodes in head and neck cutaneous malignancies can be aided by single-photon emission computed tomography/computed tomography (SPECT/CT); however, its true predictive value for identifying lymph nodes intraoperatively remains unquantified. This study aims to understand the sensitivity, specificity, and positive and negative predictive values of SPECT/CT in sentinel lymph node biopsy for cutaneous malignancies of the head and neck. Blinded retrospective imaging review with comparison to intraoperative gamma probe confirmed sentinel lymph nodes. A consecutive series of patients with a head and neck cutaneous malignancy underwent preoperative SPECT/CT followed by sentinel lymph node biopsy with a gamma probe. Two nuclear medicine physicians, blinded to clinical data, independently reviewed each SPECT/CT. Activity within radiographically defined nodal basins was recorded and compared to intraoperative gamma probe findings. Sensitivity, specificity, and negative and positive predictive values were calculated with subgroup stratification by primary tumor site. Ninety-two imaging reads were performed on 47 patients with cutaneous malignancy who underwent SPECT/CT followed by sentinel lymph node biopsy. Overall sensitivity was 73%, specificity 92%, positive predictive value 54%, and negative predictive value 96%. The predictive ability of SPECT/CT to identify the basin or an adjacent basin containing the single hottest node was 92%. SPECT/CT overestimated uptake by an average of one nodal basin. In the head and neck, SPECT/CT has higher reliability for primary lesions of the eyelid, scalp, and cheek. SPECT/CT has high sensitivity, specificity, and negative predictive value, but may overestimate relevant nodal basins in sentinel lymph node biopsy. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Usefulness of Tc-99m MDP spine SPECT imaging in differentiating malignant from benign lesions in cancer patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryu, J.S.; Moon, D.H.; Shin, M.J.

1994-05-01

Solitary or a few spinal abnormalities on planar bone scan pose a dilemma in cancer patients. The purpose of this study was to evaluate the usefulness of spine SPECT imaging in differential diagnosis of malignant and benign lesion. Subjects were 54 adult patients with solitary or a few equivocal vertebral lesions on planar bone scan. Spine SPECT imaging was obtained by a triple head SPECT system (TRIAD, Trionix). The final diagnoses were based on data from biopsy, other imaging studies, or minimum 1 year of follow up. Two blind observers reviewed the planar image first, then both planar and SPECTmore » images. The uptake patterns on SPECT images were analyzed, and the diagnostic performance was evaluated by the ROC analysis. Thirty three lesions of 22 patients were malignant, and 60 lesions of 32 patients were benign. Common characteristic patterns of malignant lesions were focal or segmental hot uptake in the body, hot uptake in the body and pedicle, and cold defect with surrounding hot uptake in the vertebra. Whereas marginal protruding hot uptakes in endplate, and hot uptakes in facet joints were benign. The ROC analysis showed that SPECT improved the diagnostic performance (the area under the ROC curve of two observers for planar image 0.903 and 0.791, for the combination of planar and SPECT : 0.950 and 0.976). In conclusion, the uptake pattern recognition in spine SPECT provides useful information for differential diagnosis of malignant and benign lesions in vertebra. Spine SPECT is a valuable complement in cancer patients with inconclusive findings on planar bone scan.« less

Apparent CBF decrease with normal aging due to partial volume effects: MR-based partial volume correction on CBF SPECT.

PubMed

Inoue, Kentaro; Ito, Hiroshi; Goto, Ryoi; Nakagawa, Manabu; Kinomura, Shigeo; Sato, Tachio; Sato, Kazunori; Fukuda, Hiroshi

2005-06-01

Several studies using single photon emission tomography (SPECT) have shown changes in cerebral blood flow (CBF) with age, which were associated with partial volume effects by some authors. Some studies have also demonstrated gender-related differences in CBF. The present study aimed to examine age and gender effects on CBF SPECT images obtained using the 99mTc-ethyl cysteinate dimer and a SPECT scanner, before and after partial volume correction (PVC) using magnetic resonance (MR) imaging. Forty-four healthy subjects (29 males and 15 females; age range, 27-64 y; mean age, 50.0 +/- 9.8 y) participated. Each MR image was segmented to yield grey and white matter images and coregistered to a corresponding SPECT image, followed by convolution to approximate the SPECT spatial resolution. PVC-SPECT images were produced using the convoluted grey matter MR (GM-MR) and white matter MR images. The age and gender effects were assessed using SPM99. Decreases with age were detected in the anterolateral prefrontal cortex and in areas along the lateral sulcus and the lateral ventricle, bilaterally, in the GM-MR images and the SPECT images. In the PVC-SPECT images, decreases in CBF in the lateral prefrontal cortex lost their statistical significance. Decreases in CBF with age found along the lateral sulcus and the lateral ventricle, on the other hand, remained statistically significant, but observation of the spatially normalized MR images suggests that these findings are associated with the dilatation of the lateral sulcus and lateral ventricle, which was not completely compensated for by the spatial normalization procedure. Our present study demonstrated that age effects on CBF in healthy subjects could reflect morphological differences with age in grey matter.

Pre-operative prediction of cervical nodal metastasis in papillary thyroid cancer by 99mTc-MIBI SPECT/CT; a pilot study.

PubMed

Tangjaturonrasme, Napadon; Vasavid, Pataramon; Sombuntham, Premsuda; Keelawat, Somboon

2013-06-01

Papillary thyroid cancer has a high prevalence of cervical nodal metastasis. There is no "gold standard" imaging for pre-operative diagnosis. The aim of the present study was to assess the accuracy of pre-operative 99mTc-MBI SPECT/CT in diagnosis of cervical nodal metastasis in patients with papillary thyroid cancer Fifteen patients were performed 99Tc-MlBI SPECT/CT pre-operatively. Either positive pathological report of neck dissection or positive post-treatment I-131 whole body scan with SPECT/CT of neck was concluded for definite neck metastasis. The PPV, NPV, and accuracy of 99mTc-MIBI SPECT/CT were analyzed. The PPV NPV and accuracy were 80%, 88.89%, and 85.71%, respectively. 99mTc-MIBI SPECT/CT could localize the abnormal lymph nodes groups correctly in most cases when compared with pathological results. However the authors found one false positive case with caseating granulomatous lymphadenitis and one false negative case with positive post-treatment 1-131 whole body scan with SPECT/CT of neck on cervical nodes zone II and IV CONCLUSION: 99mTc-MIBI SPECT/CTseem promising for pre-operative staging of cervical nodal involvement in patients with papillary thyroid cancer without the need of using iodinated contrast that may complicate subsequence 1-131 treatment. However, false positive result in granulomatous inflammatory nodes should be aware of especially in endemic areas. 99mTc-MIBI SPECT/CT scan shows a good result when compared with previous study of CT or MRI imaging. The comparative study between different imaging modality and the extension of neck dissection according to MIBI result seems interesting.

Value of planar lymphoscintigraphy versus SPECT/CT in evaluation of sentinel lymph node in trunk melanoma - one center, large series, retrospective study.

PubMed

Benke, Małgorzata; Wocial, Krzysztof; Lewandowska, Weronika; Rutkowski, Piotr Łukasz; Teterycz, Paweł; Jarek, Piotr; Dedecjus, Marek

2018-06-29

Background Localization and histopathological examination of sentinel lymph node (SLN) is a standard of melanoma treatment. The first stage of identification of the SLN is the preoperative lymphoscintigraphy. The aim of this study was to assess and compare diagnostic value of planar lymphoscintigraphy (PL) and SPECT/CT in sentinel lymph node biopsy (SLNB) procedure performed in patients with cutaneous trunk melanoma. Material and Methods Between 2015 and 2016, patients with trunk melanoma (N=255, F/M 95/160), aged from 17 to 88 after an excisional biopsy, with primary tumor ≥ pT1b (AJCC 2009, median Breslow thickness 2.0± 3.13) were included in the study. In all the patients PL was followed by SPECT/CT 1-3 h after injection of 99mTc- colloid particles, and SLNB was performed the next day. Results SPECT-CT revealed 78 (18.6%) SLN more than PL, and in 40 patients showed additional lymph drainage regions leading to surgical adjustments. In 18 patients (7.1%) SPECT-CT revealed SLN not visible in the PL (false-negative PL) and in 22 patients (8.6%), foci of uptake interpreted in PL as hot SLNs were found to be non-nodal sites of uptake when assessed on SPECT/CT (false positive PL). SPECT-CT vs. PL mismatch was observed in 31 patients (12.2%) and was the most common in patients with primary lesions located in the anterior inferior medial region (75%). Conclusions Results of the presented study indicates the high diagnostic value of SPECT-CT in assessment of SLNs and proved that SPECT-CT increases the sensitivity and accuracy of SLN identification as compared to PL even in very experienced hands.

Optimized 3D stitching algorithm for whole body SPECT based on transition error minimization (TEM)

NASA Astrophysics Data System (ADS)

Cao, Xinhua; Xu, Xiaoyin; Voss, Stephan

2017-02-01

Standard Single Photon Emission Computed Tomography (SPECT) has a limited field of view (FOV) and cannot provide a 3D image of an entire long whole body SPECT. To produce a 3D whole body SPECT image, two to five overlapped SPECT FOVs from head to foot are acquired and assembled using image stitching. Most commercial software from medical imaging manufacturers applies a direct mid-slice stitching method to avoid blurring or ghosting from 3D image blending. Due to intensity changes across the middle slice of overlapped images, direct mid-slice stitching often produces visible seams in the coronal and sagittal views and maximal intensity projection (MIP). In this study, we proposed an optimized algorithm to reduce the visibility of stitching edges. The new algorithm computed, based on transition error minimization (TEM), a 3D stitching interface between two overlapped 3D SPECT images. To test the suggested algorithm, four studies of 2-FOV whole body SPECT were used and included two different reconstruction methods (filtered back projection (FBP) and ordered subset expectation maximization (OSEM)) as well as two different radiopharmaceuticals (Tc-99m MDP for bone metastases and I-131 MIBG for neuroblastoma tumors). Relative transition errors of stitched whole body SPECT using mid-slice stitching and the TEM-based algorithm were measured for objective evaluation. Preliminary experiments showed that the new algorithm reduced the visibility of the stitching interface in the coronal, sagittal, and MIP views. Average relative transition errors were reduced from 56.7% of mid-slice stitching to 11.7% of TEM-based stitching. The proposed algorithm also avoids blurring artifacts by preserving the noise properties of the original SPECT images.

Estimation of the total effective dose from low-dose CT scans and radiopharmaceutical administrations delivered to patients undergoing SPECT/CT explorations.

PubMed

Montes, Carlos; Tamayo, Pilar; Hernandez, Jorge; Gomez-Caminero, Felipe; García, Sofia; Martín, Carlos; Rosero, Angela

2013-08-01

Hybrid imaging, such as SPECT/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85% with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose.

Cost-effectiveness of coronary CT angiography in patients with chest pain: Comparison with myocardial single photon emission tomography.

PubMed

Lee, Seung-Pyo; Jang, Eun Jin; Kim, Yong-Jin; Cha, Myung-Jin; Park, Sun-Young; Song, Hyun Jin; Choi, Ji Eun; Shim, Jung-Im; Ahn, Jeonghoon; Lee, Hyun Joo

2015-01-01

Coronary CT angiography (CCTA) has been proven accurate and is incorporated in clinical recommendations for coronary artery disease (CAD) diagnosis workup, but cost-effectiveness data, especially in comparison to other methods such as myocardial single photon emission CT (SPECT) are insufficient. To compare the cost-effectiveness of CCTA and myocardial SPECT in a real-world setting. We performed a retrospective cohort study on consecutive patients with suspected CAD and a pretest probability between 10% and 90%. Test accuracy was compared by correcting referral bias to coronary angiography depending on noninvasive test results based on the Bayes' theorem and also by incorporating 1-year follow-up results. Cost-effectiveness was analyzed using test accuracy and quality-adjusted life year (QALY). The model using diagnostic accuracy used the number of patients accurately diagnosed among 1000 persons as the effect and contained only expenses for diagnostic testing as the cost. In the model using QALY, a decision tree was developed, and the time horizon was 1 year. CCTA was performed in 635 patients and SPECT in 997 patients. An accurate diagnosis per 1000 patients was achieved in 725 patients by CCTA vs 661 patients by SPECT. In the model using diagnostic accuracy, CCTA was more effective and less expensive than SPECT ($725.38 for CCTA vs $661.46 for SPECT). In the model using QALY, CCTA was generally more effective in terms of life quality (0.00221 QALY) and cost ($513) than SPECT. However, cost utility varied among subgroups, with SPECT outperforming CCTA in patients with a pretest probability of 30% to 60% (0.01890 QALY; $113). These results suggest that CCTA may be more cost-effective than myocardial SPECT. Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Investigation and statistical modeling of InAs-based double gate tunnel FETs for RF performance enhancement

NASA Astrophysics Data System (ADS)

Poorvasha, S.; Lakshmi, B.

2018-05-01

In this paper, RF performance analysis of InAs-based double gate (DG) tunnel field effect transistors (TFETs) is investigated in both qualitative and quantitative fashion. This investigation is carried out by varying the geometrical and doping parameters of TFETs to extract various RF parameters, unity gain cut-off frequency (f t), maximum oscillation frequency (f max), intrinsic gain and admittance (Y) parameters. An asymmetric gate oxide is introduced in the gate-drain overlap and compared with that of DG TFETs. Higher ON-current (I ON) of about 0.2 mA and less leakage current (I OFF) of 29 fA is achieved for DG TFET with gate-drain overlap. Due to increase in transconductance (g m), higher f t and intrinsic gain is attained for DG TFET with gate-drain overlap. Higher f max of 985 GHz is obtained for drain doping of 5 × 1017 cm‑3 because of the reduced gate-drain capacitance (C gd) with DG TFET with gate-drain overlap. In terms of Y-parameters, gate oxide thickness variation offers better performance due to the reduced values of C gd. A second order numerical polynomial model is generated for all the RF responses as a function of geometrical and doping parameters. The simulation results are compared with this numerical model where the predicted values match with the simulated values. Project supported by the Department of Science and Technology, Government of India under SERB Scheme (No. SERB/F/2660).

The importance of Tc-MAA SPECT/CT for therapy planning of radioembolization in a patient treated with bevacizumab.

PubMed

Ahmadzadehfar, Hojjat; Sabet, Amir; Meyer, Carsten; Habibi, Elham; Biersack, Hans-Jürgen; Ezziddin, Samer

2012-11-01

A 76-year-old man with colorectal cancer and hepatic metastases was referred to us for radioembolization of the liver. Angiography with 99mTc-MAA SPECT/CT was performed 8 weeks after the discontinuation of bevacizumab. 99mTc-MAA SPECT/CT showed a diffused intrahepatic tracer distribution with no focally accentuated accumulation in the tumorous region. The test was repeated 6 weeks later and Tc-MAA SPECT/CT showed this time a tumor accentuated tracer accumulation in the liver. Subsequently, the patient was treated with resin microspheres. Tc-MAA SPECT/CT allows a better evaluation of intrahepatic tracer accumulation of Tc-MAA and facilitates the determination of the most appropriate treatment time.

99mTc MDP SPECT-CT-Based Modified Mirels Classification for Evaluation of Risk of Fracture in Skeletal Metastasis: A Pilot Study.

PubMed

Riaz, Saima; Bashir, Humayun; Niazi, Imran Khalid; Butt, Sumera; Qamar, Faisal

2018-06-01

Mirels' scoring system quantifies the risk of sustaining a pathologic fracture in osseous metastases of weight bearing long bones. Conventional Mirels' scoring is based on radiographs. Our pilot study proposes Tc MDP bone SPECT-CT based modified Mirels' scoring system and its comparison with conventional Mirels' scoring. Cortical lysis was noted in 8(24%) by SPECT-CT versus 2 (6.3%) on X-rays. Additional SPECT-CT parameters were; circumferential involvement [1/4 (31%), 1/2 (3%), 3/4 (37.5%), 4/4 (28%)] and extra-osseous soft tissue [3%]. Our pilot study suggests the potential role of SPECT-CT in predicting risk of fracture in osseous metastases.

Single photon emission computed tomography (SPECT) in epilepsy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leroy, R.F.

1991-12-31

Epilepsy is a common neurologic disorder which has just begun to be studied with single photon emission computerized tomography (SPECT). Epilepsy usually is studied with electroencephalographic (EEG) techniques that demonstrate the physiologic changes that occur during seizures, and with neuroimaging techniques that show the brain structures where seizures originate. Neither method alone has been adequate to describe the pathophysiology of the patient with epilepsy. EEG techniques lack anatomic sensitivity, and there are no structural abnormalities shown by neuroimaging which are specific for epilepsy. Functional imaging (FI) has developed as a physiologic tool with anatomic sensitivity, and SPECT has been promotedmore » as a FI technique because of its potentially wide availability. However, SPECT is early in its development and its clinical utility for epilepsy still has to be demonstrated. To understand this role of SPECT, consideration must be given to the pathophysiology of epilepsy, brain physiology, types of seizure, epileptic syndromes, and the SPECT technique itself. 44 refs., 2 tabs.« less

SU-E-J-104: Single Photon Image From PET with Insertable SPECT Collimator for Boron Neutron Capture Therapy: A Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, J; Yoon, D; Suh, T

2014-06-01

Purpose: The aim of our proposed system is to confirm the feasibility of extraction of two types of images from one positron emission tomography (PET) module with an insertable collimator for brain tumor treatment during the BNCT. Methods: Data from the PET module, neutron source, and collimator was entered in the Monte Carlo n-particle extended (MCNPX) source code. The coincidence events were first compiled on the PET detector, and then, the events of the prompt gamma ray were collected after neutron emission by using a single photon emission computed tomography (SPECT) collimator on the PET. The obtaining of full widthmore » at half maximum (FWHM) values from the energy spectrum was performed to collect effective events for reconstructed image. In order to evaluate the images easily, five boron regions in a brain phantom were used. The image profiles were extracted from the region of interest (ROI) of a phantom. The image was reconstructed using the ordered subsets expectation maximization (OSEM) reconstruction algorithm. The image profiles and the receiver operating characteristic (ROC) curve were compiled for quantitative analysis from the two kinds of reconstructed image. Results: The prompt gamma ray energy peak of 478 keV appeared in the energy spectrum with a FWHM of 41 keV (6.4%). On the basis of the ROC curve in Region A to Region E, the differences in the area under the curve (AUC) of the PET and SPECT images were found to be 10.2%, 11.7%, 8.2% (center, Region C), 12.6%, and 10.5%, respectively. Conclusion: We attempted to acquire the PET and SPECT images simultaneously using only PET without an additional isotope. Single photon images were acquired using an insertable collimator on a PET detector. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, Information and Communication Technologies (ICT) and Future Planning (MSIP)(Grant No.2009 00420) and the Radiation Technology R and D program (Grant No.2013M2A2A7043498), Republic of Korea.« less

Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pino, Francisco; Roé, Nuria; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es

2015-02-15

Purpose: Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera. Methods: Threemore » methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4–2008 image-quality phantom. Results: A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12. Conclusions: Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters.« less

Congenital atresia of the external ear and tinnitus: a new syndrome.

PubMed

Shulman, Abraham; Strashun, Arnold M; Goldstein, Barbara; Lenhardt, Martin L

2006-01-01

Congenital atresia of the external ears and severe tinnitus has been reported by two patients to be contralateral to the atretic ear. The use of the nuclear medicine imaging technique of single-photon emission computed tomography (SPECT) of brain has demonstrated hypoperfusion in brain areas supplied by the middle cerebral artery on the side of the atretic ear. Ultrahigh-frequency audiometry (UHFA) has revealed a bilateral loss of hearing greater than expected for the age of affected patients. Quantitative electroencephalography (QEEG) has shown a significant central nervous system electrical dysfunction correlated with the SPECT of brain findings. One case is reported in detail at this time. Completion of the medical audiological tinnitus patient protocol, including SPECT of brain, UHFA, and QEEG, accurately established the clinical tinnitus diagnosis of predominantly a central-type tinnitus, a clinical hypothesis that the medical significance of the tinnitus is a "soft" sign of cerebrovascular disease, and provided a rationale for treatment directed to a presumed ischemia of brain based on a receptor-targeted therapy targeted to the GABA-A receptor, resulting in significant tinnitus relief. Questions that have arisen include (1) the incidence of occurrence of hypoperfusion of the middle cerebral artery in congenital atresia patients; (2) implications and long-term consequences of this finding in this patient population for development of cerebrovascular disease; (3) brain plasticity for tinnitus relief (i.e., neuronal reprogramming, particularly in response to treatment recommendations for complaints of the cochleovestibular system in general and specifically for tinnitus); (4) the clinical significance of the UHFA thresholds of bilateral hearing loss greater than expected for the age of the patient; and (5) whether congenital atresia of the external ear may be part of a syndrome that includes hypoperfusion in brain areas supplied by the middle cerebral artery on the side of the atretic ear, ultra-high-frequency bilateral loss of hearing greater than expected for the age of the patient, and significant central nervous system electrical dysfunction. As far as we can determine, these findings, highlighted by the brain SPECT, have not previously been reported in patients with congenital atresia of the external ear.

Abdo-Man: a 3D-printed anthropomorphic phantom for validating quantitative SIRT.

PubMed

Gear, Jonathan I; Cummings, Craig; Craig, Allison J; Divoli, Antigoni; Long, Clive D C; Tapner, Michael; Flux, Glenn D

2016-12-01

The use of selective internal radiation therapy (SIRT) is rapidly increasing, and the need for quantification and dosimetry is becoming more widespread to facilitate treatment planning and verification. The aim of this project was to develop an anthropomorphic phantom that can be used as a validation tool for post-SIRT imaging and its application to dosimetry. The phantom design was based on anatomical data obtained from a T1-weighted volume-interpolated breath-hold examination (VIBE) on a Siemens Aera 1.5 T MRI scanner. The liver, lungs and abdominal trunk were segmented using the Hermes image processing workstation. Organ volumes were then uploaded to the Delft Visualization and Image processing Development Environment for smoothing and surface rendering. Triangular meshes defining the iso-surfaces were saved as stereo lithography (STL) files and imported into the Autodesk® Meshmixer software. Organ volumes were subtracted from the abdomen and a removable base designed to allow access to the liver cavity. Connection points for placing lesion inserts and filling holes were also included. The phantom was manufactured using a Stratasys Connex3 PolyJet 3D printer. The printer uses stereolithography technology combined with ink jet printing. Print material is a solid acrylic plastic, with similar properties to polymethylmethacrylate (PMMA). Measured Hounsfield units and calculated attenuation coefficients of the material were shown to also be similar to PMMA. Total print time for the phantom was approximately 5 days. Initial scans of the phantom have been performed with Y-90 bremsstrahlung SPECT/CT, Y-90 PET/CT and Tc-99m SPECT/CT. The CT component of these images compared well with the original anatomical reference, and measurements of volume agreed to within 9 %. Quantitative analysis of the phantom was performed using all three imaging techniques. Lesion and normal liver absorbed doses were calculated from the quantitative images in three dimensions using the local deposition method. 3D printing is a flexible and cost-efficient technology for manufacture of anthropomorphic phantom. Application of such phantoms will enable quantitative imaging and dosimetry methodologies to be evaluated, which with optimisation could help improve outcome for patients.

Diffusive flux in a model of stochastically gated oxygen transport in insect respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berezhkovskii, Alexander M.; Shvartsman, Stanislav Y.

Oxygen delivery to insect tissues is controlled by transport through a branched tubular network that is connected to the atmosphere by valve-like gates, known as spiracles. In certain physiological regimes, the spiracles appear to be randomly switching between open and closed states. Quantitative analysis of this regime leads a reaction-diffusion problem with stochastically switching boundary condition. We derive an expression for the diffusive flux at long times in this problem. Our approach starts with the derivation of the passage probability for a single particle that diffuses between a stochastically gated boundary, which models the opening and closing spiracle, and themore » perfectly absorbing boundary, which models oxygen absorption by the tissue. This passage probability is then used to derive an expression giving the diffusive flux as a function of the geometric parameters of the tube and characteristic time scales of diffusion and gate dynamics.« less

Diffusive flux in a model of stochastically gated oxygen transport in insect respiration.

PubMed

Berezhkovskii, Alexander M; Shvartsman, Stanislav Y

2016-05-28

Oxygen delivery to insect tissues is controlled by transport through a branched tubular network that is connected to the atmosphere by valve-like gates, known as spiracles. In certain physiological regimes, the spiracles appear to be randomly switching between open and closed states. Quantitative analysis of this regime leads a reaction-diffusion problem with stochastically switching boundary condition. We derive an expression for the diffusive flux at long times in this problem. Our approach starts with the derivation of the passage probability for a single particle that diffuses between a stochastically gated boundary, which models the opening and closing spiracle, and the perfectly absorbing boundary, which models oxygen absorption by the tissue. This passage probability is then used to derive an expression giving the diffusive flux as a function of the geometric parameters of the tube and characteristic time scales of diffusion and gate dynamics.

Structure-based membrane dome mechanism for Piezo mechanosensitivity

PubMed Central

Guo, Yusong R

2017-01-01

Mechanosensitive ion channels convert external mechanical stimuli into electrochemical signals for critical processes including touch sensation, balance, and cardiovascular regulation. The best understood mechanosensitive channel, MscL, opens a wide pore, which accounts for mechanosensitive gating due to in-plane area expansion. Eukaryotic Piezo channels have a narrow pore and therefore must capture mechanical forces to control gating in another way. We present a cryo-EM structure of mouse Piezo1 in a closed conformation at 3.7Å-resolution. The channel is a triskelion with arms consisting of repeated arrays of 4-TM structural units surrounding a pore. Its shape deforms the membrane locally into a dome. We present a hypothesis in which the membrane deformation changes upon channel opening. Quantitatively, membrane tension will alter gating energetics in proportion to the change in projected area under the dome. This mechanism can account for highly sensitive mechanical gating in the setting of a narrow, cation-selective pore. PMID:29231809

Imaging of mild traumatic brain injury using 57Co and 99mTc HMPAO SPECT as compared to other diagnostic procedures.

PubMed

Audenaert, Kurt; Jansen, Hugo M L; Otte, Andreas; Peremans, Kathelijne; Vervaet, Myriam; Crombez, Roger; de Ridder, Leo; van Heeringen, Cees; Thirot, Joel; Dierckx, Rudi; Korf, Jaap

2003-10-01

Traumatic brain injury (TBI) is usually assessed with the Glasgow Coma Scale (GCS), CT and EEG. TBI can result from either the primary mechanical impact or secondary (ischemic) brain damage, in which calcium (Ca) plays a pivotal role. This study was undertaken to compare the applicability of SPECT using 57Co as a Ca-tracer in patients with mild traumatic brain injury. 8 patients with mild TBI (GCS 15) were clinically examined and studied with EEG, neuropsychological testing (NPT) and SPECT within 2 days post-TBI. After i.v.-administration of 37 MBq (1 mCi) 57Co (effective radiation dose 0.34 mSv x MBq(-1); 1.24 rem x mCi(-1); physical half-life 270 days, biological half-life 37.6 h), single-headed SPECT (12 h pi) was performed, consecutively followed by standard 925 MBq (25 mCi) Tc-99m HMPAO SPECT. In 6 of the 8 patients, baseline NPT and SPECT showed focal abnormalities in the affected frontal and temporal brain regions, which were in good topographical accordance. CT and EEG did not detect (structural) lesions in any of these cases. Single-headed 57Co-SPECT is able to show the site and extent of brain damage in patients with mild TBI, even in the absence of structural lesions. It may confirm and localize NPT findings. The predictive value of 57Co-SPECT should be assessed in larger patient series.

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT-CT scanners

PubMed Central

DiFilippo, Frank P.

2008-01-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners. PMID:18635899

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT CT scanners

NASA Astrophysics Data System (ADS)

Di Filippo, Frank P.

2008-08-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high-resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners.

Analytically based photon scatter modeling for a multipinhole cardiac SPECT camera.

PubMed

Pourmoghaddas, Amir; Wells, R Glenn

2016-11-01

Dedicated cardiac SPECT scanners have improved performance over standard gamma cameras allowing reductions in acquisition times and/or injected activity. One approach to improving performance has been to use pinhole collimators, but this can cause position-dependent variations in attenuation, sensitivity, and spatial resolution. CT attenuation correction (AC) and an accurate system model can compensate for many of these effects; however, scatter correction (SC) remains an outstanding issue. In addition, in cameras using cadmium-zinc-telluride-based detectors, a large portion of unscattered photons is detected with reduced energy (low-energy tail). Consequently, application of energy-based SC approaches in these cameras leads to a higher increase in noise than with standard cameras due to the subtraction of true counts detected in the low-energy tail. Model-based approaches with parallel-hole collimator systems accurately calculate scatter based on the physics of photon interactions in the patient and camera and generate lower-noise estimates of scatter than energy-based SC. In this study, the accuracy of a model-based SC method was assessed using physical phantom studies on the GE-Discovery NM530c and its performance was compared to a dual energy window (DEW)-SC method. The analytical photon distribution (APD) method was used to calculate the distribution of probabilities that emitted photons will scatter in the surrounding scattering medium and be subsequently detected. APD scatter calculations for 99m Tc-SPECT (140 ± 14 keV) were validated with point-source measurements and 15 anthropomorphic cardiac-torso phantom experiments and varying levels of extra-cardiac activity causing scatter inside the heart. The activity inserted into the myocardial compartment of the phantom was first measured using a dose calibrator. CT images were acquired on an Infinia Hawkeye (GE Healthcare) SPECT/CT and coregistered with emission data for AC. For comparison, DEW scatter projections (120 ± 6 keV ) were also extracted from the acquired list-mode SPECT data. Either APD or DEW scatter projections were subtracted from corresponding 140 keV measured projections and then reconstructed with AC (APD-SC and DEW-SC). Quantitative accuracy of the activity measured in the heart for the APD-SC and DEW-SC images was assessed against dose calibrator measurements. The difference between modeled and acquired projections was measured as the root-mean-squared-error (RMSE). APD-modeled projections for a clinical cardiac study were also evaluated. APD-modeled projections showed good agreement with SPECT measurements and had reduced noise compared to DEW scatter estimates. APD-SC reduced mean error in activity measurement compared to DEW-SC in images and the reduction was statistically significant where the scatter fraction (SF) was large (mean SF = 28.5%, T-test p = 0.007). APD-SC reduced measurement uncertainties as well; however, the difference was not found to be statistically significant (F-test p > 0.5). RMSE comparisons showed that elevated levels of scatter did not significantly contribute to a change in RMSE (p > 0.2). Model-based APD scatter estimation is feasible for dedicated cardiac SPECT scanners with pinhole collimators. APD-SC images performed better than DEW-SC images and improved the accuracy of activity measurement in high-scatter scenarios.

[Myokard-Perfusions-SPECT. Myocardial perfusion SPECT - Update S1 guideline].

PubMed

Lindner, Oliver; Bengel, Frank; Burchert, Wolfgang; Dörr, Rolf; Hacker, Marcus; Schäfer, Wolfgang; Schäfers, Michael A; Schmidt, Matthias; Schwaiger, Markus; Vom Dahl, Jürgen; Zimmermann, Rainer

2017-08-14

The S1 guideline for myocardial perfusion SPECT has been published by the Association of the Scientific Medical Societies in Germany (AWMF) and is valid until 2/2022. This paper is a short summary with comments on all chapters and subchapters wich were modified and amended.

SPECT reconstruction with nonuniform attenuation from highly under-sampled projection data

NASA Astrophysics Data System (ADS)

Li, Cuifen; Wen, Junhai; Zhang, Kangping; Shi, Donghao; Dong, Haixiang; Li, Wenxiao; Liang, Zhengrong

2012-03-01

Single photon emission computed tomography (SPECT) is an important nuclear medicine imaging technique and has been using in clinical diagnoses. The SPECT image can reflect not only organizational structure but also functional activities of human body, therefore diseases can be found much earlier. In SPECT, the reconstruction is based on the measurement of gamma photons emitted by the radiotracer. The number of gamma photons detected is proportional to the dose of radiopharmaceutical, but the dose is limited because of patient safety. There is an upper limit in the number of gamma photons that can be detected per unit time, so it takes a long time to acquire SPECT projection data. Sometimes we just can obtain highly under-sampled projection data because of the limit of the scanning time or imaging hardware. How to reconstruct an image using highly under-sampled projection data is an interesting problem. One method is to minimize the total variation (TV) of the reconstructed image during the iterative reconstruction. In this work, we developed an OSEM-TV SPECT reconstruction algorithm, which could reconstruct the image from highly under-sampled projection data with non-uniform attenuation. Simulation results demonstrate that the OSEM-TV algorithm performs well in SPECT reconstruction with non-uniform attenuation.

18F-FDG SPECT/CT in the diagnosis of differentiated thyroid carcinoma with elevated thyroglobulin and negative iodine-131 scans.

PubMed

Ma, C; Wang, X; Shao, M; Zhao, L; Jiawei, X; Wu, Z; Wang, H

2015-06-01

Aim of the present study was to investigate the usefulness of 18F-FDG SPECT/CT in differentiated thyroid cancer (DTC) with elevated serum thyroglobulin (Tg) but negative iodine-131 scan. This retrospective review of patients with DTC recurrence who had 18F-FDG SPECT/CT and 18F-FDG PET/CT for elevated serum Tg but negative iodine-131 scan (March 2007-October 2012). After total thyroidectomy followed by radioiodine ablation, 86 consecutive patients with elevated Tg levels underwent 18F-FDG SPECT/CT or 18F-FDG PET/CT. Of these, 45 patients had 18F-FDG SPECT/CT, the other 41 patients had 18F-FDG PET/CT 3-4weeks after thyroid hormone withdrawal. The results of 18F-FDG PET/CT and SPECT/CT were correlated with patient follow-up information, which included the results from subsequent imaging modalities such as neck ultrasound, MRI and CT, Tg levels, and histologic examination of surgical specimens. The diagnostic accuracy of the two imaging modalities was evaluated. In 18F-FDG SPECT/CT scans, 24 (24/45) patients had positive findings, 22 true positive in 24 patients, false positive in 2 patients, true-negative and false-negative in 6, 15 patients, respectively. The overall sensitivity, specificity, and accuracy of 18F-FDG SPECT/CT were 59.5%, 75% and 62.2%, respectively. Twenty six patients had positive findings on 18F-FDG PET/CT scans, 23 true positive in 26 (26/41) patients, false positive in 3 patients, true-negative and false-negative in 9, 6 patients, respectively. The overall sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 79.3%, 81.8% and 78.1%, respectively. Clinical management changed for 13 (29%) of 45 patients by 18F-FDG SPECT/CT, 14 (34%) of 41 patients by 18F-FDG PET/CT including surgery, radiation therapy, or multikinase inhibitor. Based on the retrospective analysis of 86 patients, 18F-FDG SPECT/CT has lower sensitivity in the diagnosis of DTC recurrence with elevated Tg and negative iodine-131scan to 18F-FDG PET/CT. The clinical application of FDG SPECT/CT is then limited and cannot replace PET/CT.

Preclinical imaging characteristics and quantification of Platinum-195m SPECT.

PubMed

Aalbersberg, E A; de Wit-van der Veen, B J; Zwaagstra, O; Codée-van der Schilden, K; Vegt, E; Vogel, Wouter V

2017-08-01

In vivo biodistribution imaging of platinum-based compounds may allow better patient selection for treatment with chemo(radio)therapy. Radiolabeling with Platinum-195m ( 195m Pt) allows SPECT imaging, without altering the chemical structure or biological activity of the compound. We have assessed the feasibility of 195m Pt SPECT imaging in mice, with the aim to determine the image quality and accuracy of quantification for current preclinical imaging equipment. Enriched (>96%) 194 Pt was irradiated in the High Flux Reactor (HFR) in Petten, The Netherlands (NRG). A 0.05 M HCl 195m Pt-solution with a specific activity of 33 MBq/mg was obtained. Image quality was assessed for the NanoSPECT/CT (Bioscan Inc., Washington DC, USA) and U-SPECT + /CT (MILabs BV, Utrecht, the Netherlands) scanners. A radioactivity-filled rod phantom (rod diameter 0.85-1.7 mm) filled with 1 MBq 195m Pt was scanned with different acquisition durations (10-120 min). Four healthy mice were injected intravenously with 3-4 MBq 195m Pt. Mouse images were acquired with the NanoSPECT for 120 min at 0, 2, 4, or 24 h after injection. Organs were delineated to quantify 195m Pt concentrations. Immediately after scanning, the mice were sacrificed, and the platinum concentration was determined in organs using a gamma counter and graphite furnace - atomic absorption spectroscopy (GF-AAS) as reference standards. A 30-min acquisition of the phantom provided visually adequate image quality for both scanners. The smallest visible rods were 0.95 mm in diameter on the NanoSPECT and 0.85 mm in diameter on the U-SPECT + . The image quality in mice was visually adequate. Uptake was seen in the kidneys with excretion to the bladder, and in the liver, blood, and intestine. No uptake was seen in the brain. The Spearman correlation between SPECT and gamma counter was 0.92, between SPECT and GF-AAS it was 0.84, and between GF-AAS and gamma counter it was0.97 (all p < 0.0001). Preclinical 195m Pt SPECT is feasible with acceptable tracer doses and acquisition times, and provides good image quality and accurate signal quantification.

Reproducibility of Lobar Perfusion and Ventilation Quantification Using SPECT/CT Segmentation Software in Lung Cancer Patients.

PubMed

Provost, Karine; Leblond, Antoine; Gauthier-Lemire, Annie; Filion, Édith; Bahig, Houda; Lord, Martin

2017-09-01

Planar perfusion scintigraphy with 99m Tc-labeled macroaggregated albumin is often used for pretherapy quantification of regional lung perfusion in lung cancer patients, particularly those with poor respiratory function. However, subdividing lung parenchyma into rectangular regions of interest, as done on planar images, is a poor reflection of true lobar anatomy. New tridimensional methods using SPECT and SPECT/CT have been introduced, including semiautomatic lung segmentation software. The present study evaluated inter- and intraobserver agreement on quantification using SPECT/CT software and compared the results for regional lung contribution obtained with SPECT/CT and planar scintigraphy. Methods: Thirty lung cancer patients underwent ventilation-perfusion scintigraphy with 99m Tc-macroaggregated albumin and 99m Tc-Technegas. The regional lung contribution to perfusion and ventilation was measured on both planar scintigraphy and SPECT/CT using semiautomatic lung segmentation software by 2 observers. Interobserver and intraobserver agreement for the SPECT/CT software was assessed using the intraclass correlation coefficient, Bland-Altman plots, and absolute differences in measurements. Measurements from planar and tridimensional methods were compared using the paired-sample t test and mean absolute differences. Results: Intraclass correlation coefficients were in the excellent range (above 0.9) for both interobserver and intraobserver agreement using the SPECT/CT software. Bland-Altman analyses showed very narrow limits of agreement. Absolute differences were below 2.0% in 96% of both interobserver and intraobserver measurements. There was a statistically significant difference between planar and SPECT/CT methods ( P < 0.001) for quantification of perfusion and ventilation for all right lung lobes, with a maximal mean absolute difference of 20.7% for the right middle lobe. There was no statistically significant difference in quantification of perfusion and ventilation for the left lung lobes using either method; however, absolute differences reached 12.0%. The total right and left lung contributions were similar for the two methods, with a mean difference of 1.2% for perfusion and 2.0% for ventilation. Conclusion: Quantification of regional lung perfusion and ventilation using SPECT/CT-based lung segmentation software is highly reproducible. This tridimensional method yields statistically significant differences in measurements for right lung lobes when compared with planar scintigraphy. We recommend that SPECT/CT-based quantification be used for all lung cancer patients undergoing pretherapy evaluation of regional lung function. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Canine left ventricle electromechanical behavior under different pacing modes.

PubMed

Vo Thang, Thanh-Thuy; Thibault, Bernard; Finnerty, Vincent; Pelletier-Galarneau, Matthieu; Khairy, Paul; Grégoire, Jean; Harel, François

2012-10-01

Cardiac resynchronization therapy may improve survival and quality of life in patients suffering from heart failure with left ventricular (LV) contraction dyssynchrony. While several studies have investigated electrical or mechanical determinants of synchronous contraction, few have focused on activation contraction coupling at a macroscopic level. The objective of the study was to characterize LV electromechanical behavior and response to pacing in a heart failure model. We analyzed data from 3D electroanatomic non-contact mapping and blood pool SPECT for 12 dogs with right ventricular (RV) tachycardia pacing-induced dilated cardiomyopathy. Surfaces generated by the two modalities were registered. Electrical signals were analyzed, and endocardial wall displacement curves were portrayed. Rapid pacing decreased the mean LV ejection fraction (LVEF) to 20.9 % and prolonged the QRS duration to 79 ± 10 ms (normal range: 40-50 ms). QRS duration remained unchanged with biventricular pacing (88.5 ms), while single site pacing further prolonged the QRS duration (113.3 ms for RV pacing and 111.6 ms for LV pacing). No trend was observed in LV systolic function. Activation duration time was significantly increased with all pacing modes compared to baseline. Finally, electromechanical delay, as defined by the delay between electrical activation and mechanical response, was increased by single site pacing (172.9 ms for RV pacing and 174.6 ms for LV pacing) but not by biventricular pacing (162.4 ms). Combined temporal and spatial coregistration electroanatomic maps and baseline gated blood pool SPECT imaging allowed us to quantify activation duration time, electromechanical delay, and LVEF for different pacing modes. Even if pacing modes did not significantly modify LVEF or activation duration, they produced alterations in electromechanical delay, with biventricular pacing significantly decreasing the electromechanical delay as measured by surface tracings and endocardial non-contact mapping.

ACCF/ASNC appropriateness criteria for single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI): a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group and the American Society of Nuclear Cardiology endorsed by the American Heart Association.

PubMed

Brindis, Ralph G; Douglas, Pamela S; Hendel, Robert C; Peterson, Eric D; Wolk, Michael J; Allen, Joseph M; Patel, Manesh R; Raskin, Ira E; Hendel, Robert C; Bateman, Timothy M; Cerqueira, Manuel D; Gibbons, Raymond J; Gillam, Linda D; Gillespie, John A; Hendel, Robert C; Iskandrian, Ami E; Jerome, Scott D; Krumholz, Harlan M; Messer, Joseph V; Spertus, John A; Stowers, Stephen A

2005-10-18

Under the auspices of the American College of Cardiology Foundation (ACCF) and the American Society of Nuclear Cardiology (ASNC), an appropriateness review was conducted for radionuclide cardiovascular imaging (RNI), specifically gated single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI). The review assessed the risks and benefits of the imaging test for several indications or clinical scenarios and scored them based on a scale of 1 to 9, where the upper range (7 to 9) implies that the test is generally acceptable and is a reasonable approach, and the lower range (1 to 3) implies that the test is generally not acceptable and is not a reasonable approach. The mid range (4 to 6) implies that the test may be generally acceptable and may be a reasonable approach for the indication. The indications for this review were primarily drawn from existing clinical practice guidelines and modified based on discussion by the ACCF Appropriateness Criteria Working Group and the Technical Panel members who rated the indications. The method for this review was based on the RAND/UCLA approach for evaluating appropriateness, which blends scientific evidence and practice experience. A modified Delphi technique was used to obtain first- and second-round ratings of 52 clinical indications. The ratings were done by a Technical Panel with diverse membership, including nuclear cardiologists, referring physicians (including an echocardiographer), health services researchers, and a payer (chief medical officer). These results are expected to have a significant impact on physician decision making and performance, reimbursement policy, and future research directions. Periodic assessment and updating of criteria will be undertaken as needed.

LROC assessment of non-linear filtering methods in Ga-67 SPECT imaging

NASA Astrophysics Data System (ADS)

De Clercq, Stijn; Staelens, Steven; De Beenhouwer, Jan; D'Asseler, Yves; Lemahieu, Ignace

2006-03-01

In emission tomography, iterative reconstruction is usually followed by a linear smoothing filter to make such images more appropriate for visual inspection and diagnosis by a physician. This will result in a global blurring of the images, smoothing across edges and possibly discarding valuable image information for detection tasks. The purpose of this study is to investigate which possible advantages a non-linear, edge-preserving postfilter could have on lesion detection in Ga-67 SPECT imaging. Image quality can be defined based on the task that has to be performed on the image. This study used LROC observer studies based on a dataset created by CPU-intensive Gate Monte Carlo simulations of a voxelized digital phantom. The filters considered in this study were a linear Gaussian filter, a bilateral filter, the Perona-Malik anisotropic diffusion filter and the Catte filtering scheme. The 3D MCAT software phantom was used to simulate the distribution of Ga-67 citrate in the abdomen. Tumor-present cases had a 1-cm diameter tumor randomly placed near the edges of the anatomical boundaries of the kidneys, bone, liver and spleen. Our data set was generated out of a single noisy background simulation using the bootstrap method, to significantly reduce the simulation time and to allow for a larger observer data set. Lesions were simulated separately and added to the background afterwards. These were then reconstructed with an iterative approach, using a sufficiently large number of MLEM iterations to establish convergence. The output of a numerical observer was used in a simplex optimization method to estimate an optimal set of parameters for each postfilter. No significant improvement was found for using edge-preserving filtering techniques over standard linear Gaussian filtering.

3D dosimetry estimation for selective internal radiation therapy (SIRT) using SPECT/CT images: a phantom study

NASA Astrophysics Data System (ADS)

Debebe, Senait A.; Franquiz, Juan; McGoron, Anthony J.

2015-03-01

Selective Internal Radiation Therapy (SIRT) is a common way to treat liver cancer that cannot be treated surgically. SIRT involves administration of Yttrium - 90 (90Y) microspheres via the hepatic artery after a diagnostic procedure using 99mTechnetium (Tc)-macroaggregated albumin (MAA) to detect extrahepatic shunting to the lung or the gastrointestinal tract. Accurate quantification of radionuclide administered to patients and radiation dose absorbed by different organs is of importance in SIRT. Accurate dosimetry for SIRT allows optimization of dose delivery to the target tumor and may allow for the ability to assess the efficacy of the treatment. In this study, we proposed a method that can efficiently estimate radiation absorbed dose from 90Y bremsstrahlung SPECT/CT images of liver and the surrounding organs. Bremsstrahlung radiation from 90Y was simulated using the Compton window of 99mTc (78keV at 57%). 99mTc images acquired at the photopeak energy window were used as a standard to examine the accuracy of dosimetry prediction by the simulated bremsstrahlung images. A Liqui-Phil abdominal phantom with liver, stomach and two tumor inserts was imaged using a Philips SPECT/CT scanner. The Dose Point Kernel convolution method was used to find the radiation absorbed dose at a voxel level for a three dimensional dose distribution. This method will allow for a complete estimate of the distribution of radiation absorbed dose by tumors, liver, stomach and other surrounding organs at the voxel level. The method provides a quantitative predictive method for SIRT treatment outcome and administered dose response for patients who undergo the treatment.

Attenuation correction in emission tomography using the emission data—A review

PubMed Central

Li, Yusheng

2016-01-01

The problem of attenuation correction (AC) for quantitative positron emission tomography (PET) had been considered solved to a large extent after the commercial availability of devices combining PET with computed tomography (CT) in 2001; single photon emission computed tomography (SPECT) has seen a similar development. However, stimulated in particular by technical advances toward clinical systems combining PET and magnetic resonance imaging (MRI), research interest in alternative approaches for PET AC has grown substantially in the last years. In this comprehensive literature review, the authors first present theoretical results with relevance to simultaneous reconstruction of attenuation and activity. The authors then look back at the early history of this research area especially in PET; since this history is closely interwoven with that of similar approaches in SPECT, these will also be covered. We then review algorithmic advances in PET, including analytic and iterative algorithms. The analytic approaches are either based on the Helgason–Ludwig data consistency conditions of the Radon transform, or generalizations of John’s partial differential equation; with respect to iterative methods, we discuss maximum likelihood reconstruction of attenuation and activity (MLAA), the maximum likelihood attenuation correction factors (MLACF) algorithm, and their offspring. The description of methods is followed by a structured account of applications for simultaneous reconstruction techniques: this discussion covers organ-specific applications, applications specific to PET/MRI, applications using supplemental transmission information, and motion-aware applications. After briefly summarizing SPECT applications, we consider recent developments using emission data other than unscattered photons. In summary, developments using time-of-flight (TOF) PET emission data for AC have shown promising advances and open a wide range of applications. These techniques may both remedy deficiencies of purely MRI-based AC approaches in PET/MRI and improve standalone PET imaging. PMID:26843243

Attenuation correction in emission tomography using the emission data—A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berker, Yannick, E-mail: berker@mail.med.upenn.edu; Li, Yusheng

2016-02-15

The problem of attenuation correction (AC) for quantitative positron emission tomography (PET) had been considered solved to a large extent after the commercial availability of devices combining PET with computed tomography (CT) in 2001; single photon emission computed tomography (SPECT) has seen a similar development. However, stimulated in particular by technical advances toward clinical systems combining PET and magnetic resonance imaging (MRI), research interest in alternative approaches for PET AC has grown substantially in the last years. In this comprehensive literature review, the authors first present theoretical results with relevance to simultaneous reconstruction of attenuation and activity. The authors thenmore » look back at the early history of this research area especially in PET; since this history is closely interwoven with that of similar approaches in SPECT, these will also be covered. We then review algorithmic advances in PET, including analytic and iterative algorithms. The analytic approaches are either based on the Helgason–Ludwig data consistency conditions of the Radon transform, or generalizations of John’s partial differential equation; with respect to iterative methods, we discuss maximum likelihood reconstruction of attenuation and activity (MLAA), the maximum likelihood attenuation correction factors (MLACF) algorithm, and their offspring. The description of methods is followed by a structured account of applications for simultaneous reconstruction techniques: this discussion covers organ-specific applications, applications specific to PET/MRI, applications using supplemental transmission information, and motion-aware applications. After briefly summarizing SPECT applications, we consider recent developments using emission data other than unscattered photons. In summary, developments using time-of-flight (TOF) PET emission data for AC have shown promising advances and open a wide range of applications. These techniques may both remedy deficiencies of purely MRI-based AC approaches in PET/MRI and improve standalone PET imaging.« less

Effects of CT-based attenuation correction of rat microSPECT images on relative myocardial perfusion and quantitative tracer uptake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strydhorst, Jared H., E-mail: jared.strydhorst@gmail.com; Ruddy, Terrence D.; Wells, R. Glenn

2015-04-15

Purpose: Our goal in this work was to investigate the impact of CT-based attenuation correction on measurements of rat myocardial perfusion with {sup 99m}Tc and {sup 201}Tl single photon emission computed tomography (SPECT). Methods: Eight male Sprague-Dawley rats were injected with {sup 99m}Tc-tetrofosmin and scanned in a small animal pinhole SPECT/CT scanner. Scans were repeated weekly over a period of 5 weeks. Eight additional rats were injected with {sup 201}Tl and also scanned following a similar protocol. The images were reconstructed with and without attenuation correction, and the relative perfusion was analyzed with the commercial cardiac analysis software. The absolutemore » uptake of {sup 99m}Tc in the heart was also quantified with and without attenuation correction. Results: For {sup 99m}Tc imaging, relative segmental perfusion changed by up to +2.1%/−1.8% as a result of attenuation correction. Relative changes of +3.6%/−1.0% were observed for the {sup 201}Tl images. Interscan and inter-rat reproducibilities of relative segmental perfusion were 2.7% and 3.9%, respectively, for the uncorrected {sup 99m}Tc scans, and 3.6% and 4.3%, respectively, for the {sup 201}Tl scans, and were not significantly affected by attenuation correction for either tracer. Attenuation correction also significantly increased the measured absolute uptake of tetrofosmin and significantly altered the relationship between the rat weight and tracer uptake. Conclusions: Our results show that attenuation correction has a small but statistically significant impact on the relative perfusion measurements in some segments of the heart and does not adversely affect reproducibility. Attenuation correction had a small but statistically significant impact on measured absolute tracer uptake.« less

Angina Relief by Ranolazine Identifies False-Negative SPECT Myocardial Perfusion Scans in Patients with Coronary Disease Demonstrated by Coronary Angiography.

PubMed

Murray, Gary L

2014-09-01

Normal myocardial perfusion imaging (MPI) reduces intermediate- or high-risk pretest probability patients to low- or intermediate-risk posttest probability, respectively, for coronary disease (CD). Since ranolazine (RAN) relieves only angina, anginal patients with normal MPI whose angina is relieved by RAN present a significant dilemma. The purpose of this retrospective chart review was to confirm the impression that coronary angiography (CA) is indicated in patients whose class 3 to 4 angina is relieved by RAN, but have normal myocardial single-photon emission computed tomography (SPECT) MPIs. Charts of patients with stable class 3 to 4 angina (typical and atypical) and normal MPIs (left ventricular ejection fraction [LVEF] ≥50% and segmental score = 0) were reviewed. CA was done on all the patients with complete angina relief taking RAN, as well as nonresponders whose anginal etiology could not be explained. Stenoses were considered flow-restrictive when more than 70% diameter stenosis is observed by quantitative CA, or, when 50 to 70%, fractional flow reserve (FFR) measured ≤0.80. RAN relieved angina in 36 of 54 (67%) patients. Of the known cases, 25 of these 36 (69%) had 43 stenoses ≥50% (mean = 66%): 15 (60%) had 1 vessel disease; 9 (36%) had multivessel disease; 18 (72%) had left anterior descending (LAD) disease; 1 (4%) had left main disease. Twenty one of 43 (49%) stenosis were > 70%; 22 (51%) stenoses were 50 to 70% and required FFR measurement. Twenty nine of 43 stenoses (67%) were considered flow-restrictive in 18 of these 25 (72%) patients. Eight RAN nonresponders with no explanation for angina had no CD at CA. RAN angina relief is invaluable in identifying falsely negative SPECT MPI, and 50% of these patients have flow-restrictive stenoses.

Multipinhole SPECT helical scan parameters and imaging volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Rutao, E-mail: rutaoyao@buffalo.edu; Deng, Xiao; Wei, Qingyang

Purpose: The authors developed SPECT imaging capability on an animal PET scanner using a multiple-pinhole collimator and step-and-shoot helical data acquisition protocols. The objective of this work was to determine the preferred helical scan parameters, i.e., the angular and axial step sizes, and the imaging volume, that provide optimal imaging performance. Methods: The authors studied nine helical scan protocols formed by permuting three rotational and three axial step sizes. These step sizes were chosen around the reference values analytically calculated from the estimated spatial resolution of the SPECT system and the Nyquist sampling theorem. The nine helical protocols were evaluatedmore » by two figures-of-merit: the sampling completeness percentage (SCP) and the root-mean-square (RMS) resolution. SCP was an analytically calculated numerical index based on projection sampling. RMS resolution was derived from the reconstructed images of a sphere-grid phantom. Results: The RMS resolution results show that (1) the start and end pinhole planes of the helical scheme determine the axial extent of the effective field of view (EFOV), and (2) the diameter of the transverse EFOV is adequately calculated from the geometry of the pinhole opening, since the peripheral region beyond EFOV would introduce projection multiplexing and consequent effects. The RMS resolution results of the nine helical scan schemes show optimal resolution is achieved when the axial step size is the half, and the angular step size is about twice the corresponding values derived from the Nyquist theorem. The SCP results agree in general with that of RMS resolution but are less critical in assessing the effects of helical parameters and EFOV. Conclusions: The authors quantitatively validated the effective FOV of multiple pinhole helical scan protocols and proposed a simple method to calculate optimal helical scan parameters.« less

Simultaneous 99mtc/111in spect reconstruction using accelerated convolution-based forced detection monte carlo

NASA Astrophysics Data System (ADS)

Karamat, Muhammad I.; Farncombe, Troy H.

2015-10-01

Simultaneous multi-isotope Single Photon Emission Computed Tomography (SPECT) imaging has a number of applications in cardiac, brain, and cancer imaging. The major concern however, is the significant crosstalk contamination due to photon scatter between the different isotopes. The current study focuses on a method of crosstalk compensation between two isotopes in simultaneous dual isotope SPECT acquisition applied to cancer imaging using 99mTc and 111In. We have developed an iterative image reconstruction technique that simulates the photon down-scatter from one isotope into the acquisition window of a second isotope. Our approach uses an accelerated Monte Carlo (MC) technique for the forward projection step in an iterative reconstruction algorithm. The MC estimated scatter contamination of a radionuclide contained in a given projection view is then used to compensate for the photon contamination in the acquisition window of other nuclide. We use a modified ordered subset-expectation maximization (OS-EM) algorithm named simultaneous ordered subset-expectation maximization (Sim-OSEM), to perform this step. We have undertaken a number of simulation tests and phantom studies to verify this approach. The proposed reconstruction technique was also evaluated by reconstruction of experimentally acquired phantom data. Reconstruction using Sim-OSEM showed very promising results in terms of contrast recovery and uniformity of object background compared to alternative reconstruction methods implementing alternative scatter correction schemes (i.e., triple energy window or separately acquired projection data). In this study the evaluation is based on the quality of reconstructed images and activity estimated using Sim-OSEM. In order to quantitate the possible improvement in spatial resolution and signal to noise ratio (SNR) observed in this study, further simulation and experimental studies are required.

SU-E-I-20: Dead Time Count Loss Compensation in SPECT/CT: Projection Versus Global Correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siman, W; Kappadath, S

Purpose: To compare projection-based versus global correction that compensate for deadtime count loss in SPECT/CT images. Methods: SPECT/CT images of an IEC phantom (2.3GBq 99mTc) with ∼10% deadtime loss containing the 37mm (uptake 3), 28 and 22mm (uptake 6) spheres were acquired using a 2 detector SPECT/CT system with 64 projections/detector and 15 s/projection. The deadtime, Ti and the true count rate, Ni at each projection, i was calculated using the monitor-source method. Deadtime corrected SPECT were reconstructed twice: (1) with projections that were individually-corrected for deadtime-losses; and (2) with original projections with losses and then correcting the reconstructed SPECTmore » images using a scaling factor equal to the inverse of the average fractional loss for 5 projections/detector. For both cases, the SPECT images were reconstructed using OSEM with attenuation and scatter corrections. The two SPECT datasets were assessed by comparing line profiles in xyplane and z-axis, evaluating the count recoveries, and comparing ROI statistics. Higher deadtime losses (up to 50%) were also simulated to the individually corrected projections by multiplying each projection i by exp(-a*Ni*Ti), where a is a scalar. Additionally, deadtime corrections in phantoms with different geometries and deadtime losses were also explored. The same two correction methods were carried for all these data sets. Results: Averaging the deadtime losses in 5 projections/detector suffices to recover >99% of the loss counts in most clinical cases. The line profiles (xyplane and z-axis) and the statistics in the ROIs drawn in the SPECT images corrected using both methods showed agreement within the statistical noise. The count-loss recoveries in the two methods also agree within >99%. Conclusion: The projection-based and the global correction yield visually indistinguishable SPECT images. The global correction based on sparse sampling of projections losses allows for accurate SPECT deadtime loss correction while keeping the study duration reasonable.« less

Utility of ⁹⁹mTc-human serum albumin diethylenetriamine pentaacetic acid SPECT for evaluating endoleak after endovascular abdominal aortic aneurysm repair.

PubMed

Nakai, Motoki; Sato, Hirotatsu; Sato, Morio; Ikoma, Akira; Sonomura, Tetsuo; Nishimura, Yoshiharu; Okamura, Yoshitaka

2015-01-01

The purpose of this study was to assess the utility of (99m)Tc-human serum albumin diethylenetriamine pentaacetic acid ((99m)Tc-HSAD) SPECT in the detection of endoleaks after endovascular abdominal aortic aneurysm repair. Fifteen patients (11 men, four women) with aneurysm sac expansion of 5 mm or greater after endovascular abdominal aortic aneurysm repair underwent three-phase CT, (99m)Tc-HSAD SPECT, and CT during aortography. Sensitivity calculations for three-phase CT and (99m)Tc-HSAD SPECT were performed with CT during aortography as the reference standard. The volume of each endoleak was measured with CT during aortography. Seven subjects underwent embolization with N-butyl cyanoacrylate (NBCA)-Lipiodol (ethiodized oil, Guerbet and metallic coils. Three-phase CT and (99m)Tc-HSAD SPECT were repeated after embolization to assess their efficacy. Endoleaks were interpreted as perigraft radioisotope accumulation in 12 patients (80.0%) on (99m)Tc-HSAD SPECT images, in 13 patients (86.7%) on three-phase CT images, and in 15 patients (100%) on CT during aortography. The mean endoleak volume visualized with (99m)Tc-HSAD SPECT was 8.37 cm(3) (range, 5.2-15.1 cm(3)), and the volume not visualized was 3.47 cm(3) (2.5-4.6 cm(3)), a statistically significant difference (p = 0.019). In two patients, (99m)Tc-HSAD SPECT depicted endoleaks evident at delayed phase CT during aortography but not at three-phase CT, suggesting they were slow-filling endoleaks. Accumulation of (99m)Tc-HSAD corresponding to endoleaks disappeared after embolization, but CT evaluation of embolization was impeded by artifacts of NBCA-Lipiodol and metallic coils. Technetium-99m-labeled HSAD SPECT proved less sensitive than three-phase CT but depicted endoleaks with volumes 5.2 cm(3) or greater as perigraft radioisotope accumulation. Slow-filling endoleaks can be visualized with (99m)Tc-HSAD SPECT, which can be used to evaluate the efficacy of embolization.

MO-G-17A-02: Computer Simulation Studies for On-Board Functional and Molecular Imaging of the Prostate Using a Robotic Multi-Pinhole SPECT System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, L; Duke University Medical Center, Durham, NC; Fudan University Shanghai Cancer Center, Shanghai

Purpose: To investigate prostate imaging onboard radiation therapy machines using a novel robotic, 49-pinhole Single Photon Emission Computed Tomography (SPECT) system. Methods: Computer-simulation studies were performed for region-of-interest (ROI) imaging using a 49-pinhole SPECT collimator and for broad cross-section imaging using a parallel-hole SPECT collimator. A male XCAT phantom was computersimulated in supine position with one 12mm-diameter tumor added in the prostate. A treatment couch was added to the phantom. Four-minute detector trajectories for imaging a 7cm-diameter-sphere ROI encompassing the tumor were investigated with different parameters, including pinhole focal length, pinhole diameter and trajectory starting angle. Pseudo-random Poisson noise wasmore » included in the simulated projection data, and SPECT images were reconstructed by OSEM with 4 subsets and up to 10 iterations. Images were evaluated by visual inspection, profiles, and Root-Mean- Square-Error (RMSE). Results: The tumor was well visualized above background by the 49-pinhole SPECT system with different pinhole parameters while it was not visible with parallel-hole SPECT imaging. Minimum RMSEs were 0.30 for 49-pinhole imaging and 0.41 for parallelhole imaging. For parallel-hole imaging, the detector trajectory from rightto- left yielded slightly lower RMSEs than that from posterior to anterior. For 49-pinhole imaging, near-minimum RMSEs were maintained over a broader range of OSEM iterations with a 5mm pinhole diameter and 21cm focal length versus a 2mm diameter pinhole and 18cm focal length. The detector with 21cm pinhole focal length had the shortest rotation radius averaged over the trajectory. Conclusion: On-board functional and molecular prostate imaging may be feasible in 4-minute scan times by robotic SPECT. A 49-pinhole SPECT system could improve such imaging as compared to broadcross-section parallel-hole collimated SPECT imaging. Multi-pinhole imaging can be improved by considering pinhole focal length, pinhole diameter, and trajectory starting angle. The project is supported by the NIH grant 5R21-CA156390.« less

Control of interlayer physics in 2H transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Wang, Kuang-Chung; Stanev, Teodor K.; Valencia, Daniel; Charles, James; Henning, Alex; Sangwan, Vinod K.; Lahiri, Aritra; Mejia, Daniel; Sarangapani, Prasad; Povolotskyi, Michael; Afzalian, Aryan; Maassen, Jesse; Klimeck, Gerhard; Hersam, Mark C.; Lauhon, Lincoln J.; Stern, Nathaniel P.; Kubis, Tillmann

2017-12-01

It is assessed in detail both experimentally and theoretically how the interlayer coupling of transition metal dichalcogenides controls the electronic properties of the respective devices. Gated transition metal dichalcogenide structures show electrons and holes to either localize in individual monolayers, or delocalize beyond multiple layers—depending on the balance between spin-orbit interaction and interlayer hopping. This balance depends on the layer thickness, momentum space symmetry points, and applied gate fields. The design range of this balance, the effective Fermi levels, and all relevant effective masses is analyzed in great detail. A good quantitative agreement of predictions and measurements of the quantum confined Stark effect in gated MoS2 systems unveils intralayer excitons as the major source for the observed photoluminescence.

Reconstruction of truncated TCT and SPECT data from a right-angle dual-camera system for myocardial SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsui, B.M.W.; Frey, E.C.; Lalush, D.S.

1996-12-31

We investigated methods to accurately reconstruct 180{degrees} truncated TCT and SPECT projection data obtained from a right-angle dual-camera SPECT system for myocardial SPECT with attenuation compensation. The 180{degrees} data reconstruction methods would permit substantial savings in transmission data acquisition time. Simulation data from the 3D MCAT phantom and clinical data from large patients were used in the evaluation study. Different transmission reconstruction methods including the FBP, transmission ML-EM, transmission ML-SA, and BIT algorithms with and without using the body contour as support, were used in the TCT image reconstructions. The accuracy of both the TCT and attenuation compensated SPECT imagesmore » were evaluated for different degrees of truncation and noise levels. We found that using the FBP reconstructed TCT images resulted in higher count density in the left ventricular (LV) wall of the attenuation compensated SPECT images. The LV wall count density obtained using the iteratively reconstructed TCT images with and without support were similar to each other and were more accurate than that using the FBP. However, the TCT images obtained with support show fewer image artifacts than without support. Among the iterative reconstruction algorithms, the ML-SA algorithm provides the most accurate reconstruction but is the slowest. The BIT algorithm is the fastest but shows the most image artifacts. We conclude that accurate attenuation compensated images can be obtained with truncated 180{degrees} data from large patients using a right-angle dual-camera SPECT system.« less

Improved Diagnostic Accuracy of SPECT Through Statistical Analysis and the Detection of Hot Spots at the Primary Sensorimotor Area for the Diagnosis of Alzheimer Disease in a Community-Based Study: "The Osaki-Tajiri Project".

PubMed

Kaneta, Tomohiro; Nakatsuka, Masahiro; Nakamura, Kei; Seki, Takashi; Yamaguchi, Satoshi; Tsuboi, Masahiro; Meguro, Kenichi

2016-01-01

SPECT is an important diagnostic tool for dementia. Recently, statistical analysis of SPECT has been commonly used for dementia research. In this study, we evaluated the accuracy of visual SPECT evaluation and/or statistical analysis for the diagnosis (Dx) of Alzheimer disease (AD) and other forms of dementia in our community-based study "The Osaki-Tajiri Project." Eighty-nine consecutive outpatients with dementia were enrolled and underwent brain perfusion SPECT with 99mTc-ECD. Diagnostic accuracy of SPECT was tested using 3 methods: visual inspection (SPECT Dx), automated diagnostic tool using statistical analysis with easy Z-score imaging system (eZIS Dx), and visual inspection plus eZIS (integrated Dx). Integrated Dx showed the highest sensitivity, specificity, and accuracy, whereas eZIS was the second most accurate method. We also observed that a higher than expected rate of SPECT images indicated false-negative cases of AD. Among these, 50% showed hypofrontality and were diagnosed as frontotemporal lobar degeneration. These cases typically showed regional "hot spots" in the primary sensorimotor cortex (ie, a sensorimotor hot spot sign), which we determined were associated with AD rather than frontotemporal lobar degeneration. We concluded that the diagnostic abilities were improved by the integrated use of visual assessment and statistical analysis. In addition, the detection of a sensorimotor hot spot sign was useful to detect AD when hypofrontality is present and improved the ability to properly diagnose AD.

Estimation of sensitivity and specificity of brain magnetic resonance imaging and single photon emission computed tomography in the diagnosis of olfactory dysfunction after head traumas.

PubMed

Atighechi, Saeid; Zolfaghari, Aliasghar; Baradaranfar, Mohammadhossein; Dadgarnia, Mohammadhossein

2013-01-01

Olfactory dysfunction has an incidence of 5-10% after head injury. Several objective and subjective tests had been proposed. Recent studies showed that brain single photon emission computed tomography (SPECT) and brain magnetic resonance imaging (MRI) have good diagnostic value in this era in which the most common sites of involvement were olfactory bulb and olfactory nerve in MRI and frontal lobe in SPECT. This study aimed to estimate the sensitivity and specificity of brain MRI and brain SPECT in the diagnosis of traumatic hyposmia and anosmia. From February 2009 to March 2011, 63 patients with head injury and smell complaint were selected for this study. Using an identification test and a threshold smell test, 28 were anosmic and 27 had hyposmia and the remaining 8 were normosmic. All of them underwent brain MRI and SPECT. The sensitivity of SPECT was 81.5 and 85.7% in hyposmia and anosmia, respectively. Its specificity was 87.5% in anosmia and 87.7% in anosmia. MRI sensitivity was 66.7% in hyposmia but 82.1% in anosmia. Its specificity was 85.7% in anosmia and 87.7% in anosmia. If MRI and SPECT were considered together, the sensitivity was 92.3% in hyposmia and 92% in anosmia, but the specificity was 87% in both cases. According to our study, both brain MRI and SPECT have high sensitivity and specificity in the diagnosis of traumatic anosmia, although brain SPECT is slightly superior to MRI. If the two techniques are applied together, the accuracy will be increased.

Toward Quantifying the Electrostatic Transduction Mechanism in Carbon Nanotube Biomolecular Sensors

NASA Astrophysics Data System (ADS)

Lerner, Mitchell; Kybert, Nicholas; Mendoza, Ryan; Dailey, Jennifer; Johnson, A. T. Charlie

2013-03-01

Despite the great promise of carbon nanotube field-effect transistors (CNT FETs) for applications in chemical and biochemical detection, a quantitative understanding of sensor responses is lacking. To explore the role of electrostatics in sensor transduction, experiments were conducted with a set of similar compounds designed to adsorb onto the CNT FET via a pyrene linker group and take on a set of known charge states under ambient conditions. Acidic and basic species were observed to induce threshold voltage shifts of opposite sign, consistent with gating of the CNT FET by local charges due to protonation or deprotonation of the pyrene compounds by interfacial water. The magnitude of the gate voltage shift was controlled by the distance between the charged group and the CNT. Additionally, functionalization with an uncharged pyrene compound showed a threshold shift ascribed to its molecular dipole moment. This work illustrates a method for producing CNT FETs with controlled values of the turnoff gate voltage, and more generally, these results will inform the development of quantitative models for the response of CNT FET chemical and biochemical sensors. As an example, the results of an experiment detecting biomarkers of Lyme disease will be discussed in the context of this model.

The early years of single photon emission computed tomography (SPECT): an anthology of selected reminiscences.

PubMed

Jaszczak, Ronald Jack

2006-07-07

The origin of SPECT can be found in pioneering experiments on emission tomography performed approximately 50 years ago. This historical review consists of a compilation of first person recollections from nine trailblazing scientists who shaped the early years of SPECT instrumentation during the 1960s and 1970s.

Limited angle tomographic breast imaging: A comparison of parallel beam and pinhole collimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wessell, D.E.; Kadrmas, D.J.; Frey, E.C.

1996-12-31

Results from clinical trials have suggested no improvement in lesion detection with parallel hole SPECT scintimammography (SM) with Tc-99m over parallel hole planar SM. In this initial investigation, we have elucidated some of the unique requirements of SPECT SM. With these requirements in mind, we have begun to develop practical data acquisition and reconstruction strategies that can reduce image artifacts and improve image quality. In this paper we investigate limited angle orbits for both parallel hole and pinhole SPECT SM. Singular Value Decomposition (SVD) is used to analyze the artifacts associated with the limited angle orbits. Maximum likelihood expectation maximizationmore » (MLEM) reconstructions are then used to examine the effects of attenuation compensation on the quality of the reconstructed image. All simulations are performed using the 3D-MCAT breast phantom. The results of these simulation studies demonstrate that limited angle SPECT SM is feasible, that attenuation correction is needed for accurate reconstructions, and that pinhole SPECT SM may have an advantage over parallel hole SPECT SM in terms of improved image quality and reduced image artifacts.« less

SPECT in patients with cortical visual loss.

PubMed

Silverman, I E; Galetta, S L; Gray, L G; Moster, M; Atlas, S W; Maurer, A H; Alavi, A

1993-09-01

Single-photon emission computed tomography (SPECT) with 99mTc-hexamethylpropyleneamine oxime (HMPAO) was used to investigate changes in cerebral blood flow in seven patients with cortical visual impairment. Traumatic brain injury (TBI) was the cause of cortical damage in two patients, cerebral ischemia in two patients and carbon monoxide (CO) poisoning, status epilepticus and Alzheimer's Disease (AD) each in three separate patients. The SPECT scans of the seven patients were compared to T2-weighted magnetic resonance image (MRI) scans of the brain to determine the correlation between functional and anatomical findings. In six of the seven patients, the qualitative interpretation of the SPECT studies supported the clinical findings (i.e., the visual field defect) by revealing altered regional cerebral blood flow (rCBF) in the appropriate regions of the visual pathway. MR scans in all of the patients, on the other hand, were either normal or disclosed smaller lesions than those detected by SPECT. We conclude that SPECT may reveal altered rCBF in patients with cortical visual impairment of various etiologies, even when MRI studies are normal or nondiagnostic.

Evaluation of Hospitalized Intractable Epileptic Children with SPECT Scan in Ahvaz, South West of Iran

PubMed Central

Ahmadi, Faramarz; Malekian, Arash; Davoodzadeh, Hannaneh; Kabirinia, Hossein

2016-01-01

Introduction Seizures are the most frequent neurologic disorder seen in childhood. Epilepsy is a group of disorders that includes an abnormally increased susceptibility to seizures. Aim To examine the effectiveness of SPECT (Single Photon Emission Computerized Tomography) in detecting seizure foci in 21 Iranian children who had medically refractory epilepsy. Materials and Methods Children between 2 to 15 years of age with uncontrolled seizures were investigated using SPECT scan as a standardized protocol. Results In 16 cases (76.2%), likely seizure foci were evident, as were seen in the form of decreased regional blood flow, while in 5 cases (23.8%), SPECT scan results were normal. Left temporal lobe was the most common area which had decreased regional blood flow. Conclusion SPECT scan can potentially be used to investigate children with uncontrolled seizures. PMID:27891419

Nuclear medicine and imaging research (quantitative studies in radiopharmaceutical science). Progress report, January 1, 1992--December 31, 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, M.; Beck, R.N.

1992-06-01

This report describes three studies aimed at using radiolabeled pharmaceuticals to explore brain function and anatomy. The first section describes the chemical preparation of [F18]fluorinated benzamides (dopamine D-2 receptor tracers), [F18]fluorinated benzazepines (dopamine D-1 receptor tracers), and tissue distribution of [F18]-fluoxetine (serotonin reuptake site tracer). The second section relates pharmacological and behavioral studies of amphetamines. The third section reports on progress made with processing of brain images from CT, MRI and PET/SPECT with regards to brain metabolism of glucose during mental tasks.

Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina).

PubMed

Portu, Agustina; Postuma, Ian; Gadan, Mario Alberto; Saint Martin, Gisela; Olivera, María Silvina; Altieri, Saverio; Protti, Nicoletta; Bortolussi, Silva

2015-11-01

An inter-comparison of three boron determination techniques was carried out between laboratories from INFN-University of Pavia (Italy) and CNEA (Argentina): alpha spectrometry (alpha-spect), neutron capture radiography (NCR) and quantitative autoradiography (QTA). Samples of different nature were analysed: liquid standards, liver homogenates and tissue samples from different treatment protocols. The techniques showed a good agreement in a concentration range of interest in BNCT (1-100ppm), thus demonstrating their applicability as precise methods to quantify boron and determine its distribution in tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrocardiographic infarct size assessment after thrombolysis: insights from the Acute Myocardial Infarction STudy ADenosine (AMISTAD) trial.

PubMed

Barbagelata, Alejandro; Di Carli, Marcelo F; Califf, Robert M; Garg, Jyotsna; Birnbaum, Yochai; Grinfeld, Liliana; Gibbons, Raymond J; Granger, Christopher B; Goodman, Shaun G; Wagner, Galen S; Mahaffey, Kenneth W

2005-10-01

Noninvasive methods are needed to evaluate reperfusion success in patients with acute myocardial infarction (MI). The AMISTAD trial was analyzed to compare MI size and myocardial salvage determined by electrocardiogram (ECG) with technetium Tc 99m sestamibi single-photon emission computerized tomography (SPECT) imaging. Of 236 patients enrolled in AMISTAD, 166 (70 %) with no ECG confounding factors and no prior MI were included in this analysis. Of these, group 1 (126 patients, 53%) had final infarct size (FIS) available by both ECG and SPECT. Group 2 (56 patients, 24%) had myocardium at risk, FIS, and salvage index (SI) assessed by both SPECT and ECG techniques. Aldrich/Clemmensen scores for myocardium at risk and the Selvester QRS score for final MI size were used. Salvage index was calculated as follows: SI = (myocardium at risk-FIS)/(myocardium at risk). In group 1, FIS was 15% (6, 24) as measured by ECG and 11% (2, 27) as measured by SPECT. In the adenosine group, FIS was 12% (6, 21) and 11% (2, 22). In the placebo group, FIS was 16.5% (7.5, 24) and 11.5% (3.0, 38.5) by ECG and SPECT, respectively. The overall correlation between SPECT and ECG for FIS was 0.58 (P = .0001): 0.60 in the placebo group (P = .0001) and 0.54 (P = .0001) in the adenosine group. In group 2, myocardium at risk was 23% (17, 30) and 26% (10, 50) with ECG and SPECT, respectively (P = .0066). Final infarct size was 17% (6, 21) and 12% (1, 24) (P < .0001). The SI was 29% (-7, 57) and 46% (15, 79) with ECG and SPECT, respectively (P = .0510). The ECG measurement of infarct size has a moderate relationship with SPECT infarct size measurements in the population with available assessments. This ECG algorithm must further be validated on clinical outcomes.

99mTc-MDM Brain SPECT for the Detection of Recurrent/Remnant Glioma-Comparison With ceMRI and 18F-FLT PET Imaging: Initial Results.

PubMed

Singh, Baljinder; Kumar, Narendra; Sharma, Sarika; Watts, Ankit; Hazari, Puja P; Rani, Nisha; Vyas, Sameer; Anish, Bhattacharya; Mishra, Anil K

2015-10-01

To evaluate the diagnostic use of an indigenously developed single vial ready to label (with Tc) kit preparation of bis-methionine-DTPA (Tc-MDM) for the detection of recurrent/residual glioma. We prospectively studied 32 patients (21 male and 11 female subjects aged 43.0±16.0 years) with clinical suspicion of postoperative recurrent/residual glioma. After radical radiotherapy (54.0-60.0 Gy) with or without concurrent temozolomide as indicated, Tc-MDM SPECT and ceMRI of the brain was performed in all the patients and F-FLT-PET imaging in 16 of 32 patients. MDM SPECT and ceMRI findings were concordant in 28 patients (15 positive and 13 negative). The findings were discordant in the remaining 5 patients, with positive ceMRI and negative MDM-SPECT in 2 patients and negative ceMRI and positive MDM-SPECT in 3 patients. Tc-MDM-SPECT, F-FLT PET, and ceMRI scan findings were positive in 9 of 16 and negative in 5 of 16 patients. In the remaining 2 of 16 patients, both F-FLT-PET and Tc-MDM-SPECT were positive, but ceMRI was negative. Sensitivity, specificity, PPV, NPV, and DA of Tc-MDM-SPECT for diagnosing recurrent/residual glioma were 88.24%, 81.25%, 83.3%, 86.7%, and 84.8%, respectively. The diagnostic accuracy of Tc-bis-methionine (MDM)-SPECT imaging was comparable with that of ceMRI and F-FLT-PET and may be useful in the management of glioma patients in the postsurgical follow-up period. This imaging technique may be of special interest in peripheral hospitals/developing countries lacking access to expensive PET/cyclotron technology. However, comparison with the existing "gold standard" PET tracers, especially with C-11-methionine-PET imaging and histopathological correlation, is warranted in a large cohort of glioma patients through multicentric studies.

Comparison of ( sup 99m Tc)HMPAO SPECT with ( sup 18 F)fluoromethane PET in cerebrovascular disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heiss, W.D.; Herholz, K.; Podreka, I.

1990-09-01

Positron emission tomography (PET) of (18F)fluoromethane (FM) and single-photon emission tomography (SPECT) of (99mTc)hexamethylpropyleneamine oxime (HMPAO) were performed under identical conditions within 2 h in 22 patients suffering from cerebrovascular disease (8 ischemic infarction, 2 intracerebral hemorrhages, 7 transient ischemic attacks, and 5 multi-infarct syndrome). While gross pathological changes could be seen in the images of either procedure, focal abnormalities corresponding to transient ischemic deficits or to lesions in multi-infarct syndrome and areas of functional deactivation were sometimes missed on SPECT images. Overall, HMPAO SPECT images showed less contrast between high and low activity regions than the FM PET images,more » and differences between lesions and contralateral regions were less pronounced (6.4 vs 13.3% difference). Regional cerebral blood flow (rCBF) was calculated from FM PET studies in 14 large territorial regions and the pathological lesion, and the regional values relative to mean flow were compared to the relative HMPAO uptake in an identical set of regions defined on the SPECT images. Among individual patients, the Spearman rank-correlation coefficient between relative rCBF and HMPAO uptake varied between 0.48 and 0.89, with a mean of 0.70. While an underestimation of high flow with SPECT--which was demonstrated in a curvilinear relationship between all relative regional PET and SPECT values--could be corrected by linearization taking into account HMPAO efflux from the brain before metabolic trapping, correspondence of SPECT data with PET rCBF values was not improved since this procedure also increased the variance in high flow areas. In the cerebellum, however, a high HMPAO uptake in SPECT always overestimated CBF in relation to forebrain values; this finding might be due to high capillary density in the cerebellum.« less

Functional mechanism of lung mosaic CT attenuation: assessment with deep-inspiration breath-hold perfusion SPECT-CT fusion imaging and non-breath-hold Technegas SPECT.

PubMed

Suga, K; Yasuhiko, K; Iwanaga, H; Tokuda, O; Matsunaga, N

2009-01-01

The functional mechanism of lung mosaic computed tomography attenuation (MCA) in pulmonary vascular disease (PVD) and obstructive airway disease (OAD) has not yet been fully clarified. To clarify the mechanism of MCA in these diseases by assessing the relationship between regional lung function and CT attenuation change at MCA sites with the use of automated deep-inspiratory breath-hold (DIBrH) perfusion single-photon emission computed tomography (SPECT)-CT fusion images and non-breath-hold Technegas SPECT. Subjects were 42 PVD patients (31 pulmonary thromboembolism, four primary/two secondary pulmonary hypertension, and five Takayasu arteritis), 12 OAD patients (five acute asthma, four obliterative bronchiolitis, and three bronchiectasis), and 12 normal controls, all of whom had MCA on DIBrH CT. The relationship between regional lung function and CT attenuation change at the lung slices with MCA was assessed using DIBrH perfusion SPECT-CT fusion images and non-breath-hold Technegas SPECT. The severity of perfusion defects with or without MCA was quantified by regions-of-interest analysis. On DIBrH CT and perfusion SPECT, in contrast to no noticeable CT attenuation abnormality and fairly uniform perfusion in controls, 60 MCA and 274 perfusion defects in PVD patients, and 18 MCA and 61 defects in OAD patients were identified, with a total of 77 ventilation defects on Technegas SPECT in all patients. SPECT-CT correlation showed that, throughout the 78 MCA sites of all patients, lung perfusion was persistently decreased at low CT attenuation and preserved at intervening high CT attenuation, while lung ventilation was poorly correlated with CT attenuation change. The radioactivity ratios of reduced perfusion and the intervening preserved perfusion at the 78 perfusion defects with MCA were significantly lower than those at the remaining 257 defects without MCA (P<0.0001). Although further validation is required, our results indicate that heterogeneous pulmonary arterial perfusion may be a dominant mechanism of MCA in PVD and OAD.

Magnetoencephalography and ictal SPECT in patients with failed epilepsy surgery.

PubMed

El Tahry, Riёm; Wang, Z Irene; Thandar, Aung; Podkorytova, Irina; Krishnan, Balu; Tousseyn, Simon; Guiyun, Wu; Burgess, Richard C; Alexopoulos, Andreas V

2018-06-06

Selected patients with intractable focal epilepsy who have failed a previous epilepsy surgery can become seizure-free with reoperation. Preoperative evaluation is exceedingly challenging in this cohort. We aim to investigate the diagnostic value of two noninvasive approaches, magnetoencephalography (MEG) and ictal single-photon emission computed tomography (SPECT), in patients with failed epilepsy surgery. We retrospectively included a consecutive cohort of patients who failed prior resective epilepsy surgery, underwent re-evaluation including MEG and ictal SPECT, and had another surgery after the re-evaluation. The relationship between resection and localization from each test was determined, and their association with seizure outcomes was analyzed. A total of 46 patients were included; 21 (46%) were seizure-free at 1-year followup after reoperation. Twenty-seven (58%) had a positive MEG and 31 (67%) had a positive ictal SPECT. The resection of MEG foci was significantly associated with seizure-free outcome (p = 0.002). Overlap of ictal SPECT hyperperfusion zones with resection was significantly associated with seizure-free outcome in the subgroup of patients with injection time ≤20 seconds(p = 0.03), but did not show significant association in the overall cohort (p = 0.46) although all injections were ictal. Patients whose MEG and ictal SPECT were concordant on a sublobar level had a significantly higher chance of seizure freedom (p = 0.05). MEG alone achieved successful localization in patients with failed epilepsy surgery with a statistical significance. Only ictal SPECT with early injection (≤20 seconds) had good localization value. Sublobar concordance between both tests was significantly associated with seizure freedom. SPECT can provide essential information in MEG-negative cases and vice versa. Our results emphasize the importance of considering a multimodal presurgical evaluation including MEG and SPECT in all patients with a previous failed epilepsy surgery. Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Assessment of Treatment Response by 99mTc-MIP-1404 SPECT/CT: A Pilot Study in Patients With Metastatic Prostate Cancer.

PubMed

Schmidkonz, Christian; Cordes, Michael; Beck, Michael; Goetz, Theresa Ida; Schmidt, Daniela; Prante, Olaf; Bäuerle, Tobias; Cavallaro, Alexander; Uder, Michael; Wullich, Bernd; Goebell, Peter; Kuwert, Torsten; Ritt, Philipp

2018-06-19

We investigated the role of Tc-MIP-1404 (Progenics Pharmaceuticals, Inc, New York, NY) SPECT/CT of PSMA expression in the assessment of treatment response in patients with metastatic prostate cancer. We retrospectively analyzed Tc-MIP-1404 SPECT/CT scans from 28 patients with metastatic prostate cancer examined before initiation and after completion of therapy. Eight of these patients had been treated with androgen deprivation therapy, 10 with docetaxel, and another 10 with external beam radiotherapy. On the CT images from SPECT/CT, treatment response was assessed according to RECIST 1.1 criteria; independently from that analysis, maximal standardized uptake values (SUVmax) were quantified in representative tumor lesions and treatment response assumed at differences in SUVmax greater than 30%. Radiographic response assessment was correlated to biochemical response (BR) based on prostate-specific antigen serum levels. The concordance rate between SPECT and BR was 75% (95% confidence interval [CI], 0.55-0.89) (Cohen κ = 0.57; 95% CI, 0.29-0.85; P ≤ 0.01), higher than for that between SPECT and CT with 57% (95% CI, 0.37-0.76) (κ = 0.40; 95% CI, 0.14-0.65; P ≤ 0.01), as well as that between CT and BR with 50% (95% CI, 0.31-0.69) (κ = 0.31; 95% CI, 0.06-0.57, P ≤ 0.05). Discordant findings between SPECT and CT were most likely due to limitations of CT in assessing metastases in lymph nodes, as well as bone involvement, which was sometimes not detectable on CT scans. The high agreement between treatment response, as assessed by Tc-MIP-1404 SPECT/CT and BR, suggests a possible role of that imaging tool for monitoring treatment in metastatic prostate cancer. Larger, ideally prospective trials are needed to help to reveal the full potential of SPECT imaging of PSMA expression in that regard.

Added Value of SPECT/CT in the Evaluation of Benign Bone Diseases of the Appendicular Skeleton.

PubMed

Abikhzer, Gad; Srour, Saher; Keidar, Zohar; Bar-Shalom, Rachel; Kagna, Olga; Israel, Ora; Militianu, Daniela

2016-04-01

Bone scintigraphy is a sensitive technique to detect altered bone mineralization but has limited specificity. The use of SPECT/CT has improved significantly the diagnostic accuracy of bone scintigraphy, in patients with cancer as well as in evaluation of benign bone disease. It provides precise localization and characterization of tracer-avid foci, shortens the diagnostic workup, and decreases patient anxiety. Through both the SPECT and the CT components, SPECT/CT has an incremental value in characterizing benign bone lesions, specifically in the appendicular skeleton, as illustrated by present case series.

Improved outcomes using brain SPECT-guided treatment versus treatment-as-usual in community psychiatric outpatients: a retrospective case-control study.

PubMed

Thornton, John F; Schneider, Howard; McLean, Mary K; van Lierop, Muriel J; Tarzwell, Robert

2014-01-01

Brain single-photon emission computed tomography (SPECT) scans indirectly show functional activity via measurement of regional cerebral blood flow. Thirty patients at a community-based psychiatric clinic underwent brain SPECT scans. Changes in scoring of before-treatment and after-treatment scans correlated well with changes in patient Global Assessment of Functioning (GAF) scores before treatment and after treatment. Patients were retrospectively matched with controls with similar diagnoses and pretreatment GAF scores, and those who underwent SPECT-guided treatment improved significantly more than the control patients.

Fabrication of the pinhole aperture for AdaptiSPECT

PubMed Central

Kovalsky, Stephen; Kupinski, Matthew A.; Barrett, Harrison H.; Furenlid, Lars R.

2015-01-01

AdaptiSPECT is a pre-clinical pinhole SPECT imaging system under final construction at the Center for Gamma-Ray Imaging. The system is designed to be able to autonomously change its imaging configuration. The system comprises 16 detectors mounted on translational stages to move radially away and towards the center of the field-of-view. The system also possesses an adaptive pinhole aperture with multiple collimator diameters and pinhole sizes, as well as the possibility to switch between multiplexed and non-multiplexed imaging configurations. In this paper, we describe the fabrication of the AdaptiSPECT pinhole aperture and its controllers. PMID:26146443

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papadimitroulas, P; Kagadis, GC; Loudos, G

Purpose: Our purpose is to evaluate the administered absorbed dose in pediatric, nuclear imaging studies. Monte Carlo simulations with the incorporation of pediatric computational models can serve as reference for the accurate determination of absorbed dose. The procedure of the calculated dosimetric factors is described, while a dataset of reference doses is created. Methods: Realistic simulations were executed using the GATE toolkit and a series of pediatric computational models, developed by the “IT'IS Foundation”. The series of the phantoms used in our work includes 6 models in the range of 5–14 years old (3 boys and 3 girls). Pre-processing techniquesmore » were applied to the images, to incorporate the phantoms in GATE simulations. The resolution of the phantoms was set to 2 mm3. The most important organ densities were simulated according to the GATE “Materials Database”. Several used radiopharmaceuticals in SPECT and PET applications are being tested, following the EANM pediatric dosage protocol. The biodistributions of the several isotopes used as activity maps in the simulations, were derived by the literature. Results: Initial results of absorbed dose per organ (mGy) are presented in a 5 years old girl from the whole body exposure to 99mTc - SestaMIBI, 30 minutes after administration. Heart, kidney, liver, ovary, pancreas and brain are the most critical organs, in which the S-factors are calculated. The statistical uncertainty in the simulation procedure was kept lower than 5%. The Sfactors for each target organ are calculated in Gy/(MBq*sec) with highest dose being absorbed in kidneys and pancreas (9.29*10{sup 10} and 0.15*10{sup 10} respectively). Conclusion: An approach for the accurate dosimetry on pediatric models is presented, creating a reference dosage dataset for several radionuclides in children computational models with the advantages of MC techniques. Our study is ongoing, extending our investigation to other reference models and evaluating the results with clinical estimated doses.« less

Ion-gel-gating-induced oxygen vacancy formation in epitaxial L a0.5S r0.5Co O3 -δ films from in operando x-ray and neutron scattering

NASA Astrophysics Data System (ADS)

Walter, Jeff; Yu, Guichuan; Yu, Biqiong; Grutter, Alexander; Kirby, Brian; Borchers, Julie; Zhang, Zhan; Zhou, Hua; Birol, Turan; Greven, Martin; Leighton, Chris

2017-12-01

Ionic-liquid/gel-based transistors have emerged as a potentially ideal means to accumulate high charge-carrier densities at the surfaces of materials such as oxides, enabling control over electronic phase transitions. Substantial gaps remain in the understanding of gating mechanisms, however, particularly with respect to charge carrier vs oxygen defect creation, one contributing factor being the dearth of experimental probes beyond electronic transport. Here we demonstrate the use of synchrotron hard x-ray diffraction and polarized neutron reflectometry as in operando probes of ion-gel transistors based on ferromagnetic L a0.5S r0.5Co O3 -δ . An asymmetric gate-bias response is confirmed to derive from electrostatic hole accumulation at negative gate bias vs oxygen vacancy formation at positive bias. The latter is detected via a large gate-induced lattice expansion (up to 1%), complementary bulk measurements and density functional calculations enabling quantification of the bias-dependent oxygen vacancy density. Remarkably, the gate-induced oxygen vacancies proliferate through the entire thickness of 30-40-unit-cell-thick films, quantitatively accounting for changes in the magnetization depth profile. These results directly elucidate the issue of electrostatic vs redox-based response in electrolyte-gated oxides, also demonstrating powerful approaches to their in operando investigation.

Comparison of FDG-PET with MIBI-SPECT in the detection of breast cancer and axillary lymph node metastasis.

PubMed

Yutani, K; Shiba, E; Kusuoka, H; Tatsumi, M; Uehara, T; Taguchi, T; Takai, S I; Nishimura, T

2000-01-01

The purpose of this work was to compare [18F]2-deoxy-2-fluoro-D-glucose (FDG) PET and 99mTc-methoxyisobutylisonitrile (MIBI) SPECT in the detection of breast cancer and axillary lymph node metastasis in the same patients. FDG-PET and MIBI-SPECT were performed within 3 days for 40 women (age range 25-86 years old) with suspected breast cancer, in whom biopsies and/or mastectomies were performed. Both images were visually assessed, and the count ratio between tumor and normal tissue (T/N ratio) was calculated. Thirty-eight patients had breast cancer, and the remaining two had benign breast lesions. The sensitivities of FDG-PET and MIBI-SPECT were 78.9 and 76.3% for breast cancer and 50.0 and 37.5% for axillary lymph node metastasis, respectively. The T/N ratio of breast cancer was significantly higher in FDG-PET (6.01 +/- 3.08 mean +/- SD) than that in MIBI-SPECT (3.48 +/- 1.21) (p = 0.01). Nonmalignant diffuse uptake of FDG in the breasts and the accumulation of MIBI in heart and liver occasionally obscured tumor uptake. These results indicate that MIBI-SPECT is comparable with FDG-PET in detecting breast cancer. Neither FDG-PET nor MIBI-SPECT is sufficiently sensitive to rule out axillary lymph node metastasis.

Recovered neuronal viability revealed by Iodine-123-iomazenil SPECT following traumatic brain injury.

PubMed

Koizumi, Hiroyasu; Fujisawa, Hirosuke; Kurokawa, Tetsu; Suehiro, Eiichi; Iwanaga, Hideyuki; Nakagawara, Jyoji; Suzuki, Michiyasu

2010-10-01

We evaluated cortical damages following traumatic brain injury (TBI) in the acute phase with [(123)I] iomazenil (IMZ) single photon emission computed tomography (SPECT). In all, 12 patients with cerebral contusion following TBI were recruited. All patients underwent IMZ SPECT within 1 week after TBI. To investigate the changes in distribution of IMZ in the cortex in the chronic phase, after conventional treatment, patients underwent IMZ SPECT again. A decrease in the accumulation of radioligand for the central benzodiazepine receptor in the cortex corresponding to the contusion revealed with computed tomography (CT) scans and magnetic resonance imaging (MRI) were shown on IMZ SPECT in the acute phase in all patients. In 9 of 12 patients (75%), images of IMZ SPECT obtained in the chronic phase of TBI showed that areas with a decreased distribution of IMZ were remarkably reduced in comparison with those obtained in the acute phase. Both CT scans and MRI showed a normal appearance of the cortex morphologically, where the binding potential of IMZ recovered in the chronic phase. Reduced binding potential of radioligand for the central benzodiazepine receptor is considered to be an irreversible reaction; however, in this study, IMZ accumulation in the cortex following TBI was recovered in the chronic phase in several patients. [(123)I] iomazenil SPECT may have a potential to disclose a reversible vulnerability of neurons following TBI.

Recovered neuronal viability revealed by Iodine-123-iomazenil SPECT following traumatic brain injury

PubMed Central

Koizumi, Hiroyasu; Fujisawa, Hirosuke; Kurokawa, Tetsu; Suehiro, Eiichi; Iwanaga, Hideyuki; Nakagawara, Jyoji; Suzuki, Michiyasu

2010-01-01

We evaluated cortical damages following traumatic brain injury (TBI) in the acute phase with [123I] iomazenil (IMZ) single photon emission computed tomography (SPECT). In all, 12 patients with cerebral contusion following TBI were recruited. All patients underwent IMZ SPECT within 1 week after TBI. To investigate the changes in distribution of IMZ in the cortex in the chronic phase, after conventional treatment, patients underwent IMZ SPECT again. A decrease in the accumulation of radioligand for the central benzodiazepine receptor in the cortex corresponding to the contusion revealed with computed tomography (CT) scans and magnetic resonance imaging (MRI) were shown on IMZ SPECT in the acute phase in all patients. In 9 of 12 patients (75%), images of IMZ SPECT obtained in the chronic phase of TBI showed that areas with a decreased distribution of IMZ were remarkably reduced in comparison with those obtained in the acute phase. Both CT scans and MRI showed a normal appearance of the cortex morphologically, where the binding potential of IMZ recovered in the chronic phase. Reduced binding potential of radioligand for the central benzodiazepine receptor is considered to be an irreversible reaction; however, in this study, IMZ accumulation in the cortex following TBI was recovered in the chronic phase in several patients. [123I] iomazenil SPECT may have a potential to disclose a reversible vulnerability of neurons following TBI. PMID:20683454

Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

NASA Astrophysics Data System (ADS)

Wei, Qingyang; Wang, Shi; Ma, Tianyu; Wu, Jing; Liu, Hui; Xu, Tianpeng; Xia, Yan; Fan, Peng; Lyu, Zhenlei; Liu, Yaqiang

2015-06-01

PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance.

Comparison of SPECT/CT, MRI and CT in diagnosis of skull base bone invasion in nasopharyngeal carcinoma.

PubMed

Zhang, Shu-xu; Han, Peng-hui; Zhang, Guo-qian; Wang, Rui-hao; Ge, Yong-bin; Ren, Zhi-gang; Li, Jian-sheng; Fu, Wen-hai

2014-01-01

Early detection of skull base invasion in nasopharyngeal carcinoma (NPC) is crucial for correct staging, assessing treatment response and contouring the tumor target in radiotherapy planning, as well as improving the patient's prognosis. To compare the diagnostic efficacy of single photon emission computed tomography/computed tomography (SPECT/CT) imaging, magnetic resonance imaging (MRI) and computed tomography (CT) for the detection of skull base invasion in NPC. Sixty untreated patients with histologically proven NPC underwent SPECT/CT imaging, contrast-enhanced MRI and CT. Of the 60 patients, 30 had skull base invasion confirmed by the final results of contrast-enhanced MRI, CT and six-month follow-up imaging (MRI and CT). The diagnostic efficacy of the three imaging modalities in detecting skull base invasion was evaluated. The rates of positive findings of skull base invasion for SPECT/CT, MRI and CT were 53.3%, 48.3% and 33.3%, respectively. The sensitivity, specificity and accuracy were 93.3%, 86.7% and 90.0% for SPECT/CT fusion imaging, 96.7%, 100.0% and 98.3% for contrast-enhanced MRI, and 66.7%, 100.0% and 83.3% for contrast-enhanced CT. MRI showed the best performance for the diagnosis of skull base invasion in nasopharyngeal carcinoma, followed closely by SPECT/CT. SPECT/CT had poorer specificity than that of both MRI and CT, while CT had the lowest sensitivity.

Value of a Lower-Limb Immobilization Device for Optimization of SPECT/CT Image Fusion.

PubMed

Machado, Joana do Mar F; Monteiro, Marina S; Vieira, Victor Fernandes; Collinot, Jean-Aybert; Prior, John O; Vieira, Lina; Pires-Jorge, José A

2015-06-01

The foot and the ankle are small structures commonly affected by disorders, and their complex anatomy represents a significant diagnostic challenge. By providing information on anatomic and bone structure that cannot be obtained from functional imaging, SPECT/CT image fusion can be particularly useful in increasing diagnostic certainty about bone pathology. However, because of the lengthy duration of a SPECT acquisition, a patient's involuntary movements may lead to misalignment between SPECT and CT images. Patient motion can be reduced using a dedicated patient support. We designed an ankle- and foot-immobilizing device and measured its efficacy at improving image fusion. We enrolled 20 patients who underwent SPECT/CT of the ankle and foot with and without a foot support. The misalignment between SPECT and CT images was computed by manually measuring 14 fiducial markers chosen among anatomic landmarks also visible on bone scintigraphy. ANOVA was performed for statistical analysis. The absolute average difference without and with support was 5.1 ± 5.2 mm (mean ± SD) and 3.1 ± 2.7 mm, respectively, which is significant (P < 0.001). The introduction of the foot support significantly decreased misalignment between SPECT and CT images, which may have a positive clinical influence in the precise localization of foot and ankle pathology. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Value of automatic patient motion detection and correction in myocardial perfusion imaging using a CZT-based SPECT camera.

PubMed

van Dijk, Joris D; van Dalen, Jorn A; Mouden, Mohamed; Ottervanger, Jan Paul; Knollema, Siert; Slump, Cornelis H; Jager, Pieter L

2018-04-01

Correction of motion has become feasible on cadmium-zinc-telluride (CZT)-based SPECT cameras during myocardial perfusion imaging (MPI). Our aim was to quantify the motion and to determine the value of automatic correction using commercially available software. We retrospectively included 83 consecutive patients who underwent stress-rest MPI CZT-SPECT and invasive fractional flow reserve (FFR) measurement. Eight-minute stress acquisitions were reformatted into 1.0- and 20-second bins to detect respiratory motion (RM) and patient motion (PM), respectively. RM and PM were quantified and scans were automatically corrected. Total perfusion deficit (TPD) and SPECT interpretation-normal, equivocal, or abnormal-were compared between the noncorrected and corrected scans. Scans with a changed SPECT interpretation were compared with FFR, the reference standard. Average RM was 2.5 ± 0.4 mm and maximal PM was 4.5 ± 1.3 mm. RM correction influenced the diagnostic outcomes in two patients based on TPD changes ≥7% and in nine patients based on changed visual interpretation. In only four of these patients, the changed SPECT interpretation corresponded with FFR measurements. Correction for PM did not influence the diagnostic outcomes. Respiratory motion and patient motion were small. Motion correction did not appear to improve the diagnostic outcome and, hence, the added value seems limited in MPI using CZT-based SPECT cameras.

REVIEW: The early years of single photon emission computed tomography (SPECT): an anthology of selected reminiscences

NASA Astrophysics Data System (ADS)

Jaszczak, Ronald Jack

2006-07-01

The origin of SPECT can be found in pioneering experiments on emission tomography performed approximately 50 years ago. This historical review consists of a compilation of first person recollections from nine trailblazing scientists who shaped the early years of SPECT instrumentation during the 1960s and 1970s.

Sensitivity, stability, and precision of quantitative Ns-LIBS-based fuel-air-ratio measurements for methane-air flames at 1-11 bar.

PubMed

Hsu, Paul S; Gragston, Mark; Wu, Yue; Zhang, Zhili; Patnaik, Anil K; Kiefer, Johannes; Roy, Sukesh; Gord, James R

2016-10-01

Nanosecond laser-induced breakdown spectroscopy (ns-LIBS) is employed for quantitative local fuel-air (F/A) ratio (i.e., ratio of actual fuel-to-oxidizer mass over ratio of fuel-to-oxidizer mass at stoichiometry, measurements in well-characterized methane-air flames at pressures of 1-11 bar). We selected nitrogen and hydrogen atomic-emission lines at 568 nm and 656 nm, respectively, to establish a correlation between the line intensities and the F/A ratio. We have investigated the effects of laser-pulse energy, camera gate delay, and pressure on the sensitivity, stability, and precision of the quantitative ns-LIBS F/A ratio measurements. We determined the optimal laser energy and camera gate delay for each pressure condition and found that measurement stability and precision are degraded with an increase in pressure. We have identified primary limitations of the F/A ratio measurement employing ns-LIBS at elevated pressures as instabilities caused by the higher density laser-induced plasma and the presence of the higher level of soot. Potential improvements are suggested.

Usefulness and pitfalls of MAA SPECT/CT in identifying digestive extrahepatic uptake when planning liver radioembolization.

PubMed

Lenoir, Laurence; Edeline, Julien; Rolland, Yann; Pracht, Marc; Raoul, Jean-Luc; Ardisson, Valérie; Bourguet, Patrick; Clément, Bruno; Boucher, Eveline; Garin, Etienne

2012-05-01

Identifying gastroduodenal uptake of (99m)Tc-macroaggregated albumin (MAA), which is associated with an increased risk of ulcer disease, is a crucial part of the therapeutic management of patients undergoing radioembolization for liver tumours. Given this context, the use of MAA single photon emission computed tomography (SPECT)/CT may be essential, but the procedure has still not been thoroughly evaluated. The aim of this retrospective study was to determine the effectiveness of MAA SPECT/CT in identifying digestive extrahepatic uptake, while determining potential diagnostic pitfalls. Overall, 139 MAA SPECT/CT scans were performed on 103 patients with different hepatic tumour types. Patients were followed up for at least 6 months according to standard requirements. Digestive, or digestive-like, uptake other than free pertechnetate was identified in 5.7% of cases using planar imaging and in 36.6% of cases using SPECT/CT. Uptake sites identified by SPECT/CT included the gastroduodenal region (3.6%), gall bladder (12.2%), portal vein thrombosis (6.5%), hepatic artery (6.5%), coil embolization site (2.1%) as well as falciform artery (5.0%). For 2.1% of explorations, a coregistration error between SPECT and CT imaging could have led to a false diagnosis by erroneously attributing an uptake site to the stomach or gall bladder, when the uptake actually occurred in the liver. SPECT/CT is more efficacious than planar imaging in identifying digestive extrahepatic uptake sites, with extrahepatic uptake observed in one third of scans using the former procedure. However, more than half of the uptake sites in our study were vascular in nature, without therapeutic implications. The risk of coregistration errors must also be kept in mind.

Coregistration of Magnetic Resonance and Single Photon Emission Computed Tomography Images for Noninvasive Localization of Stem Cells Grafted in the Infarcted Rat Myocardium

PubMed Central

Shen, Dinggang; Liu, Dengfeng; Cao, Zixiong; Acton, Paul D.; Zhou, Rong

2008-01-01

This paper demonstrates the application of mutual information based coregistration of radionuclide and magnetic resonance imaging (MRI) in an effort to use multimodality imaging for noninvasive localization of stem cells grafted in the infarcted myocardium in rats. Radionuclide imaging such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) inherently has high sensitivity and is suitable for tracking of labeled stem cells, while high-resolution MRI is able to provide detailed anatomical and functional information of myocardium. Thus, coregistration of PET or SPECT images with MRI will map the location and distribution of stem cells on detailed myocardium structures. To validate this coregistration method, SPECT data were simulated by using a Monte Carlo-based projector that modeled the pinhole-imaging physics assuming nonzero diameter and photon penetration at the edge. Translational and rotational errors of the coregistration were examined with respect to various SPECT activities, and they are on average about 0.50 mm and 0.82°, respectively. Only the rotational error is dependent on activity of SPECT data. Stem cells were labeled with 111 Indium oxyquinoline and grafted in the ischemic myocardium of a rat model. Dual-tracer small-animal SPECT images were acquired, which allowed simultaneous detection of 111In-labeled stem cells and of [99mTc]sestamibi to assess myocardial perfusion deficit. The same animals were subjected to cardiac MRI. A mutual-information-based coregistration method was then applied to the SPECT and MRIs. By coregistration, the 111 In signal from labeled cells was mapped into the akinetic region identified on cine MRIs; the regional perfusion deficit on the SPECT images also coincided with the akinetic region on the MR image. PMID:17053860

Hybrid imaging by SPECT/CT for sentinel lymph node detection in patients with cancer of the uterine cervix.

PubMed

Martínez, A; Zerdoud, S; Mery, E; Bouissou, E; Ferron, G; Querleu, D

2010-12-01

Conventional lymphoscintigraphy provides planar images with little spatial information on location of pelvic sentinel lymph nodes (SLN). SPECT has better spatial resolution and, in combination with anatomic accuracy provided by CT improves SLN preoperative localization. The aim of the study was to report on the results of hybrid imaging of SLN in early cervical cancer patients treated at Claudius Regaud Cancer Center. Stages IA-IB1 cervical cancer patients undergoing preoperative SPECT/CT for SLN detection were analysed. Forty-one patients were included. A 100% SLN detection rate was achieved when a combined technique (radiotracer and blue dye) was used. At least one SLN was clearly visualized by SPECT/CT in 39 of 41 patients (95%) and full anatomic concordance with intraoperative anatomical location of SLN was found in 37 of the 39 patients with at least one SLN identified by SPECT/CT (95%). Location of removed SLN included the external and internal iliac area in 88% patients, the common iliac area in 10.5%, and the inframesenteric para-aortic area in 1.5%. No SLN was found in the infrarenal para-aortic region. Lymph node involvement was identified in 5 patients (12.1%). SLN correctly predicted lymph node involvement in all node-positive patients. However, SPECT/CT failed to identify 1 of the 5 metastatic SLN. SPECT/CT accurately detected preoperative SLN topography and enhanced diagnostic sensitivity of SLN imaging, improving surgical approach to patients with cervical cancer staging. Diagnostic quality of anatomic landmarks of CT images of SPECT/CT could be further improved by the use of contrast injected CT. Copyright © 2010 Elsevier Inc. All rights reserved.

First validation of myocardial flow reserve assessed by dynamic 99mTc-sestamibi CZT-SPECT camera: head to head comparison with 15O-water PET and fractional flow reserve in patients with suspected coronary artery disease. The WATERDAY study.

PubMed

Agostini, Denis; Roule, Vincent; Nganoa, Catherine; Roth, Nathaniel; Baavour, Raphael; Parienti, Jean-Jacques; Beygui, Farzin; Manrique, Alain

2018-07-01

We assessed the feasibility of myocardial blood flow (MBF) and flow reserve (MFR) estimation using dynamic SPECT with a novel CZT camera in patients with stable CAD, in comparison with 15 O-water PET and fractional flow reserve (FFR). Thirty patients were prospectively included and underwent FFR measurements in the main coronary arteries (LAD, LCx, RCA). A stenosis ≥50% was considered obstructive and a FFR abnormal if ≤0.8. All patients underwent a dynamic rest/stress 99m Tc-sestamibi CZT-SPECT and 15 O-water PET for MBF and MFR calculation. Net retention kinetic modeling was applied to SPECT data to estimate global uptake values, and MBF was derived using Leppo correction. Ischemia by PET and CZT-SPECT was considered present if MFR was lower than 2 and 2.1, respectively. CZT-SPECT yielded higher stress and rest MBF compared to PET for global and LAD and LCx territories, but not in RCA territory. MFR was similar in global and each vessel territory for both modalities. The sensitivity, specificity, accuracy, positive and negative predictive value of CZT-SPECT were, respectively, 83.3, 95.8, 93.3, 100 and 85.7% for the detection of ischemia and 58.3, 84.6, 81.1, 36.8 and 93% for the detection of hemodynamically significant stenosis (FFR ≤ 0.8). Dynamic 99m Tc-sestamibi CZT-SPECT was technically feasible and provided similar MFR compared to 15 O-water PET and high diagnostic value for detecting impaired MFR and abnormal FFR in patients with stable CAD.

Invisible Base Electrode Coordinates Approximation for Simultaneous SPECT and EEG Data Visualization

NASA Astrophysics Data System (ADS)

Kowalczyk, L.; Goszczynska, H.; Zalewska, E.; Bajera, A.; Krolicki, L.

2014-04-01

This work was performed as part of a larger research concerning the feasibility of improving the localization of epileptic foci, as compared to the standard SPECT examination, by applying the technique of EEG mapping. The presented study extends our previous work on the development of a method for superposition of SPECT images and EEG 3D maps when these two examinations are performed simultaneously. Due to the lack of anatomical data in SPECT images it is a much more difficult task than in the case of MRI/EEG study where electrodes are visible in morphological images. Using the appropriate dose of radioisotope we mark five base electrodes to make them visible in the SPECT image and then approximate the coordinates of the remaining electrodes using properties of the 10-20 electrode placement system and the proposed nine-ellipses model. This allows computing a sequence of 3D EEG maps spanning on all electrodes. It happens, however, that not all five base electrodes can be reliably identified in SPECT data. The aim of the current study was to develop a method for determining the coordinates of base electrode(s) missing in the SPECT image. The algorithm for coordinates approximation has been developed and was tested on data collected for three subjects with all visible electrodes. To increase the accuracy of the approximation we used head surface models. Freely available model from Oostenveld research based on data from SPM package and our own model based on data from our EEG/SPECT studies were used. For data collected in four cases with one electrode not visible we compared the invisible base electrode coordinates approximation for Oostenveld and our models. The results vary depending on the missing electrode placement, but application of the realistic head model significantly increases the accuracy of the approximation.

Clinical utility of MRI and SPECT in the diagnosis of cognitive impairment referred to memory clinic.

PubMed

Guinane, John; Ng, Boon Lung

2018-05-01

ABSTRACTBackground:Despite of their limited availability and potential for significant variation between and within each modality, this is the first study to prospectively measure the clinical utility of MRI and/or SPECT brain scanning in addition to the routine diagnostic workup of patients presenting to memory clinic. A single center study was conducted over a convenience of 12-month sampling period. For each patient referred for MRI and/or SPECT scanning, the primary geriatrician or psychogeriatrician was asked to assign an initial diagnosis. The initial diagnosis was then compared with the final consensus diagnosis after any scans or neuropsychology testing had been completed. During the 12-month study period, 66 patients (26%) were referred for scans out of a total of 253 patients included in the study. There were 16/44 (36%) positive MRI outcomes and 13/35 (37%) positive SPECT outcomes. The diagnosis changed consistent with the MRI scan findings in 11/44 (25%) and changed consistent with the SPECT scan findings in 9/35 (26%). Potentially reversible pathology was identified in a single patient, 1/50 (2%), via an MRI scan that suggested normal pressure hydrocephalus. The number needed to test for one positive outcome was 3.8 (95% CI 2.0-23.3), 6.0 (95% CI NA), and 1.7 (95% CI 1.3-2.5) for MRI only, SPECT only, and MRI and SPECT together, respectively. The clinical utility of MRI and/or SPECT scanning in this study may be broadly superior to the available international evidence, and further research is needed to identify predictors of positive scan outcomes.

Prospective Evaluation of (99m)Tc-sestamibi SPECT/CT for the Diagnosis of Renal Oncocytomas and Hybrid Oncocytic/Chromophobe Tumors.

PubMed

Gorin, Michael A; Rowe, Steven P; Baras, Alexander S; Solnes, Lilja B; Ball, Mark W; Pierorazio, Phillip M; Pavlovich, Christian P; Epstein, Jonathan I; Javadi, Mehrbod S; Allaf, Mohamad E

2016-03-01

Nuclear imaging offers a potential noninvasive means of determining the histology of renal tumors. The aim of this study was to evaluate the accuracy of technetium-99m ((99m)Tc)-sestamibi single-photon emission computed tomography/x-ray computed tomography (SPECT/CT) for the differentiation of oncocytomas and hybrid oncocytic/chromophobe tumors (HOCTs) from other renal tumor histologies. In total, 50 patients with a solid clinical T1 renal mass were imaged with (99m)Tc-sestamibi SPECT/CT prior to surgical resection. Preoperative SPECT/CT scans were reviewed by two blinded readers, and their results were compared with centrally reviewed surgical pathology data. Following surgery, 6 (12%) tumors were classified as renal oncocytomas and 2 (4%) as HOCTs. With the exception of 1 (2%) angiomyolipoma, all other tumors were renal cell carcinomas (82%). (99m)Tc-sestamibi SPECT/CT correctly identified 5 of 6 (83.3%) oncocytomas and 2 of 2 (100%) HOCTs, resulting in an overall sensitivity of 87.5% (95% confidence interval [CI], 47.4-99.7%). Only two tumors were falsely positive on SPECT/CT, resulting in a specificity of 95.2% (95% CI, 83.8-99.4%). In summary, (99m)Tc-sestamibi SPECT/CT is a promising imaging test for the noninvasive diagnosis of renal oncocytomas and HOCTs. We found that the imaging test (99m)Tc-sestamibi SPECT/CT can be used to accurately diagnose two types of benign kidney tumors. This test may be eventually used to help better evaluate patients diagnosed with a renal tumor. Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.

A 3-dimensional mathematic cylinder phantom for the evaluation of the fundamental performance of SPECT.

PubMed

Onishi, Hideo; Motomura, Nobutoku; Takahashi, Masaaki; Yanagisawa, Masamichi; Ogawa, Koichi

2010-03-01

Degradation of SPECT images results from various physical factors. The primary aim of this study was the development of a digital phantom for use in the characterization of factors that contribute to image degradation in clinical SPECT studies. A 3-dimensional mathematic cylinder (3D-MAC) phantom was devised and developed. The phantom (200 mm in diameter and 200 mm long) comprised 3 imbedded stacks of five 30-mm-long cylinders (diameters, 4, 10, 20, 40, and 60 mm). In simulations, the 3 stacks and the background were assigned radioisotope concentrations and attenuation coefficients. SPECT projection datasets that included Compton scattering effects, photoelectric effects, and gamma-camera models were generated using the electron gamma-shower Monte Carlo simulation program. Collimator parameters, detector resolution, total photons acquired, number of projections acquired, and radius of rotation were varied in simulations. The projection data were formatted in Digital Imaging and Communications in Medicine (DICOM) and imported to and reconstructed using commercial reconstruction software on clinical SPECT workstations. Using the 3D-MAC phantom, we validated that contrast depended on size of region of interest (ROI) and was overestimated when the ROI was small. The low-energy general-purpose collimator caused a greater partial-volume effect than did the low-energy high-resolution collimator, and contrast in the cold region was higher using the filtered backprojection algorithm than using the ordered-subset expectation maximization algorithm in the SPECT images. We used imported DICOM projection data and reconstructed these data using vendor software; in addition, we validated reconstructed images. The devised and developed 3D-MAC SPECT phantom is useful for the characterization of various physical factors, contrasts, partial-volume effects, reconstruction algorithms, and such, that contribute to image degradation in clinical SPECT studies.

Initial Investigation of preclinical integrated SPECT and MR imaging.

PubMed

Hamamura, Mark J; Ha, Seunghoon; Roeck, Werner W; Wagenaar, Douglas J; Meier, Dirk; Patt, Bradley E; Nalcioglu, Orhan

2010-02-01

Single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high-spatial resolution anatomical information as well as complementary functional information. In this study, we utilized a dual modality SPECT/MRI (MRSPECT) system to investigate the integration of SPECT and MRI for improved image accuracy. The MRSPECT system consisted of a cadmium-zinc-telluride (CZT) nuclear radiation detector interfaced with a specialized radiofrequency (RF) coil that was placed within a whole-body 4 T MRI system. The importance of proper corrections for non-uniform detector sensitivity and Lorentz force effects was demonstrated. MRI data were utilized for attenuation correction (AC) of the nuclear projection data and optimized Wiener filtering of the SPECT reconstruction for improved image accuracy. Finally, simultaneous dual-imaging of a nude mouse was performed to demonstrated the utility of co-registration for accurate localization of a radioactive source.

Initial Investigation of Preclinical Integrated SPECT and MR Imaging

PubMed Central

Hamamura, Mark J.; Ha, Seunghoon; Roeck, Werner W.; Wagenaar, Douglas J.; Meier, Dirk; Patt, Bradley E.; Nalcioglu, Orhan

2014-01-01

Single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high-spatial resolution anatomical information as well as complementary functional information. In this study, we utilized a dual modality SPECT/MRI (MRSPECT) system to investigate the integration of SPECT and MRI for improved image accuracy. The MRSPECT system consisted of a cadmium-zinc-telluride (CZT) nuclear radiation detector interfaced with a specialized radiofrequency (RF) coil that was placed within a whole-body 4 T MRI system. The importance of proper corrections for non-uniform detector sensitivity and Lorentz force effects was demonstrated. MRI data were utilized for attenuation correction (AC) of the nuclear projection data and optimized Wiener filtering of the SPECT reconstruction for improved image accuracy. Finally, simultaneous dual-imaging of a nude mouse was performed to demonstrated the utility of co-registration for accurate localization of a radioactive source. PMID:20082527

Upsets in Erased Floating Gate Cells With High-Energy Protons

DOE PAGES

Gerardin, S.; Bagatin, M.; Paccagnella, A.; ...

2017-01-01

We discuss upsets in erased floating gate cells, due to large threshold voltage shifts, using statistical distributions collected on a large number of memory cells. The spread in the neutral threshold voltage appears to be too low to quantitatively explain the experimental observations in terms of simple charge loss, at least in SLC devices. The possibility that memories exposed to high energy protons and heavy ions exhibit negative charge transfer between programmed and erased cells is investigated, although the analysis does not provide conclusive support to this hypothesis.

A case of Cotard syndrome: (123)I-IBZM SPECT imaging of striatal D(2) receptor binding.

PubMed

De Risio, Sergio; De Rossi, Giuseppe; Sarchiapone, Marco; Camardese, Giovanni; Carli, Vladimir; Cuomo, Chiara; Satta, Maria Antonietta; Di Giuda, Daniela

2004-01-15

A case of 'dèlire de nègation' that suddenly appeared in a 43-year-old male is presented. No alteration in regional cerebral blood, as measured by (99m)Tc-HMPAO-SPECT, was found, but (123)I-IBZM-SPECT analysis showed reduced striatal D(2) receptor binding that further decreased after treatment.

Review of two years of experiences with SPECT among psychiatric patients in a rural hospital setting.

PubMed

Sheehan, William; Thurber, Steven

2008-09-01

We summarize single proton emission computed tomography (SPECT) findings from 63 psychiatric patients in a small rural hospital in western Minnesota. SPECT scans were ordered only for patients in whom documentation of hypoperfusion and functional deficits might be helpful in clarifying diagnoses and treatment planning. The patients referred for SPECT scans had histories of traumatic brain injuries, atypical psychiatric symptom presentations, or conditions that were refractory to standard treatments. In the context of strict referral guidelines and close psychiatrist-radiologist collaboration, a much higher yield of significant findings was obtained compared with those noted in other reports in the literature.

Technetium-99m-HMPAO SPECT in the evaluation of patients with a remote history of traumatic brain injury: a comparison with x-ray computed tomography.

PubMed

Gray, B G; Ichise, M; Chung, D G; Kirsh, J C; Franks, W

1992-01-01

The functional imaging modality has potential for demonstrating parenchymal abnormalities not detectable by traditional morphological imaging. Fifty-three patients with a remote history of traumatic brain injury (TBI) were studied with SPECT using 99mTc-hexamethylpropyleneamineoxime (HMPAO) and x-ray computed tomography (CT). Overall, 42 patients (80%) showed regional cerebral blood flow (rCBF) deficits by HMPAO SPECT, whereas 29 patients (55%) showed morphological abnormalities by CT. Out of 20 patients with minor head injury, 12 patients (60%) showed rCBF deficits and 5 patients (25%) showed CT abnormalities. Of 33 patients with major head injury, 30 patients (90%) showed rCBF deficits and 24 patients (72%) showed CT abnormalities. Thus, HMPAO SPECT was more sensitive than CT in detecting abnormalities in patients with a history of TBI, particularly in the minor head injury group. In the major head injury group, three patients showed localized cortical atrophy by CT and normal rCBF by HMPAO SPECT. In the evaluation of TBI patients, HMPAO SPECT is a useful technique to demonstrate regional brain dysfunction in the presence of morphological integrity as assessed by CT.

Design and evaluation of corn starch-bonded Rhizophora spp. particleboard phantoms for SPECT/CT imaging

NASA Astrophysics Data System (ADS)

Hamid, Puteri Nor Khatijah Abd; Yusof, Mohd Fahmi Mohd; Aziz Tajuddin, Abd; Hashim, Rokiah; Zainon, Rafidah

2018-01-01

The aim of this study was to design and evaluate of corn starch-bonded Rhizophora spp. particleboards as phantom for SPECT/CT imaging. The phantom was designed according to the Jaszczak phantom commonly used in SPECT imaging with dimension of 22 cm diameter and 18 cm length. Six inserts with different diameter were made for insertion of vials filled with 1.6 µCi/ml of 99mTc unsealed source. The particleboard phantom was scanned using SPECT/CT imaging protocol. The contrast of each vial for particleboards phantom were calculated based on the ratio of counts in radionuclide volume and phantom background and compared to Perspex® and water phantom. The results showed that contrast values for each vial in particleboard phantomis near to 1.0 and in good agreement with Perspex® and water phantoms as common phantom materials for SPECT/CT. The paired sample t-test result showed no significant difference of contrast values between images in particleboard phantoms and that in water. The overall results showed the potential of corn starch-bonded Rhizophora spp. as phantom for quality control and dosimetry works in SPECT/CT imaging.

Implementation of GPU accelerated SPECT reconstruction with Monte Carlo-based scatter correction.

PubMed

Bexelius, Tobias; Sohlberg, Antti

2018-06-01

Statistical SPECT reconstruction can be very time-consuming especially when compensations for collimator and detector response, attenuation, and scatter are included in the reconstruction. This work proposes an accelerated SPECT reconstruction algorithm based on graphics processing unit (GPU) processing. Ordered subset expectation maximization (OSEM) algorithm with CT-based attenuation modelling, depth-dependent Gaussian convolution-based collimator-detector response modelling, and Monte Carlo-based scatter compensation was implemented using OpenCL. The OpenCL implementation was compared against the existing multi-threaded OSEM implementation running on a central processing unit (CPU) in terms of scatter-to-primary ratios, standardized uptake values (SUVs), and processing speed using mathematical phantoms and clinical multi-bed bone SPECT/CT studies. The difference in scatter-to-primary ratios, visual appearance, and SUVs between GPU and CPU implementations was minor. On the other hand, at its best, the GPU implementation was noticed to be 24 times faster than the multi-threaded CPU version on a normal 128 × 128 matrix size 3 bed bone SPECT/CT data set when compensations for collimator and detector response, attenuation, and scatter were included. GPU SPECT reconstructions show great promise as an every day clinical reconstruction tool.

Structure-based membrane dome mechanism for Piezo mechanosensitivity.

PubMed

Guo, Yusong R; MacKinnon, Roderick

2017-12-12

Mechanosensitive ion channels convert external mechanical stimuli into electrochemical signals for critical processes including touch sensation, balance, and cardiovascular regulation. The best understood mechanosensitive channel, MscL, opens a wide pore, which accounts for mechanosensitive gating due to in-plane area expansion. Eukaryotic Piezo channels have a narrow pore and therefore must capture mechanical forces to control gating in another way. We present a cryo-EM structure of mouse Piezo1 in a closed conformation at 3.7Å-resolution. The channel is a triskelion with arms consisting of repeated arrays of 4-TM structural units surrounding a pore. Its shape deforms the membrane locally into a dome. We present a hypothesis in which the membrane deformation changes upon channel opening. Quantitatively, membrane tension will alter gating energetics in proportion to the change in projected area under the dome. This mechanism can account for highly sensitive mechanical gating in the setting of a narrow, cation-selective pore. © 2017, Guo et al.

Sci—Thur AM: YIS - 03: irtGPUMCD: a new GPU-calculated dosimetry code for {sup 177}Lu-octreotate radionuclide therapy of neuroendocrine tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montégiani, Jean-François; Gaudin, Émilie; Després, Philippe

2014-08-15

In peptide receptor radionuclide therapy (PRRT), huge inter-patient variability in absorbed radiation doses per administered activity mandates the utilization of individualized dosimetry to evaluate therapeutic efficacy and toxicity. We created a reliable GPU-calculated dosimetry code (irtGPUMCD) and assessed {sup 177}Lu-octreotate renal dosimetry in eight patients (4 cycles of approximately 7.4 GBq). irtGPUMCD was derived from a brachytherapy dosimetry code (bGPUMCD), which was adapted to {sup 177}Lu PRRT dosimetry. Serial quantitative single-photon emission computed tomography (SPECT) images were obtained from three SPECT/CT acquisitions performed at 4, 24 and 72 hours after {sup 177}Lu-octreotate administration, and registered with non-rigid deformation of CTmore » volumes, to obtain {sup 177}Lu-octreotate 4D quantitative biodistribution. Local energy deposition from the β disintegrations was assumed. Using Monte Carlo gamma photon transportation, irtGPUMCD computed dose rate at each time point. Average kidney absorbed dose was obtained from 1-cm{sup 3} VOI dose rate samples on each cortex, subjected to a biexponential curve fit. Integration of the latter time-dose rate curve yielded the renal absorbed dose. The mean renal dose per administered activity was 0.48 ± 0.13 Gy/GBq (range: 0.30–0.71 Gy/GBq). Comparison to another PRRT dosimetry code (VRAK: Voxelized Registration and Kinetics) showed fair accordance with irtGPUMCD (11.4 ± 6.8 %, range: 3.3–26.2%). These results suggest the possibility to use the irtGPUMCD code in order to personalize administered activity in PRRT. This could allow improving clinical outcomes by maximizing per-cycle tumor doses, without exceeding the tolerable renal dose.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this exciting imaging modality can be fully integrated into the evaluationmore » of pathologic processes. The first half was devoted to a consideration of technical factors important in SPECT acquisition and the second half was devoted to those organ systems about which sufficient clinical SPECT imaging data are available. With respect to the technical aspect of the program we have selected the key areas which demand awareness and attention in order to make SPECT operational in clinical practice. These include selection of equipment, details of uniformity correction, utilization of phantoms for equipment acceptance and quality assurance, the major aspect of algorithms, an understanding of filtered back projection and appropriate choice of filters and an awareness of the most commonly generated artifacts and how to recognize them. With respect to the acquisition and interpretation of organ images, the faculty will present information on the major aspects of hepatic, brain, cardiac, skeletal, and immunologic imaging techniques. Individual papers are processed separately for the data base. (TEM)« less

Radiopharmaceuticals for SPECT cancer detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chernov, V. I., E-mail: chernov@oncology.tomsk.ru; Medvedeva, A. A., E-mail: tickayaAA@oncology.tomsk.ru; Zelchan, R. V., E-mail: r.zelchan@yandex.ru

2016-08-02

The purpose of the study was to assess the efficacy of single photon emission computed tomography (SPECT) with {sup 199}Tl and {sup 99}mTc-MIBI in the detection of breast, laryngeal and hypopharyngeal cancers. A total of 220 patients were included into the study: 120 patients with breast lesions (100 patients with breast cancer and 20 patients with benign breast tumors) and 100 patients with laryngeal/hypopharyngeal diseases (80 patients with laryngeal/hypopharyngeal cancer and 20 patients with benign laryngeal/hypopharyngeal lesions). No abnormal {sup 199}Tl uptake was seen in all patients with benign breast and laryngeal lesions, indicating a 100% specificity of {sup 199}Tlmore » SPECT. In the breast cancer patients, the increased {sup 199}Tl uptake in the breast was visualized in 94.8% patients, {sup 99m}Tc-MIBI—in 93.4% patients. The increased {sup 199}Tl uptake in axillary lymph nodes was detected in 60% patients, and {sup 99m}Tc-MIBI—in 93.1% patients. In patients with laryngeal/hypopharyngeal cancer, the sensitivity of SPECT with {sup 199}Tl and {sup 99m}Tc-MIBI was 95%. The {sup 199}Tl SPECT sensitivity in identification of regional lymph node metastases in the patients with laryngeal/hypopharyngeal cancer was 75% and the {sup 99m}Tc-MIBI SPECT sensitivity was 17%. The data obtained showed that SPECT with {sup 199}Tl and {sup 99m}Tc-MIBI can be used as one of the additional imaging methods in detection of tumors.« less

An evaluation of data-driven motion estimation in comparison to the usage of external-surrogates in cardiac SPECT imaging

PubMed Central

Mukherjee, Joyeeta Mitra; Hutton, Brian F; Johnson, Karen L; Pretorius, P Hendrik; King, Michael A

2014-01-01

Motion estimation methods in single photon emission computed tomography (SPECT) can be classified into methods which depend on just the emission data (data-driven), or those that use some other source of information such as an external surrogate. The surrogate-based methods estimate the motion exhibited externally which may not correlate exactly with the movement of organs inside the body. The accuracy of data-driven strategies on the other hand is affected by the type and timing of motion occurrence during acquisition, the source distribution, and various degrading factors such as attenuation, scatter, and system spatial resolution. The goal of this paper is to investigate the performance of two data-driven motion estimation schemes based on the rigid-body registration of projections of motion-transformed source distributions to the acquired projection data for cardiac SPECT studies. Comparison is also made of six intensity based registration metrics to an external surrogate-based method. In the data-driven schemes, a partially reconstructed heart is used as the initial source distribution. The partially-reconstructed heart has inaccuracies due to limited angle artifacts resulting from using only a part of the SPECT projections acquired while the patient maintained the same pose. The performance of different cost functions in quantifying consistency with the SPECT projection data in the data-driven schemes was compared for clinically realistic patient motion occurring as discrete pose changes, one or two times during acquisition. The six intensity-based metrics studied were mean-squared difference (MSD), mutual information (MI), normalized mutual information (NMI), pattern intensity (PI), normalized cross-correlation (NCC) and entropy of the difference (EDI). Quantitative and qualitative analysis of the performance is reported using Monte-Carlo simulations of a realistic heart phantom including degradation factors such as attenuation, scatter and system spatial resolution. Further the visual appearance of motion-corrected images using data-driven motion estimates was compared to that obtained using the external motion-tracking system in patient studies. Pattern intensity and normalized mutual information cost functions were observed to have the best performance in terms of lowest average position error and stability with degradation of image quality of the partial reconstruction in simulations. In all patients, the visual quality of PI-based estimation was either significantly better or comparable to NMI-based estimation. Best visual quality was obtained with PI-based estimation in 1 of the 5 patient studies, and with external-surrogate based correction in 3 out of 5 patients. In the remaining patient study there was little motion and all methods yielded similar visual image quality. PMID:24107647

Respiratory-gated CT as a tool for the simulation of breathing artifacts in PET and PET/CT.

PubMed

Hamill, J J; Bosmans, G; Dekker, A

2008-02-01

Respiratory motion in PET and PET/CT blurs the images and can cause attenuation-related errors in quantitative parameters such as standard uptake values. In rare instances, this problem even causes localization errors and the disappearance of tumors that should be detectable. Attenuation errors are severe near the diaphragm and can be enhanced when the attenuation correction is based on a CT series acquired during a breath-hold. To quantify the errors and identify the parameters associated with them, the authors performed a simulated PET scan based on respiratory-gated CT studies of five lung cancer patients. Diaphragmatic motion ranged from 8 to 25 mm in the five patients. The CT series were converted to 511-keV attenuation maps which were forward-projected and exponentiated to form sinograms of PET attenuation factors at each phase of respiration. The CT images were also segmented to form a PET object, moving with the same motion as the CT series. In the moving PET object, spherical 20 mm mobile tumors were created in the vicinity of the dome of the liver and immobile 20 mm tumors in the midchest region. The moving PET objects were forward-projected and attenuated, then reconstructed in several ways: phase-matched PET and CT, gated PET with ungated CT, ungated PET with gated CT, and conventional PET. Spatial resolution and statistical noise were not modeled. In each case, tumor uptake recovery factor was defined by comparing the maximum reconstructed pixel value with the known correct value. Mobile 10 and 30 mm tumors were also simulated in the case of a patient with 11 mm of breathing motion. Phase-matched gated PET and CT gave essentially perfect PET reconstructions in the simulation. Gated PET with ungated CT gave tumors of the correct shape, but recovery was too large by an amount that depended on the extent of the motion, as much as 90% for mobile tumors and 60% for immobile tumors. Gated CT with ungated PET resulted in blurred tumors and caused recovery errors between -50% and +75%. Recovery in clinical scans would be 0%-20% lower than stated because spatial resolution was not included in the simulation. Mobile tumors near the dome of the liver were subject to the largest errors in either case. Conventional PET for 20 mm tumors was quantitative in cases of motion less than 15 mm because of canceling errors in blurring and attenuation, but the recovery factors were too low by as much as 30% in cases of motion greater than 15 mm. The 10 mm tumors were blurred by motion to a greater extent, causing a greater SUV underestimation than in the case of 20 mm tumors, and the 30 mm tumors were blurred less. Quantitative PET imaging near the diaphragm requires proper matching of attenuation information to the emission information. The problem of missed tumors near the diaphragm can be reduced by acquiring attenuation-correction information near end expiration. A simple PET/CT protocol requiring no gating equipment also addresses this problem.

Genetic Circuit Performance under Conditions Relevant for Industrial Bioreactors

PubMed Central

Moser, Felix; Broers, Nicolette J.; Hartmans, Sybe; Tamsir, Alvin; Kerkman, Richard; Roubos, Johannes A.; Bovenberg, Roel; Voigt, Christopher A.

2014-01-01

Synthetic genetic programs promise to enable novel applications in industrial processes. For such applications, the genetic circuits that compose programs will require fidelity in varying and complex environments. In this work, we report the performance of two synthetic circuits in Escherichia coli under industrially relevant conditions, including the selection of media, strain, and growth rate. We test and compare two transcriptional circuits: an AND and a NOR gate. In E. coli DH10B, the AND gate is inactive in minimal media; activity can be rescued by supplementing the media and transferring the gate into the industrial strain E. coli DS68637 where normal function is observed in minimal media. In contrast, the NOR gate is robust to media composition and functions similarly in both strains. The AND gate is evaluated at three stages of early scale-up: 100 ml shake-flask experiments, a 1 ml MTP microreactor, and a 10 L bioreactor. A reference plasmid that constitutively produces a GFP reporter is used to make comparisons of circuit performance across conditions. The AND gate function is quantitatively different at each scale. The output deteriorates late in fermentation after the shift from exponential to constant feed rates, which induces rapid resource depletion and changes in growth rate. In addition, one of the output states of the AND gate failed in the bioreactor, effectively making it only responsive to a single input. Finally, cells carrying the AND gate show considerably less accumulation of biomass. Overall, these results highlight challenges and suggest modified strategies for developing and characterizing genetic circuits that function reliably during fermentation. PMID:23656232

Validation of the Spatial Accuracy of the ExacTracRTM Adaptive Gating System

NASA Astrophysics Data System (ADS)

Twork, Gregory

Stereotactic body radiation therapy (SBRT) is a method of treatment that is used in extracranial locations, including the abdominal and thoracic cavities, as well as spinal and paraspinal locations. At the McGill University Health Centre, liver SBRT treatments include gating, which places the treatment beam on a duty cycle controlled by tracking of fiducial markers moving with the patient's breathing cycle. Respiratory gated treatments aim to spare normal tissue, while delivering a dose properly to a moving target. The ExacTracRTM system (BrainLAB AG Germany) is an image-guided radiotherapy system consisting of a combination of infra-red (IR) cameras and dual kilovoltage (kV) X-ray tubes. The IR system is used to track patient positioning and respiratory motion, while the kV X-rays are used to determine a positional shift based on internal anatomy or fiducial markers. In order to validate the system's ability to treat under gating conditions, each step of the SBRT process was evaluated quantitatively. Initially the system was tested under ideal static conditions, followed by a study including gated parameters. The uncertainties of the isocenters, positioning algorithm, planning computed tomography (CT) and four dimensional CT (4DCT) scans, gating window size and tumor motion were evaluated for their contributions to the total uncertainty in treatment. The mechanical isocenter and 4DCT were found to be the largest sources of uncertainty. However, for tumors with large internal amplitudes (>2.25 cm) that are treated with large gating windows (>30%) the gating parameters can contribute more than 1.1 +/- 1.8 mm.

Measurement of absolute myocardial blood flow in humans using dynamic cardiac SPECT and 99mTc-tetrofosmin: Method and validation

DOE PAGES

Shrestha, Uttam; Sciammarella, Maria; Alhassen, Fares; ...

2015-12-29

The objective of this study was to measure myocardial blood flow (MBF) in humans using 99mTc-tetrofosmin and dynamic single-photon emission computed tomography (SPECT). Dynamic SPECT using 99mTc-tetrofosmin and dynamic positron emission tomography (PET) was performed on a group of 16 patients. The SPECT data were reconstructed using a 4D-spatiotemporal iterative reconstruction method. The data corresponding to 9 patients were used to determine the flow-extraction curve for 99mTc-tefrofosmin while data from the remaining 7 patients were used for method validation. The nonlinear tracer correction parameters A and B for 99mTc-tefrofosmin were estimated for the 9 patients by fitting the flow-extraction curvemore » K 1 = F(1–Aexp(–B/F)) for K 1 values estimated with 99mTc-tefrofosmin using SPECT and MBF values estimated with 13N-NH 3 using PET. These parameters were then used to calculate MBF and coronary flow reserve (CFR) in three coronary territories (LAD, RCA, and LCX) using SPECT for an independent cohort of 7 patients. The results were then compared with that estimated with 13N-NH 3 PET. The flow-dependent permeability surface-area product (PS) for 99mTc-tefrofosmin was also estimated. The estimated flow-extraction parameters for 99mTc-tefrofosmin were found to be A = 0.91 ± 0.11, B = 0.34 ± 0.20 (R 2 = 0.49). The range of MBF in LAD, RCA, and LCX was 0.44-3.81 mL/min/g. The MBF between PET and SPECT in the group of independent cohort of 7 patients showed statistically significant correlation, r = 0.71 (P < .001). However, the corresponding CFR correlation was moderate r = 0.39 yet statistically significant (P = .037). The PS for 99mTc-tefrofosmin was (0.019 ± 0.10)*MBF + (0.32 ± 0.16). Dynamic cardiac SPECT using 99mTc-tetrofosmin and a clinical two-headed SPECT/CT scanner can be a useful tool for estimation of MBF.« less

Measurement of absolute myocardial blood flow in humans using dynamic cardiac SPECT and 99mTc-tetrofosmin: Method and validation.

PubMed

Shrestha, Uttam; Sciammarella, Maria; Alhassen, Fares; Yeghiazarians, Yerem; Ellin, Justin; Verdin, Emily; Boyle, Andrew; Seo, Youngho; Botvinick, Elias H; Gullberg, Grant T

2017-02-01

The objective of this study was to measure myocardial blood flow (MBF) in humans using 99m Tc-tetrofosmin and dynamic single-photon emission computed tomography (SPECT). Dynamic SPECT using 99m Tc-tetrofosmin and dynamic positron emission tomography (PET) was performed on a group of 16 patients. The SPECT data were reconstructed using a 4D-spatiotemporal iterative reconstruction method. The data corresponding to 9 patients were used to determine the flow-extraction curve for 99m Tc-tefrofosmin while data from the remaining 7 patients were used for method validation. The nonlinear tracer correction parameters A and B for 99m Tc-tefrofosmin were estimated for the 9 patients by fitting the flow-extraction curve [Formula: see text] for K 1 values estimated with 99m Tc-tefrofosmin using SPECT and MBF values estimated with 13 N-NH 3 using PET. These parameters were then used to calculate MBF and coronary flow reserve (CFR) in three coronary territories (LAD, RCA, and LCX) using SPECT for an independent cohort of 7 patients. The results were then compared with that estimated with 13 N-NH 3 PET. The flow-dependent permeability surface-area product (PS) for 99m Tc-tefrofosmin was also estimated. The estimated flow-extraction parameters for 99m Tc-tefrofosmin were found to be A = 0.91 ± 0.11, B = 0.34 ± 0.20 (R 2  = 0.49). The range of MBF in LAD, RCA, and LCX was 0.44-3.81 mL/min/g. The MBF between PET and SPECT in the group of independent cohort of 7 patients showed statistically significant correlation, r = 0.71 (P < .001). However, the corresponding CFR correlation was moderate r = 0.39 yet statistically significant (P = .037). The PS for 99m Tc-tefrofosmin was (0.019 ± 0.10)*MBF + (0.32 ± 0.16). Dynamic cardiac SPECT using 99m Tc-tetrofosmin and a clinical two-headed SPECT/CT scanner can be a useful tool for estimation of MBF.

Measurement of Absolute Myocardial Blood Flow in Humans Using Dynamic Cardiac SPECT and 99mTc-tetrofosmin: Method and Validation

PubMed Central

Shrestha, Uttam; Sciammarella, Maria; Alhassen, Fares; Yeghiazarians, Yerem; Ellin, Justin; Verdin, Emily; Boyle, Andrew; Seo, Youngho; Botvinick, Elias H.; Gullberg, Grant T.

2015-01-01

Background The objective of this study was to measure myocardial blood flow (MBF) in humans using 99mTc-tetrofosmin and dynamic single photon emission computed tomography (SPECT). Methods Dynamic SPECT using 99mTc-tetrofosmin and dynamic positron emission tomography (PET) was performed on a group of 16 patients. The SPECT data were reconstructed using a 4D-spatiotemporal iterative reconstruction method. The data corresponding to 9 patients were used to determine the flow-extraction curve for 99mTc-tefrofosmin while data from the remaining 7 patients were used for method validation. The nonlinear tracer correction parameters A and B for 99mTc-tefrofosmin were estimated for the 9 patients by fitting the flow-extraction curve K1=F(1−Aexp(−BF)) for K1 values estimated with 99mTc-tefrofosmin using SPECT and MBF values estimated with 13N-NH3 using PET. These parameters were then used to calculate MBF and coronary flow reserve (CFR) in three coronary territories (LAD, RCA, and LCX) using SPECT for an independent cohort of 7 patients. The results were then compared with that estimated with 13N-NH3 PET. The flow dependent permeability surface-area product (PS) for 99mTc-tefrofosmin was also estimated. Results The estimated flow extraction parameters for 99mTc-tefrofosmin was found to be A=0.91±0.11, B=0.34±0.20 (R2 = 0.49). The range of MBF in LAD, RCA, and LCX was 0.44 ml/min/g to 3.81 ml/min/g. The MBF between PET and SPECT in the group of independent cohort of 7 patients showed statistically significant correlation, r = 0.71 (p < 0.001). However, the corresponding CFR correlation was moderate r = 0.39 yet statistically significant (p = 0.037). The PS for 99mTc-tefrofosmin was (0.091 ± 0.10) * MBF = (0.32 ± 0.16). Conclusions Dynamic cardiac SPECT using 99mTc-tetrofosmin and a clinical two-headed SPECT/CT scanner can be a useful tool for estimation of MBF. PMID:26715603

Measurement of absolute myocardial blood flow in humans using dynamic cardiac SPECT and 99mTc-tetrofosmin: Method and validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, Uttam; Sciammarella, Maria; Alhassen, Fares

The objective of this study was to measure myocardial blood flow (MBF) in humans using 99mTc-tetrofosmin and dynamic single-photon emission computed tomography (SPECT). Dynamic SPECT using 99mTc-tetrofosmin and dynamic positron emission tomography (PET) was performed on a group of 16 patients. The SPECT data were reconstructed using a 4D-spatiotemporal iterative reconstruction method. The data corresponding to 9 patients were used to determine the flow-extraction curve for 99mTc-tefrofosmin while data from the remaining 7 patients were used for method validation. The nonlinear tracer correction parameters A and B for 99mTc-tefrofosmin were estimated for the 9 patients by fitting the flow-extraction curvemore » K 1 = F(1–Aexp(–B/F)) for K 1 values estimated with 99mTc-tefrofosmin using SPECT and MBF values estimated with 13N-NH 3 using PET. These parameters were then used to calculate MBF and coronary flow reserve (CFR) in three coronary territories (LAD, RCA, and LCX) using SPECT for an independent cohort of 7 patients. The results were then compared with that estimated with 13N-NH 3 PET. The flow-dependent permeability surface-area product (PS) for 99mTc-tefrofosmin was also estimated. The estimated flow-extraction parameters for 99mTc-tefrofosmin were found to be A = 0.91 ± 0.11, B = 0.34 ± 0.20 (R 2 = 0.49). The range of MBF in LAD, RCA, and LCX was 0.44-3.81 mL/min/g. The MBF between PET and SPECT in the group of independent cohort of 7 patients showed statistically significant correlation, r = 0.71 (P < .001). However, the corresponding CFR correlation was moderate r = 0.39 yet statistically significant (P = .037). The PS for 99mTc-tefrofosmin was (0.019 ± 0.10)*MBF + (0.32 ± 0.16). Dynamic cardiac SPECT using 99mTc-tetrofosmin and a clinical two-headed SPECT/CT scanner can be a useful tool for estimation of MBF.« less

TH-C-17A-06: A Hardware Implementation and Evaluation of Robotic SPECT: Toward Molecular Imaging Onboard Radiation Therapy Machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, S; Touch, M; Bowsher, J

Purpose: To construct a robotic SPECT system and demonstrate its capability to image a thorax phantom on a radiation therapy flat-top couch. The system has potential for on-board functional and molecular imaging in radiation therapy. Methods: A robotic SPECT imaging system was developed utilizing a Digirad 2020tc detector and a KUKA KR150-L110 robot. An imaging study was performed with the PET CT Phantom, which includes 5 spheres: 10, 13, 17, 22 and 28 mm in diameter. Sphere-tobackground concentration ratio was 6:1 of Tc99m. The phantom was placed on a flat-top couch. SPECT projections were acquired with a parallel-hole collimator andmore » a single pinhole collimator. The robotic system navigated the detector tracing the flat-top table to maintain the closest possible proximity to the phantom. For image reconstruction, detector trajectories were described by six parameters: radius-of-rotation, x and z detector shifts, and detector rotation θ, tilt ϕ and twist γ. These six parameters were obtained from the robotic system by calibrating the robot base and tool coordinates. Results: The robotic SPECT system was able to maneuver parallel-hole and pinhole collimated SPECT detectors in close proximity to the phantom, minimizing impact of the flat-top couch on detector-to-COR (center-ofrotation) distance. In acquisitions with background at 1/6th sphere activity concentration, photopeak contamination was heavy, yet the 17, 22, and 28 mm diameter spheres were readily observed with the parallel hole imaging, and the single, targeted sphere (28 mm diameter) was readily observed in the pinhole region-of-interest (ROI) imaging. Conclusion: Onboard SPECT could be achieved by a robot maneuvering a SPECT detector about patients in position for radiation therapy on a flat-top couch. The robot inherent coordinate frame could be an effective means to estimate detector pose for use in SPECT image reconstruction. PHS/NIH/NCI grant R21-CA156390-01A1.« less

Evaluation of the irising effect of a slow-gating intensified charge-coupled device on laser-induced incandescence measurements of soot

NASA Astrophysics Data System (ADS)

Shaddix, Christopher R.; Williams, Timothy C.

2009-03-01

Intensified charge-coupled devices (ICCDs) are used extensively in many scientific and engineering environments to image weak or temporally short optical events. To optimize the quantum efficiency of light collection, many of these devices are chosen to have characteristic intensifier gate times that are relatively slow, on the order of tens of nanoseconds. For many measurements associated with nanosecond laser sources, such as scattering-based diagnostics and most laser-induced fluorescence applications, the signals rise and decay sufficiently fast during and after the laser pulse that the intensifier gate may be set to close after the cessation of the signal and still effectively reject interferences associated with longer time scales. However, the relatively long time scale and complex temporal response of laser-induced incandescence (LII) of nanometer-sized particles (such as soot) offer a difficult challenge to the use of slow-gating ICCDs for quantitative measurements. In this paper, ultraviolet Rayleigh scattering imaging is used to quantify the irising effect of a slow-gating scientific ICCD camera, and an analysis is conducted of LII image data collected with this camera as a function of intensifier gate width. The results demonstrate that relatively prompt LII detection, generally desirable to minimize the influences of particle size and local gas pressure and temperature on measurements of the soot volume fraction, is strongly influenced by the irising effect of slow-gating ICCDs.

Retooling Laser Speckle Contrast Analysis Algorithm to Enhance Non-Invasive High Resolution Laser Speckle Functional Imaging of Cutaneous Microcirculation

NASA Astrophysics Data System (ADS)

Gnyawali, Surya C.; Blum, Kevin; Pal, Durba; Ghatak, Subhadip; Khanna, Savita; Roy, Sashwati; Sen, Chandan K.

2017-01-01

Cutaneous microvasculopathy complicates wound healing. Functional assessment of gated individual dermal microvessels is therefore of outstanding interest. Functional performance of laser speckle contrast imaging (LSCI) systems is compromised by motion artefacts. To address such weakness, post-processing of stacked images is reported. We report the first post-processing of binary raw data from a high-resolution LSCI camera. Sharp images of low-flowing microvessels were enabled by introducing inverse variance in conjunction with speckle contrast in Matlab-based program code. Extended moving window averaging enhanced signal-to-noise ratio. Functional quantitative study of blood flow kinetics was performed on single gated microvessels using a free hand tool. Based on detection of flow in low-flow microvessels, a new sharp contrast image was derived. Thus, this work presents the first distinct image with quantitative microperfusion data from gated human foot microvasculature. This versatile platform is applicable to study a wide range of tissue systems including fine vascular network in murine brain without craniotomy as well as that in the murine dorsal skin. Importantly, the algorithm reported herein is hardware agnostic and is capable of post-processing binary raw data from any camera source to improve the sensitivity of functional flow data above and beyond standard limits of the optical system.

Retooling Laser Speckle Contrast Analysis Algorithm to Enhance Non-Invasive High Resolution Laser Speckle Functional Imaging of Cutaneous Microcirculation

PubMed Central

Gnyawali, Surya C.; Blum, Kevin; Pal, Durba; Ghatak, Subhadip; Khanna, Savita; Roy, Sashwati; Sen, Chandan K.

2017-01-01

Cutaneous microvasculopathy complicates wound healing. Functional assessment of gated individual dermal microvessels is therefore of outstanding interest. Functional performance of laser speckle contrast imaging (LSCI) systems is compromised by motion artefacts. To address such weakness, post-processing of stacked images is reported. We report the first post-processing of binary raw data from a high-resolution LSCI camera. Sharp images of low-flowing microvessels were enabled by introducing inverse variance in conjunction with speckle contrast in Matlab-based program code. Extended moving window averaging enhanced signal-to-noise ratio. Functional quantitative study of blood flow kinetics was performed on single gated microvessels using a free hand tool. Based on detection of flow in low-flow microvessels, a new sharp contrast image was derived. Thus, this work presents the first distinct image with quantitative microperfusion data from gated human foot microvasculature. This versatile platform is applicable to study a wide range of tissue systems including fine vascular network in murine brain without craniotomy as well as that in the murine dorsal skin. Importantly, the algorithm reported herein is hardware agnostic and is capable of post-processing binary raw data from any camera source to improve the sensitivity of functional flow data above and beyond standard limits of the optical system. PMID:28106129

Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

NASA Astrophysics Data System (ADS)

Ford, N. L.; Martin, E. L.; Lewis, J. F.; Veldhuizen, R. A. W.; Holdsworth, D. W.; Drangova, M.

2009-04-01

Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

Validation of GATE Monte Carlo simulations of the GE Advance/Discovery LS PET scanners.

PubMed

Schmidtlein, C Ross; Kirov, Assen S; Nehmeh, Sadek A; Erdi, Yusuf E; Humm, John L; Amols, Howard I; Bidaut, Luc M; Ganin, Alex; Stearns, Charles W; McDaniel, David L; Hamacher, Klaus A

2006-01-01

The recently developed GATE (GEANT4 application for tomographic emission) Monte Carlo package, designed to simulate positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanners, provides the ability to model and account for the effects of photon noncollinearity, off-axis detector penetration, detector size and response, positron range, photon scatter, and patient motion on the resolution and quality of PET images. The objective of this study is to validate a model within GATE of the General Electric (GE) Advance/Discovery Light Speed (LS) PET scanner. Our three-dimensional PET simulation model of the scanner consists of 12 096 detectors grouped into blocks, which are grouped into modules as per the vendor's specifications. The GATE results are compared to experimental data obtained in accordance with the National Electrical Manufactures Association/Society of Nuclear Medicine (NEMA/SNM), NEMA NU 2-1994, and NEMA NU 2-2001 protocols. The respective phantoms are also accurately modeled thus allowing us to simulate the sensitivity, scatter fraction, count rate performance, and spatial resolution. In-house software was developed to produce and analyze sinograms from the simulated data. With our model of the GE Advance/Discovery LS PET scanner, the ratio of the sensitivities with sources radially offset 0 and 10 cm from the scanner's main axis are reproduced to within 1% of measurements. Similarly, the simulated scatter fraction for the NEMA NU 2-2001 phantom agrees to within less than 3% of measured values (the measured scatter fractions are 44.8% and 40.9 +/- 1.4% and the simulated scatter fraction is 43.5 +/- 0.3%). The simulated count rate curves were made to match the experimental curves by using deadtimes as fit parameters. This resulted in deadtime values of 625 and 332 ns at the Block and Coincidence levels, respectively. The experimental peak true count rate of 139.0 kcps and the peak activity concentration of 21.5 kBq/cc were matched by the simulated results to within 0.5% and 0.1% respectively. The simulated count rate curves also resulted in a peak NECR of 35.2 kcps at 10.8 kBq/cc compared to 37.6 kcps at 10.0 kBq/cc from averaged experimental values. The spatial resolution of the simulated scanner matched the experimental results to within 0.2 mm.

Comparative Evaluation of Preprocessing Freeware on Chromatography/Mass Spectrometry Data for Signature Discovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coble, Jamie B.; Fraga, Carlos G.

2014-07-07

Preprocessing software is crucial for the discovery of chemical signatures in metabolomics, chemical forensics, and other signature-focused disciplines that involve analyzing large data sets from chemical instruments. Here, four freely available and published preprocessing tools known as metAlign, MZmine, SpectConnect, and XCMS were evaluated for impurity profiling using nominal mass GC/MS data and accurate mass LC/MS data. Both data sets were previously collected from the analysis of replicate samples from multiple stocks of a nerve-agent precursor. Each of the four tools had their parameters set for the untargeted detection of chromatographic peaks from impurities present in the stocks. The peakmore » table generated by each preprocessing tool was analyzed to determine the number of impurity components detected in all replicate samples per stock. A cumulative set of impurity components was then generated using all available peak tables and used as a reference to calculate the percent of component detections for each tool, in which 100% indicated the detection of every component. For the nominal mass GC/MS data, metAlign performed the best followed by MZmine, SpectConnect, and XCMS with detection percentages of 83, 60, 47, and 42%, respectively. For the accurate mass LC/MS data, the order was metAlign, XCMS, and MZmine with detection percentages of 80, 45, and 35%, respectively. SpectConnect did not function for the accurate mass LC/MS data. Larger detection percentages were obtained by combining the top performer with at least one of the other tools such as 96% by combining metAlign with MZmine for the GC/MS data and 93% by combining metAlign with XCMS for the LC/MS data. In terms of quantitative performance, the reported peak intensities had average absolute biases of 41, 4.4, 1.3 and 1.3% for SpectConnect, metAlign, XCMS, and MZmine, respectively, for the GC/MS data. For the LC/MS data, the average absolute biases were 22, 4.5, and 3.1% for metAlign, MZmine, and XCMS, respectively. In summary, metAlign performed the best in terms of peak discovery; however, more than one preprocessing tool should be considered to avoid missing potential chemical signatures.« less

High Resolution Spatio Temporal Moments Analysis of Solute Migration Captured using Pre-clinical Medical Imaging Techniques

NASA Astrophysics Data System (ADS)

Dogan, M.; Moysey, S. M.; Powell, B. A.; DeVol, T. A.

2016-12-01

Advances in medical imaging technologies are continuously expanding the range of applications enabled within the earth sciences. While computed x-ray tomography (CT) scans have traditionally been used for investigating the structure of geologic materials, it is now possible to perform 3D time-lapse imaging of dynamic processes, such as monitoring the infiltration of water into a soil, with sub-millimeter resolution. Likewise, single photon emission computed tomography (SPECT) can provide information on the evolution of solute transport with spatial resolution on the order of a millimeter by tracking the migration of gamma-ray emitting isotopes like 99mTc and 111In. While these imaging techniques are revolutionizing our ability to look within porous media, techniques for the analysis of such rich and large data sets are limited. The spatial and temporal moments of a plume have long been used to provide quantitative measures to describe plume movement in a wide range of settings from the lab to field. Moment analysis can also be used to estimate the hydrologic properties of the porous media. In this research, we investigate the use of moments for analyzing a high resolution 4D SPECT data set collected during a 99mTc transport experiment performed in a heterogeneous column. The 4D nature of the data set makes it amenable to the use of data mining and pattern recognition methods, such as cluster analysis, to identify regions or zones within the data that exhibit abnormal or unexpected behaviors. We then compare anomalous features within the SPECT data to similar features identified within the CT image to relate the flow behavior to pore-scale structures, such as porosity differences and macropores. Such comparisons help to identify whether these features are good predictors of preferential transport. Likewise, we evaluate whether local analysis of moments can be used to infer apparent parameters governing non-conservative transport in a heterogeneous porous media, such as hydraulic conductivity, mass transfer coefficients, and geochemical reaction rates. Our work suggests that the combination of CT and SPECT imaging can provide useful insights into flow and transport processes that may contradict traditional assumptions regarding one-dimensional flow within a laboratory column.

Photo-guided sentinel node mapping in breast cancer using marker-free photo-gamma fusion lymphoscintigraphy.

PubMed

Lee, Eun Seong; Chun, In Kook; Ha, Seunggyun; Yoon, Hai-Jeon; Jung, So-Youn; Lee, Seeyoun; Kim, Seok Won; Lee, Eun Sook; Kim, Taeyoon; Kim, Kwang Gi; Lee, Byung Il; Kim, Tae Sung; Kim, Seok-Ki

2013-03-01

Photo-gamma fusion lymphoscintigraphy (PGFLS) was developed by overlying a conventional planar gamma image on a photograph for the guidance of sentinel node biopsy. The feasibility and accuracy of PGFLS was assessed in breast cancer patients. A digital camera and a gamma camera were coordinated to obtain photograph and gamma images from the same angle. Using the distance to the object and calibration acquisition with a flat phantom and radioactive markers, PGFLS was performed both in phantom and in patients without fiducial markers. Marker-free PGFLS was verified using flat phantom, anthropomorphic phantom with markers simulating sentinel nodes and breast cancer patients. In addition, the depth of the radioactive marker or sentinel node was calculated using two gamma images taken at right angles. The feasibility and accuracy of PGFLS were assessed in terms of mismatch errors of co-registration and depth with reference to the data from SPECT/CT. The mismatch error was less than 6 mm in the flat phantom image at a distance from 50 to 62 cm without misalignment. In the anthropomorphic phantom study, co-registration error was 0.42 ± 0.29 cm; depth error was 0.51 ± 0.37 cm, which was well correlated with the reference value on SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.99, p < 0.01; depth: R(2) = 0.99, p < 0.01). In ten patients with breast cancer referred for lympho-SPECT/CT, PGFSL enabled photo-guided sentinel lymph node mapping with acceptable accuracy (co-registration error, 0.47 ± 0.24 cm; depth error, 1.20 ±0.41 cm). The results from PGFSL showed close correlation with those from SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.98, p < 0.01; depth: R(2) = 0.77, p < 0.01). The novel and convenient PGFLS technique is clinically feasible, showing acceptable accuracy and providing additional visual and quantitative information for sentinel lymph node mapping. This approach will facilitate photo-guided sentinel lymph node dissection in breast cancer.

Toward a practical template-based approach to semiquantitative SPECT myocardial perfusion imaging.

PubMed

Hughes, Tyler; Celler, Anna

2012-03-01

Our template-based quantitative perfusion single photon emission computed tomography (SPECT) method (T-QPS) performs semiquantitative analysis for myocardial perfusion imaging (MPI) without the use of normal databases. However, in its current form, T-QPS requires extensive calculations, which limits its clinical application. In the interest of clinical feasibility, the authors examine the trade-off between accuracy and processing time as the method is simplified. The T-QPS method uses the reconstructed SPECT image of the patient to create a 3D digital template of his∕her healthy heart. This template is then projected, reconstructed, and sampled into the bulls-eye map domain. A ratio of the patient and template images produces a final corrected image in which a threshold is applied to identify perfusion defects. In principle, the template should be constructed with the heart and all extracardiac activity, and the projection step should include primary and scatter components; however, this leads to lengthy calculations. In an attempt to shorten the processing time, the authors analyzed the performance of four template (T) generation methods: T(P-HRT), T(PS-HRT), T(P-HRTBKG), and T(PS-HRTBKG), where P and S represent primary and scattered photons included in the projection step, respectively; and HRT and HRTBKG represent template constructed with the heart only and the heart with background activity, respectively. Forty-eight thorax phantoms and 21 randomly selected patient studies were analyzed using each approach. All studies used GE's Infinia Hawkeye SPECT∕CT system and followed a standard cardiac acquisition protocol. Approximate processing times for the T(P-HRT), T(PS-HRT), T(P-HRTBKG), and T(PS-HRTBKG) methods were less than a minute, 2-3 h, less than a minute and 3-4 h, respectively. In both the simulation and patient studies, a significant reduction in the quality of perfusion defect definition was exhibited by the T(P-HRT) method relative to the other three methods. The optimal method with respect to perfusion defect definition and processing time was T(P-HRTBKG) with a sensitivity, specificity, and accuracy in spatially defining the perfusion defects (simulation study) of 80%, 84%, and 83%, respectively. The T-QPS method using T(P-HRTBKG) leads to accurate and fast semiquantitative analysis of SPECT MPI, without the use of normal databases.

Reconstruction of multiple-pinhole micro-SPECT data using origin ensembles.

PubMed

Lyon, Morgan C; Sitek, Arkadiusz; Metzler, Scott D; Moore, Stephen C

2016-10-01

The authors are currently developing a dual-resolution multiple-pinhole microSPECT imaging system based on three large NaI(Tl) gamma cameras. Two multiple-pinhole tungsten collimator tubes will be used sequentially for whole-body "scout" imaging of a mouse, followed by high-resolution (hi-res) imaging of an organ of interest, such as the heart or brain. Ideally, the whole-body image will be reconstructed in real time such that data need only be acquired until the area of interest can be visualized well-enough to determine positioning for the hi-res scan. The authors investigated the utility of the origin ensemble (OE) algorithm for online and offline reconstructions of the scout data. This algorithm operates directly in image space, and can provide estimates of image uncertainty, along with reconstructed images. Techniques for accelerating the OE reconstruction were also introduced and evaluated. System matrices were calculated for our 39-pinhole scout collimator design. SPECT projections were simulated for a range of count levels using the MOBY digital mouse phantom. Simulated data were used for a comparison of OE and maximum-likelihood expectation maximization (MLEM) reconstructions. The OE algorithm convergence was evaluated by calculating the total-image entropy and by measuring the counts in a volume-of-interest (VOI) containing the heart. Total-image entropy was also calculated for simulated MOBY data reconstructed using OE with various levels of parallelization. For VOI measurements in the heart, liver, bladder, and soft-tissue, MLEM and OE reconstructed images agreed within 6%. Image entropy converged after ∼2000 iterations of OE, while the counts in the heart converged earlier at ∼200 iterations of OE. An accelerated version of OE completed 1000 iterations in <9 min for a 6.8M count data set, with some loss of image entropy performance, whereas the same dataset required ∼79 min to complete 1000 iterations of conventional OE. A combination of the two methods showed decreased reconstruction time and no loss of performance when compared to conventional OE alone. OE-reconstructed images were found to be quantitatively and qualitatively similar to MLEM, yet OE also provided estimates of image uncertainty. Some acceleration of the reconstruction can be gained through the use of parallel computing. The OE algorithm is useful for reconstructing multiple-pinhole SPECT data and can be easily modified for real-time reconstruction.

Hemimegalencephaly: Clinical, EEG, neuroimaging, and IMP-SPECT correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konkol, R.J.; Maister, B.H.; Wells, R.G.

1990-11-01

Iofetamine-single photon emission computed tomography (IMP-SPECT) was performed on 2 girls (5 1/2 and 6 years of age) with histories of intractable seizures, developmental delay, and unilateral hemiparesis secondary to hemimegalencephaly. Electroencephalography (EEG) revealed frequent focal discharges in 1 patient, while a nearly continuous burst suppression pattern over the malformed hemisphere was recorded in the other. IMP-SPECT demonstrated a good correlation with neuroimaging studies. In spite of the different EEG patterns, which had been proposed to predict contrasting clinical outcomes, both IMP-SPECT scans disclosed a similar decrease in tracer uptake in the malformed hemisphere. These results are consistent with themore » pattern of decreased tracer uptake found in other interictal studies of focal seizures without cerebral malformations. In view of recent recommendations for hemispherectomy in these patients, we suggest that the IMP-SPECT scan be used to compliment EEG as a method to define the extent of abnormality which may be more relevant to long-term prognosis than EEG alone.« less

Case Report: SPECT/CT as the New Diagnostic Tool for Specific Wrist Pathology.

PubMed

Linde, Musters; Ten Broek, M; Kraan, G A

2017-01-01

Single photon emission computed tomography has been introduced as a promising new diagnostic tool in orthopaedic pathology since the early 90'. Computed tomography, the combined with SPECT, gives insight in the specific sight of wrist pathology. Literature already supports introduction of SPECT/CT in wrist pathology, but clinical application is lagging. A 40yr old patient reported first in 2004 with persisting pain after a right distal radius fracture. Several diagnostics and operative interventions were performed, all unsuccessful. Because of the persisting pain a SPECT-CT was performed which showed a cyst in the hamate bone, which was successfully enucleated. The patient was finally pain free at recent follow-up. With a QDash-score of 43 and a PRW (H) E-DLV-score of 58/150. In this case report, SPECT/CT proved a very sensitive diagnostic tool for specific pathology of the wrist. It offered precise localisation and thereby the clinically suspected diagnosis was confirmed and the patient successfully treated.