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Sample records for 4d pet images

  1. Optimized PET imaging for 4D treatment planning in radiotherapy: the virtual 4D PET strategy.

    PubMed

    Gianoli, Chiara; Riboldi, Marco; Fontana, Giulia; Giri, Maria G; Grigolato, Daniela; Ferdeghini, Marco; Cavedon, Carlo; Baroni, Guido

    2015-02-01

    The purpose of the study is to evaluate the performance of a novel strategy, referred to as "virtual 4D PET", aiming at the optimization of hybrid 4D CT-PET scan for radiotherapy treatment planning. The virtual 4D PET strategy applies 4D CT motion modeling to avoid time-resolved PET image acquisition. This leads to a reduction of radioactive tracer administered to the patient and to a total acquisition time comparable to free-breathing PET studies. The proposed method exploits a motion model derived from 4D CT, which is applied to the free-breathing PET to recover respiratory motion and motion blur. The free-breathing PET is warped according to the motion model, in order to generate the virtual 4D PET. The virtual 4D PET strategy was tested on images obtained from a 4D computational anthropomorphic phantom. The performance was compared to conventional motion compensated 4D PET. Tests were also carried out on clinical 4D CT-PET scans coming from seven lung and liver cancer patients. The virtual 4D PET strategy was able to recover lesion motion, with comparable performance with respect to the motion compensated 4D PET. The compensation of the activity blurring due to motion was successfully achieved in terms of spill out removal. Specific limitations were highlighted in terms of partial volume compensation. Results on clinical 4D CT-PET scans confirmed the efficacy in 4D PET count statistics optimization, as equal to the free-breathing PET, and recovery of lesion motion. Compared to conventional motion compensation strategies that explicitly require 4D PET imaging, the virtual 4D PET strategy reduces clinical workload and computational costs, resulting in significant advantages for radiotherapy treatment planning.

  2. Respiratory motion correction in 4D-PET by simultaneous motion estimation and image reconstruction (SMEIR)

    NASA Astrophysics Data System (ADS)

    Kalantari, Faraz; Li, Tianfang; Jin, Mingwu; Wang, Jing

    2016-08-01

    In conventional 4D positron emission tomography (4D-PET), images from different frames are reconstructed individually and aligned by registration methods. Two issues that arise with this approach are as follows: (1) the reconstruction algorithms do not make full use of projection statistics; and (2) the registration between noisy images can result in poor alignment. In this study, we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) methods for motion estimation/correction in 4D-PET. A modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM-TV) was used to obtain a primary motion-compensated PET (pmc-PET) from all projection data, using Demons derived deformation vector fields (DVFs) as initial motion vectors. A motion model update was performed to obtain an optimal set of DVFs in the pmc-PET and other phases, by matching the forward projection of the deformed pmc-PET with measured projections from other phases. The OSEM-TV image reconstruction was repeated using updated DVFs, and new DVFs were estimated based on updated images. A 4D-XCAT phantom with typical FDG biodistribution was generated to evaluate the performance of the SMEIR algorithm in lung and liver tumors with different contrasts and different diameters (10-40 mm). The image quality of the 4D-PET was greatly improved by the SMEIR algorithm. When all projections were used to reconstruct 3D-PET without motion compensation, motion blurring artifacts were present, leading up to 150% tumor size overestimation and significant quantitative errors, including 50% underestimation of tumor contrast and 59% underestimation of tumor uptake. Errors were reduced to less than 10% in most images by using the SMEIR algorithm, showing its potential in motion estimation/correction in 4D-PET.

  3. 4D MR and attenuation map generation in PET/MR imaging using 4D PET derived deformation matrices: a feasibility study for lung cancer applications.

    PubMed

    Fayad, Hadi; Schmidt, Holger; Kuestner, Thomas; Visvikis, Dimitris

    2016-10-13

    Respiratory motion may reduce accuracy in fusion of functional and anatomical images using combined Positron emission tomography / Magnetic resonance (PET/MR) systems. Methodologies for the correction of respiratory motion in PET acquisitions using such systems are mostly based on the use of respiratory synchronized MR acquisitions to derive motion fields. Existing approaches based on tagging acquisitions may introduce artifacts in the MR images, while motion model approaches require the acquisition of training datasets. The objective of this work was to investigate the possibility of generating 4D MR images and associated attenuation maps (AMs) from a single static MR image combined with motion fields obtained from simultaneously acquired 4D non-attenuation corrected (NAC) PET images.

  4. SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

    SciTech Connect

    Cui, Y; Bowsher, J; Yan, S; Cai, J; Das, S; Yin, F

    2014-06-01

    Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with {sup 18}F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medical Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy.

  5. 4D PET iterative deconvolution with spatiotemporal regularization for quantitative dynamic PET imaging.

    PubMed

    Reilhac, Anthonin; Charil, Arnaud; Wimberley, Catriona; Angelis, Georgios; Hamze, Hasar; Callaghan, Paul; Garcia, Marie-Paule; Boisson, Frederic; Ryder, Will; Meikle, Steven R; Gregoire, Marie-Claude

    2015-09-01

    Quantitative measurements in dynamic PET imaging are usually limited by the poor counting statistics particularly in short dynamic frames and by the low spatial resolution of the detection system, resulting in partial volume effects (PVEs). In this work, we present a fast and easy to implement method for the restoration of dynamic PET images that have suffered from both PVE and noise degradation. It is based on a weighted least squares iterative deconvolution approach of the dynamic PET image with spatial and temporal regularization. Using simulated dynamic [(11)C] Raclopride PET data with controlled biological variations in the striata between scans, we showed that the restoration method provides images which exhibit less noise and better contrast between emitting structures than the original images. In addition, the method is able to recover the true time activity curve in the striata region with an error below 3% while it was underestimated by more than 20% without correction. As a result, the method improves the accuracy and reduces the variability of the kinetic parameter estimates calculated from the corrected images. More importantly it increases the accuracy (from less than 66% to more than 95%) of measured biological variations as well as their statistical detectivity.

  6. Enhancing ejection fraction measurement through 4D respiratory motion compensation in cardiac PET imaging.

    PubMed

    Tang, Jing; Wang, Xinhui; Gao, Xiangzhen; Segars, Paul; Lodge, Martin; Rahmim, Arman

    2017-03-02

    ECG gated cardiac PET imaging measures functional parameters such as left ventricle (LV) ejection fraction (EF), providing diagnostic and prognostic information for management of patients with coronary artery disease (CAD). Respiratory motion degrades spatial resolution and affects the accuracy in measuring the LV volumes for EF calculation. The goal of this study is to systematically investigate the effect of respiratory motion correction on the estimation of end-diastolic volume (EDV), end-systolic volume (ESV), and EF, especially on the separation of normal and abnormal EFs. We developed a respiratory motion incorporated 4D PET image reconstruction technique which uses all gated-frame data to acquire a motion-suppressed image. Using the standard XCAT phantom and two individual-specific volunteer XCAT phantoms, we simulated dual-gated myocardial perfusion imaging data for normally and abnormally beating hearts. With and without respiratory motion correction, we measured the EDV, ESV, and EF from the cardiac gated reconstructed images. For all the phantoms, the estimated volumes increased and the biases significantly reduced with motion correction compared with those without. Furthermore, the improvement of ESV measurement in the abnormally beating heart led to better separation of normal and abnormal EFs. The simulation study demonstrated the significant effect of respiratory motion correction on cardiac imaging data with motion amplitude as small as 0.7 cm. The larger the motion amplitude the more improvement respiratory motion correction brought about on the measurement of EF. Using data-driven respiratory gating, we also demonstrated the effect of respiratory motion correction on estimation of the above functional parameters from list mode patient data. Respiratory motion correction is shown to improve the accuracy of EF measurement in clinical cardiac PET imaging.

  7. Whole-body direct 4D parametric PET imaging employing nested generalized Patlak expectation-maximization reconstruction

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Nicolas A.; Casey, Michael E.; Lodge, Martin A.; Rahmim, Arman; Zaidi, Habib

    2016-08-01

    Whole-body (WB) dynamic PET has recently demonstrated its potential in translating the quantitative benefits of parametric imaging to the clinic. Post-reconstruction standard Patlak (sPatlak) WB graphical analysis utilizes multi-bed multi-pass PET acquisition to produce quantitative WB images of the tracer influx rate K i as a complimentary metric to the semi-quantitative standardized uptake value (SUV). The resulting K i images may suffer from high noise due to the need for short acquisition frames. Meanwhile, a generalized Patlak (gPatlak) WB post-reconstruction method had been suggested to limit K i bias of sPatlak analysis at regions with non-negligible 18F-FDG uptake reversibility; however, gPatlak analysis is non-linear and thus can further amplify noise. In the present study, we implemented, within the open-source software for tomographic image reconstruction platform, a clinically adoptable 4D WB reconstruction framework enabling efficient estimation of sPatlak and gPatlak images directly from dynamic multi-bed PET raw data with substantial noise reduction. Furthermore, we employed the optimization transfer methodology to accelerate 4D expectation-maximization (EM) convergence by nesting the fast image-based estimation of Patlak parameters within each iteration cycle of the slower projection-based estimation of dynamic PET images. The novel gPatlak 4D method was initialized from an optimized set of sPatlak ML-EM iterations to facilitate EM convergence. Initially, realistic simulations were conducted utilizing published 18F-FDG kinetic parameters coupled with the XCAT phantom. Quantitative analyses illustrated enhanced K i target-to-background ratio (TBR) and especially contrast-to-noise ratio (CNR) performance for the 4D versus the indirect methods and static SUV. Furthermore, considerable convergence acceleration was observed for the nested algorithms involving 10-20 sub-iterations. Moreover, systematic reduction in K i % bias and improved TBR were

  8. WE-AB-204-09: Respiratory Motion Correction in 4D-PET by Simultaneous Motion Estimation and Image Reconstruction (SMEIR)

    SciTech Connect

    Kalantari, F; Wang, J; Li, T; Jin, M

    2015-06-15

    Purpose: In conventional 4D-PET, images from different frames are reconstructed individually and aligned by registration methods. Two issues with these approaches are: 1) Reconstruction algorithms do not make full use of all projections statistics; and 2) Image registration between noisy images can Result in poor alignment. In this study we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) method for cone beam CT for motion estimation/correction in 4D-PET. Methods: Modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM- TV) is used to obtain a primary motion-compensated PET (pmc-PET) from all projection data using Demons derived deformation vector fields (DVFs) as initial. Motion model update is done to obtain an optimal set of DVFs between the pmc-PET and other phases by matching the forward projection of the deformed pmc-PET and measured projections of other phases. Using updated DVFs, OSEM- TV image reconstruction is repeated and new DVFs are estimated based on updated images. 4D XCAT phantom with typical FDG biodistribution and a 10mm diameter tumor was used to evaluate the performance of the SMEIR algorithm. Results: Image quality of 4D-PET is greatly improved by the SMEIR algorithm. When all projections are used to reconstruct a 3D-PET, motion blurring artifacts are present, leading to a more than 5 times overestimation of the tumor size and 54% tumor to lung contrast ratio underestimation. This error reduced to 37% and 20% for post reconstruction registration methods and SMEIR respectively. Conclusion: SMEIR method can be used for motion estimation/correction in 4D-PET. The statistics is greatly improved since all projection data are combined together to update the image. The performance of the SMEIR algorithm for 4D-PET is sensitive to smoothness control parameters in the DVF estimation step.

  9. Impact of CT attenuation correction method on quantitative respiratory-correlated (4D) PET/CT imaging

    SciTech Connect

    Nyflot, Matthew J.; Lee, Tzu-Cheng; Alessio, Adam M.; Kinahan, Paul E.; Wollenweber, Scott D.; Stearns, Charles W.; Bowen, Stephen R.

    2015-01-15

    Purpose: Respiratory-correlated positron emission tomography (PET/CT) 4D PET/CT is used to mitigate errors from respiratory motion; however, the optimal CT attenuation correction (CTAC) method for 4D PET/CT is unknown. The authors performed a phantom study to evaluate the quantitative performance of CTAC methods for 4D PET/CT in the ground truth setting. Methods: A programmable respiratory motion phantom with a custom movable insert designed to emulate a lung lesion and lung tissue was used for this study. The insert was driven by one of five waveforms: two sinusoidal waveforms or three patient-specific respiratory waveforms. 3DPET and 4DPET images of the phantom under motion were acquired and reconstructed with six CTAC methods: helical breath-hold (3DHEL), helical free-breathing (3DMOT), 4D phase-averaged (4DAVG), 4D maximum intensity projection (4DMIP), 4D phase-matched (4DMATCH), and 4D end-exhale (4DEXH) CTAC. Recovery of SUV{sub max}, SUV{sub mean}, SUV{sub peak}, and segmented tumor volume was evaluated as RC{sub max}, RC{sub mean}, RC{sub peak}, and RC{sub vol}, representing percent difference relative to the static ground truth case. Paired Wilcoxon tests and Kruskal–Wallis ANOVA were used to test for significant differences. Results: For 4DPET imaging, the maximum intensity projection CTAC produced significantly more accurate recovery coefficients than all other CTAC methods (p < 0.0001 over all metrics). Over all motion waveforms, ratios of 4DMIP CTAC recovery were 0.2 ± 5.4, −1.8 ± 6.5, −3.2 ± 5.0, and 3.0 ± 5.9 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. In comparison, recovery coefficients for phase-matched CTAC were −8.4 ± 5.3, −10.5 ± 6.2, −7.6 ± 5.0, and −13.0 ± 7.7 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. When testing differences between phases over all CTAC methods and waveforms, end-exhale phases were significantly more accurate (p = 0.005). However, these differences were driven by

  10. Evaluation of the combined effects of target size, respiratory motion and background activity on 3D and 4D PET/CT images

    NASA Astrophysics Data System (ADS)

    Park, Sang-June; Ionascu, Dan; Killoran, Joseph; Mamede, Marcelo; Gerbaudo, Victor H.; Chin, Lee; Berbeco, Ross

    2008-07-01

    Gated (4D) PET/CT has the potential to greatly improve the accuracy of radiotherapy at treatment sites where internal organ motion is significant. However, the best methodology for applying 4D-PET/CT to target definition is not currently well established. With the goal of better understanding how to best apply 4D information to radiotherapy, initial studies were performed to investigate the effect of target size, respiratory motion and target-to-background activity concentration ratio (TBR) on 3D (ungated) and 4D PET images. Using a PET/CT scanner with 4D or gating capability, a full 3D-PET scan corrected with a 3D attenuation map from 3D-CT scan and a respiratory gated (4D) PET scan corrected with corresponding attenuation maps from 4D-CT were performed by imaging spherical targets (0.5-26.5 mL) filled with 18F-FDG in a dynamic thorax phantom and NEMA IEC body phantom at different TBRs (infinite, 8 and 4). To simulate respiratory motion, the phantoms were driven sinusoidally in the superior-inferior direction with amplitudes of 0, 1 and 2 cm and a period of 4.5 s. Recovery coefficients were determined on PET images. In addition, gating methods using different numbers of gating bins (1-20 bins) were evaluated with image noise and temporal resolution. For evaluation, volume recovery coefficient, signal-to-noise ratio and contrast-to-noise ratio were calculated as a function of the number of gating bins. Moreover, the optimum thresholds which give accurate moving target volumes were obtained for 3D and 4D images. The partial volume effect and signal loss in the 3D-PET images due to the limited PET resolution and the respiratory motion, respectively were measured. The results show that signal loss depends on both the amplitude and pattern of respiratory motion. However, the 4D-PET successfully recovers most of the loss induced by the respiratory motion. The 5-bin gating method gives the best temporal resolution with acceptable image noise. The results based on the 4D

  11. First Steps Toward Ultrasound-Based Motion Compensation for Imaging and Therapy: Calibration with an Optical System and 4D PET Imaging

    PubMed Central

    Schwaab, Julia; Kurz, Christopher; Sarti, Cristina; Bongers, André; Schoenahl, Frédéric; Bert, Christoph; Debus, Jürgen; Parodi, Katia; Jenne, Jürgen Walter

    2015-01-01

    Target motion, particularly in the abdomen, due to respiration or patient movement is still a challenge in many diagnostic and therapeutic processes. Hence, methods to detect and compensate this motion are required. Diagnostic ultrasound (US) represents a non-invasive and dose-free alternative to fluoroscopy, providing more information about internal target motion than respiration belt or optical tracking. The goal of this project is to develop an US-based motion tracking for real-time motion correction in radiation therapy and diagnostic imaging, notably in 4D positron emission tomography (PET). In this work, a workflow is established to enable the transformation of US tracking data to the coordinates of the treatment delivery or imaging system – even if the US probe is moving due to respiration. It is shown that the US tracking signal is equally adequate for 4D PET image reconstruction as the clinically used respiration belt and provides additional opportunities in this concern. Furthermore, it is demonstrated that the US probe being within the PET field of view generally has no relevant influence on the image quality. The accuracy and precision of all the steps in the calibration workflow for US tracking-based 4D PET imaging are found to be in an acceptable range for clinical implementation. Eventually, we show in vitro that an US-based motion tracking in absolute room coordinates with a moving US transducer is feasible. PMID:26649277

  12. First Steps Toward Ultrasound-Based Motion Compensation for Imaging and Therapy: Calibration with an Optical System and 4D PET Imaging.

    PubMed

    Schwaab, Julia; Kurz, Christopher; Sarti, Cristina; Bongers, André; Schoenahl, Frédéric; Bert, Christoph; Debus, Jürgen; Parodi, Katia; Jenne, Jürgen Walter

    2015-01-01

    Target motion, particularly in the abdomen, due to respiration or patient movement is still a challenge in many diagnostic and therapeutic processes. Hence, methods to detect and compensate this motion are required. Diagnostic ultrasound (US) represents a non-invasive and dose-free alternative to fluoroscopy, providing more information about internal target motion than respiration belt or optical tracking. The goal of this project is to develop an US-based motion tracking for real-time motion correction in radiation therapy and diagnostic imaging, notably in 4D positron emission tomography (PET). In this work, a workflow is established to enable the transformation of US tracking data to the coordinates of the treatment delivery or imaging system - even if the US probe is moving due to respiration. It is shown that the US tracking signal is equally adequate for 4D PET image reconstruction as the clinically used respiration belt and provides additional opportunities in this concern. Furthermore, it is demonstrated that the US probe being within the PET field of view generally has no relevant influence on the image quality. The accuracy and precision of all the steps in the calibration workflow for US tracking-based 4D PET imaging are found to be in an acceptable range for clinical implementation. Eventually, we show in vitro that an US-based motion tracking in absolute room coordinates with a moving US transducer is feasible.

  13. TU-F-12A-05: Sensitivity of Textural Features to 3D Vs. 4D FDG-PET/CT Imaging in NSCLC Patients

    SciTech Connect

    Yang, F; Nyflot, M; Bowen, S; Kinahan, P; Sandison, G

    2014-06-15

    Purpose: Neighborhood Gray-level difference matrices (NGLDM) based texture parameters extracted from conventional (3D) 18F-FDG PET scans in patients with NSCLC have been previously shown to associate with response to chemoradiation and poorer patient outcome. However, the change in these parameters when utilizing respiratory-correlated (4D) FDG-PET scans has not yet been characterized for NSCLC. The Objectives: of this study was to assess the extent to which NGLDM-based texture parameters on 4D PET images vary with reference to values derived from 3D scans in NSCLC. Methods: Eight patients with newly diagnosed NSCLC treated with concomitant chemoradiotherapy were included in this study. 4D PET scans were reconstructed with OSEM-IR in 5 respiratory phase-binned images and corresponding CT data of each phase were employed for attenuation correction. NGLDM-based texture features, consisting of coarseness, contrast, busyness, complexity and strength, were evaluated for gross tumor volumes defined on 3D/4D PET scans by radiation oncologists. Variation of the obtained texture parameters over the respiratory cycle were examined with respect to values extracted from 3D scans. Results: Differences between texture parameters derived from 4D scans at different respiratory phases and those extracted from 3D scans ranged from −30% to 13% for coarseness, −12% to 40% for contrast, −5% to 50% for busyness, −7% to 38% for complexity, and −43% to 20% for strength. Furthermore, no evident correlations were observed between respiratory phase and 4D scan texture parameters. Conclusion: Results of the current study showed that NGLDM-based texture parameters varied considerably based on choice of 3D PET and 4D PET reconstruction of NSCLC patient images, indicating that standardized image acquisition and analysis protocols need to be established for clinical studies, especially multicenter clinical trials, intending to validate prognostic values of texture features for NSCLC.

  14. Atlas construction for dynamic (4D) PET using diffeomorphic transformations.

    PubMed

    Bieth, Marie; Lombaert, Hervé; Reader, Andrew J; Siddiqi, Kaleem

    2013-01-01

    A novel dynamic (4D) PET to PET image registration procedure is proposed and applied to multiple PET scans acquired with the high resolution research tomograph (HRRT), the highest resolution human brain PET scanner available in the world. By extending the recent diffeomorphic log-demons (DLD) method and applying it to multiple dynamic [11C]raclopride scans from the HRRT, an important step towards construction of a PET atlas of unprecedented quality for [11C]raclopride imaging of the human brain has been achieved. Accounting for the temporal dimension in PET data improves registration accuracy when compared to registration of 3D to 3D time-averaged PET images. The DLD approach was chosen for its ease in providing both an intensity and shape template, through iterative sequential pair-wise registrations with fast convergence. The proposed method is applicable to any PET radiotracer, providing 4D atlases with useful applications in high accuracy PET data simulations and automated PET image analysis.

  15. Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

    NASA Astrophysics Data System (ADS)

    Bowen, S. R.; Nyflot, M. J.; Herrmann, C.; Groh, C. M.; Meyer, J.; Wollenweber, S. D.; Stearns, C. W.; Kinahan, P. E.; Sandison, G. A.

    2015-05-01

    Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT

  16. Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using {sup 68}Ga-labeled nanoparticles

    SciTech Connect

    Kipritidis, John Keall, Paul J.; Siva, Shankar; Hofman, Michael S.; Callahan, Jason; Hicks, Rodney J.

    2014-01-15

    Purpose: CT ventilation imaging is a novel functional lung imaging modality based on deformable image registration. The authors present the first validation study of CT ventilation using positron emission tomography with{sup 68}Ga-labeled nanoparticles (PET-Galligas). The authors quantify this agreement for different CT ventilation metrics and PET reconstruction parameters. Methods: PET-Galligas ventilation scans were acquired for 12 lung cancer patients using a four-dimensional (4D) PET/CT scanner. CT ventilation images were then produced by applying B-spline deformable image registration between the respiratory correlated phases of the 4D-CT. The authors test four ventilation metrics, two existing and two modified. The two existing metrics model mechanical ventilation (alveolar air-flow) based on Hounsfield unit (HU) change (V{sub HU}) or Jacobian determinant of deformation (V{sub Jac}). The two modified metrics incorporate a voxel-wise tissue-density scaling (ρV{sub HU} and ρV{sub Jac}) and were hypothesized to better model the physiological ventilation. In order to assess the impact of PET image quality, comparisons were performed using both standard and respiratory-gated PET images with the former exhibiting better signal. Different median filtering kernels (σ{sub m} = 0 or 3 mm) were also applied to all images. As in previous studies, similarity metrics included the Spearman correlation coefficient r within the segmented lung volumes, and Dice coefficient d{sub 20} for the (0 − 20)th functional percentile volumes. Results: The best agreement between CT and PET ventilation was obtained comparing standard PET images to the density-scaled HU metric (ρV{sub HU}) with σ{sub m} = 3 mm. This leads to correlation values in the ranges 0.22 ⩽ r ⩽ 0.76 and 0.38 ⩽ d{sub 20} ⩽ 0.68, with r{sup ¯}=0.42±0.16 and d{sup ¯}{sub 20}=0.52±0.09 averaged over the 12 patients. Compared to Jacobian-based metrics, HU-based metrics lead to statistically significant

  17. Clinical evaluation of 4D PET motion compensation strategies for treatment verification in ion beam therapy

    NASA Astrophysics Data System (ADS)

    Gianoli, Chiara; Kurz, Christopher; Riboldi, Marco; Bauer, Julia; Fontana, Giulia; Baroni, Guido; Debus, Jürgen; Parodi, Katia

    2016-06-01

    A clinical trial named PROMETHEUS is currently ongoing for inoperable hepatocellular carcinoma (HCC) at the Heidelberg Ion Beam Therapy Center (HIT, Germany). In this framework, 4D PET-CT datasets are acquired shortly after the therapeutic treatment to compare the irradiation induced PET image with a Monte Carlo PET prediction resulting from the simulation of treatment delivery. The extremely low count statistics of this measured PET image represents a major limitation of this technique, especially in presence of target motion. The purpose of the study is to investigate two different 4D PET motion compensation strategies towards the recovery of the whole count statistics for improved image quality of the 4D PET-CT datasets for PET-based treatment verification. The well-known 4D-MLEM reconstruction algorithm, embedding the motion compensation in the reconstruction process of 4D PET sinograms, was compared to a recently proposed pre-reconstruction motion compensation strategy, which operates in sinogram domain by applying the motion compensation to the 4D PET sinograms. With reference to phantom and patient datasets, advantages and drawbacks of the two 4D PET motion compensation strategies were identified. The 4D-MLEM algorithm was strongly affected by inverse inconsistency of the motion model but demonstrated the capability to mitigate the noise-break-up effects. Conversely, the pre-reconstruction warping showed less sensitivity to inverse inconsistency but also more noise in the reconstructed images. The comparison was performed by relying on quantification of PET activity and ion range difference, typically yielding similar results. The study demonstrated that treatment verification of moving targets could be accomplished by relying on the whole count statistics image quality, as obtained from the application of 4D PET motion compensation strategies. In particular, the pre-reconstruction warping was shown to represent a promising choice when combined with intra

  18. Clinical evaluation of 4D PET motion compensation strategies for treatment verification in ion beam therapy.

    PubMed

    Gianoli, Chiara; Kurz, Christopher; Riboldi, Marco; Bauer, Julia; Fontana, Giulia; Baroni, Guido; Debus, Jürgen; Parodi, Katia

    2016-06-07

    A clinical trial named PROMETHEUS is currently ongoing for inoperable hepatocellular carcinoma (HCC) at the Heidelberg Ion Beam Therapy Center (HIT, Germany). In this framework, 4D PET-CT datasets are acquired shortly after the therapeutic treatment to compare the irradiation induced PET image with a Monte Carlo PET prediction resulting from the simulation of treatment delivery. The extremely low count statistics of this measured PET image represents a major limitation of this technique, especially in presence of target motion. The purpose of the study is to investigate two different 4D PET motion compensation strategies towards the recovery of the whole count statistics for improved image quality of the 4D PET-CT datasets for PET-based treatment verification. The well-known 4D-MLEM reconstruction algorithm, embedding the motion compensation in the reconstruction process of 4D PET sinograms, was compared to a recently proposed pre-reconstruction motion compensation strategy, which operates in sinogram domain by applying the motion compensation to the 4D PET sinograms. With reference to phantom and patient datasets, advantages and drawbacks of the two 4D PET motion compensation strategies were identified. The 4D-MLEM algorithm was strongly affected by inverse inconsistency of the motion model but demonstrated the capability to mitigate the noise-break-up effects. Conversely, the pre-reconstruction warping showed less sensitivity to inverse inconsistency but also more noise in the reconstructed images. The comparison was performed by relying on quantification of PET activity and ion range difference, typically yielding similar results. The study demonstrated that treatment verification of moving targets could be accomplished by relying on the whole count statistics image quality, as obtained from the application of 4D PET motion compensation strategies. In particular, the pre-reconstruction warping was shown to represent a promising choice when combined with intra

  19. Direct 4D PET MLEM reconstruction of parametric images using the simplified reference tissue model with the basis function method for [¹¹C]raclopride.

    PubMed

    Gravel, Paul; Reader, Andrew J

    2015-06-07

    This work assesses the one-step late maximum likelihood expectation maximization (OSL-MLEM) 4D PET reconstruction algorithm for direct estimation of parametric images from raw PET data when using the simplified reference tissue model with the basis function method (SRTM-BFM) for the kinetic analysis. To date, the OSL-MLEM method has been evaluated using kinetic models based on two-tissue compartments with an irreversible component. We extend the evaluation of this method for two-tissue compartments with a reversible component, using SRTM-BFM on simulated 3D + time data sets (with use of [(11)C]raclopride time-activity curves from real data) and on real data sets acquired with the high resolution research tomograph. The performance of the proposed method is evaluated by comparing voxel-level binding potential (BPND) estimates with those obtained from conventional post-reconstruction kinetic parameter estimation. For the commonly chosen number of iterations used in practice, our results show that for the 3D + time simulation, the direct method delivers results with lower (%)RMSE at the normal count level (decreases of 9-10 percentage points, corresponding to a 38-44% reduction), and also at low count levels (decreases of 17-21 percentage points, corresponding to a 26-36% reduction). As for the real 3D data set, the results obtained follow a similar trend, with the direct reconstruction method offering a 21% decrease in (%)CV compared to the post reconstruction method at low count levels. Thus, based on the results presented herein, using the SRTM-BFM kinetic model in conjunction with the OSL-MLEM direct 4D PET MLEM reconstruction method offers an improvement in performance when compared to conventional post reconstruction methods.

  20. WE-AB-204-03: A Novel 3D Printed Phantom for 4D PET/CT Imaging and SIB Radiotherapy Verification

    SciTech Connect

    Soultan, D; Murphy, J; Moiseenko, V; Cervino, L; Gill, B

    2015-06-15

    Purpose: To construct and test a 3D printed phantom designed to mimic variable PET tracer uptake seen in lung tumor volumes. To assess segmentation accuracy of sub-volumes of the phantom following 4D PET/CT scanning with ideal and patient-specific respiratory motion. To plan, deliver and verify delivery of PET-driven, gated, simultaneous integrated boost (SIB) radiotherapy plans. Methods: A set of phantoms and inserts were designed and manufactured for a realistic representation of lung cancer gated radiotherapy steps from 4D PET/CT scanning to dose delivery. A cylindrical phantom (40x 120 mm) holds inserts for PET/CT scanning. The novel 3D printed insert dedicated to 4D PET/CT mimics high PET tracer uptake in the core and lower uptake in the periphery. This insert is a variable density porous cylinder (22.12×70 mm), ABS-P430 thermoplastic, 3D printed by uPrint SE Plus with inner void volume (5.5×42 mm). The square pores (1.8×1.8 mm2 each) fill 50% of outer volume, resulting in a 2:1 SUV ratio of PET-tracer in the void volume with respect to porous volume. A matching in size cylindrical phantom is dedicated to validate gated radiotherapy. It contains eight peripheral holes matching the location of the porous part of the 3D printed insert, and one central hole. These holes accommodate adaptors for Farmer-type ion chamber and cells vials. Results: End-to-end test were performed from 4D PET/CT scanning to transferring data to the planning system and target volume delineation. 4D PET/CT scans were acquired of the phantom with different respiratory motion patterns and gating windows. A measured 2:1 18F-FDG SUV ratio between inner void and outer volume matched the 3D printed design. Conclusion: The novel 3D printed phantom mimics variable PET tracer uptake typical of tumors. Obtained 4D PET/CT scans are suitable for segmentation, treatment planning and delivery in SIB gated treatments of NSCLC.

  1. A sinogram warping strategy for pre-reconstruction 4D PET optimization.

    PubMed

    Gianoli, Chiara; Riboldi, Marco; Fontana, Giulia; Kurz, Christopher; Parodi, Katia; Baroni, Guido

    2016-03-01

    A novel strategy for 4D PET optimization in the sinogram domain is proposed, aiming at motion model application before image reconstruction ("sinogram warping" strategy). Compared to state-of-the-art 4D-MLEM reconstruction, the proposed strategy is able to optimize the image SNR, avoiding iterative direct and inverse warping procedures, which are typical of the 4D-MLEM algorithm. A full-count statistics sinogram of the motion-compensated 4D PET reference phase is generated by warping the sinograms corresponding to the different PET phases. This is achieved relying on a motion model expressed in the sinogram domain. The strategy was tested on the anthropomorphic 4D PET-CT NCAT phantom in comparison with the 4D-MLEM algorithm, with particular reference to robustness to PET-CT co-registrations artefacts. The MLEM reconstruction of the warped sinogram according to the proposed strategy exhibited better accuracy (up to +40.90 % with respect to the ideal value), whereas images reconstructed according to the 4D-MLEM reconstruction resulted in less noisy (down to -26.90 % with respect to the ideal value) but more blurred. The sinogram warping strategy demonstrates advantages with respect to 4D-MLEM algorithm. These advantages are paid back by introducing approximation of the deformation field, and further efforts are required to mitigate the impact of such an approximation in clinical 4D PET reconstruction.

  2. Experimental investigation of irregular motion impact on 4D PET-based particle therapy monitoring

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Stützer, K.; Enghardt, W.; Priegnitz, M.; Helmbrecht, S.; Bert, C.; Fiedler, F.

    2016-01-01

    Particle therapy positron emission tomography (PT-PET) is an in vivo and non-invasive imaging technique to monitor treatment delivery in particle therapy. The inevitable patient respiratory motion during irradiation causes artefacts and inaccurate activity distribution in PET images. Four-dimensional (4D) maximum likelihood expectation maximisation (4D MLEM) allows for a compensation of these effects, but has up to now been restricted to regular motion for PT-PET investigations. However, intra-fractional motion during treatment might differ from that during acquisition of the 4D-planning CT (e.g. amplitude variation, baseline drift) and therefore might induce inaccurate 4D PET reconstruction results. This study investigates the impact of different irregular analytical one-dimensional (1D) motion patterns on PT-PET imaging by means of experiments with a radioactive source and irradiated moving phantoms. Three sorting methods, namely phase sorting, equal amplitude sorting and event-based amplitude sorting, were applied to manage the PET list-mode data. The influence of these sorting methods on the motion compensating algorithm has been analysed. The event-based amplitude sorting showed a superior performance and it is applicable for irregular motions with  ⩽4 mm amplitude elongation and drift. For motion with 10 mm baseline drift, the normalised root mean square error was as high as 10.5% and a 10 mm range deviation was observed.

  3. Cardiac 4D Ultrasound Imaging

    NASA Astrophysics Data System (ADS)

    D'hooge, Jan

    Volumetric cardiac ultrasound imaging has steadily evolved over the last 20 years from an electrocardiography (ECC) gated imaging technique to a true real-time imaging modality. Although the clinical use of echocardiography is still to a large extent based on conventional 2D ultrasound imaging it can be anticipated that the further developments in image quality, data visualization and interaction and image quantification of three-dimensional cardiac ultrasound will gradually make volumetric ultrasound the modality of choice. In this chapter, an overview is given of the technological developments that allow for volumetric imaging of the beating heart by ultrasound.

  4. 4D offline PET-based treatment verification in scanned ion beam therapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Kurz, Christopher; Bauer, Julia; Unholtz, Daniel; Richter, Daniel; Stützer, Kristin; Bert, Christoph; Parodi, Katia

    2015-08-01

    At the Heidelberg Ion-Beam Therapy Center, patient irradiation with scanned proton and carbon ion beams is verified by offline positron emission tomography (PET) imaging: the {β+} -activity measured within the patient is compared to a prediction calculated on the basis of the treatment planning data in order to identify potential delivery errors. Currently, this monitoring technique is limited to the treatment of static target structures. However, intra-fractional organ motion imposes considerable additional challenges to scanned ion beam radiotherapy. In this work, the feasibility and potential of time-resolved (4D) offline PET-based treatment verification with a commercial full-ring PET/CT (x-ray computed tomography) device are investigated for the first time, based on an experimental campaign with moving phantoms. Motion was monitored during the gated beam delivery as well as the subsequent PET acquisition and was taken into account in the corresponding 4D Monte-Carlo simulations and data evaluation. Under the given experimental conditions, millimeter agreement between the prediction and measurement was found. Dosimetric consequences due to the phantom motion could be reliably identified. The agreement between PET measurement and prediction in the presence of motion was found to be similar as in static reference measurements, thus demonstrating the potential of 4D PET-based treatment verification for future clinical applications.

  5. Fully 4D list-mode reconstruction applied to respiratory-gated PET scans

    NASA Astrophysics Data System (ADS)

    Grotus, N; Reader, A J; Stute, S; Rosenwald, J C; Giraud, P; Buvat, I

    2009-03-01

    18F-fluoro-deoxy-glucose (18F-FDG) positron emission tomography (PET) is one of the most sensitive and specific imaging modalities for the diagnosis of non-small cell lung cancer. A drawback of PET is that it requires several minutes of acquisition per bed position, which results in images being affected by respiratory blur. Respiratory gating techniques have been developed to deal with respiratory motion in the PET images. However, these techniques considerably increase the level of noise in the reconstructed images unless the acquisition time is increased. The aim of this paper is to evaluate a four-dimensional (4D) image reconstruction algorithm that combines the acquired events in all the gates whilst preserving the motion deblurring. This algorithm was compared to classic ordered subset expectation maximization (OSEM) reconstruction of gated and non-gated images, and to temporal filtering of gated images reconstructed with OSEM. Two datasets were used for comparing the different reconstruction approaches: one involving the NEMA IEC/2001 body phantom in motion, the other obtained using Monte-Carlo simulations of the NCAT breathing phantom. Results show that 4D reconstruction reaches a similar performance in terms of the signal-to-noise ratio (SNR) as non-gated reconstruction whilst preserving the motion deblurring. In particular, 4D reconstruction improves the SNR compared to respiratory-gated images reconstructed with the OSEM algorithm. Temporal filtering of the OSEM-reconstructed images helps improve the SNR, but does not achieve the same performance as 4D reconstruction. 4D reconstruction of respiratory-gated images thus appears as a promising tool to reach the same performance in terms of the SNR as non-gated acquisitions while reducing the motion blur, without increasing the acquisition time.

  6. Accuracy and Utility of Deformable Image Registration in {sup 68}Ga 4D PET/CT Assessment of Pulmonary Perfusion Changes During and After Lung Radiation Therapy

    SciTech Connect

    Hardcastle, Nicholas; Hofman, Michael S.; Hicks, Rodney J.; Callahan, Jason; Kron, Tomas; MacManus, Michael P.; Ball, David L.; Jackson, Price; Siva, Shankar

    2015-09-01

    Purpose: Measuring changes in lung perfusion resulting from radiation therapy dose requires registration of the functional imaging to the radiation therapy treatment planning scan. This study investigates registration accuracy and utility for positron emission tomography (PET)/computed tomography (CT) perfusion imaging in radiation therapy for non–small cell lung cancer. Methods: {sup 68}Ga 4-dimensional PET/CT ventilation-perfusion imaging was performed before, during, and after radiation therapy for 5 patients. Rigid registration and deformable image registration (DIR) using B-splines and Demons algorithms was performed with the CT data to obtain a deformation map between the functional images and planning CT. Contour propagation accuracy and correspondence of anatomic features were used to assess registration accuracy. Wilcoxon signed-rank test was used to determine statistical significance. Changes in lung perfusion resulting from radiation therapy dose were calculated for each registration method for each patient and averaged over all patients. Results: With B-splines/Demons DIR, median distance to agreement between lung contours reduced modestly by 0.9/1.1 mm, 1.3/1.6 mm, and 1.3/1.6 mm for pretreatment, midtreatment, and posttreatment (P<.01 for all), and median Dice score between lung contours improved by 0.04/0.04, 0.05/0.05, and 0.05/0.05 for pretreatment, midtreatment, and posttreatment (P<.001 for all). Distance between anatomic features reduced with DIR by median 2.5 mm and 2.8 for pretreatment and midtreatment time points, respectively (P=.001) and 1.4 mm for posttreatment (P>.2). Poorer posttreatment results were likely caused by posttreatment pneumonitis and tumor regression. Up to 80% standardized uptake value loss in perfusion scans was observed. There was limited change in the loss in lung perfusion between registration methods; however, Demons resulted in larger interpatient variation compared with rigid and B-splines registration

  7. Clinical Utility of 4D FDG-PET/CT Scans in Radiation Treatment Planning

    SciTech Connect

    Aristophanous, Michalis; Sher, David J.; Allen, Aaron M.; Larson, Elysia; Chen, Aileen B.

    2012-01-01

    Purpose: The potential role of four-dimensional (4D) positron emission tomography (PET)/computed tomography (CT) in radiation treatment planning, relative to standard three-dimensional (3D) PET/CT, was examined. Methods and Materials: Ten patients with non-small-cell lung cancer had sequential 3D and 4D [{sup 18}F]fluorodeoxyglucose PET/CT scans in the treatment position prior to radiation therapy. The gross tumor volume and involved lymph nodes were contoured on the PET scan by use of three different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; a technique with a constant threshold of standardized uptake value (SUV) greater than 2.5; and an automatic segmentation technique. For each technique, the tumor volume was defined on the 3D scan (VOL3D) and on the 4D scan (VOL4D) by combining the volume defined on each of the five breathing phases individually. The range of tumor motion and the location of each lesion were also recorded, and their influence on the differences observed between VOL3D and VOL4D was investigated. Results: We identified and analyzed 22 distinct lesions, including 9 primary tumors and 13 mediastinal lymph nodes. Mean VOL4D was larger than mean VOL3D with all three techniques, and the difference was statistically significant (p < 0.01). The range of tumor motion and the location of the tumor affected the magnitude of the difference. For one case, all three tumor definition techniques identified volume of moderate uptake of approximately 1 mL in the hilar region on the 4D scan (SUV maximum, 3.3) but not on the 3D scan (SUV maximum, 2.3). Conclusions: In comparison to 3D PET, 4D PET may better define the full physiologic extent of moving tumors and improve radiation treatment planning for lung tumors. In addition, reduction of blurring from free-breathing images may reveal additional information regarding regional disease.

  8. 4D flow imaging with MRI

    PubMed Central

    Stankovic, Zoran; Allen, Bradley D.; Garcia, Julio; Jarvis, Kelly B.

    2014-01-01

    Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed ‘4D flow MRI’) has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system. PMID:24834414

  9. Advances in 4D radiation therapy for managing respiration: part I - 4D imaging.

    PubMed

    Hugo, Geoffrey D; Rosu, Mihaela

    2012-12-01

    Techniques for managing respiration during imaging and planning of radiation therapy are reviewed, concentrating on free-breathing (4D) approaches. First, we focus on detailing the historical development and basic operational principles of currently-available "first generation" 4D imaging modalities: 4D computed tomography, 4D cone beam computed tomography, 4D magnetic resonance imaging, and 4D positron emission tomography. Features and limitations of these first generation systems are described, including necessity of breathing surrogates for 4D image reconstruction, assumptions made in acquisition and reconstruction about the breathing pattern, and commonly-observed artifacts. Both established and developmental methods to deal with these limitations are detailed. Finally, strategies to construct 4D targets and images and, alternatively, to compress 4D information into static targets and images for radiation therapy planning are described.

  10. TU-C-BRD-01: Image Guided SBRT I: Multi-Modality 4D Imaging

    SciTech Connect

    Cai, J; Mageras, G; Pan, T

    2014-06-15

    Motion management is one of the critical technical challenges for radiation therapy. 4D imaging has been rapidly adopted as essential tool to assess organ motion associated with respiratory breathing. A variety of 4D imaging techniques have been developed and are currently under development based on different imaging modalities such as CT, MRI, PET, and CBCT. Each modality provides specific and complementary information about organ and tumor respiratory motion. Effective use of each different technique or combined use of different techniques can introduce a comprehensive management of tumor motion. Specifically, these techniques have afforded tremendous opportunities to better define and delineate tumor volumes, more accurately perform patient positioning, and effectively apply highly conformal therapy techniques such as IMRT and SBRT. Successful implementation requires good understanding of not only each technique, including unique features, limitations, artifacts, imaging acquisition and process, but also how to systematically apply the information obtained from different imaging modalities using proper tools such as deformable image registration. Furthermore, it is important to understand the differences in the effects of breathing variation between different imaging modalities. A comprehensive motion management strategy using multi-modality 4D imaging has shown promise in improving patient care, but at the same time faces significant challenges. This session will focuses on the current status and advances in imaging respiration-induced organ motion with different imaging modalities: 4D-CT, 4D-MRI, 4D-PET, and 4D-CBCT/DTS. Learning Objectives: Understand the need and role of multimodality 4D imaging in radiation therapy. Understand the underlying physics behind each 4D imaging technique. Recognize the advantages and limitations of each 4D imaging technique.

  11. Experimental verification of a 4D MLEM reconstruction algorithm used for in-beam PET measurements in particle therapy

    NASA Astrophysics Data System (ADS)

    Stützer, K.; Bert, C.; Enghardt, W.; Helmbrecht, S.; Parodi, K.; Priegnitz, M.; Saito, N.; Fiedler, F.

    2013-08-01

    In-beam positron emission tomography (PET) has been proven to be a reliable technique in ion beam radiotherapy for the in situ and non-invasive evaluation of the correct dose deposition in static tumour entities. In the presence of intra-fractional target motion an appropriate time-resolved (four-dimensional, 4D) reconstruction algorithm has to be used to avoid reconstructed activity distributions suffering from motion-related blurring artefacts and to allow for a dedicated dose monitoring. Four-dimensional reconstruction algorithms from diagnostic PET imaging that can properly handle the typically low counting statistics of in-beam PET data have been adapted and optimized for the characteristics of the double-head PET scanner BASTEI installed at GSI Helmholtzzentrum Darmstadt, Germany (GSI). Systematic investigations with moving radioactive sources demonstrate the more effective reduction of motion artefacts by applying a 4D maximum likelihood expectation maximization (MLEM) algorithm instead of the retrospective co-registration of phasewise reconstructed quasi-static activity distributions. Further 4D MLEM results are presented from in-beam PET measurements of irradiated moving phantoms which verify the accessibility of relevant parameters for the dose monitoring of intra-fractionally moving targets. From in-beam PET listmode data sets acquired together with a motion surrogate signal, valuable images can be generated by the 4D MLEM reconstruction for different motion patterns and motion-compensated beam delivery techniques.

  12. Controlled Source 4D Seismic Imaging

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Morency, C.; Tromp, J.

    2009-12-01

    Earth's material properties may change after significant tectonic events, e.g., volcanic eruptions, earthquake ruptures, landslides, and hydrocarbon migration. While many studies focus on how to interpret observations in terms of changes in wavespeeds and attenuation, the oil industry is more interested in how we can identify and locate such temporal changes using seismic waves generated by controlled sources. 4D seismic analysis is indeed an important tool to monitor fluid movement in hydrocarbon reservoirs during production, improving fields management. Classic 4D seismic imaging involves comparing images obtained from two subsequent seismic surveys. Differences between the two images tell us where temporal changes occurred. However, when the temporal changes are small, it may be quite hard to reliably identify and characterize the differences between the two images. We propose to back-project residual seismograms between two subsequent surveys using adjoint methods, which results in images highlighting temporal changes. We use the SEG/EAGE salt dome model to illustrate our approach. In two subsequent surveys, the wavespeeds and density within a target region are changed, mimicking possible fluid migration. Due to changes in material properties induced by fluid migration, seismograms recorded in the two surveys differ. By back propagating these residuals, the adjoint images identify the location of the affected region. An important issue involves the nature of model. For instance, are we characterizing only changes in wavespeed, or do we also consider density and attenuation? How many model parameters characterize the model, e.g., is our model isotropic or anisotropic? Is acoustic wave propagation accurate enough or do we need to consider elastic or poroelastic effects? We will investigate how imaging strategies based upon acoustic, elastic and poroelastic simulations affect our imaging capabilities.

  13. 4D ML reconstruction as a tool for volumetric PET-based treatment verification in ion beam radiotherapy

    SciTech Connect

    De Bernardi, E.; Ricotti, R.; Riboldi, M.; Baroni, G.; Parodi, K.; Gianoli, C.

    2016-02-15

    Purpose: An innovative strategy to improve the sensitivity of positron emission tomography (PET)-based treatment verification in ion beam radiotherapy is proposed. Methods: Low counting statistics PET images acquired during or shortly after the treatment (Measured PET) and a Monte Carlo estimate of the same PET images derived from the treatment plan (Expected PET) are considered as two frames of a 4D dataset. A 4D maximum likelihood reconstruction strategy was adapted to iteratively estimate the annihilation events distribution in a reference frame and the deformation motion fields that map it in the Expected PET and Measured PET frames. The outputs generated by the proposed strategy are as follows: (1) an estimate of the Measured PET with an image quality comparable to the Expected PET and (2) an estimate of the motion field mapping Expected PET to Measured PET. The details of the algorithm are presented and the strategy is preliminarily tested on analytically simulated datasets. Results: The algorithm demonstrates (1) robustness against noise, even in the worst conditions where 1.5 × 10{sup 4} true coincidences and a random fraction of 73% are simulated; (2) a proper sensitivity to different kind and grade of mismatches ranging between 1 and 10 mm; (3) robustness against bias due to incorrect washout modeling in the Monte Carlo simulation up to 1/3 of the original signal amplitude; and (4) an ability to describe the mismatch even in presence of complex annihilation distributions such as those induced by two perpendicular superimposed ion fields. Conclusions: The promising results obtained in this work suggest the applicability of the method as a quantification tool for PET-based treatment verification in ion beam radiotherapy. An extensive assessment of the proposed strategy on real treatment verification data is planned.

  14. 4D numerical observer for lesion detection in respiratory-gated PET

    SciTech Connect

    Lorsakul, Auranuch; Li, Quanzheng; Ouyang, Jinsong; El Fakhri, Georges; Trott, Cathryn M.; Hoog, Christopher; Petibon, Yoann; Laine, Andrew F.

    2014-10-15

    Purpose: Respiratory-gated positron emission tomography (PET)/computed tomography protocols reduce lesion smearing and improve lesion detection through a synchronized acquisition of emission data. However, an objective assessment of image quality of the improvement gained from respiratory-gated PET is mainly limited to a three-dimensional (3D) approach. This work proposes a 4D numerical observer that incorporates both spatial and temporal informations for detection tasks in pulmonary oncology. Methods: The authors propose a 4D numerical observer constructed with a 3D channelized Hotelling observer for the spatial domain followed by a Hotelling observer for the temporal domain. Realistic {sup 18}F-fluorodeoxyglucose activity distributions were simulated using a 4D extended cardiac torso anthropomorphic phantom including 12 spherical lesions at different anatomical locations (lower, upper, anterior, and posterior) within the lungs. Simulated data based on Monte Carlo simulation were obtained using GEANT4 application for tomographic emission (GATE). Fifty noise realizations of six respiratory-gated PET frames were simulated by GATE using a model of the Siemens Biograph mMR scanner geometry. PET sinograms of the thorax background and pulmonary lesions that were simulated separately were merged to generate different conditions of the lesions to the background (e.g., lesion contrast and motion). A conventional ordered subset expectation maximization (OSEM) reconstruction (5 iterations and 6 subsets) was used to obtain: (1) gated, (2) nongated, and (3) motion-corrected image volumes (a total of 3200 subimage volumes: 2400 gated, 400 nongated, and 400 motion-corrected). Lesion-detection signal-to-noise ratios (SNRs) were measured in different lesion-to-background contrast levels (3.5, 8.0, 9.0, and 20.0), lesion diameters (10.0, 13.0, and 16.0 mm), and respiratory motion displacements (17.6–31.3 mm). The proposed 4D numerical observer applied on multiple-gated images was

  15. Comparison of an alternative and existing binning methods to reduce the acquisition duration of 4D PET/CT

    SciTech Connect

    Didierlaurent, David Ribes, Sophie; Caselles, Olivier; Jaudet, Cyril; Dierickx, Lawrence O.; Zerdoud, Slimane; Brillouet, Severine; Weits, Kathleen; Batatia, Hadj; Courbon, Frédéric

    2014-11-01

    Purpose: Respiratory motion is a source of artifacts that reduce image quality in PET. Four dimensional (4D) PET/CT is one approach to overcome this problem. Existing techniques to limiting the effects of respiratory motions are based on prospective phase binning which requires a long acquisition duration (15–25 min). This time is uncomfortable for the patients and limits the clinical exploitation of 4D PET/CT. In this work, the authors evaluated an existing method and an alternative retrospective binning method to reduce the acquisition duration of 4D PET/CT. Methods: The authors studied an existing mixed-amplitude binning (MAB) method and an alternative binning method by mixed-phases (MPhB). Before implementing MPhB, they analyzed the regularity of the breathing patterns in patients. They studied the breathing signal drift and missing CT slices that could be challenging for implementing MAB. They compared the performance of MAB and MPhB with current binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion. Results: MPhB can be implemented depending on an optimal phase (in average, the exhalation peak phase −4.1% of the entire breathing cycle duration). Signal drift of patients was in average 35% relative to the breathing amplitude. Even after correcting this drift, MAB was feasible in 4D CT for only 64% of patients. No significant differences appeared between the different binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion. The authors also determined the inaccuracies of MAB and MPhB to measure the maximum amplitude of tumor motion with three bins (less than 3 mm for movement inferior to 12 mm, up to 6.4 mm for a 21 mm movement). Conclusions: The authors proposed an alternative binning method by mixed-phase binning that halves the acquisition duration of 4D PET/CT. Mixed-amplitude binning was challenging because of signal drift and missing CT slices. They showed that more

  16. 4D XCAT phantom for multimodality imaging research

    SciTech Connect

    Segars, W. P.; Sturgeon, G.; Mendonca, S.; Grimes, Jason; Tsui, B. M. W.

    2010-09-15

    Purpose: The authors develop the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. Methods: Highly detailed whole-body anatomies for the adult male and female were defined in the XCAT using nonuniform rational B-spline (NURBS) and subdivision surfaces based on segmentation of the Visible Male and Female anatomical datasets from the National Library of Medicine as well as patient datasets. Using the flexibility of these surfaces, the Visible Human anatomies were transformed to match body measurements and organ volumes for a 50th percentile (height and weight) male and female. The desired body measurements for the models were obtained using the PEOPLESIZE program that contains anthropometric dimensions categorized from 1st to the 99th percentile for US adults. The desired organ volumes were determined from ICRP Publication 89 [ICRP, ''Basic anatomical and physiological data for use in radiological protection: reference values,'' ICRP Publication 89 (International Commission on Radiological Protection, New York, NY, 2002)]. The male and female anatomies serve as standard templates upon which anatomical variations may be modeled in the XCAT through user-defined parameters. Parametrized models for the cardiac and respiratory motions were also incorporated into the XCAT based on high-resolution cardiac- and respiratory-gated multislice CT data. To demonstrate the usefulness of the phantom, the authors show example simulation studies in PET, SPECT, and CT using publicly available simulation packages. Results: As demonstrated in the pilot studies, the 4D XCAT (which includes thousands of anatomical structures) can produce realistic imaging data when combined with accurate models of the imaging process. With the flexibility of the NURBS surface primitives, any number of different anatomies, cardiac or respiratory motions or patterns, and spatial resolutions can be simulated to perform imaging research. Conclusions: With the ability to produce

  17. Validation of a 4D-PET Maximum Intensity Projection for Delineation of an Internal Target Volume

    SciTech Connect

    Callahan, Jason; Kron, Tomas; Schneider-Kolsky, Michal; Dunn, Leon; Thompson, Mick; Siva, Shankar; Aarons, Yolanda; Binns, David; Hicks, Rodney J.

    2013-07-15

    Purpose: The delineation of internal target volumes (ITVs) in radiation therapy of lung tumors is currently performed by use of either free-breathing (FB) {sup 18}F-fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET/CT) or 4-dimensional (4D)-CT maximum intensity projection (MIP). In this report we validate the use of 4D-PET-MIP for the delineation of target volumes in both a phantom and in patients. Methods and Materials: A phantom with 3 hollow spheres was prepared surrounded by air then water. The spheres and water background were filled with a mixture of {sup 18}F and radiographic contrast medium. A 4D-PET/CT scan was performed of the phantom while moving in 4 different breathing patterns using a programmable motion device. Nine patients with an FDG-avid lung tumor who underwent FB and 4D-PET/CT and >5 mm of tumor motion were included for analysis. The 3 spheres and patient lesions were contoured by 2 contouring methods (40% of maximum and PET edge) on the FB-PET, FB-CT, 4D-PET, 4D-PET-MIP, and 4D-CT-MIP. The concordance between the different contoured volumes was calculated using a Dice coefficient (DC). The difference in lung tumor volumes between FB-PET and 4D-PET volumes was also measured. Results: The average DC in the phantom using 40% and PET edge, respectively, was lowest for FB-PET/CT (DCAir = 0.72/0.67, DCBackground 0.63/0.62) and highest for 4D-PET/CT-MIP (DCAir = 0.84/0.83, DCBackground = 0.78/0.73). The average DC in the 9 patients using 40% and PET edge, respectively, was also lowest for FB-PET/CT (DC = 0.45/0.44) and highest for 4D-PET/CT-MIP (DC = 0.72/0.73). In the 9 lesions, the target volumes of the FB-PET using 40% and PET edge, respectively, were on average 40% and 45% smaller than the 4D-PET-MIP. Conclusion: A 4D-PET-MIP produces volumes with the highest concordance with 4D-CT-MIP across multiple breathing patterns and lesion sizes in both a phantom and among patients. Freebreathing PET/CT consistently

  18. True 4D Image Denoising on the GPU.

    PubMed

    Eklund, Anders; Andersson, Mats; Knutsson, Hans

    2011-01-01

    The use of image denoising techniques is an important part of many medical imaging applications. One common application is to improve the image quality of low-dose (noisy) computed tomography (CT) data. While 3D image denoising previously has been applied to several volumes independently, there has not been much work done on true 4D image denoising, where the algorithm considers several volumes at the same time. The problem with 4D image denoising, compared to 2D and 3D denoising, is that the computational complexity increases exponentially. In this paper we describe a novel algorithm for true 4D image denoising, based on local adaptive filtering, and how to implement it on the graphics processing unit (GPU). The algorithm was applied to a 4D CT heart dataset of the resolution 512  × 512  × 445  × 20. The result is that the GPU can complete the denoising in about 25 minutes if spatial filtering is used and in about 8 minutes if FFT-based filtering is used. The CPU implementation requires several days of processing time for spatial filtering and about 50 minutes for FFT-based filtering. The short processing time increases the clinical value of true 4D image denoising significantly.

  19. 4D MR imaging using robust internal respiratory signal

    NASA Astrophysics Data System (ADS)

    Hui, CheukKai; Wen, Zhifei; Stemkens, Bjorn; Tijssen, R. H. N.; van den Berg, C. A. T.; Hwang, Ken-Pin; Beddar, Sam

    2016-05-01

    The purpose of this study is to investigate the feasibility of using internal respiratory (IR) surrogates to sort four-dimensional (4D) magnetic resonance (MR) images. The 4D MR images were constructed by acquiring fast 2D cine MR images sequentially, with each slice scanned for more than one breathing cycle. The 4D volume was then sorted retrospectively using the IR signal. In this study, we propose to use multiple low-frequency components in the Fourier space as well as the anterior body boundary as potential IR surrogates. From these potential IR surrogates, we used a clustering algorithm to identify those that best represented the respiratory pattern to derive the IR signal. A study with healthy volunteers was performed to assess the feasibility of the proposed IR signal. We compared this proposed IR signal with the respiratory signal obtained using respiratory bellows. Overall, 99% of the IR signals matched the bellows signals. The average difference between the end inspiration times in the IR signal and bellows signal was 0.18 s in this cohort of matching signals. For the acquired images corresponding to the other 1% of non-matching signal pairs, the respiratory motion shown in the images was coherent with the respiratory phases determined by the IR signal, but not the bellows signal. This suggested that the IR signal determined by the proposed method could potentially correct the faulty bellows signal. The sorted 4D images showed minimal mismatched artefacts and potential clinical applicability. The proposed IR signal therefore provides a feasible alternative to effectively sort MR images in 4D.

  20. PET Imaging of Angiogenesis

    PubMed Central

    Niu, Gang; Chen, Xiaoyuan

    2009-01-01

    Synopsis Angiogenesis is a highly-controlled process that is dependent on the intricate balance of both promoting and inhibiting factors, involved in various physiological and pathological processes. A comprehensive understanding of the molecular mechanisms that regulate angiogenesis has resulted in the design of new and more effective therapeutic strategies. Due to insufficient sensitivity to detect therapeutic effects by using standard clinical endpoints or by looking for physiological improvement, a multitude of imaging techniques have been developed to assess tissue vasculature on the structural, functional and molecular level. Imaging is expected to provide a novel approach to noninvasively monitor angiogenesis, to optimize the dose of new antiangiogenic agents and to assess the efficacy of therapies directed at modulation of the angiogenic process. All these methods have been successfully used preclinically and will hopefully aid in antiangiogenic drug development in animal studies. In this review article, the application of PET in angiogenesis imaging at both functional and molecular level will be discussed. For PET imaging of angiogenesis related molecular markers, we emphasize integrin αvβ3, VEGF/VEGFR, and MMPs. PMID:20046926

  1. Model-based image reconstruction for four-dimensional PET

    SciTech Connect

    Li Tianfang; Thorndyke, Brian; Schreibmann, Eduard; Yang Yong; Xing Lei

    2006-05-15

    Positron emission tonography (PET) is useful in diagnosis and radiation treatment planning for a variety of cancers. For patients with cancers in thoracic or upper abdominal region, the respiratory motion produces large distortions in the tumor shape and size, affecting the accuracy in both diagnosis and treatment. Four-dimensional (4D) (gated) PET aims to reduce the motion artifacts and to provide accurate measurement of the tumor volume and the tracer concentration. A major issue in 4D PET is the lack of statistics. Since the collected photons are divided into several frames in the 4D PET scan, the quality of each reconstructed frame degrades as the number of frames increases. The increased noise in each frame heavily degrades the quantitative accuracy of the PET imaging. In this work, we propose a method to enhance the performance of 4D PET by developing a new technique of 4D PET reconstruction with incorporation of an organ motion model derived from 4D-CT images. The method is based on the well-known maximum-likelihood expectation-maximization (ML-EM) algorithm. During the processes of forward- and backward-projection in the ML-EM iterations, all projection data acquired at different phases are combined together to update the emission map with the aid of deformable model, the statistics is therefore greatly improved. The proposed algorithm was first evaluated with computer simulations using a mathematical dynamic phantom. Experiment with a moving physical phantom was then carried out to demonstrate the accuracy of the proposed method and the increase of signal-to-noise ratio over three-dimensional PET. Finally, the 4D PET reconstruction was applied to a patient case.

  2. SU-D-17A-04: The Impact of Audiovisual Biofeedback On Image Quality During 4D Functional and Anatomic Imaging: Results of a Prospective Clinical Trial

    SciTech Connect

    Keall, P; Pollock, S; Yang, J; Diehn, M; Berger, J; Graves, E; Loo, B; Yamamoto, T

    2014-06-01

    Purpose: The ability of audiovisual (AV) biofeedback to improve breathing regularity has not previously been investigated for functional imaging studies. The purpose of this study was to investigate the impact of AV biofeedback on 4D-PET and 4D-CT image quality in a prospective clinical trial. We hypothesized that motion blurring in 4D-PET images and the number of artifacts in 4D-CT images are reduced using AV biofeedback. Methods: AV biofeedback is a real-time, interactive and personalized system designed to help a patient self-regulate his/her breathing using a patient-specific representative waveform and musical guides. In an IRB-approved prospective clinical trial, 4D-PET and 4D-CT images of 10 lung cancer patients were acquired with AV biofeedback (AV) and free breathing (FB). The 4D-PET images in 6 respiratory bins were analyzed for motion blurring by: (1) decrease of GTVPET and (2) increase of SUVmax in 4-DPET compared to 3D-PET. The 4D-CT images were analyzed for artifacts by: (1) comparing normalized cross correlation-based scores (NCCS); and (2) quantifying a visual assessment score (VAS). A two-tailed paired t-test was used to test the hypotheses. Results: The impact of AV biofeedback on 4D-PET and 4D-CT images varied widely between patients, suggesting inconsistent patient comprehension and capability. Overall, the 4D-PET decrease of GTVPET was 2.0±3.0cm3 with AV and 2.3±3.9cm{sup 3} for FB (p=0.61). The 4D-PET increase of SUVmax was 1.6±1.0 with AV and 1.1±0.8 with FB (p=0.002). The 4D-CT NCCS were 0.65±0.27 with AV and 0.60±0.32 for FB (p=0.32). The 4D-CT VAS was 0.0±2.7 (p=ns). Conclusion: A 10-patient study demonstrated a statistically significant reduction of motion blurring of AV over FB for 1/2 functional 4D-PET imaging metrics. No difference between AV and FB was found for 2 anatomic 4D-CT imaging metrics. Future studies will focus on optimizing the human-computer interface and including patient training sessions for improved

  3. 4D Light Field Imaging System Using Programmable Aperture

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam

    2012-01-01

    Complete depth information can be extracted from analyzing all angles of light rays emanated from a source. However, this angular information is lost in a typical 2D imaging system. In order to record this information, a standard stereo imaging system uses two cameras to obtain information from two view angles. Sometimes, more cameras are used to obtain information from more angles. However, a 4D light field imaging technique can achieve this multiple-camera effect through a single-lens camera. Two methods are available for this: one using a microlens array, and the other using a moving aperture. The moving-aperture method can obtain more complete stereo information. The existing literature suggests a modified liquid crystal panel [LC (liquid crystal) panel, similar to ones commonly used in the display industry] to achieve a moving aperture. However, LC panels cannot withstand harsh environments and are not qualified for spaceflight. In this regard, different hardware is proposed for the moving aperture. A digital micromirror device (DMD) will replace the liquid crystal. This will be qualified for harsh environments for the 4D light field imaging. This will enable an imager to record near-complete stereo information. The approach to building a proof-ofconcept is using existing, or slightly modified, off-the-shelf components. An SLR (single-lens reflex) lens system, which typically has a large aperture for fast imaging, will be modified. The lens system will be arranged so that DMD can be integrated. The shape of aperture will be programmed for single-viewpoint imaging, multiple-viewpoint imaging, and coded aperture imaging. The novelty lies in using a DMD instead of a LC panel to move the apertures for 4D light field imaging. The DMD uses reflecting mirrors, so any light transmission lost (which would be expected from the LC panel) will be minimal. Also, the MEMS-based DMD can withstand higher temperature and pressure fluctuation than a LC panel can. Robotics need

  4. Denoising and 4D visualization of OCT images

    PubMed Central

    Gargesha, Madhusudhana; Jenkins, Michael W.; Rollins, Andrew M.; Wilson, David L.

    2009-01-01

    We are using Optical Coherence Tomography (OCT) to image structure and function of the developing embryonic heart in avian models. Fast OCT imaging produces very large 3D (2D + time) and 4D (3D volumes + time) data sets, which greatly challenge ones ability to visualize results. Noise in OCT images poses additional challenges. We created an algorithm with a quick, data set specific optimization for reduction of both shot and speckle noise and applied it to 3D visualization and image segmentation in OCT. When compared to baseline algorithms (median, Wiener, orthogonal wavelet, basic non-orthogonal wavelet), a panel of experts judged the new algorithm to give much improved volume renderings concerning both noise and 3D visualization. Specifically, the algorithm provided a better visualization of the myocardial and endocardial surfaces, and the interaction of the embryonic heart tube with surrounding tissue. Quantitative evaluation using an image quality figure of merit also indicated superiority of the new algorithm. Noise reduction aided semi-automatic 2D image segmentation, as quantitatively evaluated using a contour distance measure with respect to an expert segmented contour. In conclusion, the noise reduction algorithm should be quite useful for visualization and quantitative measurements (e.g., heart volume, stroke volume, contraction velocity, etc.) in OCT embryo images. With its semi-automatic, data set specific optimization, we believe that the algorithm can be applied to OCT images from other applications. PMID:18679509

  5. Exercises in PET Image Reconstruction

    NASA Astrophysics Data System (ADS)

    Nix, Oliver

    These exercises are complementary to the theoretical lectures about positron emission tomography (PET) image reconstruction. They aim at providing some hands on experience in PET image reconstruction and focus on demonstrating the different data preprocessing steps and reconstruction algorithms needed to obtain high quality PET images. Normalisation, geometric-, attenuation- and scatter correction are introduced. To explain the necessity of those some basics about PET scanner hardware, data acquisition and organisation are reviewed. During the course the students use a software application based on the STIR (software for tomographic image reconstruction) library 1,2 which allows them to dynamically select or deselect corrections and reconstruction methods as well as to modify their most important parameters. Following the guided tutorial, the students get an impression on the effect the individual data precorrections have on image quality and what happens if they are forgotten. Several data sets in sinogram format are provided, such as line source data, Jaszczak phantom data sets with high and low statistics and NEMA whole body phantom data. The two most frequently used reconstruction algorithms in PET image reconstruction, filtered back projection (FBP) and the iterative OSEM (ordered subset expectation maximation) approach are used to reconstruct images. The exercise should help the students gaining an understanding what the reasons for inferior image quality and artefacts are and how to improve quality by a clever choice of reconstruction parameters.

  6. Application of adaptive kinetic modelling for bias propagation reduction in direct 4D image reconstruction.

    PubMed

    Kotasidis, F A; Matthews, J C; Reader, A J; Angelis, G I; Zaidi, H

    2014-10-21

    Parametric imaging in thoracic and abdominal PET can provide additional parameters more relevant to the pathophysiology of the system under study. However, dynamic data in the body are noisy due to the limiting counting statistics leading to suboptimal kinetic parameter estimates. Direct 4D image reconstruction algorithms can potentially improve kinetic parameter precision and accuracy in dynamic PET body imaging. However, construction of a common kinetic model is not always feasible and in contrast to post-reconstruction kinetic analysis, errors in poorly modelled regions may spatially propagate to regions which are well modelled. To reduce error propagation from erroneous model fits, we implement and evaluate a new approach to direct parameter estimation by incorporating a recently proposed kinetic modelling strategy within a direct 4D image reconstruction framework. The algorithm uses a secondary more general model to allow a less constrained model fit in regions where the kinetic model does not accurately describe the underlying kinetics. A portion of the residuals then is adaptively included back into the image whilst preserving the primary model characteristics in other well modelled regions using a penalty term that trades off the models. Using fully 4D simulations based on dynamic [(15)O]H2O datasets, we demonstrate reduction in propagation-related bias for all kinetic parameters. Under noisy conditions, reductions in bias due to propagation are obtained at the cost of increased noise, which in turn results in increased bias and variance of the kinetic parameters. This trade-off reflects the challenge of separating the residuals arising from poor kinetic modelling fits from the residuals arising purely from noise. Nonetheless, the overall root mean square error is reduced in most regions and parameters. Using the adaptive 4D image reconstruction improved model fits can be obtained in poorly modelled regions, leading to reduced errors potentially propagating

  7. Modelling and Simulation of 4D GeoPET Measurements with COMSOL Multiphysics 4.2a

    NASA Astrophysics Data System (ADS)

    Schikora, J.; Kulenkampff, J.; Gründig, M.; Lippmann-Pipke, J.

    2012-04-01

    Our GeoPET-method allows the 4D monitoring of (reactive) transport processes in geological material on laboratory scale (Gründig et al., 2007; Kulenkampff et al., 2008; Richter et al., 2005) by quantitative imaging of tracer concentrations. Recently we have conducted a long-term 22Na+ in-diffusion experiment in an Opalinus clay drill core over a period of 7 months. We modelled this experiment with COMSOL Multiphysics ® 4.2a (3D convection-diffusion equation, PDE mode, PARDISO solver) for reproducing the observed spatiotemporal concentration distribution data with the following underlying equation for this anisotropic diffusion and adsorption: ɛdci= \\upsidedownBigTriangle (D ·\\upsidedownBigTriangle c )- ρdq- dt e i dt - ɛ [-] porosity, ci[mol/m3] 22Na+concentration, De [m2/s] tensor of the effective diffusion constant for 22Na+ in Opalinus clay, ρ [kg/m3] bulk density and dq/dt sink term for considering the sorption. By importing GeoPET images from various time steps and applying the Optimization Module (least square fit applying the Levenberg-Marquardt algorithm) to these images we efficiently determined best fit values e.g. of the diffusion tensor. Combined with the parameter sweep operation the sensitivity analysis is performed in parallel and covers the range of literature values for porosity and Kd values for 22Na+sorption on Opalinus clay. The experimental data could be reproduced quite well, but the obtained parameter values for diffusion parallel and normal to the bedding are slightly larger than reported in Gimmi and Kosakowski (2011). This is coherent with our observations of an emerging gas bubble in the central borehole tracer reservoir: Soil moisture tension in the partly unsaturated clay must have significantly influenced the transport regime by an additional advective component. We suggest COMSOL Multiphysics ® is a powerful tool for the inverse modelling of timedependent, multidimensional experimental data as obtained by GeoPET.

  8. Respiratory triggered 4D cone-beam computed tomography: A novel method to reduce imaging dose

    SciTech Connect

    Cooper, Benjamin J.; O'Brien, Ricky T.; Keall, Paul J.; Balik, Salim; Hugo, Geoffrey D.

    2013-04-15

    Purpose: A novel method called respiratory triggered 4D cone-beam computed tomography (RT 4D CBCT) is described whereby imaging dose can be reduced without degrading image quality. RT 4D CBCT utilizes a respiratory signal to trigger projections such that only a single projection is assigned to a given respiratory bin for each breathing cycle. In contrast, commercial 4D CBCT does not actively use the respiratory signal to minimize image dose. Methods: To compare RT 4D CBCT with conventional 4D CBCT, 3600 CBCT projections of a thorax phantom were gathered and reconstructed to generate a ground truth CBCT dataset. Simulation pairs of conventional 4D CBCT acquisitions and RT 4D CBCT acquisitions were developed assuming a sinusoidal respiratory signal which governs the selection of projections from the pool of 3600 original projections. The RT 4D CBCT acquisition triggers a single projection when the respiratory signal enters a desired acquisition bin; the conventional acquisition does not use a respiratory trigger and projections are acquired at a constant frequency. Acquisition parameters studied were breathing period, acquisition time, and imager frequency. The performance of RT 4D CBCT using phase based and displacement based sorting was also studied. Image quality was quantified by calculating difference images of the test dataset from the ground truth dataset. Imaging dose was calculated by counting projections. Results: Using phase based sorting RT 4D CBCT results in 47% less imaging dose on average compared to conventional 4D CBCT. Image quality differences were less than 4% at worst. Using displacement based sorting RT 4D CBCT results in 57% less imaging dose on average, than conventional 4D CBCT methods; however, image quality was 26% worse with RT 4D CBCT. Conclusions: Simulation studies have shown that RT 4D CBCT reduces imaging dose while maintaining comparable image quality for phase based 4D CBCT; image quality is degraded for displacement based RT 4D

  9. PET Imaging in Huntington's Disease.

    PubMed

    Roussakis, Andreas-Antonios; Piccini, Paola

    2015-01-01

    To date, little is known about how neurodegeneration and neuroinflammation propagate in Huntington's disease (HD). Unfortunately, no treatment is available to cure or reverse the progressive decline of function caused by the disease, thus considering HD a fatal disease. Mutation gene carriers typically remain asymptomatic for many years although alterations in the basal ganglia and cortex occur early on in mutant HD gene-carriers. Positron Emission Tomography (PET) is a functional imaging technique of nuclear medicine which enables in vivo visualization of numerous biological molecules expressed in several human tissues. Brain PET is most powerful to study in vivo neuronal and glial cells function as well as cerebral blood flow in a plethora of neurodegenerative disorders including Parkinson's disease, Alzheimer's and HD. In absence of HD-specific biomarkers for monitoring disease progression, previous PET studies in HD were merely focused on the study of dopaminergic terminals, cerebral blood flow and glucose metabolism in manifest and premanifest HD-gene carriers. More recently, research interest has been exploring novel PET targets in HD including the state of phosphodiesterse expression and the role of activated microglia. Hence, a better understanding of the HD pathogenesis mechanisms may lead to the development of targeted therapies. PET imaging follow-up studies with novel selective PET radiotracers such as 11C-IMA-107 and 11C-PBR28 may provide insight on disease progression and identify prognostic biomarkers, elucidate the underlying HD pathology and assess novel pharmaceutical agents and over time.

  10. 4D Imaging of Protein Aggregation in Live Cells

    PubMed Central

    Kaganovich, Daniel

    2013-01-01

    proteins that are not ubiquitinated are diverted to the IPOD, where they are actively aggregated in a protective compartment. Up until this point, the methodological paradigm of live-cell fluorescence microscopy has largely been to label proteins and track their locations in the cell at specific time-points and usually in two dimensions. As new technologies have begun to grant experimenters unprecedented access to the submicron scale in living cells, the dynamic architecture of the cytosol has come into view as a challenging new frontier for experimental characterization. We present a method for rapidly monitoring the 3D spatial distributions of multiple fluorescently labeled proteins in the yeast cytosol over time. 3D timelapse (4D imaging) is not merely a technical challenge; rather, it also facilitates a dramatic shift in the conceptual framework used to analyze cellular structure. We utilize a cytosolic folding sensor protein in live yeast to visualize distinct fates for misfolded proteins in cellular aggregation quality control, using rapid 4D fluorescent imaging. The temperature sensitive mutant of the Ubc9 protein10-12 (Ubc9ts) is extremely effective both as a sensor of cellular proteostasis, and a physiological model for tracking aggregation quality control. As with most ts proteins, Ubc9ts is fully folded and functional at permissive temperatures due to active cellular chaperones. Above 30 °C, or when the cell faces misfolding stress, Ubc9ts misfolds and follows the fate of a native globular protein that has been misfolded due to mutation, heat denaturation, or oxidative damage. By fusing it to GFP or other fluorophores, it can be tracked in 3D as it forms Stress Foci, or is directed to JUNQ or IPOD. PMID:23608881

  11. MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research

    PubMed Central

    Paul Segars, W.; Tsui, Benjamin M. W.

    2012-01-01

    Recent work in the development of computerized phantoms has focused on the creation of ideal “hybrid” models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be

  12. Edge preserving smoothing and segmentation of 4-D images via transversely isotropic scale-space processing and fingerprint analysis

    SciTech Connect

    Reutter, Bryan W.; Algazi, V. Ralph; Gullberg, Grant T; Huesman, Ronald H.

    2004-01-19

    Enhancements are described for an approach that unifies edge preserving smoothing with segmentation of time sequences of volumetric images, based on differential edge detection at multiple spatial and temporal scales. Potential applications of these 4-D methods include segmentation of respiratory gated positron emission tomography (PET) transmission images to improve accuracy of attenuation correction for imaging heart and lung lesions, and segmentation of dynamic cardiac single photon emission computed tomography (SPECT) images to facilitate unbiased estimation of time-activity curves and kinetic parameters for left ventricular volumes of interest. Improved segmentation of lung surfaces in simulated respiratory gated cardiac PET transmission images is achieved with a 4-D edge detection operator composed of edge preserving 1-D operators applied in various spatial and temporal directions. Smoothing along the axis of a 1-D operator is driven by structure separation seen in the scale-space fingerprint, rather than by image contrast. Spurious noise structures are reduced with use of small-scale isotropic smoothing in directions transverse to the 1-D operator axis. Analytic expressions are obtained for directional derivatives of the smoothed, edge preserved image, and the expressions are used to compose a 4-D operator that detects edges as zero-crossings in the second derivative in the direction of the image intensity gradient. Additional improvement in segmentation is anticipated with use of multiscale transversely isotropic smoothing and a novel interpolation method that improves the behavior of the directional derivatives. The interpolation method is demonstrated on a simulated 1-D edge and incorporation of the method into the 4-D algorithm is described.

  13. 4D ultrasound imaging - ethically justifiable in India?

    PubMed

    Indiran, Venkatraman

    2017-01-01

    Four-dimensional (4D) ultrasound (real-time volume sonography), which has been used in the West since the last decade for the determination of gender as well as for bonding and entertainment of the parents, has become widely available in India in this decade. Here, I would like to discuss the ethical issues associated with 4D ultrasonography in India. These are self-referral, the use of the technology for non-medical indications, a higher possibility of the disclosure of the foetus' gender and safety concerns.

  14. 2D/4D marker-free tumor tracking using 4D CBCT as the reference image.

    PubMed

    Wang, Mengjiao; Sharp, Gregory C; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

    2014-05-07

    Tumor motion caused by respiration is an important issue in image-guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and a streak-free 3DCBCT volume are combined to improve the image quality of the digitally reconstructed radiographs (DRRs). Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and one-minute and two-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. The diaphragm matching accuracy was 1.88 ± 1.35 mm in the isocenter plane and the 2D tumor tracking accuracy was 2.13 ± 1.26 mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purposes.

  15. TU-G-BRA-02: Can We Extract Lung Function Directly From 4D-CT Without Deformable Image Registration?

    SciTech Connect

    Kipritidis, J; Woodruff, H; Counter, W; Keall, P; Hofman, M; Siva, S; Callahan, J; Le Roux, P; Hardcastle, N

    2015-06-15

    Purpose: Dynamic CT ventilation imaging (CT-VI) visualizes air volume changes in the lung by evaluating breathing-induced lung motion using deformable image registration (DIR). Dynamic CT-VI could enable functionally adaptive lung cancer radiation therapy, but its sensitivity to DIR parameters poses challenges for validation. We hypothesize that a direct metric using CT parameters derived from Hounsfield units (HU) alone can provide similar ventilation images without DIR. We compare the accuracy of Direct and Dynamic CT-VIs versus positron emission tomography (PET) images of inhaled {sup 68}Ga-labelled nanoparticles (‘Galligas’). Methods: 25 patients with lung cancer underwent Galligas 4D-PET/CT scans prior to radiation therapy. For each patient we produced three CT- VIs. (i) Our novel method, Direct CT-VI, models blood-gas exchange as the product of air and tissue density at each lung voxel based on time-averaged 4D-CT HU values. Dynamic CT-VIs were produced by evaluating: (ii) regional HU changes, and (iii) regional volume changes between the exhale and inhale 4D-CT phase images using a validated B-spline DIR method. We assessed the accuracy of each CT-VI by computing the voxel-wise Spearman correlation with free-breathing Galligas PET, and also performed a visual analysis. Results: Surprisingly, Direct CT-VIs exhibited better global correlation with Galligas PET than either of the dynamic CT-VIs. The (mean ± SD) correlations were (0.55 ± 0.16), (0.41 ± 0.22) and (0.29 ± 0.27) for Direct, Dynamic HU-based and Dynamic volume-based CT-VIs respectively. Visual comparison of Direct CT-VI to PET demonstrated similarity for emphysema defects and ventral-to-dorsal gradients, but inability to identify decreased ventilation distal to tumor-obstruction. Conclusion: Our data supports the hypothesis that Direct CT-VIs are as accurate as Dynamic CT-VIs in terms of global correlation with Galligas PET. Visual analysis, however, demonstrated that different CT

  16. 4D laser camera for accurate patient positioning, collision avoidance, image fusion and adaptive approaches during diagnostic and therapeutic procedures.

    PubMed

    Brahme, Anders; Nyman, Peter; Skatt, Björn

    2008-05-01

    A four-dimensional (4D) laser camera (LC) has been developed for accurate patient imaging in diagnostic and therapeutic radiology. A complementary metal-oxide semiconductor camera images the intersection of a scanned fan shaped laser beam with the surface of the patient and allows real time recording of movements in a three-dimensional (3D) or four-dimensional (4D) format (3D +time). The LC system was first designed as an accurate patient setup tool during diagnostic and therapeutic applications but was found to be of much wider applicability as a general 4D photon "tag" for the surface of the patient in different clinical procedures. It is presently used as a 3D or 4D optical benchmark or tag for accurate delineation of the patient surface as demonstrated for patient auto setup, breathing and heart motion detection. Furthermore, its future potential applications in gating, adaptive therapy, 3D or 4D image fusion between most imaging modalities and image processing are discussed. It is shown that the LC system has a geometrical resolution of about 0, 1 mm and that the rigid body repositioning accuracy is about 0, 5 mm below 20 mm displacements, 1 mm below 40 mm and better than 2 mm at 70 mm. This indicates a slight need for repeated repositioning when the initial error is larger than about 50 mm. The positioning accuracy with standard patient setup procedures for prostate cancer at Karolinska was found to be about 5-6 mm when independently measured using the LC system. The system was found valuable for positron emission tomography-computed tomography (PET-CT) in vivo tumor and dose delivery imaging where it potentially may allow effective correction for breathing artifacts in 4D PET-CT and image fusion with lymph node atlases for accurate target volume definition in oncology. With a LC system in all imaging and radiation therapy rooms, auto setup during repeated diagnostic and therapeutic procedures may save around 5 min per session, increase accuracy and allow

  17. PET/CT for radiotherapy: image acquisition and data processing.

    PubMed

    Bettinardi, V; Picchio, M; Di Muzio, N; Gianolli, L; Messa, C; Gilardi, M C

    2010-10-01

    This paper focuses on acquisition and processing methods in positron emission tomography/computed tomography (PET/CT) for radiotherapy (RT) applications. The recent technological evolutions of PET/CT systems are described. Particular emphasis is dedicated to the tools needed for the patient positioning and immobilization, to be used in PET/CT studies as well as during RT treatment sessions. The effect of organ and lesion motion due to patient's respiration on PET/CT imaging is discussed. Breathing protocols proposed to minimize PET/CT spatial mismatches in relation to respiratory movements are illustrated. The respiratory gated (RG) 4D-PET/CT techniques, developed to measure and compensate for organ and lesion motion, are then introduced. Finally a description is provided of different acquisition and data processing techniques, implemented with the aim at improving: i) image quality and quantitative accuracy of PET images, and ii) target volume definition and treatment planning in RT, by using specific and personalised motion information.

  18. SU-E-J-123: Assessing Segmentation Accuracy of Internal Volumes and Sub-Volumes in 4D PET/CT of Lung Tumors Using a Novel 3D Printed Phantom

    SciTech Connect

    Soultan, D; Murphy, J; James, C; Hoh, C; Moiseenko, V; Cervino, L; Gill, B

    2015-06-15

    Purpose: To assess the accuracy of internal target volume (ITV) segmentation of lung tumors for treatment planning of simultaneous integrated boost (SIB) radiotherapy as seen in 4D PET/CT images, using a novel 3D-printed phantom. Methods: The insert mimics high PET tracer uptake in the core and 50% uptake in the periphery, by using a porous design at the periphery. A lung phantom with the insert was placed on a programmable moving platform. Seven breathing waveforms of ideal and patient-specific respiratory motion patterns were fed to the platform, and 4D PET/CT scans were acquired of each of them. CT images were binned into 10 phases, and PET images were binned into 5 phases following the clinical protocol. Two scenarios were investigated for segmentation: a gate 30–70 window, and no gating. The radiation oncologist contoured the outer ITV of the porous insert with on CT images, while the internal void volume with 100% uptake was contoured on PET images for being indistinguishable from the outer volume in CT images. Segmented ITVs were compared to the expected volumes based on known target size and motion. Results: 3 ideal breathing patterns, 2 regular-breathing patient waveforms, and 2 irregular-breathing patient waveforms were used for this study. 18F-FDG was used as the PET tracer. The segmented ITVs from CT closely matched the expected motion for both no gating and gate 30–70 window, with disagreement of contoured ITV with respect to the expected volume not exceeding 13%. PET contours were seen to overestimate volumes in all the cases, up to more than 40%. Conclusion: 4DPET images of a novel 3D printed phantom designed to mimic different uptake values were obtained. 4DPET contours overestimated ITV volumes in all cases, while 4DCT contours matched expected ITV volume values. Investigation of the cause and effects of the discrepancies is undergoing.

  19. Towards real-time registration of 4D ultrasound images.

    PubMed

    Foroughi, Pezhman; Abolmaesumi, Purang; Hashtrudi-Zaad, Keyvan

    2006-01-01

    In this paper, we demonstrate a method for fast registration of sequences of 3D liver images, which could be used for the future real-time applications. In our method, every image is elastically registered to a so called fixed ultrasound image exploiting the information from previous registration. A few feature points are automatically selected, and tracked inside the images, while the deformation of other points are extrapolated with respect to the tracked points employing a fast free-form approach. The main intended application of the proposed method is real-time tracking of tumors for radiosurgery. The algorithm is evaluated on both naturally and artificially deformed images. Experimental results show that for around 85 percent accuracy, the process of tracking is completed very close to real time.

  20. Quantitative simultaneous PET-MR imaging

    NASA Astrophysics Data System (ADS)

    Ouyang, Jinsong; Petibon, Yoann; Huang, Chuan; Reese, Timothy G.; Kolnick, Aleksandra L.; El Fakhri, Georges

    2014-06-01

    Whole-body PET is currently limited by the degradation due to patient motion. Respiratory motion degrades imaging studies of the abdomen. Similarly, both respiratory and cardiac motions significantly hamper the assessment of myocardial ischemia and/or metabolism in perfusion and viability cardiac PET studies. Based on simultaneous PET-MR, we have developed robust and accurate MRI methods allowing the tracking and measurement of both respiratory and cardiac motions during abdominal or cardiac studies. Our list-mode iterative PET reconstruction framework incorporates the measured motion fields into PET emission system matrix as well as the time-dependent PET attenuation map and the position dependent point spread function. Our method significantly enhances the PET image quality as compared to conventional methods.

  1. Proton Therapy Verification with PET Imaging

    PubMed Central

    Zhu, Xuping; Fakhri, Georges El

    2013-01-01

    Proton therapy is very sensitive to uncertainties introduced during treatment planning and dose delivery. PET imaging of proton induced positron emitter distributions is the only practical approach for in vivo, in situ verification of proton therapy. This article reviews the current status of proton therapy verification with PET imaging. The different data detecting systems (in-beam, in-room and off-line PET), calculation methods for the prediction of proton induced PET activity distributions, and approaches for data evaluation are discussed. PMID:24312147

  2. Pulmonary imaging using respiratory motion compensated simultaneous PET/MR

    PubMed Central

    Dutta, Joyita; Huang, Chuan; Li, Quanzheng; El Fakhri, Georges

    2015-01-01

    Purpose: Pulmonary positron emission tomography (PET) imaging is confounded by blurring artifacts caused by respiratory motion. These artifacts degrade both image quality and quantitative accuracy. In this paper, the authors present a complete data acquisition and processing framework for respiratory motion compensated image reconstruction (MCIR) using simultaneous whole body PET/magnetic resonance (MR) and validate it through simulation and clinical patient studies. Methods: The authors have developed an MCIR framework based on maximum a posteriori or MAP estimation. For fast acquisition of high quality 4D MR images, the authors developed a novel Golden-angle RAdial Navigated Gradient Echo (GRANGE) pulse sequence and used it in conjunction with sparsity-enforcing k-t FOCUSS reconstruction. The authors use a 1D slice-projection navigator signal encapsulated within this pulse sequence along with a histogram-based gate assignment technique to retrospectively sort the MR and PET data into individual gates. The authors compute deformation fields for each gate via nonrigid registration. The deformation fields are incorporated into the PET data model as well as utilized for generating dynamic attenuation maps. The framework was validated using simulation studies on the 4D XCAT phantom and three clinical patient studies that were performed on the Biograph mMR, a simultaneous whole body PET/MR scanner. Results: The authors compared MCIR (MC) results with ungated (UG) and one-gate (OG) reconstruction results. The XCAT study revealed contrast-to-noise ratio (CNR) improvements for MC relative to UG in the range of 21%–107% for 14 mm diameter lung lesions and 39%–120% for 10 mm diameter lung lesions. A strategy for regularization parameter selection was proposed, validated using XCAT simulations, and applied to the clinical studies. The authors’ results show that the MC image yields 19%–190% increase in the CNR of high-intensity features of interest affected by

  3. Comparison of Texture Features Derived from Static and Respiratory-Gated PET Images in Non-Small Cell Lung Cancer

    PubMed Central

    Yip, Stephen; McCall, Keisha; Aristophanous, Michalis; Chen, Aileen B.

    2014-01-01

    Background PET-based texture features have been used to quantify tumor heterogeneity due to their predictive power in treatment outcome. We investigated the sensitivity of texture features to tumor motion by comparing static (3D) and respiratory-gated (4D) PET imaging. Methods Twenty-six patients (34 lesions) received 3D and 4D [18F]FDG-PET scans before the chemo-radiotherapy. The acquired 4D data were retrospectively binned into five breathing phases to create the 4D image sequence. Texture features, including Maximal correlation coefficient (MCC), Long run low gray (LRLG), Coarseness, Contrast, and Busyness, were computed within the physician-defined tumor volume. The relative difference (δ3D-4D) in each texture between the 3D- and 4D-PET imaging was calculated. Coefficient of variation (CV) was used to determine the variability in the textures between all 4D-PET phases. Correlations between tumor volume, motion amplitude, and δ3D-4D were also assessed. Results 4D-PET increased LRLG ( = 1%–2%, p<0.02), Busyness ( = 7%–19%, p<0.01), and decreased MCC ( = 1%–2%, p<7.5×10−3), Coarseness ( = 5%–10%, p<0.05) and Contrast ( = 4%–6%, p>0.08) compared to 3D-PET. Nearly negligible variability was found between the 4D phase bins with CV<5% for MCC, LRLG, and Coarseness. For Contrast and Busyness, moderate variability was found with CV = 9% and 10%, respectively. No strong correlation was found between the tumor volume and δ3D-4D for the texture features. Motion amplitude had moderate impact on δ for MCC and Busyness and no impact for LRLG, Coarseness, and Contrast. Conclusions Significant differences were found in MCC, LRLG, Coarseness, and Busyness between 3D and 4D PET imaging. The variability between phase bins for MCC, LRLG, and Coarseness was negligible, suggesting that similar quantification can be obtained from all phases. Texture features, blurred out by respiratory motion during 3D-PET acquisition, can be better resolved by

  4. Quantitative PET imaging with the 3T MR-BrainPET

    NASA Astrophysics Data System (ADS)

    Weirich, C.; Scheins, J.; Lohmann, P.; Tellmann, L.; Byars, L.; Michel, C.; Rota Kops, E.; Brenner, D.; Herzog, H.; Shah, N. J.

    2013-02-01

    The new hybrid imaging technology of MR-PET allows for simultaneous acquisition of versatile MRI contrasts and the quantitative metabolic imaging with PET. In order to achieve the quantification of PET images with minimal residual error the application of several corrections is crucial. In this work we present our results on quantification with the 3T MR BrainPET scanner.

  5. The use of a generalized reconstruction by inversion of coupled systems (GRICS) approach for generic respiratory motion correction in PET/MR imaging.

    PubMed

    Fayad, Hadi; Odille, Freddy; Schmidt, Holger; Würslin, Christian; Küstner, Thomas; Feblinger, Jacques; Visvikis, Dimitris

    2015-03-21

    Respiratory motion is a source of artifacts in multimodality imaging such as PET/MR. Solutions include retrospective or prospective gating. They have however found limited use in clinical practice, since their increased overall acquisition duration to maintain overall image quality. More elaborate methods consist of using 4D MR datasets to extract spatial deformations in order to correct for the respiratory motion in PET. The main drawbacks of such approaches is the relatively long acquisition times associated with 4D MR imaging which is often incompatible with clinical PET/MR protocols. The objective of this work was to overcome these limitations by exploiting a generalized reconstruction by inversion of coupled systems (GRICS) approach. The methodology is based on a joint estimation of motion during the MR image reconstruction process, providing internal structure motion and associated deformation matrices for retrospective use in PET respiratory motion correction. This method was first validated on four MR volunteers and two PET/MR patient datasets by comparing GRICS generated MR images to 4D MR series obtained by retrospective gating. In a second step 4D PET datasets corresponding to acquired 4D MR images were simulated using the GATE Monte Carlo simulation platform. GRICS generated deformation matrices were subsequently used to correct respiratory motion in comparison to the 4D MR image based deformations both for the simulated and the two 4D PET/MR patient datasets. Results confirm that GRICS synchronized MR images correlate well with the acquired 4D MR series. Similarly, the use of GRICS for respiratory motion correction allows an equivalent percentage improvement on lesion contrast, position and size, considering the PET simulated tumors as well as PET real tumors. This work demonstrates the potential interest of using GRICS for PET respiratory motion correction in combined PET/MR using shorter duration acquisitions without the need for 4D MRI and

  6. Dependence of ventilation image derived from 4D CT on deformable image registration and ventilation algorithms.

    PubMed

    Latifi, Kujtim; Forster, Kenneth M; Hoffe, Sarah E; Dilling, Thomas J; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G

    2013-07-08

    Ventilation imaging using 4D CT is a convenient and low-cost functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. Deformable image registration (DIR) is needed to calculate ventilation imaging from 4D CT. This study investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. DIR of the normal end expiration and normal end inspiration phases of the 4D CT images was used to correlate the voxels between the two respiratory phases. Three different DIR algorithms, optical flow (OF), diffeomorphic demons (DD), and diffeomorphic morphons (DM) were retrospectively applied to ten esophagus and ten lung cancer cases with 4D CT image sets that encompassed the entire lung volume. The three ventilation extraction methods were used based on either the Jacobian, the change in volume of the voxel, or directly calculated from Hounsfield units. The ventilation calculation algorithms used are the Jacobian, ΔV, and HU method. They were compared using the Dice similarity coefficient (DSC) index and Bland-Altman plots. Dependence of ventilation images on the DIR was greater for the ΔV and the Jacobian methods than for the HU method. The DSC index for 20% of low-ventilation volume for ΔV was 0.33 ± 0.03 (1 SD) between OF and DM, 0.44 ± 0.05 between OF and DD, and 0.51 ± 0.04 between DM and DD. The similarity comparisons for Jacobian were 0.32 ± 0.03, 0.44 ± 0.05, and 0.51 ± 0.04, respectively, and for HU they were 0.53 ± 0.03, 0.56 ± 0.03, and 0.76 ± 0.04, respectively. Dependence of extracted ventilation on the ventilation algorithm used showed good agreement between the ΔV and Jacobian methods, but differed significantly for the HU method. DSC index for using OF as DIR was 0.86 ± 0.01 between ΔV and Jacobian, 0.28 ± 0.04 between ΔV and HU, and 0.28 ± 0.04 between Jacobian and HU, respectively. When using DM or DD as DIR, similar values were obtained when

  7. A hybrid reconstruction algorithm for fast and accurate 4D cone-beam CT imaging

    SciTech Connect

    Yan, Hao; Folkerts, Michael; Jiang, Steve B. E-mail: steve.jiang@UTSouthwestern.edu; Jia, Xun E-mail: steve.jiang@UTSouthwestern.edu; Zhen, Xin; Li, Yongbao; Pan, Tinsu; Cervino, Laura

    2014-07-15

    Purpose: 4D cone beam CT (4D-CBCT) has been utilized in radiation therapy to provide 4D image guidance in lung and upper abdomen area. However, clinical application of 4D-CBCT is currently limited due to the long scan time and low image quality. The purpose of this paper is to develop a new 4D-CBCT reconstruction method that restores volumetric images based on the 1-min scan data acquired with a standard 3D-CBCT protocol. Methods: The model optimizes a deformation vector field that deforms a patient-specific planning CT (p-CT), so that the calculated 4D-CBCT projections match measurements. A forward-backward splitting (FBS) method is invented to solve the optimization problem. It splits the original problem into two well-studied subproblems, i.e., image reconstruction and deformable image registration. By iteratively solving the two subproblems, FBS gradually yields correct deformation information, while maintaining high image quality. The whole workflow is implemented on a graphic-processing-unit to improve efficiency. Comprehensive evaluations have been conducted on a moving phantom and three real patient cases regarding the accuracy and quality of the reconstructed images, as well as the algorithm robustness and efficiency. Results: The proposed algorithm reconstructs 4D-CBCT images from highly under-sampled projection data acquired with 1-min scans. Regarding the anatomical structure location accuracy, 0.204 mm average differences and 0.484 mm maximum difference are found for the phantom case, and the maximum differences of 0.3–0.5 mm for patients 1–3 are observed. As for the image quality, intensity errors below 5 and 20 HU compared to the planning CT are achieved for the phantom and the patient cases, respectively. Signal-noise-ratio values are improved by 12.74 and 5.12 times compared to results from FDK algorithm using the 1-min data and 4-min data, respectively. The computation time of the algorithm on a NVIDIA GTX590 card is 1–1.5 min per phase

  8. PET and SPECT imaging in veterinary medicine.

    PubMed

    LeBlanc, Amy K; Peremans, Kathelijne

    2014-01-01

    Veterinarians have gained increasing access to positron emission tomography (PET and PET/CT) imaging facilities, allowing them to use this powerful molecular imaging technique for clinical and research applications. SPECT is currently being used more in Europe than in the United States and has been shown to be useful in veterinary oncology and in the evaluation of orthopedic diseases. SPECT brain perfusion and receptor imaging is used to investigate behavioral disorders in animals that have interesting similarities to human psychiatric disorders. This article provides an overview of the potential applications of PET and SPECT. The use of commercially available and investigational PET radiopharmaceuticals in the management of veterinary disease has been discussed. To date, most of the work in this field has utilized the commercially available PET tracer, (18)F-fluorodeoxyglucose for oncologic imaging. Normal biodistribution studies in several companion animal species (cats, dogs, and birds) have been published to assist in lesion detection and interpretation for veterinary radiologists and clinicians. Studies evaluating other (18)F-labeled tracers for research applications are underway at several institutions and companion animal models of human diseases are being increasingly recognized for their value in biomarker and therapy development. Although PET and SPECT technologies are in their infancy for clinical veterinary medicine, increasing access to and interest in these applications and other molecular imaging techniques has led to a greater knowledge and collective body of expertise for veterinarians worldwide. Initiation and fostering of physician-veterinarian collaborations are key components to the forward movement of this field.

  9. Radiolucent 4D Ultrasound Imaging: System Design and Application to Radiotherapy Guidance.

    PubMed

    Schlosser, Jeffrey; Hristov, Dimitre

    2016-04-27

    Four-dimensional (4D) ultrasound (US) is an attractive modality for image guidance due to its real-time, non-ionizing, volumetric imaging capability with high soft tissue contrast. However, existing 4D US imaging systems contain large volumes of metal which interfere with diagnostic and therapeutic ionizing radiation in procedures such as CT imaging and radiation therapy. This study aimed to design and characterize a novel 4D Radiolucent Remotely-Actuated UltraSound Scanning (RRUSS) device that overcomes this limitation. In a phantom, we evaluated the imaging performance of the RRUSS device including frame rate, resolution, spatial integrity, and motion tracking accuracy. To evaluate compatibility with radiation therapy workflow, we evaluated device-induced CT imaging artifacts, US tracking performance during beam delivery, and device compatibility with commercial radiotherapy planning software. The RRUSS device produced 4D volumes at 0.1-3.0 Hz with 60⁰ lateral field of view (FOV), 50⁰ maximum elevational FOV, and 200 mm maximum depth. Imaging resolution (-3 dB point spread width) was 1.2-7.9 mm at depths up to 100 mm and motion tracking accuracy was ≤0.3±0.5 mm. No significant effect of the RRUSS device on CT image integrity was found, and RRUSS device performance was not affected by radiotherapy beam exposure. Agreement within ±3.0% / 2.0 mm was achieved between computed and measured radiotherapy dose delivered directly through the RRUSS device at 6 MV and 15 MV. In-vivo liver, kidney, and prostate images were successfully acquired. Our investigations suggest that a RRUSS device can offer non-interfering 4D guidance for radiation therapy and other diagnostic and therapeutic procedures.

  10. Radiolucent 4D Ultrasound Imaging: System Design and Application to Radiotherapy Guidance.

    PubMed

    Schlosser, Jeffrey; Hristov, Dimitre

    2016-10-01

    Four-dimensional (4D) ultrasound (US) is an attractive modality for image guidance due to its real-time, non-ionizing, volumetric imaging capability with high soft tissue contrast. However, existing 4D US imaging systems contain large volumes of metal which interfere with diagnostic and therapeutic ionizing radiation in procedures such as CT imaging and radiation therapy. This study aimed to design and characterize a novel 4D Radiolucent Remotely-Actuated UltraSound Scanning (RRUSS) device that overcomes this limitation. In a phantom, we evaluated the imaging performance of the RRUSS device including frame rate, resolution, spatial integrity, and motion tracking accuracy. To evaluate compatibility with radiation therapy workflow, we evaluated device-induced CT imaging artifacts, US tracking performance during beam delivery, and device compatibility with commercial radiotherapy planning software. The RRUSS device produced 4D volumes at 0.1-3.0 Hz with 60° lateral field of view (FOV), 50° maximum elevational FOV, and 200 mm maximum depth. Imaging resolution (-3 dB point spread width) was 1.2-7.9 mm at depths up to 100 mm and motion tracking accuracy was ≤ 0.3±0.5 mm. No significant effect of the RRUSS device on CT image integrity was found, and RRUSS device performance was not affected by radiotherapy beam exposure. Agreement within ±3.0% / 2.0 mm was achieved between computed and measured radiotherapy dose delivered directly through the RRUSS device at 6 MV and 15 MV. In vivo liver, kidney, and prostate images were successfully acquired. Our investigations suggest that a RRUSS device can offer non-interfering 4D guidance for radiation therapy and other diagnostic and therapeutic procedures.

  11. Novel Developments in Instrumentation for PET Imaging

    NASA Astrophysics Data System (ADS)

    Karp, Joel

    2013-04-01

    Advances in medical imaging, in particular positron emission tomography (PET), have been based on technical developments in physics and instrumentation that have common foundations with detection systems used in other fields of physics. New detector materials are used in PET systems that maximize efficiency, timing characteristics and robustness, and which lead to improved image quality and quantitative accuracy for clinical imaging. Time of flight (TOF) techniques are now routinely used in commercial PET scanners that combine physiological imaging with anatomical imaging provided by x-ray computed tomography. Using new solid-state photo-sensors instead of traditional photo-multiplier tubes makes it possible to combine PET with magnetic resonance imaging which is a significant technical challenge, but one that is creating new opportunities for both research and clinical applications. An overview of recent advances in instrumentation, such as TOF and PET/MR will be presented, along with examples of imaging studies to demonstrate the impact on patient care and basic research of diseases.

  12. PET Imaging of Skull Base Neoplasms.

    PubMed

    Mittra, Erik S; Iagaru, Andrei; Quon, Andrew; Fischbein, Nancy

    2007-10-01

    The utility of 18-F-fluorodeoxyglucose-positron emission tomography (PET) and PET/CT for the evaluation of skull base tumors is incompletely investigated, as a limited number of studies specifically focus on this region with regard to PET imaging. Several patterns can be ascertained, however, by synthesizing the data from various published reports and cases of primary skull base malignancies, as well as head and neck malignancies that extend secondarily to the skull base, including nasopharyngeal carcinoma, nasal cavity and paranasal sinus tumors, parotid cancers, and orbital tumors.

  13. Modular Strategies for PET Imaging Agents

    PubMed Central

    Hooker, Jacob M

    2009-01-01

    Summary of Recent Advances In recent years, modular and simplified chemical and biological strategies have been developed for the synthesis and implementation of positron emission tomography (PET) radiotracers. New developments in bioconjugation and synthetic methodologies, in combination with advances in macromolecular delivery systems and gene-expression imaging, reflect a need to reduce radiosynthesis burden in order to accelerate imaging agent development. These new approaches, which are often mindful of existing infrastructure and available resources, are anticipated to provide a more approachable entry point for researchers interested in using PET to translate in vitro research to in vivo imaging. PMID:19880343

  14. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  15. Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis.

    PubMed

    Thengumpallil, Sheeba; Smith, Kathleen; Monnin, Pascal; Bourhis, Jean; Bochud, François; Moeckli, Raphaël

    2016-11-08

    The study was to describe and to compare the performance of 3D and 4D CBCT imaging modalities by measuring and analyzing the delivered dose and the image quality. The 3D (Chest) and 4D (Symmetry) CBCT Elekta XVI lung IGRT protocols were analyzed. Dose profiles were measured with TLDs inside a dedicated phantom. The dosimetric indicator cone-beam dose index (CBDI) was evaluated. The image quality analysis was performed by assessing the contrast transfer function (CTF), the noise power spectrum (NPS) and the noise-equivalent quanta (NEQ). Artifacts were also evaluated by simulating irregular breathing variations. The two imaging modalities showed different dose distributions within the phantom. At the center, the 3D CBCT delivered twice the dose of the 4D CBCT. The CTF was strongly reduced by motion compared to static conditions, resulting in a CTF reduction of 85% for the 3D CBCT and 65% for the 4D CBCT. The amplitude of the NPS was two times higher for the 4D CBCT than for the 3D CBCT. In the presence of motion, the NEQ of the 4D CBCT was 50% higher than the 3D CBCT. In the presence of breathing irregularities, the 4D CBCT protocol was mainly affected by view-aliasing artifacts, which were typically cone-beam artifacts, while the 3D CBCT protocol was mainly affected by duplication artifacts. The results showed that the 4D CBCT ensures a reasonable dose and better image quality when mov-ing targets are involved compared to 3D CBCT. Therefore, 4D CBCT is a reliable imaging modality for lung free-breathing radiation therapy.

  16. 4D rotational x-ray imaging of wrist joint dynamic motion

    SciTech Connect

    Carelsen, Bart; Bakker, Niels H.; Strackee, Simon D.; Boon, Sjirk N.; Maas, Mario; Sabczynski, Joerg; Grimbergen, Cornelis A.; Streekstra, Geert J.

    2005-09-15

    Current methods for imaging joint motion are limited to either two-dimensional (2D) video fluoroscopy, or to animated motions from a series of static three-dimensional (3D) images. 3D movement patterns can be detected from biplane fluoroscopy images matched with computed tomography images. This involves several x-ray modalities and sophisticated 2D to 3D matching for the complex wrist joint. We present a method for the acquisition of dynamic 3D images of a moving joint. In our method a 3D-rotational x-ray (3D-RX) system is used to image a cyclically moving joint. The cyclic motion is synchronized to the x-ray acquisition to yield multiple sets of projection images, which are reconstructed to a series of time resolved 3D images, i.e., four-dimensional rotational x ray (4D-RX). To investigate the obtained image quality parameters the full width at half maximum (FWHM) of the point spread function (PSF) via the edge spread function and the contrast to noise ratio between air and phantom were determined on reconstructions of a bullet and rod phantom, using 4D-RX as well as stationary 3D-RX images. The CNR in volume reconstructions based on 251 projection images in the static situation and on 41 and 34 projection images of a moving phantom were 6.9, 3.0, and 2.9, respectively. The average FWHM of the PSF of these same images was, respectively, 1.1, 1.7, and 2.2 mm orthogonal to the motion and parallel to direction of motion 0.6, 0.7, and 1.0 mm. The main deterioration of 4D-RX images compared to 3D-RX images is due to the low number of projection images used and not to the motion of the object. Using 41 projection images seems the best setting for the current system. Experiments on a postmortem wrist show the feasibility of the method for imaging 3D dynamic joint motion. We expect that 4D-RX will pave the way to improved assessment of joint disorders by detection of 3D dynamic motion patterns in joints.

  17. PET imaging of primary mediastinal tumours.

    PubMed Central

    Kubota, K.; Yamada, S.; Kondo, T.; Yamada, K.; Fukuda, H.; Fujiwara, T.; Ito, M.; Ido, T.

    1996-01-01

    Mediastinal masses include a wide variety of tumours and remain an interesting diagnostic challenge for radiologist. We performed positron emission tomography (PET) studies of primary mediastinal tumours in order to predict the malignancy of these tumours preoperatively. Twenty-two patients with primary mediastinal tumours were studied with PET using 2-deoxy-2-[18F]fluoro-D-glucose (FDG). The histological findings of surgical pathology or biopsy, or mediastinoscopy were compared with those of computerised tomography (CT) and PET. PET images were evaluated semiquantitatively using the differential uptake ratio (DUR). Increased FDG uptake was observed in nine of ten patients with malignant tumours, including thymic carcinomas, lymphomas, invasive thymomas and a case of sarcoidosis. A moderate level of FDG uptake was found in a myeloma, non-invasive thymomas, and a schwannoma, whereas a low uptake was observed in a teratoma and various benign cysts. The mean FDG uptake of malignant tumours was significantly higher than that of benign tumours. Both thymic cancer and invasive thymoma showed a high FDG uptake. CT examination resulted in three false-negative and two false-positive cases when used in predicting tumour invasion, while PET was associated with a false-positive and a false-negative case. In conclusion, the use of FDG with PET is clinically helpful in evaluating the malignant nature of primary mediastinal tumours. Our results also suggest that a high FDG uptake reflects the invasiveness of malignant nature of thymic tumours. Images Figure 1 Figure 2 PMID:8611400

  18. Real time image-based tracking of 4D ultrasound data.

    PubMed

    Øye, Ola Kristoffer; Wein, Wolfgang; Ulvang, Dag Magne; Matre, Knut; Viola, Ivan

    2012-01-01

    We propose a methodology to perform real time image-based tracking on streaming 4D ultrasound data, using image registration to deduce the positioning of each ultrasound frame in a global coordinate system. Our method provides an alternative approach to traditional external tracking devices used for tracking probe movements. We compare the performance of our method against magnetic tracking on phantom and liver data, and show that our method is able to provide results in agreement with magnetic tracking.

  19. Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

    SciTech Connect

    Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E.; Williams, Cameron H.; Frush, D.; Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

    2013-04-15

    Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve

  20. From Wheatstone to Cameron and beyond: overview in 3-D and 4-D imaging technology

    NASA Astrophysics Data System (ADS)

    Gilbreath, G. Charmaine

    2012-02-01

    This paper reviews three-dimensional (3-D) and four-dimensional (4-D) imaging technology, from Wheatstone through today, with some prognostications for near future applications. This field is rich in variety, subject specialty, and applications. A major trend, multi-view stereoscopy, is moving the field forward to real-time wide-angle 3-D reconstruction as breakthroughs in parallel processing and multi-processor computers enable very fast processing. Real-time holography meets 4-D imaging reconstruction at the goal of achieving real-time, interactive, 3-D imaging. Applications to telesurgery and telemedicine as well as to the needs of the defense and intelligence communities are also discussed.

  1. A Workstation for Interactive Display and Quantitative Analysis of 3-D and 4-D Biomedical Images

    PubMed Central

    Robb, R.A.; Heffeman, P.B.; Camp, J.J.; Hanson, D.P.

    1986-01-01

    The capability to extract objective and quantitatively accurate information from 3-D radiographic biomedical images has not kept pace with the capabilities to produce the images themselves. This is rather an ironic paradox, since on the one hand the new 3-D and 4-D imaging capabilities promise significant potential for providing greater specificity and sensitivity (i.e., precise objective discrimination and accurate quantitative measurement of body tissue characteristics and function) in clinical diagnostic and basic investigative imaging procedures than ever possible before, but on the other hand, the momentous advances in computer and associated electronic imaging technology which have made these 3-D imaging capabilities possible have not been concomitantly developed for full exploitation of these capabilities. Therefore, we have developed a powerful new microcomputer-based system which permits detailed investigations and evaluation of 3-D and 4-D (dynamic 3-D) biomedical images. The system comprises a special workstation to which all the information in a large 3-D image data base is accessible for rapid display, manipulation, and measurement. The system provides important capabilities for simultaneously representing and analyzing both structural and functional data and their relationships in various organs of the body. This paper provides a detailed description of this system, as well as some of the rationale, background, theoretical concepts, and practical considerations related to system implementation. ImagesFigure 5Figure 7Figure 8Figure 9Figure 10Figure 11Figure 12Figure 13Figure 14Figure 15Figure 16

  2. PET-based molecular imaging in neuroscience.

    PubMed

    Jacobs, A H; Li, H; Winkeler, A; Hilker, R; Knoess, C; Rüger, A; Galldiks, N; Schaller, B; Sobesky, J; Kracht, L; Monfared, P; Klein, M; Vollmar, S; Bauer, B; Wagner, R; Graf, R; Wienhard, K; Herholz, K; Heiss, W D

    2003-07-01

    Positron emission tomography (PET) allows non-invasive assessment of physiological, metabolic and molecular processes in humans and animals in vivo. Advances in detector technology have led to a considerable improvement in the spatial resolution of PET (1-2 mm), enabling for the first time investigations in small experimental animals such as mice. With the developments in radiochemistry and tracer technology, a variety of endogenously expressed and exogenously introduced genes can be analysed by PET. This opens up the exciting and rapidly evolving field of molecular imaging, aiming at the non-invasive localisation of a biological process of interest in normal and diseased cells in animal models and humans in vivo. The main and most intriguing advantage of molecular imaging is the kinetic analysis of a given molecular event in the same experimental subject over time. This will allow non-invasive characterisation and "phenotyping" of animal models of human disease at various disease stages, under certain pathophysiological stimuli and after therapeutic intervention. The potential broad applications of imaging molecular events in vivo lie in the study of cell biology, biochemistry, gene/protein function and regulation, signal transduction, transcriptional regulation and characterisation of transgenic animals. Most importantly, molecular imaging will have great implications for the identification of potential molecular therapeutic targets, in the development of new treatment strategies, and in their successful implementation into clinical application. Here, the potential impact of molecular imaging by PET in applications in neuroscience research with a special focus on neurodegeneration and neuro-oncology is reviewed.

  3. In-treatment 4D cone-beam CT with image-based respiratory phase recognition.

    PubMed

    Kida, Satoshi; Masutani, Yoshitaka; Yamashita, Hideomi; Imae, Toshikazu; Matsuura, Taeko; Saotome, Naoya; Ohtomo, Kuni; Nakagawa, Keiichi; Haga, Akihiro

    2012-07-01

    The use of respiration-correlated cone-beam computed tomography (4D-CBCT) appears to be crucial for implementing precise radiation therapy of lung cancer patients. The reconstruction of 4D-CBCT images requires a respiratory phase. In this paper, we propose a novel method based on an image-based phase recognition technique using normalized cross correlation (NCC). We constructed the respiratory phase by searching for a region in an adjacent projection that achieves the maximum correlation with a region in a reference projection along the cranio-caudal direction. The data on 12 lung cancer patients acquired just prior to treatment and on 3 lung cancer patients acquired during volumetric modulated arc therapy treatment were analyzed in the search for the effective area of cone-beam projection images for performing NCC with 12 combinations of registration area and segment size. The evaluation was done by a "recognition rate" defined as the ratio of the number of peak inhales detected with our method to that detected by eye (manual tracking). The average recognition rate of peak inhale with the most efficient area in the present method was 96.4%. The present method was feasible even when the diaphragm was outside the field of view. With the most efficient area, we reconstructed in-treatment 4D-CBCT by dividing the breathing signal into four phase bins; peak exhale, peak inhale, and two intermediate phases. With in-treatment 4D-CBCT images, it was possible to identify the tumor position and the tumor size in moments of inspiration and expiration, in contrast to in-treatment CBCT reconstructed with all projections.

  4. Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: A feasibility study

    PubMed Central

    Cai, Jing; Chang, Zheng; Wang, Zhiheng; Paul Segars, William; Yin, Fang-Fang

    2011-01-01

    Purpose: Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. Methods: The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. Results: Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (±SD) difference in phase: −3.9% (±6.4%); mean (±SD) absolute difference in phase: 10.40% (±3.3%); mean (±SD) correlation coefficient: 0.93 (±0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (±SD) absolute difference in motion amplitude: −0.3 (±0.5) mm. In the 4D-XCAT phantom study, the simulated “4D-MRI” images showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized “tumor” matched

  5. Simultaneous water activation and glucose metabolic rate imaging with PET

    NASA Astrophysics Data System (ADS)

    Verhaeghe, Jeroen; Reader, Andrew J.

    2013-02-01

    A novel imaging and signal separation strategy is proposed to be able to separate [18F]FDG and multiple [15O]H2O signals from a simultaneously acquired dynamic PET acquisition of the two tracers. The technique is based on the fact that the dynamics of the two tracers are very distinct. By adopting an appropriate bolus injection strategy and by defining tailored sets of basis functions that model either the FDG or water component, it is possible to separate the FDG and water signal. The basis functions are inspired from the spectral analysis description of dynamic PET studies and are defined as the convolution of estimated generating functions (GFs) with a set of decaying exponential functions. The GFs are estimated from the overall measured head curve, while the decaying exponential functions are pre-determined. In this work, the time activity curves (TACs) are modelled post-reconstruction but the model can be incorporated in a global 4D reconstruction strategy. Extensive PET simulation studies are performed considering single [18F]FDG and 6 [15O]H2O bolus injections for a total acquisition time of 75 min. The proposed method is evaluated at multiple noise levels and different parameters were estimated such as [18F]FDG uptake and blood flow estimated from the [15O]H2O component, requiring a full dynamic analysis of the two components, static images of [18F]FDG and the water components as well as [15O]H2O activation. It is shown that the resulting images and parametric values in ROIs are comparable to images obtained from separate imaging, illustrating the feasibility of simultaneous imaging of [18F]FDG and [15O]H2O components. For more information on this article, see medicalphysicsweb.org

  6. Real-time volume rendering of 4D image using 3D texture mapping

    NASA Astrophysics Data System (ADS)

    Hwang, Jinwoo; Kim, June-Sic; Kim, Jae Seok; Kim, In Young; Kim, Sun Il

    2001-05-01

    Four dimensional image is 3D volume data that varies with time. It is used to express deforming or moving object in virtual surgery of 4D ultrasound. It is difficult to render 4D image by conventional ray-casting or shear-warp factorization methods because of their time-consuming rendering time or pre-processing stage whenever the volume data are changed. Even 3D texture mapping is used, repeated volume loading is also time-consuming in 4D image rendering. In this study, we propose a method to reduce data loading time using coherence between currently loaded volume and previously loaded volume in order to achieve real time rendering based on 3D texture mapping. Volume data are divided into small bricks and each brick being loaded is tested for similarity to one which was already loaded in memory. If the brick passed the test, it is defined as 3D texture by OpenGL functions. Later, the texture slices of the brick are mapped into polygons and blended by OpenGL blending functions. All bricks undergo this test. Continuously deforming fifty volumes are rendered in interactive time with SGI ONYX. Real-time volume rendering based on 3D texture mapping is currently available on PC.

  7. PET Imaging - from Physics to Clinical Molecular Imaging

    NASA Astrophysics Data System (ADS)

    Majewski, Stan

    2008-03-01

    From the beginnings many years ago in a few physics laboratories and first applications as a research brain function imager, PET became lately a leading molecular imaging modality used in diagnosis, staging and therapy monitoring of cancer, as well as has increased use in assessment of brain function (early diagnosis of Alzheimer's, etc) and in cardiac function. To assist with anatomic structure map and with absorption correction CT is often used with PET in a duo system. Growing interest in the last 5-10 years in dedicated organ specific PET imagers (breast, prostate, brain, etc) presents again an opportunity to the particle physics instrumentation community to contribute to the important field of medical imaging. In addition to the bulky standard ring structures, compact, economical and high performance mobile imagers are being proposed and build. The latest development in standard PET imaging is introduction of the well known TOF concept enabling clearer tomographic pictures of the patient organs. Development and availability of novel photodetectors such as Silicon PMT immune to magnetic fields offers an exciting opportunity to use PET in conjunction with MRI and fMRI. As before with avalanche photodiodes, particle physics community plays a leading role in developing these devices. The presentation will mostly focus on present and future opportunities for better PET designs based on new technologies and methods: new scintillators, photodetectors, readout, software.

  8. 4-D Cardiac MR Image Analysis: Left and Right Ventricular Morphology and Function

    PubMed Central

    Wahle, Andreas; Johnson, Ryan K.; Scholz, Thomas D.; Sonka, Milan

    2010-01-01

    In this study, a combination of active shape model (ASM) and active appearance model (AAM) was used to segment the left and right ventricles of normal and Tetralogy of Fallot (TOF) hearts on 4-D (3-D+time) MR images. For each ventricle, a 4-D model was first used to achieve robust preliminary segmentation on all cardiac phases simultaneously and a 3-D model was then applied to each phase to improve local accuracy while maintaining the overall robustness of the 4-D segmentation. On 25 normal and 25 TOF hearts, in comparison to the expert traced independent standard, our comprehensive performance assessment showed subvoxel segmentation accuracy, high overlap ratios, good ventricular volume correlations, and small percent volume differences. Following 4-D segmentation, novel quantitative shape and motion features were extracted using shape information, volume-time and dV/dt curves, analyzed and used for disease status classification. Automated discrimination between normal/TOF subjects achieved 90%–100% sensitivity and specificity. The features obtained from TOF hearts show higher variability compared to normal subjects, suggesting their potential use as disease progression indicators. The abnormal shape and motion variations of the TOF hearts were accurately captured by both the segmentation and feature characterization. PMID:19709962

  9. The development of a population of 4D pediatric XCAT phantoms for CT imaging research and optimization

    NASA Astrophysics Data System (ADS)

    Norris, Hannah; Zhang, Yakun; Frush, Jack; Sturgeon, Gregory M.; Minhas, Anum; Tward, Daniel J.; Ratnanather, J. Tilak; Miller, M. I.; Frush, Donald; Samei, Ehsan; Segars, W. Paul

    2014-03-01

    With the increased use of CT examinations, the associated radiation dose has become a large concern, especially for pediatrics. Much research has focused on reducing radiation dose through new scanning and reconstruction methods. Computational phantoms provide an effective and efficient means for evaluating image quality, patient-specific dose, and organ-specific dose in CT. We previously developed a set of highly-detailed 4D reference pediatric XCAT phantoms at ages of newborn, 1, 5, 10, and 15 years with organ and tissues masses matched to ICRP Publication 89 values. We now extend this reference set to a series of 64 pediatric phantoms of a variety of ages and height and weight percentiles, representative of the public at large. High resolution PET-CT data was reviewed by a practicing experienced radiologist for anatomic regularity and was then segmented with manual and semi-automatic methods to form a target model. A Multi-Channel Large Deformation Diffeomorphic Metric Mapping (MC-LDDMM) algorithm was used to calculate the transform from the best age matching pediatric reference phantom to the patient target. The transform was used to complete the target, filling in the non-segmented structures and defining models for the cardiac and respiratory motions. The complete phantoms, consisting of thousands of structures, were then manually inspected for anatomical accuracy. 3D CT data was simulated from the phantoms to demonstrate their ability to generate realistic, patient quality imaging data. The population of pediatric phantoms developed in this work provides a vital tool to investigate dose reduction techniques in 3D and 4D pediatric CT.

  10. Comparison of spatiotemporal interpolators for 4D image reconstruction from 2D transesophageal ultrasound

    NASA Astrophysics Data System (ADS)

    Haak, Alexander; van Stralen, Marijn; van Burken, Gerard; Klein, Stefan; Pluim, Josien P. W.; de Jong, Nico; van der Steen, Antonius F. W.; Bosch, Johan G.

    2012-03-01

    °For electrophysiology intervention monitoring, we intend to reconstruct 4D ultrasound (US) of structures in the beating heart from 2D transesophageal US by scanplane rotation. The image acquisition is continuous but unsynchronized to the heart rate, which results in a sparsely and irregularly sampled dataset and a spatiotemporal interpolation method is desired. Previously, we showed the potential of normalized convolution (NC) for interpolating such datasets. We explored 4D interpolation by 3 different methods: NC, nearest neighbor (NN), and temporal binning followed by linear interpolation (LTB). The test datasets were derived by slicing three 4D echocardiography datasets at random rotation angles (θ, range: 0-180) and random normalized cardiac phase (τ, range: 0-1). Four different distributions of rotated 2D images with 600, 900, 1350, and 1800 2D input images were created from all TEE sets. A 2D Gaussian kernel was used for NC and optimal kernel sizes (σθ and στ) were found by performing an exhaustive search. The RMS gray value error (RMSE) of the reconstructed images was computed for all interpolation methods. The estimated optimal kernels were in the range of σθ = 3.24 - 3.69°/ στ = 0.045 - 0.048, σθ = 2.79°/ στ = 0.031 - 0.038, σθ = 2.34°/ στ = 0.023 - 0.026, and σθ = 1.89°/ στ = 0.021 - 0.023 for 600, 900, 1350, and 1800 input images respectively. We showed that NC outperforms NN and LTB. For a small number of input images the advantage of NC is more pronounced.

  11. PET Imaging in Huntington’s Disease

    PubMed Central

    Roussakis, Andreas-Antonios; Piccini, Paola

    2015-01-01

    To date, little is known about how neurodegeneration and neuroinflammation propagate in Huntington’s disease (HD). Unfortunately, no treatment is available to cure or reverse the progressive decline of function caused by the disease, thus considering HD a fatal disease. Mutation gene carriers typically remain asymptomatic for many years although alterations in the basal ganglia and cortex occur early on in mutant HD gene–carriers. Positron Emission Tomography (PET) is a functional imaging technique of nuclear medicine which enables in vivo visualization of numerous biological molecules expressed in several human tissues. Brain PET is most powerful to study in vivo neuronal and glial cells function as well as cerebral blood flow in a plethora of neurodegenerative disorders including Parkinson’s disease, Alzheimer’s and HD. In absence of HD–specific biomarkers for monitoring disease progression, previous PET studies in HD were merely focused on the study of dopaminergic terminals, cerebral blood flow and glucose metabolism in manifest and premanifest HD–gene carriers. More recently, research interest has been exploring novel PET targets in HD including the state of phosphodiesterse expression and the role of activated microglia. Hence, a better understanding of the HD pathogenesis mechanisms may lead to the development of targeted therapies. PET imaging follow–up studies with novel selective PET radiotracers such as 11C-IMA–107 and 11C-PBR28 may provide insight on disease progression and identify prognostic biomarkers, elucidate the underlying HD pathology and assess novel pharmaceutical agents and over time. PMID:26683130

  12. 3D and 4D Seismic Imaging in the Oilfield; the state of the art

    NASA Astrophysics Data System (ADS)

    Strudley, A.

    2005-05-01

    Seismic imaging in the oilfield context has seen enormous changes over the last 20 years driven by a combination of improved subsurface illumination (2D to 3D), increased computational power and improved physical understanding. Today Kirchhoff Pre-stack migration (in time or depth) is the norm with anisotropic parameterisation and finite difference methods being increasingly employed. In the production context Time-Lapse (4D) Seismic is of growing importance as a tool for monitoring reservoir changes to facilitate increased productivity and recovery. In this paper we present an overview of state of the art technology in 3D and 4D seismic and look at future trends. Pre-stack Kirchhoff migration in time or depth is the imaging tool of choice for the majority of contemporary 3D datasets. Recent developments in 3D pre-stack imaging have been focussed around finite difference solutions to the acoustic wave equation, the so-called Wave Equation Migration methods (WEM). Application of finite difference solutions to imaging is certainly not new, however 3D pre-stack migration using these schemes is a relatively recent development driven by the need for imaging complex geologic structures such as sub salt, and facilitated by increased computational resources. Finally there are a class of imaging methods referred to as beam migration. These methods may be based on either the wave equation or rays, but all operate on a localised (in space and direction) part of the wavefield. These methods offer a bridge between the computational efficiency of Kirchhoff schemes and the improved image quality of WEM methods. Just as 3D seismic has had a radical impact on the quality of the static model of the reservoir, 4D seismic is having a dramatic impact on the dynamic model. Repeat shooting of seismic surveys after a period of production (typically one to several years) reveals changes in pressure and saturation through changes in the seismic response. The growth in interest in 4D seismic

  13. Imaging rotational dynamics of nanoparticles in liquid by 4D electron microscopy

    NASA Astrophysics Data System (ADS)

    Fu, Xuewen; Chen, Bin; Tang, Jau; Hassan, Mohammed Th.; Zewail, Ahmed H.

    2017-02-01

    In real time and space, four-dimensional electron microscopy (4D EM) has enabled observation of transient structures and morphologies of inorganic and organic materials. We have extended 4D EM to include liquid cells without the time resolution being limited by the response of the detector. Our approach permits the imaging of the motion and morphological dynamics of a single, same particle on nanometer and ultrashort time scales. As a first application, we studied the rotational dynamics of gold nanoparticles in aqueous solution. A full transition from the conventional diffusive rotation to superdiffusive rotation and further to a ballistic rotation was observed with increasing asymmetry of the nanoparticle morphology. We explored the underlying physics both experimentally and theoretically according to the morphological asymmetry of the nanoparticles.

  14. Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain

    SciTech Connect

    Jung, Jin Ho; Choi, Yong Jung, Jiwoong; Kim, Sangsu; Lim, Hyun Keong; Im, Ki Chun; Oh, Chang Hyun; Park, Hyun-wook; Kim, Kyung Min; Kim, Jong Guk

    2015-05-15

    Purpose: The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. Methods: The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 array LYSO coupled to a 4 × 4 Geiger-mode avalanche photodiode (GAPD) array. The PET insert consisted of 18 detector blocks, circularly mounted on a custom-made plastic base to form a ring with an inner diameter of 390 mm and axial length of 60 mm. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with a thickness of 0.24 mm. The position decoder circuit and field programmable gate array-embedded DAQ modules were enclosed in an aluminum box with a thickness of 10 mm and located at the rear of the MR bore inside the MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and inner bore diameter of 60 cm was used as the PET/MRI hybrid system. A custom-made radio frequency (RF) coil with an inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside the MRI scanner using echo planar imaging, spin echo, turbo spin echo, and gradient echo sequences. MRI performance was also evaluated with and without the PET insert. The stability of the newly developed PET insert was evaluated and simultaneous PET and MR images of a brain phantom were acquired. Results: No significant degradation of the PET performance caused by MR was observed when the PET was operated using various MR imaging sequences. The signal-to-noise ratio of MR images was slightly degraded due to the PET insert installed inside the MR bore while the homogeneity was

  15. Current Status of Hybrid PET/MRI in Oncologic Imaging

    PubMed Central

    Rosenkrantz, Andrew B.; Friedman, Kent; Chandarana, Hersh; Melsaether, Amy; Moy, Linda; Ding, Yu-Shin; Jhaveri, Komal; Beltran, Luis; Jain, Rajan

    2016-01-01

    OBJECTIVE This review article explores recent advancements in PET/MRI for clinical oncologic imaging. CONCLUSION Radiologists should understand the technical considerations that have made PET/MRI feasible within clinical workflows, the role of PET tracers for imaging various molecular targets in oncology, and advantages of hybrid PET/MRI compared with PET/CT. To facilitate this understanding, we discuss clinical examples (including gliomas, breast cancer, bone metastases, prostate cancer, bladder cancer, gynecologic malignancy, and lymphoma) as well as future directions, challenges, and areas for continued technical optimization for PET/MRI. PMID:26491894

  16. Statistical modeling of 4D respiratory lung motion using diffeomorphic image registration.

    PubMed

    Ehrhardt, Jan; Werner, René; Schmidt-Richberg, Alexander; Handels, Heinz

    2011-02-01

    Modeling of respiratory motion has become increasingly important in various applications of medical imaging (e.g., radiation therapy of lung cancer). Current modeling approaches are usually confined to intra-patient registration of 3D image data representing the individual patient's anatomy at different breathing phases. We propose an approach to generate a mean motion model of the lung based on thoracic 4D computed tomography (CT) data of different patients to extend the motion modeling capabilities. Our modeling process consists of three steps: an intra-subject registration to generate subject-specific motion models, the generation of an average shape and intensity atlas of the lung as anatomical reference frame, and the registration of the subject-specific motion models to the atlas in order to build a statistical 4D mean motion model (4D-MMM). Furthermore, we present methods to adapt the 4D mean motion model to a patient-specific lung geometry. In all steps, a symmetric diffeomorphic nonlinear intensity-based registration method was employed. The Log-Euclidean framework was used to compute statistics on the diffeomorphic transformations. The presented methods are then used to build a mean motion model of respiratory lung motion using thoracic 4D CT data sets of 17 patients. We evaluate the model by applying it for estimating respiratory motion of ten lung cancer patients. The prediction is evaluated with respect to landmark and tumor motion, and the quantitative analysis results in a mean target registration error (TRE) of 3.3 ±1.6 mm if lung dynamics are not impaired by large lung tumors or other lung disorders (e.g., emphysema). With regard to lung tumor motion, we show that prediction accuracy is independent of tumor size and tumor motion amplitude in the considered data set. However, tumors adhering to non-lung structures degrade local lung dynamics significantly and the model-based prediction accuracy is lower in these cases. The statistical respiratory

  17. SU-D-201-07: Exploring the Utility of 4D FDG-PET/CT Scans in Design of Radiation Therapy Planning Compared with 3D PET/CT: A Prospective Study

    SciTech Connect

    Ma, C; Yin, Y

    2015-06-15

    Purpose: A method using four-dimensional(4D) PET/CT in design of radiation treatment planning was proposed and the target volume and radiation dose distribution changes relative to standard three-dimensional (3D) PET/CT were examined. Methods: A target deformable registration method was used by which the whole patient’s respiration process was considered and the effect of respiration motion was minimized when designing radiotherapy planning. The gross tumor volume of a non-small-cell lung cancer was contoured on the 4D FDG-PET/CT and 3D PET/CT scans by use of two different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; another technique using a constant threshold of standardized uptake value (SUV) greater than 2.5. The target volume and radiotherapy dose distribution between VOL3D and VOL4D were analyzed. Results: For all phases, the average automatic and manually GTV volume was 18.61 cm3 (range, 16.39–22.03 cm3) and 31.29 cm3 (range, 30.11–35.55 cm3), respectively. The automatic and manually volume of merged IGTV were 27.82 cm3 and 49.37 cm3, respectively. For the manual contour, compared to 3D plan the mean dose for the left, right, and total lung of 4D plan have an average decrease 21.55%, 15.17% and 15.86%, respectively. The maximum dose of spinal cord has an average decrease 2.35%. For the automatic contour, the mean dose for the left, right, and total lung have an average decrease 23.48%, 16.84% and 17.44%, respectively. The maximum dose of spinal cord has an average decrease 1.68%. Conclusion: In comparison to 3D PET/CT, 4D PET/CT may better define the extent of moving tumors and reduce the contouring tumor volume thereby optimize radiation treatment planning for lung tumors.

  18. Manifold learning for image-based breathing gating with application to 4D ultrasound.

    PubMed

    Wachinger, Christian; Yigitsoy, Mehmet; Navab, Nassir

    2010-01-01

    Breathing motion leads to a significant displacement and deformation of organs in the abdominal region. This makes the detection of the breathing phase for numerous applications necessary. We propose a new, purely image-based respiratory gating method for ultrasound. Further, we use this technique to provide a solution for breathing affected 4D ultrasound acquisitions with a wobbler probe. We achieve the gating with Laplacian eigenmaps, a manifold learning technique, to determine the low-dimensional manifold embedded in the high-dimensional image space. Since Laplacian eigenmaps assign each ultrasound frame a coordinate in low-dimensional space by respecting the neighborhood relationship, they are well suited for analyzing the breathing cycle. For the 4D application, we perform the manifold learning for each angle, and consecutively, align all the local curves and perform a curve fitting to achieve a globally consistent breathing signal. We performed the image-based gating on several 2D and 3D ultrasound datasets over time, and quantified its very good performance by comparing it to measurements from an external gating system.

  19. [Possibilities of 4D ultrasonography in imaging of the pelvic floor structures].

    PubMed

    Dlouhá, K; Krofta, L

    2011-12-01

    Technological boom of the last decades brought urogynaecologists and other specialists new possibilities in imaging of the pelvic floor structures which may substantially add to search for etiology of pelvic floor dysfunction. Magnetic resonance imaging (MRI) is an expensive, less accessible method and may pose certain dyscomphort to the patient. 3D/4D ultrasonography overcomes these disadvantages and brings new possibilities especially in dynamic, real time imaging and consequently enables focus on functional anatomy of complex of muscles and fascial structures of the pelvic floor. With 3D/4D ultrasound we can visualise urethra and surrounding structures, levator ani and urogenital hiatus, its changes during muscle contraction and Valsalva manévre. This method has great potential in diagnostics of pelvic organ prolapse, it may bring new knowledge of factors contributing to loss of integrity of pelvic floor structures resulting in prolapse and incontinence. Studies exist which describe changes in urogenital hiatus after vaginal delivery, further studies of large numbers of patients during longer period of time are though necessary so that conclusions can be drawn for clinical praxis.

  20. Joint Segmentation of Anatomical and Functional Images: Applications in Quantification of Lesions from PET, PET-CT, MRI-PET, and MRI-PET-CT Images

    PubMed Central

    Bagci, Ulas; Udupa, Jayaram K.; Mendhiratta, Neil; Foster, Brent; Xu, Ziyue; Yao, Jianhua; Chen, Xinjian; Mollura, Daniel J.

    2013-01-01

    We present a novel method for the joint segmentation of anatomical and functional images. Our proposed methodology unifies the domains of anatomical and functional images, represents them in a product lattice, and performs simultaneous delineation of regions based on random walk image segmentation. Furthermore, we also propose a simple yet effective object/background seed localization method to make the proposed segmentation process fully automatic. Our study uses PET, PET-CT, MRI-PET, and fused MRI-PET-CT scans (77 studies in all) from 56 patients who had various lesions in different body regions. We validated the effectiveness of the proposed method on different PET phantoms as well as on clinical images with respect to the ground truth segmentation provided by clinicians. Experimental results indicate that the presented method is superior to threshold and Bayesian methods commonly used in PET image segmentation, is more accurate and robust compared to the other PET-CT segmentation methods recently published in the literature, and also it is general in the sense of simultaneously segmenting multiple scans in real-time with high accuracy needed in routine clinical use. PMID:23837967

  1. [A non-local means approach for PET image denoising].

    PubMed

    Yin, Yong; Sun, Weifeng; Lu, Jie; Liu, Tonghai

    2010-04-01

    Denoising is an important issue for medical image processing. Based on the analysis of the Non-local means algorithm recently reported by Buades A, et al. in international journals we herein propose adapting it for PET image denoising. Experimental de-noising results for real clinical PET images show that Non-local means method is superior to median filtering and wiener filtering methods and it can suppress noise in PET images effectively and preserve important details of structure for diagnosis.

  2. SPECT and PET Imaging of Meningiomas

    PubMed Central

    Valotassiou, Varvara; Leondi, Anastasia; Angelidis, George; Psimadas, Dimitrios; Georgoulias, Panagiotis

    2012-01-01

    Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue. PMID:22623896

  3. SPECT and PET imaging of meningiomas.

    PubMed

    Valotassiou, Varvara; Leondi, Anastasia; Angelidis, George; Psimadas, Dimitrios; Georgoulias, Panagiotis

    2012-01-01

    Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.

  4. SU-E-T-300: Dosimetric Comparision of 4D Radiation Therapy and 3D Radiation Therapy for the Liver Tumor Based On 4D Medical Image

    SciTech Connect

    Ma, C; Yin, Y

    2015-06-15

    Purpose: The purpose of this work was to determine the dosimetric benefit to normal tissues by tracking liver tumor dose in four dimensional radiation therapy (4DRT) on ten phases of four dimensional computer tomagraphy(4DCT) images. Methods: Target tracking each phase with the beam aperture for ten liver cancer patients were converted to cumulative plan and compared to the 3D plan with a merged target volume based on 4DCT image in radiation treatment planning system (TPS). The change in normal tissue dose was evaluated in the plan by using the parameters V5, V10, V15, V20,V25, V30, V35 and V40 (volumes receiving 5, 10, 15, 20, 25, 30, 35 and 40Gy, respectively) in the dose-volume histogram for the liver; mean dose for the following structures: liver, left kidney and right kidney; and maximum dose for the following structures: bowel, duodenum, esophagus, stomach and heart. Results: There was significant difference between 4D PTV(average 115.71cm3 )and ITV(169.86 cm3). When the planning objective is 95% volume of PTV covered by the prescription dose, the mean dose for the liver, left kidney and right kidney have an average decrease 23.13%, 49.51%, and 54.38%, respectively. The maximum dose for bowel, duodenum,esophagus, stomach and heart have an average decrease 16.77%, 28.07%, 24.28%, 4.89%, and 4.45%, respectively. Compared to 3D RT, radiation volume for the liver V5, V10, V15, V20, V25, V30, V35 and V40 by using the 4D plans have a significant decrease(P≤0.05). Conclusion: The 4D plan method creates plans that permit better sparing of the normal structures than the commonly used ITV method, which delivers the same dosimetric effects to the target.

  5. Performance evaluation and optimization of BM4D-AV denoising algorithm for cone-beam CT images

    NASA Astrophysics Data System (ADS)

    Huang, Kuidong; Tian, Xiaofei; Zhang, Dinghua; Zhang, Hua

    2015-12-01

    The broadening application of cone-beam Computed Tomography (CBCT) in medical diagnostics and nondestructive testing, necessitates advanced denoising algorithms for its 3D images. The block-matching and four dimensional filtering algorithm with adaptive variance (BM4D-AV) is applied to the 3D image denoising in this research. To optimize it, the key filtering parameters of the BM4D-AV algorithm are assessed firstly based on the simulated CBCT images and a table of optimized filtering parameters is obtained. Then, considering the complexity of the noise in realistic CBCT images, possible noise standard deviations in BM4D-AV are evaluated to attain the chosen principle for the realistic denoising. The results of corresponding experiments demonstrate that the BM4D-AV algorithm with optimized parameters presents excellent denosing effect on the realistic 3D CBCT images.

  6. The development of a population of 4D pediatric XCAT phantoms for imaging research and optimization

    SciTech Connect

    Segars, W. P. Norris, Hannah; Sturgeon, Gregory M.; Zhang, Yakun; Bond, Jason; Samei, E.; Minhas, Anum; Frush, D.; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

    2015-08-15

    Purpose: We previously developed a set of highly detailed 4D reference pediatric extended cardiac-torso (XCAT) phantoms at ages of newborn, 1, 5, 10, and 15 yr with organ and tissue masses matched to ICRP Publication 89 values. In this work, we extended this reference set to a series of 64 pediatric phantoms of varying age and height and body mass percentiles representative of the public at large. The models will provide a library of pediatric phantoms for optimizing pediatric imaging protocols. Methods: High resolution positron emission tomography-computed tomography data obtained from the Duke University database were reviewed by a practicing experienced radiologist for anatomic regularity. The CT portion of the data was then segmented with manual and semiautomatic methods to form a target model defined using nonuniform rational B-spline surfaces. A multichannel large deformation diffeomorphic metric mapping algorithm was used to calculate the transform from the best age matching pediatric XCAT reference phantom to the patient target. The transform was used to complete the target, filling in the nonsegmented structures and defining models for the cardiac and respiratory motions. The complete phantoms, consisting of thousands of structures, were then manually inspected for anatomical accuracy. The mass for each major tissue was calculated and compared to linearly interpolated ICRP values for different ages. Results: Sixty four new pediatric phantoms were created in this manner. Each model contains the same level of detail as the original XCAT reference phantoms and also includes parameterized models for the cardiac and respiratory motions. For the phantoms that were 10 yr old and younger, we included both sets of reproductive organs. This gave them the capability to simulate both male and female anatomy. With this, the population can be expanded to 92. Wide anatomical variation was clearly seen amongst the phantom models, both in organ shape and size, even for

  7. Long-Term Live Cell Imaging and Automated 4D Analysis of Drosophila Neuroblast Lineages

    PubMed Central

    Berger, Christian; Lendl, Thomas; Knoblich, Juergen A.

    2013-01-01

    The developing Drosophila brain is a well-studied model system for neurogenesis and stem cell biology. In the Drosophila central brain, around 200 neural stem cells called neuroblasts undergo repeated rounds of asymmetric cell division. These divisions typically generate a larger self-renewing neuroblast and a smaller ganglion mother cell that undergoes one terminal division to create two differentiating neurons. Although single mitotic divisions of neuroblasts can easily be imaged in real time, the lack of long term imaging procedures has limited the use of neuroblast live imaging for lineage analysis. Here we describe a method that allows live imaging of cultured Drosophila neuroblasts over multiple cell cycles for up to 24 hours. We describe a 4D image analysis protocol that can be used to extract cell cycle times and growth rates from the resulting movies in an automated manner. We use it to perform lineage analysis in type II neuroblasts where clonal analysis has indicated the presence of a transit-amplifying population that potentiates the number of neurons. Indeed, our experiments verify type II lineages and provide quantitative parameters for all cell types in those lineages. As defects in type II neuroblast lineages can result in brain tumor formation, our lineage analysis method will allow more detailed and quantitative analysis of tumorigenesis and asymmetric cell division in the Drosophila brain. PMID:24260257

  8. The application of PET imaging in psychoneuroimmunology research.

    PubMed

    Hannestad, Jonas

    2012-01-01

    Positron emission tomography (PET) imaging is a research tool that allows in vivo measurements of brain metabolism and specific target molecules. PET imaging can be used to measure these brain variables in a variety of species, including human and non-human primates, and rodents. PET imaging can therefore be combined with various experimental and clinical model systems that are commonly used in psychoneuroimmunology research.

  9. Using 4D Cardiovascular Magnetic Resonance Imaging to Validate Computational Fluid Dynamics: A Case Study.

    PubMed

    Biglino, Giovanni; Cosentino, Daria; Steeden, Jennifer A; De Nova, Lorenzo; Castelli, Matteo; Ntsinjana, Hopewell; Pennati, Giancarlo; Taylor, Andrew M; Schievano, Silvia

    2015-01-01

    Computational fluid dynamics (CFD) can have a complementary predictive role alongside the exquisite visualization capabilities of 4D cardiovascular magnetic resonance (CMR) imaging. In order to exploit these capabilities (e.g., for decision-making), it is necessary to validate computational models against real world data. In this study, we sought to acquire 4D CMR flow data in a controllable, experimental setup and use these data to validate a corresponding computational model. We applied this paradigm to a case of congenital heart disease, namely, transposition of the great arteries (TGA) repaired with arterial switch operation. For this purpose, a mock circulatory loop compatible with the CMR environment was constructed and two detailed aortic 3D models (i.e., one TGA case and one normal aortic anatomy) were tested under realistic hemodynamic conditions, acquiring 4D CMR flow. The same 3D domains were used for multi-scale CFD simulations, whereby the remainder of the mock circulatory system was appropriately summarized with a lumped parameter network. Boundary conditions of the simulations mirrored those measured in vitro. Results showed a very good quantitative agreement between experimental and computational models in terms of pressure (overall maximum % error = 4.4% aortic pressure in the control anatomy) and flow distribution data (overall maximum % error = 3.6% at the subclavian artery outlet of the TGA model). Very good qualitative agreement could also be appreciated in terms of streamlines, throughout the cardiac cycle. Additionally, velocity vectors in the ascending aorta revealed less symmetrical flow in the TGA model, which also exhibited higher wall shear stress in the anterior ascending aorta.

  10. Using 4D Cardiovascular Magnetic Resonance Imaging to Validate Computational Fluid Dynamics: A Case Study

    PubMed Central

    Biglino, Giovanni; Cosentino, Daria; Steeden, Jennifer A.; De Nova, Lorenzo; Castelli, Matteo; Ntsinjana, Hopewell; Pennati, Giancarlo; Taylor, Andrew M.; Schievano, Silvia

    2015-01-01

    Computational fluid dynamics (CFD) can have a complementary predictive role alongside the exquisite visualization capabilities of 4D cardiovascular magnetic resonance (CMR) imaging. In order to exploit these capabilities (e.g., for decision-making), it is necessary to validate computational models against real world data. In this study, we sought to acquire 4D CMR flow data in a controllable, experimental setup and use these data to validate a corresponding computational model. We applied this paradigm to a case of congenital heart disease, namely, transposition of the great arteries (TGA) repaired with arterial switch operation. For this purpose, a mock circulatory loop compatible with the CMR environment was constructed and two detailed aortic 3D models (i.e., one TGA case and one normal aortic anatomy) were tested under realistic hemodynamic conditions, acquiring 4D CMR flow. The same 3D domains were used for multi-scale CFD simulations, whereby the remainder of the mock circulatory system was appropriately summarized with a lumped parameter network. Boundary conditions of the simulations mirrored those measured in vitro. Results showed a very good quantitative agreement between experimental and computational models in terms of pressure (overall maximum % error = 4.4% aortic pressure in the control anatomy) and flow distribution data (overall maximum % error = 3.6% at the subclavian artery outlet of the TGA model). Very good qualitative agreement could also be appreciated in terms of streamlines, throughout the cardiac cycle. Additionally, velocity vectors in the ascending aorta revealed less symmetrical flow in the TGA model, which also exhibited higher wall shear stress in the anterior ascending aorta. PMID:26697416

  11. Enhancing a diffusion algorithm for 4D image segmentation using local information

    NASA Astrophysics Data System (ADS)

    Lösel, Philipp; Heuveline, Vincent

    2016-03-01

    Inspired by the diffusion of a particle, we present a novel approach for performing a semiautomatic segmentation of tomographic images in 3D, 4D or higher dimensions to meet the requirements of high-throughput measurements in a synchrotron X-ray microtomograph. Given a small number of 2D-slices with at least two manually labeled segments, one can either analytically determine the probability that an intelligently weighted random walk starting at one labeled pixel will be at a certain time at a specific position in the dataset or determine the probability approximately by performing several random walks. While the weights of a random walk take into account local information at the starting point, the random walk itself can be in any dimension. Starting a great number of random walks in each labeled pixel, a voxel in the dataset will be hit by several random walks over time. Hence, the image can be segmented by assigning each voxel to the label where the random walks most likely started from. Due to the high scalability of random walks, this approach is suitable for high throughput measurements. Additionally, we describe an interactively adjusted active contours slice by slice method considering local information, where we start with one manually labeled slice and move forward in any direction. This approach is superior with respect to accuracy towards the diffusion algorithm but inferior in the amount of tedious manual processing steps. The methods were applied on 3D and 4D datasets and evaluated by means of manually labeled images obtained in a realistic scenario with biologists.

  12. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    SciTech Connect

    Bernatowicz, K. Knopf, A.; Lomax, A.; Keall, P.; Kipritidis, J.; Mishra, P.

    2015-01-15

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm{sup 3} spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results

  13. Dedicated PET scanners for breast imaging.

    PubMed

    Freifelder, R; Karp, J S

    1997-12-01

    We have used computer simulations to compare two designs for a PET scanner dedicated to breast imaging with a whole-body PET scanner. The new designs combine high spatial resolution, high sensitivity, and good energy resolution to detect small, low-contrast masses. The detectors are position sensitive NaI(Tl) scintillators. The first design is a ring scanner surrounding the breast and the second consists of two planar detectors placed on opposite sides of the breast. We have employed standard performance measures to compare the different designs: contrast, percentage standard deviation of the background, and signal-to-noise ratios of reconstructed images. The results of the simulations show that both of the proposed designs have better lesion detectability than a whole-body scanner. The results also show that contrast is higher in the ring breast system but that the noise is lower in the planar breast system. Overall, the ring system yields images with the best signal-to-noise ratios, although the planar system offers practical advantages for imaging the breast and axilla.

  14. Dedicated PET scanners for breast imaging

    NASA Astrophysics Data System (ADS)

    Freifelder, Richard; Karp, Joel S.

    1997-12-01

    We have used computer simulations to compare two designs for a PET scanner dedicated to breast imaging with a whole-body PET scanner. The new designs combine high spatial resolution, high sensitivity, and good energy resolution to detect small, low-contrast masses. The detectors are position sensitive NaI(Tl) scintillators. The first design is a ring scanner surrounding the breast and the second consists of two planar detectors placed on opposite sides of the breast. We have employed standard performance measures to compare the different designs: contrast, percentage standard deviation of the background, and signal-to-noise ratios of reconstructed images. The results of the simulations show that both of the proposed designs have better lesion detectability than a whole-body scanner. The results also show that contrast is higher in the ring breast system but that the noise is lower in the planar breast system. Overall, the ring system yields images with the best signal-to-noise ratios, although the planar system offers practical advantages for imaging the breast and axilla.

  15. brainR: Interactive 3 and 4D Images of High Resolution Neuroimage Data

    PubMed Central

    Muschelli, John; Sweeney, Elizabeth; Crainiceanu, Ciprian

    2016-01-01

    We provide software tools for displaying and publishing interactive 3-dimensional (3D) and 4-dimensional (4D) figures to html webpages, with examples of high-resolution brain imaging. Our framework is based in the R statistical software using the rgl package, a 3D graphics library. We build on this package to allow manipulation of figures including rotation and translation, zooming, coloring of brain substructures, adjusting transparency levels, and addition/or removal of brain structures. The need for better visualization tools of ultra high dimensional data is ever present; we are providing a clean, simple, web-based option. We also provide a package (brainR) for users to readily implement these tools. PMID:27330829

  16. Multiscale Texture Analysis: From 18F-FDG PET Images to Histologic Images.

    PubMed

    Orlhac, Fanny; Thézé, Benoit; Soussan, Michaël; Boisgard, Raphaël; Buvat, Irène

    2016-11-01

    Characterizing tumor heterogeneity using texture indices derived from PET images has shown promise in predicting treatment response and patient survival in some types of cancer. Yet, the relationship between PET-derived texture indices, precise tracer distribution, and biologic heterogeneity needs to be clarified. We investigated this relationship using PET images, autoradiographic images, and histologic images.

  17. A patient specific 4D MRI liver motion model based on sparse imaging and registration

    NASA Astrophysics Data System (ADS)

    Noorda, Y. H.; Bartels, L. W.; van Stralen, Marijn; Pluim, J. P. W.

    2013-03-01

    Introduction: Image-guided minimally invasive procedures are becoming increasingly popular. Currently, High-Intensity Focused Ultrasound (HIFU) treatment of lesions in mobile organs, such as the liver, is in development. A requirement for such treatment is automatic motion tracking, such that the position of the lesion can be followed in real time. We propose a 4D liver motion model, which can be used during planning of this procedure. During treatment, the model can serve as a motion predictor. In a similar fashion, this model could be used for radiotherapy treatment of the liver. Method: The model is built by acquiring 2D dynamic sagittal MRI data at six locations in the liver. By registering these dynamics to a 3D MRI liver image, 2D deformation fields are obtained at every location. The 2D fields are ordered according to the position of the liver at that specific time point, such that liver motion during an average breathing period can be simulated. This way, a sparse deformation field is created over time. This deformation field is finally interpolated over the entire volume, yielding a 4D motion model. Results: The accuracy of the model is evaluated by comparing unseen slices to the slice predicted by the model at that specific location and phase in the breathing cycle. The mean Dice coefficient of the liver regions was 0.90. The mean misalignment of the vessels was 1.9 mm. Conclusion: The model is able to predict patient specific deformations of the liver and can predict regular motion accurately.

  18. Dual-Modality PET/Ultrasound imaging of the Prostate

    SciTech Connect

    Huber, Jennifer S.; Moses, William W.; Pouliot, Jean; Hsu, I.C.

    2005-11-11

    Functional imaging with positron emission tomography (PET)will detect malignant tumors in the prostate and/or prostate bed, as well as possibly help determine tumor ''aggressiveness''. However, the relative uptake in a prostate tumor can be so great that few other anatomical landmarks are visible in a PET image. Ultrasound imaging with a transrectal probe provides anatomical detail in the prostate region that can be co-registered with the sensitive functional information from the PET imaging. Imaging the prostate with both PET and transrectal ultrasound (TRUS) will help determine the location of any cancer within the prostate region. This dual-modality imaging should help provide better detection and treatment of prostate cancer. LBNL has built a high performance positron emission tomograph optimized to image the prostate.Compared to a standard whole-body PET camera, our prostate-optimized PET camera has the same sensitivity and resolution, less backgrounds and lower cost. We plan to develop the hardware and software tools needed for a validated dual PET/TRUS prostate imaging system. We also plan to develop dual prostate imaging with PET and external transabdominal ultrasound, in case the TRUS system is too uncomfortable for some patients. We present the design and intended clinical uses for these dual imaging systems.

  19. SiPM-PET with a short optical fiber bundle for simultaneous PET-MR imaging.

    PubMed

    Hong, Seong Jong; Kang, Han Gyoo; Ko, Guen Bae; Song, In Chan; Rhee, June-Tak; Lee, Jae Sung

    2012-06-21

    For positron emission tomography (PET) inserts to magnetic resonance imaging (MRI) applications, optical fibers have been used for some time to transfer scintillation photons to photomultiplier tubes positioned outside the fringe magnetic field. We previously proposed a novel utilization of an optical fiber for good radio frequency (RF) transmission from body coils to an imaging object. Optical fiber bundles between silicon photomultipliers (SiPM) and scintillation crystals provide an increased spacing between RF-shielded electronics boxes, facilitating RF passage from the body RF coils to imaging objects. In this paper, we present test results of a SiPM-PET system with a short optical fiber bundle for simultaneous PET-MR imaging. We built the SiPM-PET system which consisted of 12 SiPM-PET modules; each module was assembled with a lutetium yttrium oxyorthosilicatecrystal block, a 31 mm optical fiber bundle, a Hamamatsu multi-pixel photon counter S11064-050P and a signal processing box shielded with copper. The SiPM-PET system, with a face-to-face distance of 71 mm, was placed inside a 3 T MRI. A small surface coil placed inside the SiPM-PET system was used to receive the signal from phantoms while the body RF coil transmitted the RF pulses. The SiPM-PET system showed little performance degradation during the simultaneous PET-MR imaging and it caused no significant degradation of MR images with turbo spin echo (TSE), gradient echo or 3D spoiled gradient recalled sequences. Echo planar imaging MR images with and without the SiPM-PET inside the MR scanner were significantly worse than the images obtained with the TSE sequence.

  20. 3D and 4D magnetic susceptibility tomography based on complex MR images

    DOEpatents

    Chen, Zikuan; Calhoun, Vince D

    2014-11-11

    Magnetic susceptibility is the physical property for T2*-weighted magnetic resonance imaging (T2*MRI). The invention relates to methods for reconstructing an internal distribution (3D map) of magnetic susceptibility values, .chi. (x,y,z), of an object, from 3D T2*MRI phase images, by using Computed Inverse Magnetic Resonance Imaging (CIMRI) tomography. The CIMRI technique solves the inverse problem of the 3D convolution by executing a 3D Total Variation (TV) regularized iterative convolution scheme, using a split Bregman iteration algorithm. The reconstruction of .chi. (x,y,z) can be designed for low-pass, band-pass, and high-pass features by using a convolution kernel that is modified from the standard dipole kernel. Multiple reconstructions can be implemented in parallel, and averaging the reconstructions can suppress noise. 4D dynamic magnetic susceptibility tomography can be implemented by reconstructing a 3D susceptibility volume from a 3D phase volume by performing 3D CIMRI magnetic susceptibility tomography at each snapshot time.

  1. Vessel Enhancement and Segmentation of 4D CT Lung Image Using Stick Tensor Voting

    NASA Astrophysics Data System (ADS)

    Cong, Tan; Hao, Yang; Jingli, Shi; Xuan, Yang

    2016-12-01

    Vessel enhancement and segmentation plays a significant role in medical image analysis. This paper proposes a novel vessel enhancement and segmentation method for 4D CT lung image using stick tensor voting algorithm, which focuses on addressing the vessel distortion issue of vessel enhancement diffusion (VED) method. Furthermore, the enhanced results are easily segmented using level-set segmentation. In our method, firstly, vessels are filtered using Frangi's filter to reduce intrapulmonary noises and extract rough blood vessels. Secondly, stick tensor voting algorithm is employed to estimate the correct direction along the vessel. Then the estimated direction along the vessel is used as the anisotropic diffusion direction of vessel in VED algorithm, which makes the intensity diffusion of points locating at the vessel wall be consistent with the directions of vessels and enhance the tubular features of vessels. Finally, vessels can be extracted from the enhanced image by applying level-set segmentation method. A number of experiments results show that our method outperforms traditional VED method in vessel enhancement and results in satisfied segmented vessels.

  2. Advanced Tracers in PET Imaging of Cardiovascular Disease

    PubMed Central

    Zhang, Wei; Wu, Hua; Liu, Gang

    2014-01-01

    Cardiovascular disease is the leading cause of death worldwide. Molecular imaging with targeted tracers by positron emission tomography (PET) allows for the noninvasive detection and characterization of biological changes at the molecular level, leading to earlier disease detection, objective monitoring of therapies, and better prognostication of cardiovascular diseases progression. Here we review, the current role of PET in cardiovascular disease, with emphasize on tracers developed for PET imaging of cardiovascular diseases. PMID:25389529

  3. Automated image registration for FDOPA PET studies

    NASA Astrophysics Data System (ADS)

    Lin, Kang-Ping; Huang, Sung-Cheng; Yu, Dan-Chu; Melega, William; Barrio, Jorge R.; Phelps, Michael E.

    1996-12-01

    In this study, various image registration methods are investigated for their suitability for registration of L-6-[18F]-fluoro-DOPA (FDOPA) PET images. Five different optimization criteria including sum of absolute difference (SAD), mean square difference (MSD), cross-correlation coefficient (CC), standard deviation of pixel ratio (SDPR), and stochastic sign change (SSC) were implemented and Powell's algorithm was used to optimize the criteria. The optimization criteria were calculated either unidirectionally (i.e. only evaluating the criteria for comparing the resliced image 1 with the original image 2) or bidirectionally (i.e. averaging the criteria for comparing the resliced image 1 with the original image 2 and those for the sliced image 2 with the original image 1). Monkey FDOPA images taken at various known orientations were used to evaluate the accuracy of different methods. A set of human FDOPA dynamic images was used to investigate the ability of the methods for correcting subject movement. It was found that a large improvement in performance resulted when bidirectional rather than unidirectional criteria were used. Overall, the SAD, MSD and SDPR methods were found to be comparable in performance and were suitable for registering FDOPA images. The MSD method gave more adequate results for frame-to-frame image registration for correcting subject movement during a dynamic FDOPA study. The utility of the registration method is further demonstrated by registering FDOPA images in monkeys before and after amphetamine injection to reveal more clearly the changes in spatial distribution of FDOPA due to the drug intervention.

  4. PET imaging of adoptive progenitor cell therapies.

    SciTech Connect

    Gelovani, Juri G.

    2008-05-13

    Objectives. The overall objective of this application is to develop novel technologies for non-invasive imaging of adoptive stem cell-based therapies with positron emission tomography (PET) that would be applicable to human patients. To achieve this objective, stem cells will be genetically labeled with a PET-reporter gene and repetitively imaged to assess their distribution, migration, differentiation, and persistence using a radiolabeled reporter probe. This new imaging technology will be tested in adoptive progenitor cell-based therapy models in animals, including: delivery pro-apoptotic genes to tumors, and T-cell reconstitution for immunostimulatory therapy during allogeneic bone marrow progenitor cell transplantation. Technical and Scientific Merits. Non-invasive whole body imaging would significantly aid in the development and clinical implementation of various adoptive progenitor cell-based therapies by providing the means for non-invasive monitoring of the fate of injected progenitor cells over a long period of observation. The proposed imaging approaches could help to address several questions related to stem cell migration and homing, their long-term viability, and their subsequent differentiation. The ability to image these processes non-invasively in 3D and repetitively over a long period of time is very important and will help the development and clinical application of various strategies to control and direct stem cell migration and differentiation. Approach to accomplish the work. Stem cells will be genetically with a reporter gene which will allow for repetitive non-invasive “tracking” of the migration and localization of genetically labeled stem cells and their progeny. This is a radically new approach that is being developed for future human applications and should allow for a long term (many years) repetitive imaging of the fate of tissues that develop from the transplanted stem cells. Why the approach is appropriate. The novel approach to

  5. Imaging corn plants with PhytoPET, a modular PET system for plant biology

    SciTech Connect

    Lee, S.; Kross, B.; McKisson, J.; McKisson, J. E.; Weisenberger, A. G.; Xi, W.; Zorn, C.; Bonito, G.; Howell, C. R.; Reid, C. D.; Crowell, A.; Cumberbatch, L. C.; Topp, C.; Smith, M. F.

    2013-11-01

    PhytoPET is a modular positron emission tomography (PET) system designed specifically for plant imaging. The PhytoPET design allows flexible arrangements of PET detectors based on individual standalone detector modules built from single Hamamatsu H8500 position sensitive photomultiplier tubes and pixelated LYSO arrays. We have used the PhytoPET system to perform preliminary corn plant imaging studies at the Duke University Biology Department Phytotron. Initial evaluation of the PhytoPET system to image the biodistribution of the positron emitting tracer {sup 11}C in corn plants is presented. {sup 11}CO{sub 2} is loaded into corn seedlings by a leaf-labeling cuvette and translocation of {sup 11}C-sugars is imaged by a flexible arrangement of PhytoPET modules on each side. The PhytoPET system successfully images {sup 11}C within corn plants and allows for the dynamic measurement of {sup 11}C-sugar translocation from the leaf to the roots.

  6. Development of a PET Scanner for Simultaneously Imaging Small Animals with MRI and PET

    PubMed Central

    Thompson, Christopher J; Goertzen, Andrew L; Thiessen, Jonathan D; Bishop, Daryl; Stortz, Greg; Kozlowski, Piotr; Retière, Fabrice; Zhang, Xuezhu; Sossi, Vesna

    2014-01-01

    Recently, positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT) scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and magnetic resonance imaging (MRI) is being explored in many sites. Combining PET and MRI has presented many challenges since the photo-multiplier tubes (PMT) in PET do not function in high magnetic fields, and conventional PET detectors distort MRI images. Solid state light sensors like avalanche photo-diodes (APDs) and more recently silicon photo-multipliers (SiPMs) are much less sensitive to magnetic fields thus easing the compatibility issues. This paper presents the results of a group of Canadian scientists who are developing a PET detector ring which fits inside a high field small animal MRI scanner with the goal of providing simultaneous PET and MRI images of small rodents used in pre-clinical medical research. We discuss the evolution of both the crystal blocks (which detect annihilation photons from positron decay) and the SiPM array performance in the last four years which together combine to deliver significant system performance in terms of speed, energy and timing resolution. PMID:25120157

  7. PET/MR Imaging in Cancers of the Gastrointestinal Tract.

    PubMed

    Paspulati, Raj Mohan; Gupta, Amit

    2016-10-01

    PET/computed tomography (PET/CT) is an established hybrid imaging technique for staging and follow-up of gastrointestinal (GI) tract malignancies, especially for colorectal carcinoma. Dedicated hybrid PET/MR imaging scanners are currently available for clinical use. Although they will not replace regular use of PET/CT, they may have utility in selected cases of GI tract malignancies. The superior soft tissue contrast resolution and depiction of anatomy and the functional information obtained from diffusion-weighted imaging (DWI) provided by MR imaging in PET/MR imaging are advantages over CT of PET/CT for T staging and follow-up of rectal carcinoma and for better characterization of liver lesions. Functional information from DWI and use of liver-specific MR imaging contrast agents are an added advantage in follow-up of liver metastases after systemic and locoregional treatment. New radiotracers will improve the utility of PET/MR imaging in staging and follow-up of tumors, which may not be [18F]-2-fluoro-2-deoxy-d-glucose avid, such as hepatocellular carcinoma and neuroendocrine tumors. PET/MR imaging also has application in selected cases of cholangiocarcinoma, gallbladder cancer, and pancreatic carcinoma for initial staging and follow-up assessment.

  8. Deblurring of breathing motion artifacts in thoracic PET images by deconvolution methods

    SciTech Connect

    Naqa, Issam El; Low, Daniel A.; Bradley, Jeffrey D.; Vicic, Milos; Deasy, Joseph O.

    2006-10-15

    results show that the proposed method provides a feasible framework for improving PET thoracic images, without the need for gated/4-D PET imaging, when 4-D CT is available to estimate tumor motion.

  9. Automatic landmark generation for deformable image registration evaluation for 4D CT images of lung

    NASA Astrophysics Data System (ADS)

    Vickress, J.; Battista, J.; Barnett, R.; Morgan, J.; Yartsev, S.

    2016-10-01

    Deformable image registration (DIR) has become a common tool in medical imaging across both diagnostic and treatment specialties, but the methods used offer varying levels of accuracy. Evaluation of DIR is commonly performed using manually selected landmarks, which is subjective, tedious and time consuming. We propose a semi-automated method that saves time and provides accuracy comparable to manual selection. Three landmarking methods including manual (with two independent observers), scale invariant feature transform (SIFT), and SIFT with manual editing (SIFT-M) were tested on 10 thoracic 4DCT image studies corresponding to the 0% and 50% phases of respiration. Results of each method were evaluated against a gold standard (GS) landmark set comparing both mean and proximal landmark displacements. The proximal method compares the local deformation magnitude between a test landmark pair and the closest GS pair. Statistical analysis was done using an intra class correlation (ICC) between test and GS displacement values. The creation time per landmark pair was 22, 34, 2.3, and 4.3 s for observers 1 and 2, SIFT, and SIFT-M methods respectively. Across 20 lungs from the 10 CT studies, the ICC values between the GS and observer 1 and 2, SIFT, and SIFT-M methods were 0.85, 0.85, 0.84, and 0.82 for mean lung deformation, and 0.97, 0.98, 0.91, and 0.96 for proximal landmark deformation, respectively. SIFT and SIFT-M methods have an accuracy that is comparable to manual methods when tested against a GS landmark set while saving 90% of the time. The number and distribution of landmarks significantly affected the analysis as manifested by the different results for mean deformation and proximal landmark deformation methods. Automatic landmark methods offer a promising alternative to manual landmarking, if the quantity, quality and distribution of landmarks can be optimized for the intended application.

  10. CYBPET: a cylindrical PET system for breast imaging

    NASA Astrophysics Data System (ADS)

    Karimian, A.; Thompson, C. J.; Sarkar, S.; Raisali, G.; Pani, R.; Davilu, H.; Sardari, D.

    2005-06-01

    We propose a Cylindrical Breast PET (CYBPET) system for breast imaging with patients in the prone position. An individual pendulous breast is covered by thin plastic to provide reduced pressure fixation and surrounded by the crystals inside the CYBPET ring. Each breast is imaged separately. The rest of the body is shielded properly to minimize the contribution of scattered photons from the other breast and the rest of the body. To compare the CYBPET with whole-body PET (WB-PET) the simulations of CYBPET and a WB-PET (GE-Advance) for a 10 mm tumor inside the breast with a lesion to background (breast) activity concentration of 6 to 1 were made. The noise effective count rate (NECR) of CYBPET is about twice that of WB-PET at activity concentrations less than 3.1 μCi/cc. The spatial resolution of CYBPET is better by 25% than the WB-PET.

  11. Body-wide anatomy recognition in PET/CT images

    NASA Astrophysics Data System (ADS)

    Wang, Huiqian; Udupa, Jayaram K.; Odhner, Dewey; Tong, Yubing; Zhao, Liming; Torigian, Drew A.

    2015-03-01

    With the rapid growth of positron emission tomography/computed tomography (PET/CT)-based medical applications, body-wide anatomy recognition on whole-body PET/CT images becomes crucial for quantifying body-wide disease burden. This, however, is a challenging problem and seldom studied due to unclear anatomy reference frame and low spatial resolution of PET images as well as low contrast and spatial resolution of the associated low-dose CT images. We previously developed an automatic anatomy recognition (AAR) system [15] whose applicability was demonstrated on diagnostic computed tomography (CT) and magnetic resonance (MR) images in different body regions on 35 objects. The aim of the present work is to investigate strategies for adapting the previous AAR system to low-dose CT and PET images toward automated body-wide disease quantification. Our adaptation of the previous AAR methodology to PET/CT images in this paper focuses on 16 objects in three body regions - thorax, abdomen, and pelvis - and consists of the following steps: collecting whole-body PET/CT images from existing patient image databases, delineating all objects in these images, modifying the previous hierarchical models built from diagnostic CT images to account for differences in appearance in low-dose CT and PET images, automatically locating objects in these images following object hierarchy, and evaluating performance. Our preliminary evaluations indicate that the performance of the AAR approach on low-dose CT images achieves object localization accuracy within about 2 voxels, which is comparable to the accuracies achieved on diagnostic contrast-enhanced CT images. Object recognition on low-dose CT images from PET/CT examinations without requiring diagnostic contrast-enhanced CT seems feasible.

  12. A deformable phantom for 4D radiotherapy verification: Design and image registration evaluation

    SciTech Connect

    Serban, Monica; Heath, Emily; Stroian, Gabriela; Collins, D. Louis; Seuntjens, Jan

    2008-03-15

    peak inhale. The SI displacement of the landmarks varied between 94% and 3% of the piston excursion for positions closer and farther away from the piston, respectively. The reproducibility of the phantom deformation was within the image resolution (0.7x0.7x1.25 mm{sup 3}). Vector average registration accuracy based on point landmarks was found to be 0.5 (0.4 SD) mm. The tumor and lung mean 3D DTA obtained from triangulated surfaces were 0.4 (0.1 SD) mm and 1.0 (0.8 SD) mm, respectively. This phantom is capable of reproducibly emulating the physically realistic lung features and deformations and has a wide range of potential applications, including four-dimensional (4D) imaging, evaluation of deformable registration accuracy, 4D planning and dose delivery.

  13. A deformable phantom for 4D radiotherapy verification: design and image registration evaluation.

    PubMed

    Serban, Monica; Heath, Emily; Stroian, Gabriela; Collins, D Louis; Seuntjens, Jan

    2008-03-01

    . The SI displacement of the landmarks varied between 94% and 3% of the piston excursion for positions closer and farther away from the piston, respectively. The reproducibility of the phantom deformation was within the image resolution (0.7 x 0.7 x 1.25 mm3). Vector average registration accuracy based on point landmarks was found to be 0.5 (0.4 SD) mm. The tumor and lung mean 3D DTA obtained from triangulated surfaces were 0.4 (0.1 SD) mm and 1.0 (0.8 SD) mm, respectively. This phantom is capable of reproducibly emulating the physically realistic lung features and deformations and has a wide range of potential applications, including four-dimensional (4D) imaging, evaluation of deformable registration accuracy, 4D planning and dose delivery.

  14. MULTIMODALITY IMAGING: BEYOND PET/CT AND SPECT/CT

    PubMed Central

    Cherry, Simon R.

    2009-01-01

    Multimodality imaging with PET/CT and SPECT/CT has become commonplace in clinical practice and in preclinical and basic medical research. Do other combinations of imaging modalities have a similar potential to impact medical science and clinical medicine? The combination of PET or SPECT with MRI is an area of active research at the present time, while other, perhaps less obvious combinations, including CT/MR and PET/optical also are being studied. In addition to the integration of the instrumentation, there are parallel developments in synthesizing imaging agents that can be viewed by multiple imaging modalities. Is the fusion of PET and SPECT with CT the ultimate answer in multimodality imaging, or is it just the first example of a more general trend towards harnessing the complementary nature of the different modalities on integrated imaging platforms? PMID:19646559

  15. Sparsity-constrained PET image reconstruction with learned dictionaries

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Yang, Bao; Wang, Yanhua; Ying, Leslie

    2016-09-01

    PET imaging plays an important role in scientific and clinical measurement of biochemical and physiological processes. Model-based PET image reconstruction such as the iterative expectation maximization algorithm seeking the maximum likelihood solution leads to increased noise. The maximum a posteriori (MAP) estimate removes divergence at higher iterations. However, a conventional smoothing prior or a total-variation (TV) prior in a MAP reconstruction algorithm causes over smoothing or blocky artifacts in the reconstructed images. We propose to use dictionary learning (DL) based sparse signal representation in the formation of the prior for MAP PET image reconstruction. The dictionary to sparsify the PET images in the reconstruction process is learned from various training images including the corresponding MR structural image and a self-created hollow sphere. Using simulated and patient brain PET data with corresponding MR images, we study the performance of the DL-MAP algorithm and compare it quantitatively with a conventional MAP algorithm, a TV-MAP algorithm, and a patch-based algorithm. The DL-MAP algorithm achieves improved bias and contrast (or regional mean values) at comparable noise to what the other MAP algorithms acquire. The dictionary learned from the hollow sphere leads to similar results as the dictionary learned from the corresponding MR image. Achieving robust performance in various noise-level simulation and patient studies, the DL-MAP algorithm with a general dictionary demonstrates its potential in quantitative PET imaging.

  16. Sparsity-constrained PET image reconstruction with learned dictionaries.

    PubMed

    Tang, Jing; Yang, Bao; Wang, Yanhua; Ying, Leslie

    2016-09-07

    PET imaging plays an important role in scientific and clinical measurement of biochemical and physiological processes. Model-based PET image reconstruction such as the iterative expectation maximization algorithm seeking the maximum likelihood solution leads to increased noise. The maximum a posteriori (MAP) estimate removes divergence at higher iterations. However, a conventional smoothing prior or a total-variation (TV) prior in a MAP reconstruction algorithm causes over smoothing or blocky artifacts in the reconstructed images. We propose to use dictionary learning (DL) based sparse signal representation in the formation of the prior for MAP PET image reconstruction. The dictionary to sparsify the PET images in the reconstruction process is learned from various training images including the corresponding MR structural image and a self-created hollow sphere. Using simulated and patient brain PET data with corresponding MR images, we study the performance of the DL-MAP algorithm and compare it quantitatively with a conventional MAP algorithm, a TV-MAP algorithm, and a patch-based algorithm. The DL-MAP algorithm achieves improved bias and contrast (or regional mean values) at comparable noise to what the other MAP algorithms acquire. The dictionary learned from the hollow sphere leads to similar results as the dictionary learned from the corresponding MR image. Achieving robust performance in various noise-level simulation and patient studies, the DL-MAP algorithm with a general dictionary demonstrates its potential in quantitative PET imaging.

  17. Application of 4D resistivity image profiling to detect DNAPLs plume.

    NASA Astrophysics Data System (ADS)

    Liu, H.; Yang, C.; Tsai, Y.

    2008-12-01

    In July 1993, the soil and groundwater of the factory of Taiwan , Miaoli was found to be contaminated by dichloroethane, chlorobenzene and other hazardous solvents. The contaminants were termed to be dense non-aqueous phase liquids (DNAPLs). The contaminated site was neglected for the following years until May 1998, the Environment Protection Agency of Miaoli ordered the company immediately take an action for treatment of the contaminated site. Excavating and exposing the contaminated soil was done at the previous waste DNAPL dumped area. In addition, more than 53 wells were drilled around the pool with a maximum depth of 12 m where a clayey layer was found. Continuous pumping the groundwater and monitoring the concentration of residual DNAPL contained in the well water samples have done in different stages of remediation. However, it is suspected that the DNAPL has existed for a long time, therefore the contaminants might dilute but remnants of a DNAPL plume that are toxic to humans still remain in the soil and migrate to deeper aquifers. A former contaminated site was investigated using the 2D, 3D and 4D resisitivity image technique, with aims of determining buried contaminant geometry. This paper emphasizes the use of resistivity image profiling (RIP) method to map the limit of this DNAPL waste disposal site where the records of operations are not variations. A significant change in resistivity values was detected between known polluted and non-polluted subsurface; a high resistivity value implies that the subsurface was contaminated by DNAPL plume. The results of the survey serve to provide insight into the sensitivity of RIP method for detecting DNAPL plumes within the shallow subsurface, and help to provide valuable information related to monitoring the possible migration path of DNAPL plume in the past. According to the formerly studies in this site, affiliation by excavates with pumps water remediation had very long time, Therefore this research was used

  18. MR-Based Cardiac and Respiratory Motion-Compensation Techniques for PET-MR Imaging.

    PubMed

    Munoz, Camila; Kolbitsch, Christoph; Reader, Andrew J; Marsden, Paul; Schaeffter, Tobias; Prieto, Claudia

    2016-04-01

    Cardiac and respiratory motion cause image quality degradation in PET imaging, affecting diagnostic accuracy of the images. Whole-body simultaneous PET-MR scanners allow for using motion information estimated from MR images to correct PET data and produce motion-compensated PET images. This article reviews methods that have been proposed to estimate motion from MR images and different techniques to include this information in PET reconstruction, in order to overcome the problem of cardiac and respiratory motion in PET-MR imaging. MR-based motion correction techniques significantly increase lesion detectability and contrast, and also improve accuracy of uptake values in PET images.

  19. Improving PET imaging for breast cancer using Virtual Pinhole PET half ring insert

    PubMed Central

    Mathews, Aswin John; Komarov, Sergey; Wu, Heyu; O’Sullivan, Joseph A.; Tai, Yuan-Chuan

    2013-01-01

    A PET insert with detector having smaller crystals and placed near a region of interest in a conventional PET scanner can improve image resolution locally due to the Virtual-Pinhole PET (VP-PET) effect. This improvement is from the higher spatial sampling of the imaging area near the detector. We have built a prototype half-ring PET insert for head-and-neck cancer imaging applications. In this paper, we extend the use of the insert to breast imaging and show that such a system provides high resolution images of breast and axillary lymph nodes while maintaining the full imaging field of view capability of a clinical PET scanner. We characterize the resolution and contrast recovery for tumors across the imaging field of view. First, we model the system using Monte Carlo methods to determine its theoretical limit of improvement. Simulations were conducted with hot spherical tumors embedded in background activity at tumor-to-background contrast ranging from 3:1 to 12:1. Tumors are arranged in a Derenzo-like pattern with their diameters ranging from 2 to 12 mm. Experimental studies were performed using a chest phantom with cylindrical breast attachment. Tumors of different sizes arranged in a Derenzo-like pattern with tumor-to- background ratio of 6:1 are inserted into the breast phantom. Imaging capability of mediastinum and axillary lymph nodes is explored. Both Monte Carlo simulations and experiment show clear improvement in image resolution and contrast recovery with VP-PET half ring insert. The degree of improvement in resolution and contrast recovery depends on location of the tumor. The full field of view imaging capability is shown to be maintained. Minor artifacts are introduced in certain regions. PMID:23999026

  20. Update on time-of-flight PET imaging

    PubMed Central

    Surti, Suleman

    2015-01-01

    Time-of-flight (TOF) PET was initially introduced in the early days of PET. TOF PET scanners developed in the 1980s had limited sensitivity and spatial resolution, operated in 2D mode with septa, and used analytic image reconstruction methods. Current generation of TOF PET scanners have the highest sensitivity and spatial resolution ever achieved in commercial whole-body PET, operate in fully-3D mode, and use iterative reconstruction with full system modeling. Previously, it was shown that TOF provides a gain in image signal-to-noise-ratio (SNR) that is proportional to the square root of the object size divided by the system timing resolution. With oncologic studies being the primary application of PET, more recent work has shown that in modern TOF PET scanners there is an improved trade-off between lesion contrast, image noise, and total imaging time, leading to a combination of improved lesion detectability, reduced scan time or injected dose, and more accurate and precise lesion uptake measurement. The benefit of TOF PET is also higher for heavier patients, which leads to a more uniform clinical performance over all patient sizes. PMID:25525181

  1. Dynamic whole-body PET parametric imaging: II. Task-oriented statistical estimation.

    PubMed

    Karakatsanis, Nicolas A; Lodge, Martin A; Zhou, Y; Wahl, Richard L; Rahmim, Arman

    2013-10-21

    In the context of oncology, dynamic PET imaging coupled with standard graphical linear analysis has been previously employed to enable quantitative estimation of tracer kinetic parameters of physiological interest at the voxel level, thus, enabling quantitative PET parametric imaging. However, dynamic PET acquisition protocols have been confined to the limited axial field-of-view (~15-20 cm) of a single-bed position and have not been translated to the whole-body clinical imaging domain. On the contrary, standardized uptake value (SUV) PET imaging, considered as the routine approach in clinical oncology, commonly involves multi-bed acquisitions, but is performed statically, thus not allowing for dynamic tracking of the tracer distribution. Here, we pursue a transition to dynamic whole-body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. In a companion study, we presented a novel clinically feasible dynamic (4D) multi-bed PET acquisition protocol as well as the concept of whole-body PET parametric imaging employing Patlak ordinary least squares (OLS) regression to estimate the quantitative parameters of tracer uptake rate Ki and total blood distribution volume V. In the present study, we propose an advanced hybrid linear regression framework, driven by Patlak kinetic voxel correlations, to achieve superior trade-off between contrast-to-noise ratio (CNR) and mean squared error (MSE) than provided by OLS for the final Ki parametric images, enabling task-based performance optimization. Overall, whether the observer's task is to detect a tumor or quantitatively assess treatment response, the proposed statistical estimation framework can be adapted to satisfy the specific task performance criteria, by adjusting the Patlak correlation-coefficient (WR) reference value. The multi-bed dynamic acquisition protocol, as optimized in the preceding companion study

  2. Automated cardiac motion compensation in PET/CT for accurate reconstruction of PET myocardial perfusion images

    NASA Astrophysics Data System (ADS)

    Khurshid, Khawar; McGough, Robert J.; Berger, Kevin

    2008-10-01

    Error-free reconstruction of PET data with a registered CT attenuation map is essential for accurate quantification and interpretation of cardiac perfusion. Misalignment of the CT and PET data can produce an erroneous attenuation map that projects lung attenuation parameters onto the heart wall, thereby underestimating the attenuation and creating artifactual areas of hypoperfusion that can be misinterpreted as myocardial ischemia or infarction. The major causes of misregistration between CT and PET images are the respiratory motion, cardiac motion and gross physical motion of the patient. The misalignment artifact problem is overcome with automated cardiac registration software that minimizes the alignment error between the two modalities. Results show that the automated registration process works equally well for any respiratory phase in which the CT scan is acquired. Further evaluation of this procedure on 50 patients demonstrates that the automated registration software consistently aligns the two modalities, eliminating artifactual hypoperfusion in reconstructed PET images due to PET/CT misregistration. With this registration software, only one CT scan is required for PET/CT imaging, which reduces the radiation dose required for CT-based attenuation correction and improves the clinical workflow for PET/CT.

  3. Thoracic cancer imaging with PET/CT in radiation oncology

    NASA Astrophysics Data System (ADS)

    Chi, Pai-Chun Melinda

    Significance. Respiratory motion has been shown to cause artifacts in PET/CT imaging. This breathing artifact can have a significant impact on PET quantification and it can lead to large uncertainties when using PET for radiation therapy planning. We have demonstrated a promising solution to resolve the breathing artifact by acquiring respiration-averaged CT (ACT) for PET/CT. The purpose of this work was to optimize the ACT acquisition for clinical implementation and to evaluate the impact of ACT on PET/CT quantification. The hypothesis was that ACT is an effective method in removing the breathing artifact when compared to our current clinical protocol. Methods. Phase and cine approaches for acquiring ACT were investigated and the results of these two approaches were compared to the ACT generated from clinical 4DCT data sets (abbreviated as ACT10phs ). In the phase approach, ACT was generated based on combinations of selected respiratory phases; in the cine approach, ACT was generated based on cine images acquired over a fixed cine duration. The phase combination and cine duration that best approximated the ACT10phs were determined to be the optimized scanning parameters. 216 thoracic PET/CT patients were scanned with both current clinical and the ACT protocols. The effects of ACT on PET/CT quantification were assessed by comparing clinical PET/CT and ACT PET/CT using 3 metrics: PET/CT image alignment, maximum standardized uptake value (SUVmax), and threshold segmented gross tumor volume (GTV). Results. ACT10phs can be best approximated to within 2% of SUV variation by phase averaging based on 4 representative phases, and to within 3% by cine image averaging based on >3s of cine duration. We implemented the cine approach on the PET/CT scanners and acquired 216 patient data sets. 68% of patients had breathing artifacts in their clinical PET/CT and the artifacts were removed/reduced in all corresponding ACT PET/CT. PET/CT quantification for lesions <50 cm3 and

  4. PET IMAGING STUDIES IN DRUG ABUSE RESEARCH.

    SciTech Connect

    Fowler, J.S.; Volkow, N.D.; Ding, Y.S.; Logan, J.; Wang, G.J.

    2001-01-29

    There is overwhelming evidence that addiction is a disease of the brain (Leshner, 1997). Yet public perception that addiction is a reflection of moral weakness or a lack of willpower persists. The insidious consequence of this perception is that we lose sight of the fact that there are enormous medical consequences of addiction including the fact that a large fraction of the total deaths from cancer and heart disease are caused by smoking addiction. Ironically the medical school that educates physicians in addiction medicine and the cancer hospital that has a smoking cessation clinic are vanishingly rare and efforts at harm reduction are frequently met with a public indignation. Meanwhile the number of people addicted to substances is enormous and increasing particularly the addictions to cigarettes and alcohol. It is particularly tragic that addiction usually begins in adolescence and becomes a chronic relapsing problem and there are basically no completely effective treatments. Clearly we need to understand how drugs of abuse affect the brain and we need to be creative in using this information to develop effective treatments. Imaging technologies have played a major role in the conceptualization of addiction as a disease of the brain (Fowler et al., 1998a; Fowler et al., 1999a). New knowledge has been driven by advances in radiotracer design and chemistry and positron emission tomography (PET) instrumentation and the integration of these scientific tools with the tools of biochemistry, pharmacology and medicine. This topic cuts across the medical specialties of neurology, psychiatry, cancer and heart disease because of the high medical, social and economic toll that drugs of abuse, including and especially the legal drugs, cigarettes and alcohol, take on society. In this chapter we will begin by highlighting the important role that chemistry has played in making it possible to quantitatively image the movement of drugs as well as their effects on the human brain

  5. Development of a PET/Cerenkov-light hybrid imaging system

    SciTech Connect

    Yamamoto, Seiichi Hamamura, Fuka; Kato, Katsuhiko; Ogata, Yoshimune; Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Hatazawa, Jun; Watabe, Hiroshi

    2014-09-15

    Purpose: Cerenkov-light imaging is a new molecular imaging technology that detects visible photons from high-speed electrons using a high sensitivity optical camera. However, the merit of Cerenkov-light imaging remains unclear. If a PET/Cerenkov-light hybrid imaging system were developed, the merit of Cerenkov-light imaging would be clarified by directly comparing these two imaging modalities. Methods: The authors developed and tested a PET/Cerenkov-light hybrid imaging system that consists of a dual-head PET system, a reflection mirror located above the subject, and a high sensitivity charge coupled device (CCD) camera. The authors installed these systems inside a black box for imaging the Cerenkov-light. The dual-head PET system employed a 1.2 × 1.2 × 10 mm{sup 3} GSO arranged in a 33 × 33 matrix that was optically coupled to a position sensitive photomultiplier tube to form a GSO block detector. The authors arranged two GSO block detectors 10 cm apart and positioned the subject between them. The Cerenkov-light above the subject is reflected by the mirror and changes its direction to the side of the PET system and is imaged by the high sensitivity CCD camera. Results: The dual-head PET system had a spatial resolution of ∼1.2 mm FWHM and sensitivity of ∼0.31% at the center of the FOV. The Cerenkov-light imaging system's spatial resolution was ∼275μm for a {sup 22}Na point source. Using the combined PET/Cerenkov-light hybrid imaging system, the authors successfully obtained fused images from simultaneously acquired images. The image distributions are sometimes different due to the light transmission and absorption in the body of the subject in the Cerenkov-light images. In simultaneous imaging of rat, the authors found that {sup 18}F-FDG accumulation was observed mainly in the Harderian gland on the PET image, while the distribution of Cerenkov-light was observed in the eyes. Conclusions: The authors conclude that their developed PET/Cerenkov-light hybrid

  6. A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner.

    PubMed

    Slates, R B; Farahani, K; Shao, Y; Marsden, P K; Taylor, J; Summers, P E; Williams, S; Beech, J; Cherry, S R

    1999-08-01

    We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

  7. 4D cone-beam CT imaging for guidance in radiation therapy: setup verification by use of implanted fiducial markers

    NASA Astrophysics Data System (ADS)

    Jin, Peng; van Wieringen, Niek; Hulshof, Maarten C. C. M.; Bel, Arjan; Alderliesten, Tanja

    2016-03-01

    The use of 4D cone-beam computed tomography (CBCT) and fiducial markers for guidance during radiation therapy of mobile tumors is challenging due to the trade-off between image quality, imaging dose, and scanning time. We aimed to investigate the visibility of markers and the feasibility of marker-based 4D registration and manual respiration-induced marker motion quantification for different CBCT acquisition settings. A dynamic thorax phantom and a patient with implanted gold markers were included. For both the phantom and patient, the peak-to-peak amplitude of marker motion in the cranial-caudal direction ranged from 5.3 to 14.0 mm, which did not affect the marker visibility and the associated marker-based registration feasibility. While using a medium field of view (FOV) and the same total imaging dose as is applied for 3D CBCT scanning in our clinic, it was feasible to attain an improved marker visibility by reducing the imaging dose per projection and increasing the number of projection images. For a small FOV with a shorter rotation arc but similar total imaging dose, streak artifacts were reduced due to using a smaller sampling angle. Additionally, the use of a small FOV allowed reducing total imaging dose and scanning time (~2.5 min) without losing the marker visibility. In conclusion, by using 4D CBCT with identical or lower imaging dose and a reduced gantry speed, it is feasible to attain sufficient marker visibility for marker-based 4D setup verification. Moreover, regardless of the settings, manual marker motion quantification can achieve a high accuracy with the error <1.2 mm.

  8. Quantifying the image quality and dose reduction of respiratory triggered 4D cone-beam computed tomography with patient-measured breathing

    NASA Astrophysics Data System (ADS)

    Cooper, Benjamin J.; O'Brien, Ricky T.; Kipritidis, John; Shieh, Chun-Chien; Keall, Paul J.

    2015-12-01

    Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient’s respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations. Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique. A set containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 pairs of RT 4D CBCT and conventional 4D CBCT image sets from realistic simulations of a 4D CBCT system using a Rando phantom and the digital phantom, XCAT. Each of these image sets were compared to a ground truth dataset from which a mean absolute pixel difference (MAPD) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation was counted and was assumed as a surrogate for imaging dose. Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT, the average image quality was reduced by 7.6% (Rando study) and 11.1% (XCAT study). However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). The simulation studies have demonstrated that the RT 4D CBCT method can potentially offer a 53% saving in imaging dose on average compared to conventional 4D CBCT in simulation studies using a wide range of patient-measured breathing traces with a minimal impact on image quality.

  9. SU-E-J-183: Quantifying the Image Quality and Dose Reduction of Respiratory Triggered 4D Cone-Beam Computed Tomography with Patient- Measured Breathing

    SciTech Connect

    Cooper, B; OBrien, R; Kipritidis, J; Keall, P

    2014-06-01

    Purpose: Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient's respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations instead of synthetic sinusoidal signals used in previous work. Methods: Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique from a database of oversampled Rando phantom CBCT projections. A database containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 RT 4D CBCT and 111 conventional 4D CBCT image datasets from realistic simulations of a 4D RT CBCT system. Each of these image datasets were compared to a ground truth dataset from which a root mean square error (RMSE) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation is counted and was assumed as a surrogate for imaging dose. Results: Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT the average image quality was reduced by 7.6%. However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). Conclusion: The simulation studies using a wide range of patient breathing traces have demonstrated that the RT 4D CBCT method can potentially offer a substantial saving of imaging dose of 53% on average compared to conventional 4D CBCT in simulation studies with a minimal impact on image quality. A patent application (PCT/US2012/048693) has been filed which is related to this work.

  10. Analysis and dynamic 3D visualization of cerebral blood flow combining 3D and 4D MR image sequences

    NASA Astrophysics Data System (ADS)

    Forkert, Nils Daniel; Säring, Dennis; Fiehler, Jens; Illies, Till; Möller, Dietmar; Handels, Heinz

    2009-02-01

    In this paper we present a method for the dynamic visualization of cerebral blood flow. Spatio-temporal 4D magnetic resonance angiography (MRA) image datasets and 3D MRA datasets with high spatial resolution were acquired for the analysis of arteriovenous malformations (AVMs). One of the main tasks is the combination of the information of the 3D and 4D MRA image sequences. Initially, in the 3D MRA dataset the vessel system is segmented and a 3D surface model is generated. Then, temporal intensity curves are analyzed voxelwise in the 4D MRA image sequences. A curve fitting of the temporal intensity curves to a patient individual reference curve is used to extract the bolus arrival times in the 4D MRA sequences. After non-linear registration of both MRA datasets the extracted hemodynamic information is transferred to the surface model where the time points of inflow can be visualized color coded dynamically over time. The dynamic visualizations computed using the curve fitting method for the estimation of the bolus arrival times were rated superior compared to those computed using conventional approaches for bolus arrival time estimation. In summary the procedure suggested allows a dynamic visualization of the individual hemodynamic situation and better understanding during the visual evaluation of cerebral vascular diseases.

  11. Quantifying hypoxia in human cancers using static PET imaging.

    PubMed

    Taylor, Edward; Yeung, Ivan; Keller, Harald; Wouters, Bradley G; Milosevic, Michael; Hedley, David W; Jaffray, David A

    2016-11-21

    Compared to FDG, the signal of (18)F-labelled hypoxia-sensitive tracers in tumours is low. This means that in addition to the presence of hypoxic cells, transport properties contribute significantly to the uptake signal in static PET images. This sensitivity to transport must be minimized in order for static PET to provide a reliable standard for hypoxia quantification. A dynamic compartmental model based on a reaction-diffusion formalism was developed to interpret tracer pharmacokinetics and applied to static images of FAZA in twenty patients with pancreatic cancer. We use our model to identify tumour properties-well-perfused without substantial necrosis or partitioning-for which static PET images can reliably quantify hypoxia. Normalizing the measured activity in a tumour voxel by the value in blood leads to a reduction in the sensitivity to variations in 'inter-corporal' transport properties-blood volume and clearance rate-as well as imaging study protocols. Normalization thus enhances the correlation between static PET images and the FAZA binding rate K 3, a quantity which quantifies hypoxia in a biologically significant way. The ratio of FAZA uptake in spinal muscle and blood can vary substantially across patients due to long muscle equilibration times. Normalized static PET images of hypoxia-sensitive tracers can reliably quantify hypoxia for homogeneously well-perfused tumours with minimal tissue partitioning. The ideal normalizing reference tissue is blood, either drawn from the patient before PET scanning or imaged using PET. If blood is not available, uniform, homogeneously well-perfused muscle can be used. For tumours that are not homogeneously well-perfused or for which partitioning is significant, only an analysis of dynamic PET scans can reliably quantify hypoxia.

  12. Quantifying hypoxia in human cancers using static PET imaging

    NASA Astrophysics Data System (ADS)

    Taylor, Edward; Yeung, Ivan; Keller, Harald; Wouters, Bradley G.; Milosevic, Michael; Hedley, David W.; Jaffray, David A.

    2016-11-01

    Compared to FDG, the signal of 18F-labelled hypoxia-sensitive tracers in tumours is low. This means that in addition to the presence of hypoxic cells, transport properties contribute significantly to the uptake signal in static PET images. This sensitivity to transport must be minimized in order for static PET to provide a reliable standard for hypoxia quantification. A dynamic compartmental model based on a reaction-diffusion formalism was developed to interpret tracer pharmacokinetics and applied to static images of FAZA in twenty patients with pancreatic cancer. We use our model to identify tumour properties—well-perfused without substantial necrosis or partitioning—for which static PET images can reliably quantify hypoxia. Normalizing the measured activity in a tumour voxel by the value in blood leads to a reduction in the sensitivity to variations in ‘inter-corporal’ transport properties—blood volume and clearance rate—as well as imaging study protocols. Normalization thus enhances the correlation between static PET images and the FAZA binding rate K 3, a quantity which quantifies hypoxia in a biologically significant way. The ratio of FAZA uptake in spinal muscle and blood can vary substantially across patients due to long muscle equilibration times. Normalized static PET images of hypoxia-sensitive tracers can reliably quantify hypoxia for homogeneously well-perfused tumours with minimal tissue partitioning. The ideal normalizing reference tissue is blood, either drawn from the patient before PET scanning or imaged using PET. If blood is not available, uniform, homogeneously well-perfused muscle can be used. For tumours that are not homogeneously well-perfused or for which partitioning is significant, only an analysis of dynamic PET scans can reliably quantify hypoxia.

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

    SciTech Connect

    Kida, S; Bal, M; Kabus, S; Loo, B; Keall, P; Yamamoto, T

    2014-06-15

    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 (a 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

  14. Counting Rate Characteristics and Image Distortion in Preclinical PET Imaging During Radiopharmaceutical Therapy.

    PubMed

    Mellhammar, Emma; Dahlbom, Magnus; Axelsson, Johan; Strand, Sven-Erik

    2016-12-01

    PET may provide important information on the response during radiopharmaceutical therapy (RPT). Emission of radiation from the RPT radionuclide may disturb coincidence detection and impair image resolution. In this study, we tested the feasibility of performing intratherapeutic PET on 3 preclinical PET systems.

  15. Towards optimal imaging with PET: an in silico feasibility study.

    PubMed

    McNamara, A L; Toghyani, M; Gillam, J E; Wu, K; Kuncic, Z

    2014-12-21

    The efficacy of Positron Emission Tomography (PET) imaging relies fundamentally on the ability of the system to accurately identify true coincidence events. With existing systems, this is currently accomplished with an energy acceptance criterion followed by correction techniques to remove suspected false coincidence events. These corrections generally result in signal and contrast loss and thus limit the PET system's ability to achieve optimum image quality. A key property of annihilation radiation is that the photons are polarised with respect to each other. This polarisation correlation offers a potentially powerful discriminator, independent of energy, to accurately identify true events. In this proof of concept study, we investigate how photon polarisation information can be exploited in PET imaging by developing a method to discriminate true coincidences using the polarisation correlation of annihilation pairs. We implement this method using a Geant4 PET simulation of a GE Advance/Discovery LS system and demonstrate the potential advantages of the polarisation coincidence selection method over a standard energy criterion method. Current PET ring detectors are not capable of exploiting the polarisation correlation of the photon pairs. Compton PET systems, however are promising candidates for this application. We demonstrate the feasibility of a two-component Compton camera system in identifying true coincidences with Monte Carlo simulations. Our study demonstrates the potential of improving signal gain using polarisation, particularly for high photon emission rates. We also demonstrate the ability of the Compton camera at exploiting this polarisation correlation in PET.

  16. Towards optimal imaging with PET: an in silico feasibility study

    NASA Astrophysics Data System (ADS)

    McNamara, A. L.; Toghyani, M.; Gillam, J. E.; Wu, K.; Kuncic, Z.

    2014-12-01

    The efficacy of Positron Emission Tomography (PET) imaging relies fundamentally on the ability of the system to accurately identify true coincidence events. With existing systems, this is currently accomplished with an energy acceptance criterion followed by correction techniques to remove suspected false coincidence events. These corrections generally result in signal and contrast loss and thus limit the PET system’s ability to achieve optimum image quality. A key property of annihilation radiation is that the photons are polarised with respect to each other. This polarisation correlation offers a potentially powerful discriminator, independent of energy, to accurately identify true events. In this proof of concept study, we investigate how photon polarisation information can be exploited in PET imaging by developing a method to discriminate true coincidences using the polarisation correlation of annihilation pairs. We implement this method using a Geant4 PET simulation of a GE Advance/Discovery LS system and demonstrate the potential advantages of the polarisation coincidence selection method over a standard energy criterion method. Current PET ring detectors are not capable of exploiting the polarisation correlation of the photon pairs. Compton PET systems, however are promising candidates for this application. We demonstrate the feasibility of a two-component Compton camera system in identifying true coincidences with Monte Carlo simulations. Our study demonstrates the potential of improving signal gain using polarisation, particularly for high photon emission rates. We also demonstrate the ability of the Compton camera at exploiting this polarisation correlation in PET.

  17. Applying an animal model to quantify the uncertainties of an image-based 4D-CT algorithm

    NASA Astrophysics Data System (ADS)

    Pierce, Greg; Wang, Kevin; Battista, Jerry; Lee, Ting-Yim

    2012-06-01

    The purpose of this paper is to use an animal model to quantify the spatial displacement uncertainties and test the fundamental assumptions of an image-based 4D-CT algorithm in vivo. Six female Landrace cross pigs were ventilated and imaged using a 64-slice CT scanner (GE Healthcare) operating in axial cine mode. The breathing amplitude pattern of the pigs was varied by periodically crimping the ventilator gas return tube during the image acquisition. The image data were used to determine the displacement uncertainties that result from matching CT images at the same respiratory phase using normalized cross correlation (NCC) as the matching criteria. Additionally, the ability to match the respiratory phase of a 4.0 cm subvolume of the thorax to a reference subvolume using only a single overlapping 2D slice from the two subvolumes was tested by varying the location of the overlapping matching image within the subvolume and examining the effect this had on the displacement relative to the reference volume. The displacement uncertainty resulting from matching two respiratory images using NCC ranged from 0.54 ± 0.10 mm per match to 0.32 ± 0.16 mm per match in the lung of the animal. The uncertainty was found to propagate in quadrature, increasing with number of NCC matches performed. In comparison, the minimum displacement achievable if two respiratory images were matched perfectly in phase ranged from 0.77 ± 0.06 to 0.93 ± 0.06 mm in the lung. The assumption that subvolumes from separate cine scan could be matched by matching a single overlapping 2D image between to subvolumes was validated. An in vivo animal model was developed to test an image-based 4D-CT algorithm. The uncertainties associated with using NCC to match the respiratory phase of two images were quantified and the assumption that a 4.0 cm 3D subvolume can by matched in respiratory phase by matching a single 2D image from the 3D subvolume was validated. The work in this paper shows the image-based 4D

  18. Simultaneous MRI and PET imaging of a rat brain

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan K.; Sendhil Velan, S.; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Zorn, Carl; Marano, Gary D.

    2006-12-01

    Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI will allow the correlation of form with function. Our group is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode. Each MRI-PET detector module consists of an array of LSO detector elements coupled through a long fibre optic light guide to a single Hamamatsu flat panel position-sensitive photomultiplier tube (PSPMT). The use of light guides allows the PSPMTs to be positioned outside the bore of a 3T MRI scanner where the magnetic field is relatively small. To test the device, simultaneous MRI and PET images of the brain of a male Sprague Dawley rat injected with FDG were successfully obtained. The images revealed no noticeable artefacts in either image set. Future work includes the construction of a full ring PET scanner, improved light guides and construction of a specialized MRI coil to permit higher quality MRI imaging.

  19. FDG PET Imaging in Pneumocystis Pneumonia.

    PubMed

    Kono, Masanori; Yamashita, Hiroyuki; Kubota, Kazuo; Kano, Toshikazu; Mimori, Akio

    2015-08-01

    A 69-year-old woman with rheumatoid arthritis and pleuritis presented with dyspnea. On admission, she was afebrile and had an oxygen saturation of 97% on ambient air. Chest radiography and CT revealed only subtle ground-glass opacities. However, FDG PET revealed pathological uptake in both lungs. A diagnosis of Pneumocystis pneumonia was made based on a positive β-D-glucan assay and polymerase chain reaction amplification of Pneumocystis jirovecii from the sputum. Posttreatment FDG PET revealed resolution of the previously noted uptake. This case illustrates that FDG PET can be used to diagnose Pneumocystis pneumonia when the CT findings are equivocal.

  20. SU-E-T-428: Feasibility Study of 4D Image Reconstruction by Organ Motion Vector Extension Based On Portal Images

    SciTech Connect

    Yoon, J; Jung, J; Yeo, I; Kim, J; Yi, B

    2015-06-15

    Purpose: To develop and to test a method to generate a new 4D CT images of the treatment day from the old 4D CT and the portal images of the day when the motion extent exceeded from that represented by plan CTs. Methods: A motion vector of a moving tumor in a patient may be extended to reconstruct the tumor position when the motion extent exceeded from that represented by plan CTs. To test this, 1. a phantom that consists of a polystyrene cylinder (tumor) embedded in cork (lung) was placed on a moving platform with 4 sec/cycle and amplitudes of 1 cm and 2 cm, and was 4D-scanned. 2. A 6MV photon beam was irradiated on the moving phantoms and cineEPID images were obtained. 3. A motion vector of the tumor was acquired from 4D CT images of the phantom with 1 cm amplitude. 4. From cine EPID images of the phantom with the 2 cm amplitude, various motion extents (0.3 cm, 0.5 cm, etc) were acquired and programmed into the motion vector, producing CT images at each position. 5. The reconstructed CT images were then compared with pre-acquired “reference” 4D CT images at each position (i.e. phase). Results: The CT image was reconstructed and compared with the reference image, showing a slight mismatch in the transition direction limited by voxel size (slice thickness) in CT image. Due to the rigid nature of the phantom studied, the modeling the displacement of the center of object was sufficient. When deformable tumors are to be modeled, more complex scheme is necessary, which utilize cine EPID and 4D CT images. Conclusion: The new idea of CT image reconstruction was demonstrated. Deformable tumor movements need to be considered in the future.

  1. Evaluation of a silicon photomultiplier PET insert for simultaneous PET and MR imaging

    SciTech Connect

    Ko, Guen Bae; Kim, Kyeong Yun; Yoon, Hyun Suk; Son, Jeong-Whan; Lee, Min Sun; Im, Hyung-Jun; Lee, Jae Sung

    2016-01-15

    Purpose: In this study, the authors present a silicon photomultiplier (SiPM)-based positron emission tomography (PET) insert dedicated to small animal imaging with high system performance and robustness to temperature change. Methods: The insert consists of 64 LYSO-SiPM detector blocks arranged in 4 rings of 16 detector blocks to yield a ring diameter of 64 mm and axial field of view of 55 mm. Each detector block consists of a 9 × 9 array of LYSO crystals (1.2 × 1.2 × 10 mm{sup 3}) and a monolithic 4 × 4 SiPM array. The temperature of each monolithic SiPM is monitored, and the proper bias voltage is applied according to the temperature reading in real time to maintain uniform performance. The performance of this PET insert was characterized using National Electrical Manufacturers Association NU 4-2008 standards, and its feasibility was evaluated through in vivo mouse imaging studies. Results: The PET insert had a peak sensitivity of 3.4% and volumetric spatial resolutions of 1.92 (filtered back projection) and 0.53 (ordered subset expectation maximization) mm{sup 3} at center. The peak noise equivalent count rate and scatter fraction were 42.4 kcps at 15.08 MBq and 16.5%, respectively. By applying the real-time bias voltage adjustment, an energy resolution of 14.2% ± 0.3% was maintained and the count rate varied ≤1.2%, despite severe temperature changes (10–30 °C). The mouse imaging studies demonstrate that this PET insert can produce high-quality images useful for imaging studies on the small animals. Conclusions: The developed MR-compatible PET insert is designed for insertion into a narrow-bore magnetic resonance imaging scanner, and it provides excellent imaging performance for PET/MR preclinical studies.

  2. Dual PET and Near-Infrared Fluorescence Imaging Probes as Tools for Imaging in Oncology

    PubMed Central

    An, Fei-Fei; Chan, Mark; Kommidi, Harikrishna; Ting, Richard

    2016-01-01

    OBJECTIVE The purpose of this article is to summarize advances in PET fluorescence resolution, agent design, and preclinical imaging that make a growing case for clinical PET fluorescence imaging. CONCLUSION Existing SPECT, PET, fluorescence, and MRI contrast imaging techniques are already deeply integrated into the management of cancer, from initial diagnosis to the observation and management of metastases. Combined positron-emitting fluorescent contrast agents can convey new or substantial benefits that improve on these proven clinical contrast agents. PMID:27223168

  3. [Spatio-temporal image correlation (STIC) and tomographic ultrasound imaging (TUI)--combined clinical implementation in 3D/4D fetal echocardiography].

    PubMed

    Markov, D

    2010-01-01

    Two new forms of volume data image processing by three (3D) and four (4D) dimensional ultrasound named Spatio-Temporal Image Correlation (STIC) and Tomographic Ultrasound Imaging (TUI) are presented. The advantages and disadvantages of the combined clinical implementation of both modalities in fetal echocardiography are discussed.

  4. Thresholding in PET images of static and moving targets

    NASA Astrophysics Data System (ADS)

    Yaremko, Brian; Riauka, Terence; Robinson, Don; Murray, Brad; Alexander, Abraham; McEwan, Alexander; Roa, Wilson

    2005-12-01

    Continued therapeutic gain in the treatment of non-small-cell lung cancer (NSCLC) will depend upon our ability to escalate the dose to the primary tumour while minimizing normal tissue toxicity. Both these objectives are facilitated by the accurate definition of a target volume that is as small as possible. To this end, both tumour immobilizations via deep inspiratory breath-hold, along with positron emission tomography (PET), have emerged as two promising approaches. Though PET is an excellent means of defining the general location of a tumour focus, its ability to define exactly the geometric extent of such a focus strongly depends upon selection of an appropriate image threshold. However, in clinical practice, the image threshold is typically not chosen according to consistent, well-established criteria. This study explores the relationship between image threshold and the resultant PET-defined volume using a series of F-18 radiotracer-filled hollow spheres of known internal volumes, both static and under oscillatory motion. The effects of both image threshold and tumour motion on the resultant PET image are examined. Imaging data are further collected from a series of simulated gated PET acquisitions in order to test the feasibility of a patient-controlled gating mechanism during deep inspiratory breath-hold. This study illustrates quantitatively considerable variability in resultant PET-defined tumour volumes depending upon numerous factors, including image threshold, size of the lesion, the presence of tumour motion and the scanning protocol. In this regard, when using PET in treatment planning for NSCLC, the radiation oncologist must select the image threshold very carefully to avoid either under-dosing the tumour or overdosing normal tissues.

  5. Real-time dynamic display of registered 4D cardiac MR and ultrasound images using a GPU

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Huang, X.; Eagleson, R.; Guiraudon, G.; Peters, T. M.

    2007-03-01

    In minimally invasive image-guided surgical interventions, different imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), and real-time three-dimensional (3D) ultrasound (US), can provide complementary, multi-spectral image information. Multimodality dynamic image registration is a well-established approach that permits real-time diagnostic information to be enhanced by placing lower-quality real-time images within a high quality anatomical context. For the guidance of cardiac procedures, it would be valuable to register dynamic MRI or CT with intraoperative US. However, in practice, either the high computational cost prohibits such real-time visualization of volumetric multimodal images in a real-world medical environment, or else the resulting image quality is not satisfactory for accurate guidance during the intervention. Modern graphics processing units (GPUs) provide the programmability, parallelism and increased computational precision to begin to address this problem. In this work, we first outline our research on dynamic 3D cardiac MR and US image acquisition, real-time dual-modality registration and US tracking. Then we describe image processing and optimization techniques for 4D (3D + time) cardiac image real-time rendering. We also present our multimodality 4D medical image visualization engine, which directly runs on a GPU in real-time by exploiting the advantages of the graphics hardware. In addition, techniques such as multiple transfer functions for different imaging modalities, dynamic texture binding, advanced texture sampling and multimodality image compositing are employed to facilitate the real-time display and manipulation of the registered dual-modality dynamic 3D MR and US cardiac datasets.

  6. Prediction of standard-dose brain PET image by using MRI and low-dose brain [{sup 18}F]FDG PET images

    SciTech Connect

    Kang, Jiayin; Gao, Yaozong; Shi, Feng; Lalush, David S.; Lin, Weili; Shen, Dinggang

    2015-09-15

    Purpose: Positron emission tomography (PET) is a nuclear medical imaging technology that produces 3D images reflecting tissue metabolic activity in human body. PET has been widely used in various clinical applications, such as in diagnosis of brain disorders. High-quality PET images play an essential role in diagnosing brain diseases/disorders. In practice, in order to obtain high-quality PET images, a standard-dose radionuclide (tracer) needs to be used and injected into a living body. As a result, it will inevitably increase the patient’s exposure to radiation. One solution to solve this problem is predicting standard-dose PET images using low-dose PET images. As yet, no previous studies with this approach have been reported. Accordingly, in this paper, the authors propose a regression forest based framework for predicting a standard-dose brain [{sup 18}F]FDG PET image by using a low-dose brain [{sup 18}F]FDG PET image and its corresponding magnetic resonance imaging (MRI) image. Methods: The authors employ a regression forest for predicting the standard-dose brain [{sup 18}F]FDG PET image by low-dose brain [{sup 18}F]FDG PET and MRI images. Specifically, the proposed method consists of two main steps. First, based on the segmented brain tissues (i.e., cerebrospinal fluid, gray matter, and white matter) in the MRI image, the authors extract features for each patch in the brain image from both low-dose PET and MRI images to build tissue-specific models that can be used to initially predict standard-dose brain [{sup 18}F]FDG PET images. Second, an iterative refinement strategy, via estimating the predicted image difference, is used to further improve the prediction accuracy. Results: The authors evaluated their algorithm on a brain dataset, consisting of 11 subjects with MRI, low-dose PET, and standard-dose PET images, using leave-one-out cross-validations. The proposed algorithm gives promising results with well-estimated standard-dose brain [{sup 18}F]FDG PET

  7. Contrast Media in PET/Computed Tomography Imaging.

    PubMed

    Dhull, Varun Singh; Rana, Neelima; Nazar, Aftab Hasan

    2016-01-01

    Is there a need for the contrast-enhanced PET/computed tomography (CT) scan or is the low-dose, non-contrast-enhanced PET/CT scan sufficient? The topic has been debated time and again. Although low-dose noncontrast CT serves the purpose of simple anatomic correlation and attenuation correction of PET images, many times patients have to undergo additional contrast-enhanced diagnostic imaging modalities, which may lead to a delay in decision-making. In this review, the authors have addressed various such issues related to the use of contrast agents and special techniques of clinical interest based on their utility in dual-modality PET/CT.

  8. Tau Positron Emission Tomography (PET) Imaging: Past, Present, and Future.

    PubMed

    Ariza, Manuela; Kolb, Hartmuth C; Moechars, Dieder; Rombouts, Frederik; Andrés, José Ignacio

    2015-06-11

    Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the most common cause of dementia among the elderly population. The good correlation of the density and neocortical spread of neurofibrillary tangles (NFTs) with clinical AD disease progression offers an opportunity for the early diagnosis and staging using a noninvasive imaging technique such as positron emission tomography (PET). Thus, PET imaging of NFTs not only holds promise as a diagnostic tool but also may enable the development of disease modifying therapeutics for AD. In this review, we focus on the structural diversity of tau PET tracers, the challenges related to the identification of high affinity and highly selective NFT ligands, and recent progress in the clinical development of tau PET radioligands.

  9. Super-Resolution Reconstruction of Diffusion-Weighted Images using 4D Low-Rank and Total Variation

    PubMed Central

    Shi, Feng; Cheng, Jian; Wang, Li; Yap, Pew-Thian; Shen, Dinggang

    2016-01-01

    Diffusion-weighted imaging (DWI) provides invaluable information in white matter microstructure and is widely applied in neurological applications. However, DWI is largely limited by its relatively low spatial resolution. In this paper, we propose an image post-processing method, referred to as super-resolution reconstruction, to estimate a high spatial resolution DWI from the input low-resolution DWI, e.g., at a factor of 2. Instead of requiring specially designed DWI acquisition of multiple shifted or orthogonal scans, our method needs only a single DWI scan. To do that, we propose to model both the blurring and downsampling effects in the image degradation process where the low-resolution image is observed from the latent high-resolution image, and recover the latent high-resolution image with the help of two regularizations. The first regularization is 4-dimensional (4D) low-rank, proposed to gather self-similarity information from both the spatial domain and the diffusion domain of 4D DWI. The second regularization is total variation, proposed to depress noise and preserve local structures such as edges in the image recovery process. Extensive experiments were performed on 20 subjects, and results show that the proposed method is able to recover the fine details of white matter structures, and outperform other approaches such as interpolation methods, non-local means based upsampling, and total variation based upsampling. PMID:27845833

  10. SU-E-J-02: 4D Digital Tomosynthesis Based On Algebraic Image Reconstruction and Total-Variation Minimization for the Improvement of Image Quality

    SciTech Connect

    Kim, D; Kang, S; Kim, T; Suh, T; Kim, S

    2014-06-01

    Purpose: In this paper, we implemented the four-dimensional (4D) digital tomosynthesis (DTS) imaging based on algebraic image reconstruction technique and total-variation minimization method in order to compensate the undersampled projection data and improve the image quality. Methods: The projection data were acquired as supposed the cone-beam computed tomography system in linear accelerator by the Monte Carlo simulation and the in-house 4D digital phantom generation program. We performed 4D DTS based upon simultaneous algebraic reconstruction technique (SART) among the iterative image reconstruction technique and total-variation minimization method (TVMM). To verify the effectiveness of this reconstruction algorithm, we performed systematic simulation studies to investigate the imaging performance. Results: The 4D DTS algorithm based upon the SART and TVMM seems to give better results than that based upon the existing method, or filtered-backprojection. Conclusion: The advanced image reconstruction algorithm for the 4D DTS would be useful to validate each intra-fraction motion during radiation therapy. In addition, it will be possible to give advantage to real-time imaging for the adaptive radiation therapy. This research was supported by Leading Foreign Research Institute Recruitment Program (Grant No.2009-00420) and Basic Atomic Energy Research Institute (BAERI); (Grant No. 2009-0078390) through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT and Future Planning (MSIP)

  11. 3.5D dynamic PET image reconstruction incorporating kinetics-based clusters

    PubMed Central

    Lu, Lijun; Karakatsanis, Nicolas A.; Tang, Jing; Chen, Wufan; Rahmim, Arman

    2012-01-01

    Standard 3D dynamic PET imaging consists of independent image reconstructions of individual frames followed by application of appropriate kinetic model to the time activity curves (TACs) at the voxel or region-of-interest. The emerging field of 4D PET reconstruction, by contrast, seeks to move beyond this scheme and incorporate information from multiple frames within the image reconstruction task. Here we propose a novel reconstruction framework aiming to enhance quantitative accuracy of parametric images via introduction of priors based on voxel kinetics, as generated via clustering of preliminary reconstructed dynamic images to define clustered neighborhoods of voxels with similar kinetics. This is then followed by straightforward maximum a posterior (MAP) 3D PET reconstruction as applied to individual frames; and as such the method is labeled “3.5D” image reconstruction. The use of cluster-based priors has the advantage of further enhancing quantitative performance in dynamic PET imaging, because: (a) there are typically more voxels in clusters than in conventional local neighborhoods, and (b) neighboring voxels with distinct kinetics are less likely to be clustered together. Using realistic simulated 11C-raclopride dynamic PET data, the quantitative performance of the proposed method was investigated. Parametric distribution-volume (DV) and DV ratio (DVR) images were estimated from dynamic image reconstructions using (a) MLEM, and MAP reconstructions using (b) the quadratic prior (QP-MAP), (c) the Green prior (GP-MAP) and (d, e) two proposed cluster-based priors (CP-U-MAP and CP-W-MAP), followed by graphical modeling, and were qualitatively and quantitatively compared for 11 regions-of-interest (ROIs). Overall, the proposed dynamic PET reconstruction methodology resulted in substantial visual as well as quantitative accuracy improvements (in terms of noise vs. bias performance) for parametric DV and DVR images. The method was also tested on a 90 min 11C

  12. SU-E-J-157: Improving the Quality of T2-Weighted 4D Magnetic Resonance Imaging for Clinical Evaluation

    SciTech Connect

    Du, D; Mutic, S; Hu, Y; Caruthers, S; Glide-Hurst, C; Low, D

    2014-06-01

    Purpose: To develop an imaging technique that enables us to acquire T2- weighted 4D Magnetic Resonance Imaging (4DMRI) with sufficient spatial coverage, temporal resolution and spatial resolution for clinical evaluation. Methods: T2-weighed 4DMRI images were acquired from a healthy volunteer using a respiratory amplitude triggered T2-weighted Turbo Spin Echo sequence. 10 respiratory states were used to equally sample the respiratory range based on amplitude (0%, 20%i, 40%i, 60%i, 80%i, 100%, 80%e, 60%e, 40%e and 20%e). To avoid frequent scanning halts, a methodology was devised that split 10 respiratory states into two packages in an interleaved manner and packages were acquired separately. Sixty 3mm sagittal slices at 1.5mm in-plane spatial resolution were acquired to offer good spatial coverage and reasonable spatial resolution. The in-plane field of view was 375mm × 260mm with nominal scan time of 3 minutes 42 seconds. Acquired 2D images at the same respiratory state were combined to form the 3D image set corresponding to that respiratory state and reconstructed in the coronal view to evaluate whether all slices were at the same respiratory state. 3D image sets of 10 respiratory states represented a complete 4D MRI image set. Results: T2-weighted 4DMRI image were acquired in 10 minutes which was within clinical acceptable range. Qualitatively, the acquired MRI images had good image quality for delineation purposes. There were no abrupt position changes in reconstructed coronal images which confirmed that all sagittal slices were in the same respiratory state. Conclusion: We demonstrated it was feasible to acquire T2-weighted 4DMRI image set within a practical amount of time (10 minutes) that had good temporal resolution (10 respiratory states), spatial resolution (1.5mm × 1.5mm × 3.0mm) and spatial coverage (60 slices) for future clinical evaluation.

  13. MO-G-BRF-01: BEST IN PHYSICS (JOINT IMAGING-THERAPY) - Sensitivity of PET-Based Texture Features to Respiratory Motion in Non-Small Cell Lung Cancer (NSCLC)

    SciTech Connect

    Yip, S; Aerts, H; Berbeco, R; McCall, K; Aristophanous, M; Chen, A

    2014-06-15

    Purpose: PET-based texture features are used to quantify tumor heterogeneity due to their predictive power in treatment outcome. We investigated the sensitivity of texture features to tumor motion by comparing whole body (3D) and respiratory-gated (4D) PET imaging. Methods: Twenty-six patients (34 lesions) received 3D and 4D [F-18]FDG-PET scans before chemo-radiotherapy. The acquired 4D data were retrospectively binned into five breathing phases to create the 4D image sequence. Four texture features (Coarseness, Contrast, Busyness, and Complexity) were computed within the the physician-defined tumor volume. The relative difference (δ) in each measure between the 3D- and 4D-PET imaging was calculated. Wilcoxon signed-rank test (p<0.01) was used to determine if δ was significantly different from zero. Coefficient of variation (CV) was used to determine the variability in the texture features between all 4D-PET phases. Pearson correlation coefficient was used to investigate the impact of tumor size and motion amplitude on δ. Results: Significant differences (p<<0.01) between 3D and 4D imaging were found for Coarseness, Busyness, and Complexity. The difference for Contrast was not significant (p>0.24). 4D-PET increased Busyness (∼20%) and Complexity (∼20%), and decreased Coarseness (∼10%) and Contrast (∼5%) compared to 3D-PET. Nearly negligible variability (CV=3.9%) was found between the 4D phase bins for Coarseness and Complexity. Moderate variability was found for Contrast and Busyness (CV∼10%). Poor correlation was found between the tumor volume and δ for the texture features (R=−0.34−0.34). Motion amplitude had moderate impact on δ for Contrast and Busyness (R=−0.64− 0.54) and no impact for Coarseness and Complexity (R=−0.29−0.17). Conclusion: Substantial differences in textures were found between 3D and 4D-PET imaging. Moreover, the variability between phase bins for Coarseness and Complexity was negligible, suggesting that similar

  14. Compact and mobile high resolution PET brain imager

    DOEpatents

    Majewski, Stanislaw [Yorktown, VA; Proffitt, James [Newport News, VA

    2011-02-08

    A brain imager includes a compact ring-like static PET imager mounted in a helmet-like structure. When attached to a patient's head, the helmet-like brain imager maintains the relative head-to-imager geometry fixed through the whole imaging procedure. The brain imaging helmet contains radiation sensors and minimal front-end electronics. A flexible mechanical suspension/harness system supports the weight of the helmet thereby allowing for patient to have limited movements of the head during imaging scans. The compact ring-like PET imager enables very high resolution imaging of neurological brain functions, cancer, and effects of trauma using a rather simple mobile scanner with limited space needs for use and storage.

  15. Fusion of PET and MRI for Hybrid Imaging

    NASA Astrophysics Data System (ADS)

    Cho, Zang-Hee; Son, Young-Don; Kim, Young-Bo; Yoo, Seung-Schik

    Recently, the development of the fusion PET-MRI system has been actively studied to meet the increasing demand for integrated molecular and anatomical imaging. MRI can provide detailed anatomical information on the brain, such as the locations of gray and white matter, blood vessels, axonal tracts with high resolution, while PET can measure molecular and genetic information, such as glucose metabolism, neurotransmitter-neuroreceptor binding and affinity, protein-protein interactions, and gene trafficking among biological tissues. State-of-the-art MRI systems, such as the 7.0 T whole-body MRI, now can visualize super-fine structures including neuronal bundles in the pons, fine blood vessels (such as lenticulostriate arteries) without invasive contrast agents, in vivo hippocampal substructures, and substantia nigra with excellent image contrast. High-resolution PET, known as High-Resolution Research Tomograph (HRRT), is a brain-dedicated system capable of imaging minute changes of chemicals, such as neurotransmitters and -receptors, with high spatial resolution and sensitivity. The synergistic power of the two, i.e., ultra high-resolution anatomical information offered by a 7.0 T MRI system combined with the high-sensitivity molecular information offered by HRRT-PET, will significantly elevate the level of our current understanding of the human brain, one of the most delicate, complex, and mysterious biological organs. This chapter introduces MRI, PET, and PET-MRI fusion system, and its algorithms are discussed in detail.

  16. Pixel-feature hybrid fusion for PET/CT images.

    PubMed

    Zhu, Yang-Ming; Nortmann, Charles A

    2011-02-01

    Color blending is a popular display method for functional and anatomic image fusion. The underlay image is typically displayed in grayscale, and the overlay image is displayed in pseudo colors. This pixel-level fusion provides too much information for reviewers to analyze quickly and effectively and clutters the display. To improve the fusion image reviewing speed and reduce the information clutter, a pixel-feature hybrid fusion method is proposed and tested for PET/CT images. Segments of the colormap are selectively masked to have a few discrete colors, and pixels displayed in the masked colors are made transparent. The colormap thus creates a false contouring effect on overlay images and allows the underlay to show through to give contours an anatomic context. The PET standardized uptake value (SUV) is used to control where colormap segments are masked. Examples show that SUV features can be extracted and blended with CT image instantaneously for viewing and diagnosis, and the non-feature part of the PET image is transparent. The proposed pixel-feature hybrid fusion highlights PET SUV features on CT images and reduces display clutters. It is easy to implement and can be used as complementarily to existing pixel-level fusion methods.

  17. Development and Application of a Suite of 4-D Virtual Breast Phantoms for Optimization and Evaluation of Breast Imaging Systems

    PubMed Central

    Lin, Yuan; Ikejimba, Lynda C.; Ghate, Sujata V.; Dobbins, James T.; Segars, William P.

    2014-01-01

    Mammography is currently the most widely utilized tool for detection and diagnosis of breast cancer. However, in women with dense breast tissue, tissue overlap may obscure lesions. Digital breast tomosynthesis can reduce tissue overlap. Furthermore, imaging with contrast enhancement can provide additional functional information about lesions, such as morphology and kinetics, which in turn may improve lesion identification and characterization. The performance of these imaging techniques is strongly dependent on the structural composition of the breast, which varies significantly among patients. Therefore, imaging system and imaging technique optimization should take patient variability into consideration. Furthermore, optimization of imaging techniques that employ contrast agents should include the temporally varying breast composition with respect to the contrast agent uptake kinetics. To these ends, we have developed a suite of 4-D virtual breast phantoms, which are incorporated with the kinetics of contrast agent propagation in different tissues and can realistically model normal breast parenchyma as well as benign and malignant lesions. This development presents a new approach in performing simulation studies using truly anthropomorphic models. To demonstrate the utility of the proposed 4-D phantoms, we present a simplified example study to compare the performance of 14 imaging paradigms qualitatively and quantitatively. PMID:24691118

  18. Toward time resolved 4D cardiac CT imaging with patient dose reduction: estimating the global heart motion

    NASA Astrophysics Data System (ADS)

    Taguchi, Katsuyuki; Segars, W. Paul; Fung, George S. K.; Tsui, Benjamin M. W.

    2006-03-01

    Coronary artery imaging with multi-slice helical computed tomography is a promising noninvasive imaging technique. The current major issues include the insufficient temporal resolution and large patient dose. We propose an image reconstruction method which provides a solution to both of the problems. The method uses an iterative approach repeating the following four steps until the difference between the two projection data sets falls below a certain criteria in step-4: 1) estimating or updating the cardiac motion vectors, 2) reconstructing the time-resolved 4D dynamic volume images using the motion vectors, 3) calculating the projection data from the current 4D images, 4) comparing them with the measured ones. In this study, we obtain the first estimate of the motion vector. We use the 4D NCAT phantom, a realistic computer model for the human anatomy and cardiac motions, to generate the dynamic fan-beam projection data sets as well to provide a known truth for the motion. Then, the halfscan reconstruction with the sliding time-window technique is used to generate cine images: f(t, r r). Here, we use one heart beat for each position r so that the time information is retained. Next, the magnitude of the first derivative of f(t, r r) with respect to time, i.e., |df/dt|, is calculated and summed over a region-of-interest (ROI), which is called the mean-absolute difference (MAD). The initial estimation of the vector field are obtained using MAD for each ROI. Results of the preliminary study are presented.

  19. On the accuracy of a mutual information algorithm for PET-MR image registration

    NASA Astrophysics Data System (ADS)

    Karaiskos, P.; Malamitsi, J.; Andreou, J.; Prassopoulos, V.; Valotassiou, V.; Laspas, F.; Sandilos, P.; Torrens, M.

    2009-07-01

    Image registration has been increasingly used in radiation diagnosis and treatment planning as a means of information integration from different imaging modalities (e.g. MRI, PET, CT). Especially for brain lesions, accurate 3D registration and fusion of MR and PET images can provide comprehensive information about the patient under study by relating functional information from PET images to the detailed anatomical information available in MR images. However, direct PET-MR image fusion in soft tissue is complicated mainly due to the lack of conspicuous anatomical features in PET images. This study describes the implementation and validation of a mutual information registration algorithm for this purpose. Ten patients with brain lesions underwent MR and PET/CT scanning. MR-PET registration was performed a) based on the well validated MR-CT registration technique and copying the transformation to the PET images derived from the PET/CT scan (MR/PET/CT registration method) and b) directly from the MR and PET images without taking into account the CT images (MR/PET registration method). In order to check the registration accuracy of the MR/PET method, the lesion (target) was contoured in the PET images and it was transferred to the MR images using both the above methods. The MR/PET/CT method served as the gold standard for target contouring. Target contours derived by the MR/PET method were compared with the gold standard target contours for each patient and the deviation between the two contours was used to estimate the accuracy of the PET-MR registration method. This deviation was less than 3 mm (i.e. comparable to the imaging voxel of the PET/CT scanning) for 9/10 of the cases studied. Results show that the mutual information algorithm used is able to perform the PET-MR registration reliably and accurately.

  20. PET/CT imaging in lung cancer: indications and findings*

    PubMed Central

    Hochhegger, Bruno; Alves, Giordano Rafael Tronco; Irion, Klaus Loureiro; Fritscher, Carlos Cezar; Fritscher, Leandro Genehr; Concatto, Natália Henz; Marchiori, Edson

    2015-01-01

    The use of PET/CT imaging in the work-up and management of patients with lung cancer has greatly increased in recent decades. The ability to combine functional and anatomical information has equipped PET/CT to look into various aspects of lung cancer, allowing more precise disease staging and providing useful data during the characterization of indeterminate pulmonary nodules. In addition, the accuracy of PET/CT has been shown to be greater than is that of conventional modalities in some scenarios, making PET/CT a valuable noninvasive method for the investigation of lung cancer. However, the interpretation of PET/CT findings presents numerous pitfalls and potential confounders. Therefore, it is imperative for pulmonologists and radiologists to familiarize themselves with the most relevant indications for and limitations of PET/CT, seeking to protect their patients from unnecessary radiation exposure and inappropriate treatment. This review article aimed to summarize the basic principles, indications, cancer staging considerations, and future applications related to the use of PET/CT in lung cancer. PMID:26176525

  1. 5D respiratory motion model based image reconstruction algorithm for 4D cone-beam computed tomography

    NASA Astrophysics Data System (ADS)

    Liu, Jiulong; Zhang, Xue; Zhang, Xiaoqun; Zhao, Hongkai; Gao, Yu; Thomas, David; Low, Daniel A.; Gao, Hao

    2015-11-01

    4D cone-beam computed tomography (4DCBCT) reconstructs a temporal sequence of CBCT images for the purpose of motion management or 4D treatment in radiotherapy. However the image reconstruction often involves the binning of projection data to each temporal phase, and therefore suffers from deteriorated image quality due to inaccurate or uneven binning in phase, e.g., under the non-periodic breathing. A 5D model has been developed as an accurate model of (periodic and non-periodic) respiratory motion. That is, given the measurements of breathing amplitude and its time derivative, the 5D model parametrizes the respiratory motion by three time-independent variables, i.e., one reference image and two vector fields. In this work we aim to develop a new 4DCBCT reconstruction method based on 5D model. Instead of reconstructing a temporal sequence of images after the projection binning, the new method reconstructs time-independent reference image and vector fields with no requirement of binning. The image reconstruction is formulated as a optimization problem with total-variation regularization on both reference image and vector fields, and the problem is solved by the proximal alternating minimization algorithm, during which the split Bregman method is used to reconstruct the reference image, and the Chambolle's duality-based algorithm is used to reconstruct the vector fields. The convergence analysis of the proposed algorithm is provided for this nonconvex problem. Validated by the simulation studies, the new method has significantly improved image reconstruction accuracy due to no binning and reduced number of unknowns via the use of the 5D model.

  2. 4-D photoacoustic tomography.

    PubMed

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy.

  3. 4-D Photoacoustic Tomography

    NASA Astrophysics Data System (ADS)

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy.

  4. Adaptive conductance filtering for spatially varying noise in PET images

    NASA Astrophysics Data System (ADS)

    Padfield, Dirk R.; Manjeshwar, Ravindra

    2006-03-01

    PET images that have been reconstructed with unregularized algorithms are commonly smoothed with linear Gaussian filters to control noise. Since these filters are spatially invariant, they degrade feature contrast in the image, compromising lesion detectability. Edge-preserving smoothing filters can differentially preserve edges and features while smoothing noise. These filters assume spatially uniform noise models. However, the noise in PET images is spatially variant, approximately following a Poisson behavior. Therefore, different regions of a PET image need smoothing by different amounts. In this work, we introduce an adaptive filter, based on anisotropic diffusion, designed specifically to overcome this problem. In this algorithm, the diffusion is varied according to a local estimate of the noise using either the local median or the grayscale image opening to weight the conductance parameter. The algorithm is thus tailored to the task of smoothing PET images, or any image with Poisson-like noise characteristics, by adapting itself to varying noise while preserving significant features in the image. This filter was compared with Gaussian smoothing and a representative anisotropic diffusion method using three quantitative task-relevant metrics calculated on simulated PET images with lesions in the lung and liver. The contrast gain and noise ratio metrics were used to measure the ability to do accurate quantitation; the Channelized Hotelling Observer lesion detectability index was used to quantify lesion detectability. The adaptive filter improved the signal-to-noise ratio by more than 45% and lesion detectability by more than 55% over the Gaussian filter while producing "natural" looking images and consistent image quality across different anatomical regions.

  5. The effect of different adaptation strengths on image quality and radiation dose using Siemens Care Dose 4D.

    PubMed

    Söderberg, Marcus; Gunnarsson, Mikael

    2010-01-01

    The purpose of this study was to evaluate the effect of different choices of adaptation strengths on image quality and radiation exposure to the patient with Siemens automatic exposure control system called CARE Dose 4D. An anthropomorphic chest phantom was used to simulate the patient and computed tomography scans were performed with a Siemens SOMATOM Sensation 16 and 64. Owing to adaptation strengths, a considerable reduction (26.6-51.5 % and 27.5-49.5 % for Sensation 16 and Sensation 64, respectively) in the radiation dose was found when compared with using a fixed tube current. There was a substantial difference in the image quality (image noise) between the adaptation strengths. Independent of selected adaptation strengths, the level of image noise throughout the chest phantom increased when CARE Dose 4D was used (p < 0.0001). We conclude that the adaptation strengths can be used to obtain user-specified modifications to image quality or radiation exposure to the patient.

  6. Adrenal masses of varied etiology: anatomical and molecular imaging features on PET-CT.

    PubMed

    Sharma, Punit; Singh, Harmandeep; Dhull, Varun Singh; Suman KC, Sudhir; Kumar, Abhishek; Bal, Chandrasekhar; Kumar, Rakesh

    2014-03-01

    A wide spectrum of benign and malignant diseases can present as an adrenal mass. Combined PET-CT is useful for evaluation of adrenocortical and adrenomedullary masses. F-FDG has been extensively used as PET radiotracer for this purpose. F-FDOPA PET, Ga-DOTA peptide (Ga-DOTANOC/TATE) PET, and C-HED PET have also been used for imaging of adrenal medullary lesions, whereas C-MTO PET has been used for adrenocortical imaging. We provide a review of imaging characteristics of adrenal gland pathologies on PET-CT using different tracers.

  7. 4D ultrafast ultrasound flow imaging: in vivo quantification of arterial volumetric flow rate in a single heartbeat

    NASA Astrophysics Data System (ADS)

    Correia, Mafalda; Provost, Jean; Tanter, Mickael; Pernot, Mathieu

    2016-12-01

    We present herein 4D ultrafast ultrasound flow imaging, a novel ultrasound-based volumetric imaging technique for the quantitative mapping of blood flow. Complete volumetric blood flow distribution imaging was achieved through 2D tilted plane-wave insonification, 2D multi-angle cross-beam beamforming, and 3D vector Doppler velocity components estimation by least-squares fitting. 4D ultrafast ultrasound flow imaging was performed in large volumetric fields of view at very high volume rate (>4000 volumes s-1) using a 1024-channel 4D ultrafast ultrasound scanner and a 2D matrix-array transducer. The precision of the technique was evaluated in vitro by using 3D velocity vector maps to estimate volumetric flow rates in a vessel phantom. Volumetric Flow rate errors of less than 5% were found when volumetric flow rates and peak velocities were respectively less than 360 ml min-1 and 100 cm s-1. The average volumetric flow rate error increased to 18.3% when volumetric flow rates and peak velocities were up to 490 ml min-1 and 1.3 m s-1, respectively. The in vivo feasibility of the technique was shown in the carotid arteries of two healthy volunteers. The 3D blood flow velocity distribution was assessed during one cardiac cycle in a full volume and it was used to quantify volumetric flow rates (375  ±  57 ml min-1 and 275  ±  43 ml min-1). Finally, the formation of 3D vortices at the carotid artery bifurcation was imaged at high volume rates.

  8. 4D ultrafast ultrasound flow imaging: in vivo quantification of arterial volumetric flow rate in a single heartbeat.

    PubMed

    Correia, Mafalda; Provost, Jean; Tanter, Mickael; Pernot, Mathieu

    2016-12-07

    We present herein 4D ultrafast ultrasound flow imaging, a novel ultrasound-based volumetric imaging technique for the quantitative mapping of blood flow. Complete volumetric blood flow distribution imaging was achieved through 2D tilted plane-wave insonification, 2D multi-angle cross-beam beamforming, and 3D vector Doppler velocity components estimation by least-squares fitting. 4D ultrafast ultrasound flow imaging was performed in large volumetric fields of view at very high volume rate (>4000 volumes s(-1)) using a 1024-channel 4D ultrafast ultrasound scanner and a 2D matrix-array transducer. The precision of the technique was evaluated in vitro by using 3D velocity vector maps to estimate volumetric flow rates in a vessel phantom. Volumetric Flow rate errors of less than 5% were found when volumetric flow rates and peak velocities were respectively less than 360 ml min(-1) and 100 cm s(-1). The average volumetric flow rate error increased to 18.3% when volumetric flow rates and peak velocities were up to 490 ml min(-1) and 1.3 m s(-1), respectively. The in vivo feasibility of the technique was shown in the carotid arteries of two healthy volunteers. The 3D blood flow velocity distribution was assessed during one cardiac cycle in a full volume and it was used to quantify volumetric flow rates (375  ±  57 ml min(-1) and 275  ±  43 ml min(-1)). Finally, the formation of 3D vortices at the carotid artery bifurcation was imaged at high volume rates.

  9. Diagnostic algorithm: how to make use of new 2D, 3D and 4D ultrasound technologies in breast imaging.

    PubMed

    Weismann, C F; Datz, L

    2007-11-01

    The aim of this publication is to present a time saving diagnostic algorithm consisting of two-dimensional (2D), three-dimensional (3D) and four-dimensional (4D) ultrasound (US) technologies. This algorithm of eight steps combines different imaging modalities and render modes which allow a step by step analysis of 2D, 3D and 4D diagnostic criteria. Advanced breast US systems with broadband high frequency linear transducers, full digital data management and high resolution are the actual basis for two-dimensional breast US studies in order to detect early breast cancer (step 1). The continuous developments of 2D US technologies including contrast resolution imaging (CRI) and speckle reduction imaging (SRI) have a direct influence on the high quality of three-dimensional and four-dimensional presentation of anatomical breast structures and pathological details. The diagnostic options provided by static 3D volume datasets according to US BI-RADS analogue assessment, concerning lesion shape, orientation, margin, echogenic rim sign, lesion echogenicity, acoustic transmission, associated calcifications, 3D criteria of the coronal plane, surrounding tissue composition (step 2) and lesion vascularity (step 6) are discussed. Static 3D datasets offer the combination of long axes distance measurements and volume calculations, which are the basis for an accurate follow-up in BI-RADS II and BI-RADS III lesions (step 3). Real time 4D volume contrast imaging (VCI) is able to demonstrate tissue elasticity (step 5). Glass body rendering is a static 3D tool which presents greyscale and colour information to study the vascularity and the vascular architecture of a lesion (step 6). Tomographic ultrasound imaging (TUI) is used for a slice by slice documentation in different investigation planes (A-,B- or C-plane) (steps 4 and 7). The final step 8 uses the panoramic view technique (XTD-View) to document the localisation within the breast and to make the position of a lesion simply

  10. Optimally stabilized PET image denoising using trilateral filtering.

    PubMed

    Mansoor, Awais; Bagci, Ulas; Mollura, Daniel J

    2014-01-01

    Low-resolution and signal-dependent noise distribution in positron emission tomography (PET) images makes denoising process an inevitable step prior to qualitative and quantitative image analysis tasks. Conventional PET denoising methods either over-smooth small-sized structures due to resolution limitation or make incorrect assumptions about the noise characteristics. Therefore, clinically important quantitative information may be corrupted. To address these challenges, we introduced a novel approach to remove signal-dependent noise in the PET images where the noise distribution was considered as Poisson-Gaussian mixed. Meanwhile, the generalized Anscombe's transformation (GAT) was used to stabilize varying nature of the PET noise. Other than noise stabilization, it is also desirable for the noise removal filter to preserve the boundaries of the structures while smoothing the noisy regions. Indeed, it is important to avoid significant loss of quantitative information such as standard uptake value (SUV)-based metrics as well as metabolic lesion volume. To satisfy all these properties, we extended bilateral filtering method into trilateral filtering through multiscaling and optimal Gaussianization process. The proposed method was tested on more than 50 PET-CT images from various patients having different cancers and achieved the superior performance compared to the widely used denoising techniques in the literature.

  11. Monitoring proton radiation therapy with in-room PET imaging.

    PubMed

    Zhu, Xuping; España, Samuel; Daartz, Juliane; Liebsch, Norbert; Ouyang, Jinsong; Paganetti, Harald; Bortfeld, Thomas R; El Fakhri, Georges

    2011-07-07

    We used a mobile positron emission tomography (PET) scanner positioned within the proton therapy treatment room to study the feasibility of proton range verification with an in-room, stand-alone PET system, and compared with off-line equivalent studies. Two subjects with adenoid cystic carcinoma were enrolled into a pilot study in which in-room PET scans were acquired in list-mode after a routine fractionated treatment session. The list-mode PET data were reconstructed with different time schemes to generate in-room short, in-room long and off-line equivalent (by skipping coincidences from the first 15 min during the list-mode reconstruction) PET images for comparison in activity distribution patterns. A phantom study was followed to evaluate the accuracy of range verification for different reconstruction time schemes quantitatively. The in-room PET has a higher sensitivity compared to the off-line modality so that the PET acquisition time can be greatly reduced from 30 to <5 min. Features in deep-site, soft-tissue regions were better retained with in-room short PET acquisitions because of the collection of (15)O component and lower biological washout. For soft tissue-equivalent material, the distal fall-off edge of an in-room short acquisition is deeper compared to an off-line equivalent scan, indicating a better coverage of the high-dose end of the beam. In-room PET is a promising low cost, high sensitivity modality for the in vivo verification of proton therapy. Better accuracy in Monte Carlo predictions, especially for biological decay modeling, is necessary.

  12. Quantitative PET image reconstruction employing nested expectation-maximization deconvolution for motion compensation.

    PubMed

    Karakatsanis, Nicolas A; Tsoumpas, Charalampos; Zaidi, Habib

    2016-11-16

    Bulk body motion may randomly occur during PET acquisitions introducing blurring, attenuation-emission mismatches and, in dynamic PET, discontinuities in the measured time activity curves between consecutive frames. Meanwhile, dynamic PET scans are longer, thus increasing the probability of bulk motion. In this study, we propose a streamlined 3D PET motion-compensated image reconstruction (3D-MCIR) framework, capable of robustly deconvolving intra-frame motion from a static or dynamic 3D sinogram. The presented 3D-MCIR methods need not partition the data into multiple gates, such as 4D MCIR algorithms, or access list-mode (LM) data, such as LM MCIR methods, both associated with increased computation or memory resources. The proposed algorithms can support compensation for any periodic and non-periodic motion, such as cardio-respiratory or bulk motion, the latter including rolling, twisting or drifting. Inspired from the widely adopted point-spread function (PSF) deconvolution 3D PET reconstruction techniques, here we introduce an image-based 3D generalized motion deconvolution method within the standard 3D maximum-likelihood expectation-maximization (ML-EM) reconstruction framework. In particular, we initially integrate a motion blurring kernel, accounting for every tracked motion within a frame, as an additional MLEM modeling component in the image space (integrated 3D-MCIR). Subsequently, we replaced the integrated model component with a nested iterative Richardson-Lucy (RL) image-based deconvolution method to accelerate the MLEM algorithm convergence rate (RL-3D-MCIR). The final method was evaluated with realistic simulations of whole-body dynamic PET data employing the XCAT phantom and real human bulk motion profiles, the latter estimated from volunteer dynamic MRI scans. In addition, metabolic uptake rate Ki parametric images were generated with the standard Patlak method. Our results demonstrate significant improvement in contrast-to-noise ratio (CNR) and

  13. 4D reconstruction of the past: the image retrieval and 3D model construction pipeline

    NASA Astrophysics Data System (ADS)

    Hadjiprocopis, Andreas; Ioannides, Marinos; Wenzel, Konrad; Rothermel, Mathias; Johnsons, Paul S.; Fritsch, Dieter; Doulamis, Anastasios; Protopapadakis, Eftychios; Kyriakaki, Georgia; Makantasis, Kostas; Weinlinger, Guenther; Klein, Michael; Fellner, Dieter; Stork, Andre; Santos, Pedro

    2014-08-01

    One of the main characteristics of the Internet era we are living in, is the free and online availability of a huge amount of data. This data is of varied reliability and accuracy and exists in various forms and formats. Often, it is cross-referenced and linked to other data, forming a nexus of text, images, animation and audio enabled by hypertext and, recently, by the Web3.0 standard. Our main goal is to enable historians, architects, archaeolo- gists, urban planners and affiliated professionals to reconstruct views of historical monuments from thousands of images floating around the web. This paper aims to provide an update of our progress in designing and imple- menting a pipeline for searching, filtering and retrieving photographs from Open Access Image Repositories and social media sites and using these images to build accurate 3D models of archaeological monuments as well as enriching multimedia of cultural / archaeological interest with metadata and harvesting the end products to EU- ROPEANA. We provide details of how our implemented software searches and retrieves images of archaeological sites from Flickr and Picasa repositories as well as strategies on how to filter the results, on two levels; a) based on their built-in metadata including geo-location information and b) based on image processing and clustering techniques. We also describe our implementation of a Structure from Motion pipeline designed for producing 3D models using the large collection of 2D input images (>1000) retrieved from Internet Repositories.

  14. 4D optical coherence tomography of the embryonic heart using gated imaging

    NASA Astrophysics Data System (ADS)

    Jenkins, Michael W.; Rothenberg, Florence; Roy, Debashish; Nikolski, Vladimir P.; Wilson, David L.; Efimov, Igor R.; Rollins, Andrew M.

    2005-04-01

    Computed tomography (CT), ultrasound, and magnetic resonance imaging have been used to image and diagnose diseases of the human heart. By gating the acquisition of the images to the heart cycle (gated imaging), these modalities enable one to produce 3D images of the heart without significant motion artifact and to more accurately calculate various parameters such as ejection fractions [1-3]. Unfortunately, these imaging modalities give inadequate resolution when investigating embryonic development in animal models. Defects in developmental mechanisms during embryogenesis have long been thought to result in congenital cardiac anomalies. Our understanding of normal mechanisms of heart development and how abnormalities can lead to defects has been hampered by our inability to detect anatomic and physiologic changes in these small (<2mm) organs. Optical coherence tomography (OCT) has made it possible to visualize internal structures of the living embryonic heart with high-resolution in two- and threedimensions. OCT offers higher resolution than ultrasound (30 um axial, 90 um lateral) and magnetic resonance microscopy (25 um axial, 31 um lateral) [4, 5], with greater depth penetration over confocal microscopy (200 um). Optical coherence tomography (OCT) uses back reflected light from a sample to create an image with axial resolutions ranging from 2-15 um, while penetrating 1-2 mm in depth [6]. In the past, OCT groups estimated ejection fractions using 2D images in a Xenopus laevis [7], created 3D renderings of chick embryo hearts [8], and used a gated reconstruction technique to produce 2D Doppler OCT image of an in vivo Xenopus laevis heart [9]. In this paper we present a gated imaging system that allowed us to produce a 16-frame 3D movie of a beating chick embryo heart. The heart was excised from a day two (stage 13) chicken embryo and electrically paced at 1 Hz. We acquired 2D images (B-scans) in 62.5 ms, which provides enough temporal resolution to distinguish end

  15. WE-G-BRF-09: Force- and Image-Adaptive Strategies for Robotised Placement of 4D Ultrasound Probes

    SciTech Connect

    Kuhlemann, I; Bruder, R; Ernst, F; Schweikard, A

    2014-06-15

    Purpose: To allow continuous acquisition of high quality 4D ultrasound images for non-invasive live tracking of tumours for IGRT, image- and force-adaptive strategies for robotised placement of 4D ultrasound probes are developed and evaluated. Methods: The developed robotised ultrasound system is based on a 6-axes industrial robot (adept Viper s850) carrying a 4D ultrasound transducer with a mounted force-torque sensor. The force-adaptive placement strategies include probe position control using artificial potential fields and contact pressure regulation by a PD controller strategy. The basis for live target tracking is a continuous minimum contact pressure to ensure good image quality and high patient comfort. This contact pressure can be significantly disturbed by respiratory movements and has to be compensated. All measurements were performed on human subjects under realistic conditions. When performing cardiac ultrasound, rib- and lung shadows are a common source of interference and can disrupt the tracking. To ensure continuous tracking, these artefacts had to be detected to automatically realign the probe. The detection is realised by multiple algorithms based on entropy calculations as well as a determination of the image quality. Results: Through active contact pressure regulation it was possible to reduce the variance of the contact pressure by 89.79% despite respiratory motion of the chest. The results regarding the image processing clearly demonstrate the feasibility to detect image artefacts like rib shadows in real-time. Conclusion: In all cases, it was possible to stabilise the image quality by active contact pressure control and automatically detected image artefacts. This fact enables the possibility to compensate for such interferences by realigning the probe and thus continuously optimising the ultrasound images. This is a huge step towards fully automated transducer positioning and opens the possibility for stable target tracking in

  16. Dual-Modality Prostate Imaging with PET and Transrectal Ultrasound

    DTIC Science & Technology

    2011-09-01

    Emission Tomography–Transrectal Ultrasound (PET-TRUS) imaging of the prostate and validate the technology with phantom and “proof of principle” human...position a prostate near the PET-center, and this method was also used for phantom imaging in Years 2-5. The TRUS probe is rigidly attached to the TRUS...scanner table. This stabilizer arm moves to allow correct positioning of the TRUS probe in a human subject (or phantom ), then its position is fixed by

  17. Influence of Iterative Reconstruction Algorithms on PET Image Resolution

    NASA Astrophysics Data System (ADS)

    Karpetas, G. E.; Michail, C. M.; Fountos, G. P.; Valais, I. G.; Nikolopoulos, D.; Kandarakis, I. S.; Panayiotakis, G. S.

    2015-09-01

    The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction. The simulated PET scanner was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the modulation transfer function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL, the ordered subsets separable paraboloidal surrogate (OSSPS), the median root prior (MRP) and OSMAPOSL with quadratic prior, algorithms. OSMAPOSL reconstruction was assessed by using fixed subsets and various iterations, as well as by using various beta (hyper) parameter values. MTF values were found to increase with increasing iterations. MTF also improves by using lower beta values. The simulated PET evaluation method, based on the TLC plane source, can be useful in the resolution assessment of PET scanners.

  18. Common-mask guided image reconstruction (c-MGIR) for enhanced 4D cone-beam computed tomography

    NASA Astrophysics Data System (ADS)

    Park, Justin C.; Zhang, Hao; Chen, Yunmei; Fan, Qiyong; Li, Jonathan G.; Liu, Chihray; Lu, Bo

    2015-12-01

    Compared to 3D cone beam computed tomography (3D CBCT), the image quality of commercially available four-dimensional (4D) CBCT is severely impaired due to the insufficient amount of projection data available for each phase. Since the traditional Feldkamp-Davis-Kress (FDK)-based algorithm is infeasible for reconstructing high quality 4D CBCT images with limited projections, investigators had developed several compress-sensing (CS) based algorithms to improve image quality. The aim of this study is to develop a novel algorithm which can provide better image quality than the FDK and other CS based algorithms with limited projections. We named this algorithm ‘the common mask guided image reconstruction’ (c-MGIR). In c-MGIR, the unknown CBCT volume is mathematically modeled as a combination of phase-specific motion vectors and phase-independent static vectors. The common-mask matrix, which is the key concept behind the c-MGIR algorithm, separates the common static part across all phase images from the possible moving part in each phase image. The moving part and the static part of the volumes were then alternatively updated by solving two sub-minimization problems iteratively. As the novel mathematical transformation allows the static volume and moving volumes to be updated (during each iteration) with global projections and ‘well’ solved static volume respectively, the algorithm was able to reduce the noise and under-sampling artifact (an issue faced by other algorithms) to the maximum extent. To evaluate the performance of our proposed c-MGIR, we utilized imaging data from both numerical phantoms and a lung cancer patient. The qualities of the images reconstructed with c-MGIR were compared with (1) standard FDK algorithm, (2) conventional total variation (CTV) based algorithm, (3) prior image constrained compressed sensing (PICCS) algorithm, and (4) motion-map constrained image reconstruction (MCIR) algorithm, respectively. To improve the efficiency of the

  19. Common-mask guided image reconstruction (c-MGIR) for enhanced 4D cone-beam computed tomography.

    PubMed

    Park, Justin C; Zhang, Hao; Chen, Yunmei; Fan, Qiyong; Li, Jonathan G; Liu, Chihray; Lu, Bo

    2015-12-07

    Compared to 3D cone beam computed tomography (3D CBCT), the image quality of commercially available four-dimensional (4D) CBCT is severely impaired due to the insufficient amount of projection data available for each phase. Since the traditional Feldkamp-Davis-Kress (FDK)-based algorithm is infeasible for reconstructing high quality 4D CBCT images with limited projections, investigators had developed several compress-sensing (CS) based algorithms to improve image quality. The aim of this study is to develop a novel algorithm which can provide better image quality than the FDK and other CS based algorithms with limited projections. We named this algorithm 'the common mask guided image reconstruction' (c-MGIR).In c-MGIR, the unknown CBCT volume is mathematically modeled as a combination of phase-specific motion vectors and phase-independent static vectors. The common-mask matrix, which is the key concept behind the c-MGIR algorithm, separates the common static part across all phase images from the possible moving part in each phase image. The moving part and the static part of the volumes were then alternatively updated by solving two sub-minimization problems iteratively. As the novel mathematical transformation allows the static volume and moving volumes to be updated (during each iteration) with global projections and 'well' solved static volume respectively, the algorithm was able to reduce the noise and under-sampling artifact (an issue faced by other algorithms) to the maximum extent. To evaluate the performance of our proposed c-MGIR, we utilized imaging data from both numerical phantoms and a lung cancer patient. The qualities of the images reconstructed with c-MGIR were compared with (1) standard FDK algorithm, (2) conventional total variation (CTV) based algorithm, (3) prior image constrained compressed sensing (PICCS) algorithm, and (4) motion-map constrained image reconstruction (MCIR) algorithm, respectively. To improve the efficiency of the algorithm

  20. Sensitivity study of voxel-based PET image comparison to image registration algorithms

    SciTech Connect

    Yip, Stephen Chen, Aileen B.; Berbeco, Ross; Aerts, Hugo J. W. L.

    2014-11-01

    Purpose: Accurate deformable registration is essential for voxel-based comparison of sequential positron emission tomography (PET) images for proper adaptation of treatment plan and treatment response assessment. The comparison may be sensitive to the method of deformable registration as the optimal algorithm is unknown. This study investigated the impact of registration algorithm choice on therapy response evaluation. Methods: Sixteen patients with 20 lung tumors underwent a pre- and post-treatment computed tomography (CT) and 4D FDG-PET scans before and after chemoradiotherapy. All CT images were coregistered using a rigid and ten deformable registration algorithms. The resulting transformations were then applied to the respective PET images. Moreover, the tumor region defined by a physician on the registered PET images was classified into progressor, stable-disease, and responder subvolumes. Particularly, voxels with standardized uptake value (SUV) decreases >30% were classified as responder, while voxels with SUV increases >30% were progressor. All other voxels were considered stable-disease. The agreement of the subvolumes resulting from difference registration algorithms was assessed by Dice similarity index (DSI). Coefficient of variation (CV) was computed to assess variability of DSI between individual tumors. Root mean square difference (RMS{sub rigid}) of the rigidly registered CT images was used to measure the degree of tumor deformation. RMS{sub rigid} and DSI were correlated by Spearman correlation coefficient (R) to investigate the effect of tumor deformation on DSI. Results: Median DSI{sub rigid} was found to be 72%, 66%, and 80%, for progressor, stable-disease, and responder, respectively. Median DSI{sub deformable} was 63%–84%, 65%–81%, and 82%–89%. Variability of DSI was substantial and similar for both rigid and deformable algorithms with CV > 10% for all subvolumes. Tumor deformation had moderate to significant impact on DSI for progressor

  1. Differential Receptor Tyrosine Kinase PET Imaging for Therapeutic Guidance

    PubMed Central

    Wehrenberg-Klee, Eric; Turker, N. Selcan; Heidari, Pedram; Larimer, Benjamin; Juric, Dejan; Baselga, José; Scaltriti, Maurizio

    2016-01-01

    Inhibitors of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway hold promise for the treatment of breast cancer, but resistance to these treatments can arise via feedback loops that increase surface expression of the receptor tyrosine kinases (RTK) epidermal growth factor receptor 1 (EGFR) and human epidermal growth factor receptor 3 (HER3), leading to persistent growth pathway signaling. We developed PET probes that provide a method of imaging this response in vivo, determining which tumors may use this escape pathway while avoiding the need for repeated biopsies. Methods: Anti-EGFR-F(ab′)2 and anti-HER3-F(ab′)2 were generated from monoclonal antibodies by enzymatic digestion, conjugated to DOTA, and labeled with 64Cu. A panel of breast cancer cell lines was treated with increasing concentrations of the AKT inhibitor GDC-0068 or the PI3K inhibitor GDC-0941. Pre- and posttreatment expression of EGFR and HER3 was compared using Western blot and correlated to probe accumulation with binding studies. Nude mice xenografts of HCC-70 or MDA-MB-468 were treated with either AKT inhibitor or PI3K inhibitor and imaged with either EGFR or HER3 PET probe. Results: Changes in HER3 and EGFR PET probe accumulation correlate to RTK expression change as assessed by Western blot (R2 of 0.85–0.98). EGFR PET probe PET/CT imaging of HCC70 tumors shows an SUV of 0.32 ± 0.03 for vehicle-, 0.50 ± 0.01 for GDC-0941–, and 0.62 ± 0.01 for GDC-0068–treated tumors, respectively (P < 0.01 for both comparisons to vehicle). HER3 PET probe PET/CT imaging of MDAMB468 tumors shows an SUV of 0.35 ± 0.02 for vehicle- and 0.73 ± 0.05 for GDC-0068–treated tumors (P < 0.01). Conclusion: Our imaging studies, using PET probes specific to EGFR and HER3, show that changes in RTK expression indicative of resistance to PI3K and AKT inhibitors can be seen within days of therapy initiation and are of sufficient magnitude as to allow reliable

  2. 4D motion modeling of the coronary arteries from CT images for robotic assisted minimally invasive surgery

    NASA Astrophysics Data System (ADS)

    Zhang, Dong Ping; Edwards, Eddie; Mei, Lin; Rueckert, Daniel

    2009-02-01

    In this paper, we present a novel approach for coronary artery motion modeling from cardiac Computed Tomography( CT) images. The aim of this work is to develop a 4D motion model of the coronaries for image guidance in robotic-assisted totally endoscopic coronary artery bypass (TECAB) surgery. To utilize the pre-operative cardiac images to guide the minimally invasive surgery, it is essential to have a 4D cardiac motion model to be registered with the stereo endoscopic images acquired intraoperatively using the da Vinci robotic system. In this paper, we are investigating the extraction of the coronary arteries and the modelling of their motion from a dynamic sequence of cardiac CT. We use a multi-scale vesselness filter to enhance vessels in the cardiac CT images. The centerlines of the arteries are extracted using a ridge traversal algorithm. Using this method the coronaries can be extracted in near real-time as only local information is used in vessel tracking. To compute the deformation of the coronaries due to cardiac motion, the motion is extracted from a dynamic sequence of cardiac CT. Each timeframe in this sequence is registered to the end-diastole timeframe of the sequence using a non-rigid registration algorithm based on free-form deformations. Once the images have been registered a dynamic motion model of the coronaries can be obtained by applying the computed free-form deformations to the extracted coronary arteries. To validate the accuracy of the motion model we compare the actual position of the coronaries in each time frame with the predicted position of the coronaries as estimated from the non-rigid registration. We expect that this motion model of coronaries can facilitate the planning of TECAB surgery, and through the registration with real-time endoscopic video images it can reduce the conversion rate from TECAB to conventional procedures.

  3. Gallium-68 EDTA PET/CT for Renal Imaging.

    PubMed

    Hofman, Michael S; Hicks, Rodney J

    2016-09-01

    Nuclear medicine renal imaging provides important functional data to assist in the diagnosis and management of patients with a variety of renal disorders. Physiologically stable metal chelates like ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine penta-acetate (DTPA) are excreted by glomerular filtration and have been radiolabelled with a variety of isotopes for imaging glomerular filtration and quantitative assessment of glomerular filtration rate. Gallium-68 ((68)Ga) EDTA PET usage predates Technetium-99m ((99m)Tc) renal imaging, but virtually disappeared with the widespread adoption of gamma camera technology that was not optimal for imaging positron decay. There is now a reemergence of interest in (68)Ga owing to the greater availability of PET technology and use of (68)Ga to label other radiotracers. (68)Ga EDTA can be used a substitute for (99m)Tc DTPA for wide variety of clinical indications. A key advantage of PET for renal imaging over conventional scintigraphy is 3-dimensional dynamic imaging, which is particularly helpful in patients with complex anatomy in whom planar imaging may be nondiagnostic or difficult to interpret owing to overlying structures containing radioactive urine that cannot be differentiated. Other advantages include accurate and absolute (rather than relative) camera-based quantification, superior spatial and temporal resolution and integrated multislice CT providing anatomical correlation. Furthermore, the (68)Ga generator enables on-demand production at low cost, with no additional patient radiation exposure compared with conventional scintigraphy. Over the past decade, we have employed (68)Ga EDTA PET/CT primarily to answer difficult clinical questions in patients in whom other modalities have failed, particularly when it was envisaged that dynamic 3D imaging would be of assistance. We have also used it as a substitute for (99m)Tc DTPA if unavailable owing to supply issues, and have additionally examined the role of

  4. MRI and PET image fusion using fuzzy logic and image local features.

    PubMed

    Javed, Umer; Riaz, Muhammad Mohsin; Ghafoor, Abdul; Ali, Syed Sohaib; Cheema, Tanveer Ahmed

    2014-01-01

    An image fusion technique for magnetic resonance imaging (MRI) and positron emission tomography (PET) using local features and fuzzy logic is presented. The aim of proposed technique is to maximally combine useful information present in MRI and PET images. Image local features are extracted and combined with fuzzy logic to compute weights for each pixel. Simulation results show that the proposed scheme produces significantly better results compared to state-of-art schemes.

  5. Dynamic Multiscale Boundary Conditions for 4D CT Images of Healthy and Emphysematous Rat

    SciTech Connect

    Jacob, Rick E.; Carson, James P.; Thomas, Mathew; Einstein, Daniel R.

    2013-06-14

    Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically – without breath-holds – allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis.

  6. 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

  7. A novel non-registration based segmentation approach of 4D dynamic upper airway MR images: minimally interactive fuzzy connectedness

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Odhner, Dewey; Sin, Sanghun; Wagshul, Mark E.; Arens, Raanan

    2014-03-01

    There are several disease conditions that lead to upper airway restrictive disorders. In the study of these conditions, it is important to take into account the dynamic nature of the upper airway. Currently, dynamic MRI is the modality of choice for studying these diseases. Unfortunately, the contrast resolution obtainable in the images poses many challenges for an effective segmentation of the upper airway structures. No viable methods have been developed to date to solve this problem. In this paper, we demonstrate the adaptation of the iterative relative fuzzy connectedness (IRFC) algorithm for this application as a potential practical tool. After preprocessing to correct for background image non-uniformities and the non-standardness of MRI intensities, seeds are specified for the airway and its crucial background tissue components in only the 3D image corresponding to the first time instance of the 4D volume. Subsequently the process runs without human interaction and completes segmenting the whole 4D volume in 10 sec. Our evaluations indicate that the segmentations are of very good quality achieving true positive and false positive volume fractions and boundary distance with respect to reference manual segmentations of about 93%, 0.1%, and 0.5 mm, respectively.

  8. PET image reconstruction: a robust state space approach.

    PubMed

    Liu, Huafeng; Tian, Yi; Shi, Pengcheng

    2005-01-01

    Statistical iterative reconstruction algorithms have shown improved image quality over conventional nonstatistical methods in PET by using accurate system response models and measurement noise models. Strictly speaking, however, PET measurements, pre-corrected for accidental coincidences, are neither Poisson nor Gaussian distributed and thus do not meet basic assumptions of these algorithms. In addition, the difficulty in determining the proper system response model also greatly affects the quality of the reconstructed images. In this paper, we explore the usage of state space principles for the estimation of activity map in tomographic PET imaging. The proposed strategy formulates the organ activity distribution through tracer kinetics models, and the photon-counting measurements through observation equations, thus makes it possible to unify the dynamic reconstruction problem and static reconstruction problem into a general framework. Further, it coherently treats the uncertainties of the statistical model of the imaging system and the noisy nature of measurement data. Since H(infinity) filter seeks minimummaximum-error estimates without any assumptions on the system and data noise statistics, it is particular suited for PET image reconstruction where the statistical properties of measurement data and the system model are very complicated. The performance of the proposed framework is evaluated using Shepp-Logan simulated phantom data and real phantom data with favorable results.

  9. MO-F-CAMPUS-J-03: Sorting 2D Dynamic MR Images Using Internal Respiratory Signal for 4D MRI

    SciTech Connect

    Wen, Z; Hui, C; Beddar, S; Stemkens, B; Tijssen, R; Berg, C van den

    2015-06-15

    Purpose: To develop a novel algorithm to extract internal respiratory signal (IRS) for sorting dynamic magnetic resonance (MR) images in order to achieve four-dimensional (4D) MR imaging. Methods: Dynamic MR images were obtained with the balanced steady state free precession by acquiring each two-dimensional sagittal slice repeatedly for more than one breathing cycle. To generate a robust IRS, we used 5 different representative internal respiratory surrogates in both the image space (body area) and the Fourier space (the first two low-frequency phase components in the anterior-posterior direction, and the first two low-frequency phase components in the superior-inferior direction). A clustering algorithm was then used to search for a group of similar individual internal signals, which was then used to formulate the final IRS. A phantom study and a volunteer study were performed to demonstrate the effectiveness of this algorithm. The IRS was compared to the signal from the respiratory bellows. Results: The IRS computed by our algorithm matched well with the bellows signal in both the phantom and the volunteer studies. On average, the normalized cross correlation between the IRS and the bellows signal was 0.97 in the phantom study and 0.87 in the volunteer study, respectively. The average difference between the end inspiration times in the IRS and bellows signal was 0.18 s in the phantom study and 0.14 s in the volunteer study, respectively. 4D images sorted based on the IRS showed minimal mismatched artifacts, and the motion of the anatomy was coherent with the respiratory phases. Conclusion: A novel algorithm was developed to generate IRS from dynamic MR images to achieve 4D MR imaging. The performance of the IRS was comparable to that of the bellows signal. It can be easily implemented into the clinic and potentially could replace the use of external respiratory surrogates. This research was partially funded by the the Center for Radiation Oncology Research from

  10. Improving PET spatial resolution and detectability for prostate cancer imaging

    NASA Astrophysics Data System (ADS)

    Bal, H.; Guerin, L.; Casey, M. E.; Conti, M.; Eriksson, L.; Michel, C.; Fanti, S.; Pettinato, C.; Adler, S.; Choyke, P.

    2014-08-01

    Prostate cancer, one of the most common forms of cancer among men, can benefit from recent improvements in positron emission tomography (PET) technology. In particular, better spatial resolution, lower noise and higher detectability of small lesions could be greatly beneficial for early diagnosis and could provide a strong support for guiding biopsy and surgery. In this article, the impact of improved PET instrumentation with superior spatial resolution and high sensitivity are discussed, together with the latest development in PET technology: resolution recovery and time-of-flight reconstruction. Using simulated cancer lesions, inserted in clinical PET images obtained with conventional protocols, we show that visual identification of the lesions and detectability via numerical observers can already be improved using state of the art PET reconstruction methods. This was achieved using both resolution recovery and time-of-flight reconstruction, and a high resolution image with 2 mm pixel size. Channelized Hotelling numerical observers showed an increase in the area under the LROC curve from 0.52 to 0.58. In addition, a relationship between the simulated input activity and the area under the LROC curve showed that the minimum detectable activity was reduced by more than 23%.

  11. Initial tests of a prototype MRI-compatible PET imager

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan; Velan, S. Sendhil; Kross, Brain; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Wojcik, Randy

    2006-12-01

    Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI, will allow the correlation of form with function. Our group (a collaboration of West Virginia University and Jefferson Lab) is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode with an active FOV of 5×5×4 cm 3. Each MRI-PET detector module consists of an array of LSO detector elements (2.5×2.5×15 mm 3) coupled through a long fiber optic light guide to a single Hamamatsu flat panel PSPMT. The fiber optic light guide is made of a glued assembly of 2 mm diameter acrylic fibers with a total length of 2.5 m. The use of a light guides allows the PSPMTs to be positioned outside the bore of the 3 T General Electric MRI scanner used in the tests. Photon attenuation in the light guides resulted in an energy resolution of ˜60% FWHM, interaction of the magnetic field with PSPMT further reduced energy resolution to ˜85% FWHM. Despite this effect, excellent multi-plane PET and MRI images of a simple disk phantom were acquired simultaneously. Future work includes improved light guides, optimized magnetic shielding for the PSPMTs, construction of specialized coils to permit high-resolution MRI imaging, and use of the system to perform simultaneous PET and MRI or MR-spectroscopy .

  12. Metabolic PET Imaging in Cancer Detection and Therapy Response

    PubMed Central

    Zhu, Aizhi; Lee, Daniel; Shim, Hyunsuk

    2010-01-01

    Positron emission tomography (PET) is a noninvasive imaging technique that provides a functional or metabolic assessment of normal tissue or disease conditions. 18F-fluorodeoxyglucose PET imaging (FDG-PET) is widely used clinically for tumor imaging due to increased glucose metabolism in most types of tumors, and has been shown to improve the diagnosis and subsequent treatment of cancers. In this chapter, we review its use in cancer diagnosis, staging, restaging, and assessment of response to treatment. In addition, other metabolic PET imaging agents in research or clinical trial stages are discussed, including amino acid analogs based on increased protein synthesis, and choline, which is based on increased membrane lipid synthesis. Amino acid analogs and choline are more specific to tumor cells than FDG, so they play an important role in differentiating cancers from benign conditions and in the diagnosis of cancers with low FDG uptake or high background FDG uptake. For decades, researchers have shown that tumors have altered metabolic profiles and display elevated uptake of glucose, amino acids, and lipids, which can be used for cancer diagnosis and monitoring of the therapeutic response with excellent signal-to-noise ratios. PMID:21362516

  13. Early Recognition of Chronic Traumatic Encephalopathy through FDDNP PET Imaging

    DTIC Science & Technology

    2014-10-01

    cumulative head trauma. All operational aspects of this study have been accomplished including local IRB approval, identification of potential... head injuries sustained in battle have been associated with the development of chronic traumatic encephalopathy (CTE). Pathological series have...will examine whether FDDNP PET imaging correlates with, and/or can predict, decline in cognitive function in those exposed to cumulative head trauma

  14. Online 4d Reconstruction Using Multi-Images Available Under Open Access

    NASA Astrophysics Data System (ADS)

    Ioannides, M.; Hadjiprocopi, A.; Doulamis, N.; Doulamis, A.; Protopapadakis, E.; Makantasis, K.; Santos, P.; Fellner, D.; Stork, A.; Balet, O.; Julien, M.; Weinlinger, G.; Johnson, P. S.; Klein, M.; Fritsch, D.

    2013-07-01

    The advent of technology in digital cameras and their incorporation into virtually any smart mobile device has led to an explosion of the number of photographs taken every day. Today, the number of images stored online and available freely has reached unprecedented levels. It is estimated that in 2011, there were over 100 billion photographs stored in just one of the major social media sites. This number is growing exponentially. Moreover, advances in the fields of Photogrammetry and Computer Vision have led to significant breakthroughs such as the Structure from Motion algorithm which creates 3D models of objects using their twodimensional photographs. The existence of powerful and affordable computational machinery not only the reconstruction of complex structures but also entire cities. This paper illustrates an overview of our methodology for producing 3D models of Cultural Heritage structures such as monuments and artefacts from 2D data (pictures, video), available on Internet repositories, social media, Google Maps, Bing, etc. We also present new approaches to semantic enrichment of the end results and their subsequent export to Europeana, the European digital library, for integrated, interactive 3D visualisation within regular web browsers using WebGl and X3D. Our main goal is to enable historians, architects, archaeologists, urban planners and affiliated professionals to reconstruct views of historical structures from millions of images floating around the web and interact with them.

  15. Innovative LuYAP:Ce array for PET imaging

    NASA Astrophysics Data System (ADS)

    Cinti, M. N.; Scafe, R.; Bennati, P.; Lo Meo, S.; Frantellizzi, V.; Pellegrini, R.; De Vincentis, G.; Sacco, D.; Fabbri, A.; Pani, R.

    2017-03-01

    We present an imaging characterization of a 10 × 10 LuYAP array (2 × 2 × 10 mm3 pixels) with an innovative dielectric coating insulation (0.015 mm thick), in view of its possible use in a gamma camera for imaging positron emission tomography (PET) or in similar applications, e.g. as γ -prompt detector in hadron therapy. The particular assembly of this array was realized in order to obtain a packing fraction of 98%, improving detection efficiency and light collection. For imaging purpose, the array has been coupled with a selected Hamamatsu H10966-100 Multi Anode Photomultiplier read out by a customized 64 independent channels electronics. This tube presents a superbialkali photocathode with 38% of quantum efficiency, permitting to enhance energy resolution and consequently image quality. A pixel identification of about 0.5 mm at 662 keV was obtained, highlighting the potentiality of this detector in PET applications.

  16. A radiobiological analysis of the effect of 3D versus 4D image-based planning in lung cancer radiotherapy.

    PubMed

    Roland, Teboh; Mavroidis, Panayiotis; Gutierrez, Alonso; Goytia, Virginia; Papanikolaou, Niko

    2009-09-21

    Dose distributions generated on a static anatomy may differ significantly from those delivered to temporally varying anatomy such as for abdominal and thoracic tumors, due largely in part to the unavoidable organ motion and deformation effects stemming from respiration. In this work, the degree of such variation for three treatment techniques, namely static conventional, gating and target tracking radiotherapy, was investigated. The actual delivered dose was approximated by planning all the phases of a 4DCT image set. Data from six (n = 6) previously treated lung cancer patients were used for this study with tumor motion ranging from 2 to 10 mm. Complete radiobiological analyses were performed to assess the clinical significance of the observed discrepancies between the 3D and 4DCT image-based dose distributions. Using the complication-free tumor control probability (P+) objective, we observed small differences in P+ between the 3D and 4DCT image-based plans (<2.0% difference on average) for the gating and static conventional regimens and higher differences in P+ (4.0% on average) for the tracking regimen. Furthermore, we observed, as a general trend, that the 3D plan underestimated the P+ values. While it is not possible to draw any general conclusions from a small patient cohort, our results suggest that there exists a patient population in which 4D planning does not provide any additional benefits beyond that afforded by 3D planning for static conventional or gated radiotherapy. This statement is consistent with previous studies based on physical dosimetric evaluations only. The higher differences observed with the tracking technique suggest that individual patient plans should be evaluated on a case-by-case basis to assess if 3D or 4D imaging is appropriate for the tracking technique.

  17. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing.

    PubMed

    Jahani, Nariman; Choi, Sanghun; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A; Lin, Ching-Long

    2015-11-15

    This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R(2) ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs.

  18. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing

    PubMed Central

    Jahani, Nariman; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A.

    2015-01-01

    This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R2 ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs. PMID:26316512

  19. 4-D imaging and monitoring of the Solfatara crater (Italy) by ambient noise tomography

    NASA Astrophysics Data System (ADS)

    Pilz, Marco; Parolai, Stefano; Woith, Heiko; Gresse, Marceau; Vandemeulebrouck, Jean

    2016-04-01

    Imaging shallow subsurface structures and monitoring related temporal variations are two of the main tasks for modern geosciences and seismology. Although many observations have reported temporal velocity changes, e.g., in volcanic areas and on landslides, new methods based on passive sources like ambient seismic noise can provide accurate spatially and temporally resolved information on the velocity structure and on velocity changes. The success of these passive applications is explained by the fact that these methods are based on surface waves which are always present in the ambient seismic noise wave field because they are excited preferentially by superficial sources. Such surface waves can easily be extracted because they dominate the Greeńs function between receivers located at the surface. For real-time monitoring of the shallow velocity structure of the Solfatara crater, one of the forty volcanoes in the Campi Flegrei area characterized by an intense hydrothermal activity due to the interaction of deep convection and meteoric water, we have installed a dense network of 50 seismological sensing units covering the whole surface area in the framework of the European project MED-SUV (The MED-SUV project has received funding from the European Union Seventh Framework Programme FP7 under Grant agreement no 308665). Continuous recordings of the ambient seismic noise over several days as well as signals of an active vibroseis source have been used. Based on a weighted inversion procedure for 3D-passive imaging using ambient noise cross-correlations of both Rayleigh and Love waves, we will present a high-resolution shear-wave velocity model of the structure beneath the Solfatara crater and its temporal changes. Results of seismic tomography are compared with a 3-D electrical resistivity model and CO2 flux map.

  20. Dynamic whole-body PET parametric imaging: I. Concept, acquisition protocol optimization and clinical application

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Nicolas A.; Lodge, Martin A.; Tahari, Abdel K.; Zhou, Y.; Wahl, Richard L.; Rahmim, Arman

    2013-10-01

    Static whole-body PET/CT, employing the standardized uptake value (SUV), is considered the standard clinical approach to diagnosis and treatment response monitoring for a wide range of oncologic malignancies. Alternative PET protocols involving dynamic acquisition of temporal images have been implemented in the research setting, allowing quantification of tracer dynamics, an important capability for tumor characterization and treatment response monitoring. Nonetheless, dynamic protocols have been confined to single-bed-coverage limiting the axial field-of-view to ˜15-20 cm, and have not been translated to the routine clinical context of whole-body PET imaging for the inspection of disseminated disease. Here, we pursue a transition to dynamic whole-body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. We investigate solutions to address the challenges of: (i) long acquisitions, (ii) small number of dynamic frames per bed, and (iii) non-invasive quantification of kinetics in the plasma. In the present study, a novel dynamic (4D) whole-body PET acquisition protocol of ˜45 min total length is presented, composed of (i) an initial 6 min dynamic PET scan (24 frames) over the heart, followed by (ii) a sequence of multi-pass multi-bed PET scans (six passes × seven bed positions, each scanned for 45 s). Standard Patlak linear graphical analysis modeling was employed, coupled with image-derived plasma input function measurements. Ordinary least squares Patlak estimation was used as the baseline regression method to quantify the physiological parameters of tracer uptake rate Ki and total blood distribution volume V on an individual voxel basis. Extensive Monte Carlo simulation studies, using a wide set of published kinetic FDG parameters and GATE and XCAT platforms, were conducted to optimize the acquisition protocol from a range of ten different clinically

  1. MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research: Computer models that take account of body movements promise to provide evaluation and improvement of medical imaging devices and technology.

    PubMed

    Paul Segars, W; Tsui, Benjamin M W

    2009-12-01

    Recent work in the development of computerized phantoms has focused on the creation of ideal "hybrid" models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be

  2. Predicting standard-dose PET image from low-dose PET and multimodal MR images using mapping-based sparse representation

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Zhang, Pei; An, Le; Ma, Guangkai; Kang, Jiayin; Shi, Feng; Wu, Xi; Zhou, Jiliu; Lalush, David S.; Lin, Weili; Shen, Dinggang

    2016-01-01

    Positron emission tomography (PET) has been widely used in clinical diagnosis for diseases and disorders. To obtain high-quality PET images requires a standard-dose radionuclide (tracer) injection into the human body, which inevitably increases risk of radiation exposure. One possible solution to this problem is to predict the standard-dose PET image from its low-dose counterpart and its corresponding multimodal magnetic resonance (MR) images. Inspired by the success of patch-based sparse representation (SR) in super-resolution image reconstruction, we propose a mapping-based SR (m-SR) framework for standard-dose PET image prediction. Compared with the conventional patch-based SR, our method uses a mapping strategy to ensure that the sparse coefficients, estimated from the multimodal MR images and low-dose PET image, can be applied directly to the prediction of standard-dose PET image. As the mapping between multimodal MR images (or low-dose PET image) and standard-dose PET images can be particularly complex, one step of mapping is often insufficient. To this end, an incremental refinement framework is therefore proposed. Specifically, the predicted standard-dose PET image is further mapped to the target standard-dose PET image, and then the SR is performed again to predict a new standard-dose PET image. This procedure can be repeated for prediction refinement of the iterations. Also, a patch selection based dictionary construction method is further used to speed up the prediction process. The proposed method is validated on a human brain dataset. The experimental results show that our method can outperform benchmark methods in both qualitative and quantitative measures.

  3. Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity.

    PubMed

    Ambroziński, Łukasz; Song, Shaozhen; Yoon, Soon Joon; Pelivanov, Ivan; Li, David; Gao, Liang; Shen, Tueng T; Wang, Ruikang K; O'Donnell, Matthew

    2016-12-23

    Elastography plays a key role in characterizing soft media such as biological tissue. Although this technology has found widespread use in both clinical diagnostics and basic science research, nearly all methods require direct physical contact with the object of interest and can even be invasive. For a number of applications, such as diagnostic measurements on the anterior segment of the eye, physical contact is not desired and may even be prohibited. Here we present a fundamentally new approach to dynamic elastography using non-contact mechanical stimulation of soft media with precise spatial and temporal shaping. We call it acoustic micro-tapping (AμT) because it employs focused, air-coupled ultrasound to induce significant mechanical displacement at the boundary of a soft material using reflection-based radiation force. Combining it with high-speed, four-dimensional (three space dimensions plus time) phase-sensitive optical coherence tomography creates a non-contact tool for high-resolution and quantitative dynamic elastography of soft tissue at near real-time imaging rates. The overall approach is demonstrated in ex-vivo porcine cornea.

  4. Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

    PubMed Central

    Ambroziński, Łukasz; Song, Shaozhen; Yoon, Soon Joon; Pelivanov, Ivan; Li, David; Gao, Liang; Shen, Tueng T.; Wang, Ruikang K.; O’Donnell, Matthew

    2016-01-01

    Elastography plays a key role in characterizing soft media such as biological tissue. Although this technology has found widespread use in both clinical diagnostics and basic science research, nearly all methods require direct physical contact with the object of interest and can even be invasive. For a number of applications, such as diagnostic measurements on the anterior segment of the eye, physical contact is not desired and may even be prohibited. Here we present a fundamentally new approach to dynamic elastography using non-contact mechanical stimulation of soft media with precise spatial and temporal shaping. We call it acoustic micro-tapping (AμT) because it employs focused, air-coupled ultrasound to induce significant mechanical displacement at the boundary of a soft material using reflection-based radiation force. Combining it with high-speed, four-dimensional (three space dimensions plus time) phase-sensitive optical coherence tomography creates a non-contact tool for high-resolution and quantitative dynamic elastography of soft tissue at near real-time imaging rates. The overall approach is demonstrated in ex-vivo porcine cornea. PMID:28008920

  5. 4D imaging of fracturing in organic-rich shales during heating

    SciTech Connect

    Maya Kobchenko; Hamed Panahi; François Renard; Dag K. Dysthe; Anders Malthe-Sørenssen; Adriano Mazzini; Julien Scheibert1; Bjørn Jamtveit; Paul Meakin

    2011-12-01

    To better understand the mechanisms of fracture pattern development and fluid escape in low permeability rocks, we performed time-resolved in situ X-ray tomography imaging to investigate the processes that occur during the slow heating (from 60 to 400 C) of organic-rich Green River shale. At about 350 C cracks nucleated in the sample, and as the temperature continued to increase, these cracks propagated parallel to shale bedding and coalesced, thus cutting across the sample. Thermogravimetry and gas chromatography revealed that the fracturing occurring at {approx}350 C was associated with significant mass loss and release of light hydrocarbons generated by the decomposition of immature organic matter. Kerogen decomposition is thought to cause an internal pressure build up sufficient to form cracks in the shale, thus providing pathways for the outgoing hydrocarbons. We show that a 2D numerical model based on this idea qualitatively reproduces the experimentally observed dynamics of crack nucleation, growth and coalescence, as well as the irregular outlines of the cracks. Our results provide a new description of fracture pattern formation in low permeability shales.

  6. Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

    NASA Astrophysics Data System (ADS)

    Ambroziński, Łukasz; Song, Shaozhen; Yoon, Soon Joon; Pelivanov, Ivan; Li, David; Gao, Liang; Shen, Tueng T.; Wang, Ruikang K.; O’Donnell, Matthew

    2016-12-01

    Elastography plays a key role in characterizing soft media such as biological tissue. Although this technology has found widespread use in both clinical diagnostics and basic science research, nearly all methods require direct physical contact with the object of interest and can even be invasive. For a number of applications, such as diagnostic measurements on the anterior segment of the eye, physical contact is not desired and may even be prohibited. Here we present a fundamentally new approach to dynamic elastography using non-contact mechanical stimulation of soft media with precise spatial and temporal shaping. We call it acoustic micro-tapping (AμT) because it employs focused, air-coupled ultrasound to induce significant mechanical displacement at the boundary of a soft material using reflection-based radiation force. Combining it with high-speed, four-dimensional (three space dimensions plus time) phase-sensitive optical coherence tomography creates a non-contact tool for high-resolution and quantitative dynamic elastography of soft tissue at near real-time imaging rates. The overall approach is demonstrated in ex-vivo porcine cornea.

  7. New SPECT and PET Radiopharmaceuticals for Imaging Cardiovascular Disease

    PubMed Central

    Sogbein, Oyebola O.; Pelletier-Galarneau, Matthieu; Schindler, Thomas H.; Wei, Lihui; Wells, R. Glenn; Ruddy, Terrence D.

    2014-01-01

    Nuclear cardiology has experienced exponential growth within the past four decades with converging capacity to diagnose and influence management of a variety of cardiovascular diseases. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with technetium-99m radiotracers or thallium-201 has dominated the field; however new hardware and software designs that optimize image quality with reduced radiation exposure are fuelling a resurgence of interest at the preclinical and clinical levels to expand beyond MPI. Other imaging modalities including positron emission tomography (PET) and magnetic resonance imaging (MRI) continue to emerge as powerful players with an expanded capacity to diagnose a variety of cardiac conditions. At the forefront of this resurgence is the development of novel target vectors based on an enhanced understanding of the underlying pathophysiological process in the subcellular domain. Molecular imaging with novel radiopharmaceuticals engineered to target a specific subcellular process has the capacity to improve diagnostic accuracy and deliver enhanced prognostic information to alter management. This paper, while not comprehensive, will review the recent advancements in radiotracer development for SPECT and PET MPI, autonomic dysfunction, apoptosis, atherosclerotic plaques, metabolism, and viability. The relevant radiochemistry and preclinical and clinical development in addition to molecular imaging with emerging modalities such as cardiac MRI and PET-MR will be discussed. PMID:24901002

  8. Parametric myocardial perfusion PET imaging using physiological clustering

    NASA Astrophysics Data System (ADS)

    Mohy-ud-Din, Hassan; Karakatsanis, Nikolaos A.; Lodge, Martin A.; Tang, Jing; Rahmim, Arman

    2014-03-01

    We propose a novel framework of robust kinetic parameter estimation applied to absolute ow quanti cation in dynamic PET imaging. Kinetic parameter estimation is formulated as a nonlinear least squares with spatial constraints problem (NLLS-SC) where the spatial constraints are computed from a physiologically driven clustering of dynamic images, and used to reduce noise contamination. An ideal clustering of dynamic images depends on the underlying physiology of functional regions, and in turn, physiological processes are quanti ed by kinetic parameter estimation. Physiologically driven clustering of dynamic images is performed using a clustering algorithm (e.g. K-means, Spectral Clustering etc) with Kinetic modeling in an iterative handshaking fashion. This gives a map of labels where each functionally homogenous cluster is represented by mean kinetics (cluster centroid). Parametric images are acquired by solving the NLLS-SC problem for each voxel which penalizes spatial variations from its mean kinetics. This substantially reduces noise in the estimation process for each voxel by utilizing kinetic information from physiologically similar voxels (cluster members). Resolution degradation is also substantially minimized as no spatial smoothing between heterogeneous functional regions is performed. The proposed framework is shown to improve the quantitative accuracy of Myocardial Perfusion (MP) PET imaging, and in turn, has the long-term potential to enhance capabilities of MP PET in the detection, staging and management of coronary artery disease.

  9. Lung tumor segmentation in PET images using graph cuts.

    PubMed

    Ballangan, Cherry; Wang, Xiuying; Fulham, Michael; Eberl, Stefan; Feng, David Dagan

    2013-03-01

    The aim of segmentation of tumor regions in positron emission tomography (PET) is to provide more accurate measurements of tumor size and extension into adjacent structures, than is possible with visual assessment alone and hence improve patient management decisions. We propose a segmentation energy function for the graph cuts technique to improve lung tumor segmentation with PET. Our segmentation energy is based on an analysis of the tumor voxels in PET images combined with a standardized uptake value (SUV) cost function and a monotonic downhill SUV feature. The monotonic downhill feature avoids segmentation leakage into surrounding tissues with similar or higher PET tracer uptake than the tumor and the SUV cost function improves the boundary definition and also addresses situations where the lung tumor is heterogeneous. We evaluated the method in 42 clinical PET volumes from patients with non-small cell lung cancer (NSCLC). Our method improves segmentation and performs better than region growing approaches, the watershed technique, fuzzy-c-means, region-based active contour and tumor customized downhill.

  10. Reconstruction of 4D-CT from a Single Free-Breathing 3D-CT by Spatial-Temporal Image Registration

    PubMed Central

    Wu, Guorong; Wang, Qian; Lian, Jun; Shen, Dinggang

    2011-01-01

    In the radiation therapy of lung cancer, a free-breathing 3D-CT image is usually acquired in the treatment day for image-guided patient setup, by registering with the free-breathing 3D-CT image acquired in the planning day. In this way, the optimal dose plan computed in the planning day can be transferred onto the treatment day for cancer radiotherapy. However, patient setup based on the simple registration of the free-breathing 3D-CT images of the planning and the treatment days may mislead the radiotherapy, since the free-breathing 3D-CT is actually the mixed-phase image, with different slices often acquired from different respiratory phases. Moreover, a 4D-CT that is generally acquired in the planning day for improvement of dose planning is often ignored for guiding patient setup in the treatment day. To overcome these limitations, we present a novel two-step method to reconstruct the 4D-CT from a single free-breathing 3D-CT of the treatment day, by utilizing the 4D-CT model built in the planning day. Specifically, in the first step, we proposed a new spatial-temporal registration algorithm to align all phase images of the 4D-CT acquired in the planning day, for building a 4D-CT model with temporal correspondences established among all respiratory phases. In the second step, we first determine the optimal phase for each slice of the free-breathing (mixed-phase) 3D-CT of the treatment day by comparing with the 4D-CT of the planning day and thus obtain a sequence of partial 3D-CT images for the treatment day, each with only the incomplete image information in certain slices; and then we reconstruct a complete 4D-CT for the treatment day by warping the 4D-CT of the planning day (with complete information) to the sequence of partial 3D-CT images of the treatment day, under the guidance of the 4D-CT model built in the planning day. We have comprehensively evaluated our 4D-CT model building algorithm on a public lung image database, achieving the best registration

  11. 4D imaging of fluid escape in low permeability shales during heating

    NASA Astrophysics Data System (ADS)

    Renard, F.; Kobchenko, M.

    2012-04-01

    The coupling between thermal effects and deformation is relevant in many natural geological environments (rising magma, primary migration of hydrocarbons, vents) and has many industrial applications (storage of nuclear wastes, enhanced hydrocarbon recovery, coal exploitation, geothermic plants). When thermal effects involve phase transformation in the rock and production of fluids, a strong coupling may emerge between the processes of fluid escape and the ability of the rock to deform and transport fluids. To better understand the mechanisms of fracture pattern development and fluid escape in low permeability rocks, we performed time-resolved in situ X-ray tomography imaging to investigate the processes that occur during the slow heating (from 60° to 400°C) of organic-rich Green River shale. At about 350°C cracks nucleated in the sample, and as the temperature continued to increase, these cracks propagated parallel to shale bedding and coalesced, thus cutting across the sample. Thermogravimetry and gas chromatography revealed that the fracturing occurring at ~350°C was associated with significant mass loss and release of light hydrocarbons generated by the decomposition of immature organic matter. Kerogen decomposition is thought to cause an internal pressure build up sufficient to form cracks in the shale, thus providing pathways for the outgoing hydrocarbons. We show that a 2D numerical model based on this idea qualitatively reproduces the experimentally observed dynamics of crack nucleation, growth and coalescence, as well as the irregular outlines of the cracks. Our results provide a new description of fracture pattern formation in low permeability shales.

  12. Multidimensional immunolabeling and 4D time-lapse imaging of vital ex vivo lung tissue

    PubMed Central

    Vierkotten, Sarah; Lindner, Michael; Königshoff, Melanie; Eickelberg, Oliver

    2015-01-01

    During the last decades, the study of cell behavior was largely accomplished in uncoated or extracellular matrix (ECM)-coated plastic dishes. To date, considerable cell biological efforts have tried to model in vitro the natural microenvironment found in vivo. For the lung, explants cultured ex vivo as lung tissue cultures (LTCs) provide a three-dimensional (3D) tissue model containing all cells in their natural microenvironment. Techniques for assessing the dynamic live interaction between ECM and cellular tissue components, however, are still missing. Here, we describe specific multidimensional immunolabeling of living 3D-LTCs, derived from healthy and fibrotic mouse lungs, as well as patient-derived 3D-LTCs, and concomitant real-time four-dimensional multichannel imaging thereof. This approach allowed the evaluation of dynamic interactions between mesenchymal cells and macrophages with their ECM. Furthermore, fibroblasts transiently expressing focal adhesions markers incorporated into the 3D-LTCs, paving new ways for studying the dynamic interaction between cellular adhesions and their natural-derived ECM. A novel protein transfer technology (FuseIt/Ibidi) shuttled fluorescently labeled α-smooth muscle actin antibodies into the native cells of living 3D-LTCs, enabling live monitoring of α-smooth muscle actin-positive stress fibers in native tissue myofibroblasts residing in fibrotic lesions of 3D-LTCs. Finally, this technique can be applied to healthy and diseased human lung tissue, as well as to adherent cells in conventional two-dimensional cell culture. This novel method will provide valuable new insights into the dynamics of ECM (patho)biology, studying in detail the interaction between ECM and cellular tissue components in their natural microenvironment. PMID:26092995

  13. Computational biomechanics and experimental validation of vessel deformation based on 4D-CT imaging of the porcine aorta

    NASA Astrophysics Data System (ADS)

    Hazer, Dilana; Finol, Ender A.; Kostrzewa, Michael; Kopaigorenko, Maria; Richter, Götz-M.; Dillmann, Rüdiger

    2009-02-01

    Cardiovascular disease results from pathological biomechanical conditions and fatigue of the vessel wall. Image-based computational modeling provides a physical and realistic insight into the patient-specific biomechanics and enables accurate predictive simulations of development, growth and failure of cardiovascular disease. An experimental validation is necessary for the evaluation and the clinical implementation of such computational models. In the present study, we have implemented dynamic Computed-Tomography (4D-CT) imaging and catheter-based in vivo measured pressures to numerically simulate and experimentally evaluate the biomechanics of the porcine aorta. The computations are based on the Finite Element Method (FEM) and simulate the arterial wall response to the transient pressure-based boundary condition. They are evaluated by comparing the numerically predicted wall deformation and that calculated from the acquired 4D-CT data. The dynamic motion of the vessel is quantified by means of the hydraulic diameter, analyzing sequences at 5% increments over the cardiac cycle. Our results show that accurate biomechanical modeling is possible using FEM-based simulations. The RMS error of the computed hydraulic diameter at five cross-sections of the aorta was 0.188, 0.252, 0.280, 0.237 and 0.204 mm, which is equivalent to 1.7%, 2.3%, 2.7%, 2.3% and 2.0%, respectively, when expressed as a function of the time-averaged hydraulic diameter measured from the CT images. The present investigation is a first attempt to simulate and validate vessel deformation based on realistic morphological data and boundary conditions. An experimentally validated system would help in evaluating individual therapies and optimal treatment strategies in the field of minimally invasive endovascular surgery.

  14. Automated Movement Correction for Dynamic PET/CT Images: Evaluation with Phantom and Patient Data

    PubMed Central

    Ye, Hu; Wong, Koon-Pong; Wardak, Mirwais; Dahlbom, Magnus; Kepe, Vladimir; Barrio, Jorge R.; Nelson, Linda D.; Small, Gary W.; Huang, Sung-Cheng

    2014-01-01

    Head movement during a dynamic brain PET/CT imaging results in mismatch between CT and dynamic PET images. It can cause artifacts in CT-based attenuation corrected PET images, thus affecting both the qualitative and quantitative aspects of the dynamic PET images and the derived parametric images. In this study, we developed an automated retrospective image-based movement correction (MC) procedure. The MC method first registered the CT image to each dynamic PET frames, then re-reconstructed the PET frames with CT-based attenuation correction, and finally re-aligned all the PET frames to the same position. We evaluated the MC method's performance on the Hoffman phantom and dynamic FDDNP and FDG PET/CT images of patients with neurodegenerative disease or with poor compliance. Dynamic FDDNP PET/CT images (65 min) were obtained from 12 patients and dynamic FDG PET/CT images (60 min) were obtained from 6 patients. Logan analysis with cerebellum as the reference region was used to generate regional distribution volume ratio (DVR) for FDDNP scan before and after MC. For FDG studies, the image derived input function was used to generate parametric image of FDG uptake constant (Ki) before and after MC. Phantom study showed high accuracy of registration between PET and CT and improved PET images after MC. In patient study, head movement was observed in all subjects, especially in late PET frames with an average displacement of 6.92 mm. The z-direction translation (average maximum = 5.32 mm) and x-axis rotation (average maximum = 5.19 degrees) occurred most frequently. Image artifacts were significantly diminished after MC. There were significant differences (P<0.05) in the FDDNP DVR and FDG Ki values in the parietal and temporal regions after MC. In conclusion, MC applied to dynamic brain FDDNP and FDG PET/CT scans could improve the qualitative and quantitative aspects of images of both tracers. PMID:25111700

  15. Automated movement correction for dynamic PET/CT images: evaluation with phantom and patient data.

    PubMed

    Ye, Hu; Wong, Koon-Pong; Wardak, Mirwais; Dahlbom, Magnus; Kepe, Vladimir; Barrio, Jorge R; Nelson, Linda D; Small, Gary W; Huang, Sung-Cheng

    2014-01-01

    Head movement during a dynamic brain PET/CT imaging results in mismatch between CT and dynamic PET images. It can cause artifacts in CT-based attenuation corrected PET images, thus affecting both the qualitative and quantitative aspects of the dynamic PET images and the derived parametric images. In this study, we developed an automated retrospective image-based movement correction (MC) procedure. The MC method first registered the CT image to each dynamic PET frames, then re-reconstructed the PET frames with CT-based attenuation correction, and finally re-aligned all the PET frames to the same position. We evaluated the MC method's performance on the Hoffman phantom and dynamic FDDNP and FDG PET/CT images of patients with neurodegenerative disease or with poor compliance. Dynamic FDDNP PET/CT images (65 min) were obtained from 12 patients and dynamic FDG PET/CT images (60 min) were obtained from 6 patients. Logan analysis with cerebellum as the reference region was used to generate regional distribution volume ratio (DVR) for FDDNP scan before and after MC. For FDG studies, the image derived input function was used to generate parametric image of FDG uptake constant (Ki) before and after MC. Phantom study showed high accuracy of registration between PET and CT and improved PET images after MC. In patient study, head movement was observed in all subjects, especially in late PET frames with an average displacement of 6.92 mm. The z-direction translation (average maximum = 5.32 mm) and x-axis rotation (average maximum = 5.19 degrees) occurred most frequently. Image artifacts were significantly diminished after MC. There were significant differences (P<0.05) in the FDDNP DVR and FDG Ki values in the parietal and temporal regions after MC. In conclusion, MC applied to dynamic brain FDDNP and FDG PET/CT scans could improve the qualitative and quantitative aspects of images of both tracers.

  16. Registration of parametric dynamic F-18-FDG PET/CT breast images with parametric dynamic Gd-DTPA breast images

    NASA Astrophysics Data System (ADS)

    Magri, Alphonso; Krol, Andrzej; Lipson, Edward; Mandel, James; McGraw, Wendy; Lee, Wei; Tillapaugh-Fay, Gwen; Feiglin, David

    2009-02-01

    This study was undertaken to register 3D parametric breast images derived from Gd-DTPA MR and F-18-FDG PET/CT dynamic image series. Nonlinear curve fitting (Levenburg-Marquardt algorithm) based on realistic two-compartment models was performed voxel-by-voxel separately for MR (Brix) and PET (Patlak). PET dynamic series consists of 50 frames of 1-minute duration. Each consecutive PET image was nonrigidly registered to the first frame using a finite element method and fiducial skin markers. The 12 post-contrast MR images were nonrigidly registered to the precontrast frame using a free-form deformation (FFD) method. Parametric MR images were registered to parametric PET images via CT using FFD because the first PET time frame was acquired immediately after the CT image on a PET/CT scanner and is considered registered to the CT image. We conclude that nonrigid registration of PET and MR parametric images using CT data acquired during PET/CT scan and the FFD method resulted in their improved spatial coregistration. The success of this procedure was limited due to relatively large target registration error, TRE = 15.1+/-7.7 mm, as compared to spatial resolution of PET (6-7 mm), and swirling image artifacts created in MR parametric images by the FFD. Further refinement of nonrigid registration of PET and MR parametric images is necessary to enhance visualization and integration of complex diagnostic information provided by both modalities that will lead to improved diagnostic performance.

  17. Impact of scanning parameters and breathing patterns on image quality and accuracy of tumor motion reconstruction in 4D CBCT: a phantom study.

    PubMed

    Lee, Soyoung; Yan, Guanghua; Lu, Bo; Kahler, Darren; Li, Jonathan G; Sanjiv, Samat S

    2015-11-08

    Four-dimensional, cone-beam CT (4D CBCT) substantially reduces respiration-induced motion blurring artifacts in three-dimension (3D) CBCT. However, the image quality of 4D CBCT is significantly degraded which may affect its accuracy in localizing a mobile tumor for high-precision, image-guided radiation therapy (IGRT). The purpose of this study was to investigate the impact of scanning parameters hereinafter collectively referred to as scanning sequence) and breathing patterns on the image quality and the accuracy of computed tumor trajectory for a commercial 4D CBCT system, in preparation for its clinical implementation. We simulated a series of periodic and aperiodic sinusoidal breathing patterns with a respiratory motion phantom. The aperiodic pattern was created by varying the period or amplitude of individual sinusoidal breathing cycles. 4D CBCT scans of the phantom were acquired with a manufacturer-supplied scanning sequence (4D-S-slow) and two in-house modified scanning sequences (4D-M-slow and 4D-M-fast). While 4D-S-slow used small field of view (FOV), partial rotation (200°), and no imaging filter, 4D-M-slow and 4D-M-fast used medium FOV, full rotation, and the F1 filter. The scanning speed was doubled in 4D-M-fast (100°/min gantry rotation). The image quality of the 4D CBCT scans was evaluated using contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and motion blurring ratio (MBR). The trajectory of the moving target was reconstructed by registering each phase of the 4D CBCT with a reference CT. The root-mean-squared-error (RMSE) analysis was used to quantify its accuracy. Significant decrease in CNR and SNR from 3D CBCT to 4D CBCT was observed. The 4D-S-slow and 4D-M-fast scans had comparable image quality, while the 4D-M-slow scans had better performance due to doubled projections. Both CNR and SNR decreased slightly as the breathing period increased, while no dependence on the amplitude was observed. The difference of both CNR and SNR

  18. Data Acquisition and Image Reconstruction Systems from the miniPET Scanners to the CARDIOTOM Camera

    NASA Astrophysics Data System (ADS)

    Valastván, I.; Imrek, J.; Hegyesi, G.; Molnár, J.; Novák, D.; Bone, D.; Kerek, A.

    2007-11-01

    Nuclear imaging devices play an important role in medical diagnosis as well as drug research. The first and second generation data acquisition systems and the image reconstruction library developed provide a unified hardware and software platform for the miniPET-I, miniPET-II small animal PET scanners and for the CARDIOTOM™.

  19. A small animal PET based on GAPDs and charge signal transmission approach for hybrid PET-MR imaging

    NASA Astrophysics Data System (ADS)

    Kang, Jihoon; Choi, Yong; Hong, Key Jo; Hu, Wei; Jung, Jin Ho; Huh, Yoonsuk; Kim, Byung-Tae

    2011-08-01

    Positron emission tomography (PET) employing Geiger-mode avalanche photodiodes (GAPDs) and charge signal transmission approach was developed for small animal imaging. Animal PET contained 16 LYSO and GAPD detector modules that were arranged in a 70 mm diameter ring with an axial field of view of 13 mm. The GAPDs charge output signals were transmitted to a preamplifier located remotely using 300 cm flexible flat cables. The position decoder circuits (PDCs) were used to multiplex the PET signals from 256 to 4 channels. The outputs of the PDCs were digitized and further-processed in the data acquisition unit. The cross-compatibilities of the PET detectors and MRI were assessed outside and inside the MRI. Experimental studies of the developed full ring PET were performed to examine the spatial resolution and sensitivity. Phantom and mouse images were acquired to examine the imaging performance. The mean energy and time resolution of the PET detector were 17.6% and 1.5 ns, respectively. No obvious degradation on PET and MRI was observed during simultaneous PET-MRI data acquisition. The measured spatial resolution and sensitivity at the CFOV were 2.8 mm and 0.7%, respectively. In addition, a 3 mm diameter line source was clearly resolved in the hot-sphere phantom images. The reconstructed transaxial PET images of the mouse brain and tumor displaying the glucose metabolism patterns were imaged well. These results demonstrate GAPD and the charge signal transmission approach can allow the development of high performance small animal PET with improved MR compatibility.

  20. SU-E-J-74: Impact of Respiration-Correlated Image Quality On Tumor Motion Reconstruction in 4D-CBCT: A Phantom Study

    SciTech Connect

    Lee, S; Lu, B; Samant, S

    2014-06-01

    Purpose: To investigate the effects of scanning parameters and respiratory patterns on the image quality for 4-dimensional cone-beam computed tomography(4D-CBCT) imaging, and assess the accuracy of computed tumor trajectory for lung imaging using registration of phased 4D-CBCT imaging with treatment planning-CT. Methods: We simulated a periodic and non-sinusoidal respirations with various breathing periods and amplitudes using a respiratory phantom(Quasar, Modus Medical Devices Inc) to acquire respiration-correlated 4D-CBCT images. 4D-CBCT scans(Elekta Oncology Systems Ltd) were performed with different scanning parameters for collimation size(e.g., small and medium field-of-views) and scanning speed(e.g., slow 50°·min{sup −1}, fast 100°·min{sup −1}). Using a standard CBCT-QA phantom(Catphan500, The Phantom Laboratory), the image qualities of all phases in 4D-CBCT were evaluated with contrast-to-noise ratio(CNR) for lung tissue and uniformity in each module. Using a respiratory phantom, the target imaging in 4D-CBCT was compared to 3D-CBCT target image. The target trajectory from 10-respiratory phases in 4D-CBCT was extracted using an automatic image registration and subsequently assessed the accuracy by comparing with actual motion of the target. Results: Image analysis indicated that a short respiration with a small amplitude resulted in superior CNR and uniformity. Smaller variation of CNR and uniformity was present amongst different respiratory phases. The small field-of-view with a partial scan using slow scan can improve CNR, but degraded uniformity. Large amplitude of respiration can degrade image quality. RMS of voxel densities in tumor area of 4D-CBCT images between sinusoidal and non-sinusoidal motion exhibited no significant difference. The maximum displacement errors of motion trajectories were less than 1.0 mm and 13.5 mm, for sinusoidal and non-sinusoidal breathings, respectively. The accuracy of motion reconstruction showed good overall

  1. Gallium-68 Prostate-Specific Membrane Antigen PET Imaging.

    PubMed

    Hofman, Michael S; Iravani, Amir

    2017-04-01

    The role of gallium-68 ((68)Ga) prostate-specific membrane antigen (PSMA) PET imaging is evolving and finding its place in the imaging armamentarium for prostate cancer (PCa). Despite the progress of conventional imaging strategies, significant limitations remain, including identification of small-volume disease and assessment of bone. Clinical studies have demonstrated that (68)Ga-PSMA is a promising tracer for detection of PCa metastases, even in patients with low prostate-specific antigen. To provide an accurate interpretation of (68)Ga-PSMA PET/computed tomography, nuclear medicine specialists and radiologists should be familiar with physiologic (68)Ga-PSMA uptake, common variants, patterns of locoregional and distant spread of PCa, and inherent pitfalls.

  2. Energy dependence of scatter components in multispectral PET imaging.

    PubMed

    Bentourkia, M; Msaki, P; Cadorette, J; Lecomte, R

    1995-01-01

    High resolution images in PET based on small individual detectors are obtained at the cost of low sensitivity and increased detector scatter. These limitations can be partially overcome by enlarging discrimination windows to include more low-energy events and by developing more efficient energy-dependent methods to correct for scatter radiation from all sources. The feasibility of multispectral scatter correction was assessed by decomposing response functions acquired in multiple energy windows into four basic components: object, collimator and detector scatter, and trues. The shape and intensity of these components are different and energy-dependent. They are shown to contribute to image formation in three ways: useful (true), potentially useful (detector scatter), and undesirable (object and collimator scatter) information to the image over the entire energy range. With the Sherbrooke animal PET system, restoration of detector scatter in every energy window would allow nearly 90% of all detected events to participate in image formation. These observations suggest that multispectral acquisition is a promising solution for increasing sensitivity in high resolution PET. This can be achieved without loss of image quality if energy-dependent methods are made available to preserve useful events as potentially useful events are restored and undesirable events removed.

  3. PET image reconstruction: mean, variance, and optimal minimax criterion

    NASA Astrophysics Data System (ADS)

    Liu, Huafeng; Gao, Fei; Guo, Min; Xue, Liying; Nie, Jing; Shi, Pengcheng

    2015-04-01

    Given the noise nature of positron emission tomography (PET) measurements, it is critical to know the image quality and reliability as well as expected radioactivity map (mean image) for both qualitative interpretation and quantitative analysis. While existing efforts have often been devoted to providing only the reconstructed mean image, we present a unified framework for joint estimation of the mean and corresponding variance of the radioactivity map based on an efficient optimal min-max criterion. The proposed framework formulates the PET image reconstruction problem to be a transformation from system uncertainties to estimation errors, where the minimax criterion is adopted to minimize the estimation errors with possibly maximized system uncertainties. The estimation errors, in the form of a covariance matrix, express the measurement uncertainties in a complete way. The framework is then optimized by ∞-norm optimization and solved with the corresponding H∞ filter. Unlike conventional statistical reconstruction algorithms, that rely on the statistical modeling methods of the measurement data or noise, the proposed joint estimation stands from the point of view of signal energies and can handle from imperfect statistical assumptions to even no a priori statistical assumptions. The performance and accuracy of reconstructed mean and variance images are validated using Monte Carlo simulations. Experiments on phantom scans with a small animal PET scanner and real patient scans are also conducted for assessment of clinical potential.

  4. Generalized whole-body Patlak parametric imaging for enhanced quantification in clinical PET

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Nicolas A.; Zhou, Yun; Lodge, Martin A.; Casey, Michael E.; Wahl, Richard L.; Zaidi, Habib; Rahmim, Arman

    2015-11-01

    We recently developed a dynamic multi-bed PET data acquisition framework to translate the quantitative benefits of Patlak voxel-wise analysis to the domain of routine clinical whole-body (WB) imaging. The standard Patlak (sPatlak) linear graphical analysis assumes irreversible PET tracer uptake, ignoring the effect of FDG dephosphorylation, which has been suggested by a number of PET studies. In this work: (i) a non-linear generalized Patlak (gPatlak) model is utilized, including a net efflux rate constant kloss, and (ii) a hybrid (s/g)Patlak (hPatlak) imaging technique is introduced to enhance contrast to noise ratios (CNRs) of uptake rate Ki images. Representative set of kinetic parameter values and the XCAT phantom were employed to generate realistic 4D simulation PET data, and the proposed methods were additionally evaluated on 11 WB dynamic PET patient studies. Quantitative analysis on the simulated Ki images over 2 groups of regions-of-interest (ROIs), with low (ROI A) or high (ROI B) true kloss relative to Ki, suggested superior accuracy for gPatlak. Bias of sPatlak was found to be 16-18% and 20-40% poorer than gPatlak for ROIs A and B, respectively. By contrast, gPatlak exhibited, on average, 10% higher noise than sPatlak. Meanwhile, the bias and noise levels for hPatlak always ranged between the other two methods. In general, hPatlak was seen to outperform all methods in terms of target-to-background ratio (TBR) and CNR for all ROIs. Validation on patient datasets demonstrated clinical feasibility for all Patlak methods, while TBR and CNR evaluations confirmed our simulation findings, and suggested presence of non-negligible kloss reversibility in clinical data. As such, we recommend gPatlak for highly quantitative imaging tasks, while, for tasks emphasizing lesion detectability (e.g. TBR, CNR) over quantification, or for high levels of noise, hPatlak is instead preferred. Finally, gPatlak and hPatlak CNR was systematically higher compared to routine SUV

  5. Generalized whole-body Patlak parametric imaging for enhanced quantification in clinical PET

    PubMed Central

    Zhou, Yun; Lodge, Martin A.; Casey, Michael E.; Wahl, Richard L.; Zaidi, Habib; Rahmim, Arman

    2015-01-01

    We recently developed a dynamic multi-bed PET data acquisition framework to translate the quantitative benefits of Patlak voxel-wise analysis to the domain of routine clinical whole-body (WB) imaging. The standard Patlak (sPatlak) linear graphical analysis assumes irreversible PET tracer uptake, ignoring the effect of FDG dephosphorylation, which has been suggested by a number of PET studies. In this work: (i) a non-linear generalized Patlak (gPatlak) model is utilized, including a net efflux rate constant kloss, and (ii) a hybrid (s/g)Patlak (hPatlak) imaging technique is introduced to enhance contrast to noise ratios (CNRs) of uptake rate Ki images. Representative set of kinetic parameter values and the XCAT phantom were employed to generate realistic 4D simulation PET data, and the proposed methods were additionally evaluated on 11 WB dynamic PET patient studies. Quantitative analysis on the simulated Ki images over 2 groups of regions-of-interest (ROIs), with low (ROI A) or high (ROI B) true kloss relative to Ki, suggested superior accuracy for gPatlak. Bias of sPatlak was found to be 16–18% and 20–40% poorer than gPatlak for ROIs A and B, respectively. By contrast, gPatlak exhibited, on average, 10% higher noise than sPatlak. Meanwhile, the bias and noise levels for hPatlak always ranged between the other two methods. In general, hPatlak was seen to outperform all methods in terms of target-to-background ratio (TBR) and CNR for all ROIs. Validation on patient datasets demonstrated clinical feasibility for all Patlak methods, while TBR and CNR evaluations confirmed our simulation findings, and suggested presence of non-negligible kloss reversibility in clinical data. As such, we recommend gPatlak for highly quantitative imaging tasks, while, for tasks emphasizing lesion detectability (e.g. TBR, CNR) over quantification, or for high levels of noise, hPatlak is instead preferred. Finally, gPatlak and hPatlak CNR was systematically higher compared to routine

  6. Advancement in Understanding Volcanic Processes by 4D Synchrotron X-ray Computed Microtomography Imaging of Rock Textures

    NASA Astrophysics Data System (ADS)

    Polacci, M.; Arzilli, F.; La Spina, G.

    2015-12-01

    X-ray computed microtomography (μCT) is the only high-resolution, non-destructive technique that allows visualization and processing of geomaterials directly in three-dimensions. This, together with the development of more and more sophisticated imaging techniques, have generated in the last ten years a widespread application of this methodology in Earth Sciences, from structural geology to palaeontology to igneous petrology to volcanology. Here, I will describe how X-ray μCT has contributed to advance our knowledge of volcanic processes and eruption dynamics and illustrate the first, preliminary results from 4D (space+time) X-ray microtomographic experiments of magma kinetics in basaltic systems.

  7. Automatic detection of cardiac cycle and measurement of the mitral annulus diameter in 4D TEE images

    NASA Astrophysics Data System (ADS)

    Graser, Bastian; Hien, Maximilian; Rauch, Helmut; Meinzer, Hans-Peter; Heimann, Tobias

    2012-02-01

    Mitral regurgitation is a wide spread problem. For successful surgical treatment quantification of the mitral annulus, especially its diameter, is essential. Time resolved 3D transesophageal echocardiography (TEE) is suitable for this task. Yet, manual measurement in four dimensions is extremely time consuming, which confirms the need for automatic quantification methods. The method we propose is capable of automatically detecting the cardiac cycle (systole or diastole) for each time step and measuring the mitral annulus diameter. This is done using total variation noise filtering, the graph cut segmentation algorithm and morphological operators. An evaluation took place using expert measurements on 4D TEE data of 13 patients. The cardiac cycle was detected correctly on 78% of all images and the mitral annulus diameter was measured with an average error of 3.08 mm. Its full automatic processing makes the method easy to use in the clinical workflow and it provides the surgeon with helpful information.

  8. SU-F-303-02: Achieving 4D MRI in Regular Breathing Cycle with Extended Acquisition Time of Dynamic MR Images

    SciTech Connect

    Hui, C; Beddar, S; Wen, Z; Stemkens, B; Tijssen, R; Berg, C van den

    2015-06-15

    Purpose: The purpose of this study is to develop a technique to obtain four-dimensional (4D) magnetic resonance (MR) images that are more representative of a patient’s typical breathing cycle by utilizing an extended acquisition time while minimizing the image artifacts. Methods: The 4D MR data were acquired with the balanced steady state free precession in two-dimensional sagittal plane of view. Each slice was acquired repeatedly for about 15 s, thereby obtaining multiple images at each of the 10 phases in the respiratory cycle. This improves the probability that at least one of the images were acquired at the desired phase during a regular breathing cycle. To create optimal 4D MR images, an iterative approach was used to identify the set of images that yielded the highest slice-to-slice similarity. To assess the effectiveness of the approach, the data set was truncated into periods of 7 s (50 time points), 11 s (75 time points) and the full 15 s (100 time points). The 4D MR images were then sorted with data of the three different acquisition periods for comparison. Results: In general, the 4D MR images sorted using data from longer acquisition periods showed less mismatched artifacts. In addition, the normalized cross correlation (NCC) between slices of a 4D volume increases with increased acquisition period. The average NCC was 0.791 from the 7 s period, 0.794 from the 11 s period and 0.796 from the 15 s period. Conclusion: Our preliminary study showed that extending the acquisition time with the proposed sorting technique can improve image quality and reduce artifact presence in the 4D MR images. Data acquisition over two breathing cycles is a good trade-off between artifact reduction and scan time. This research was partially funded by the the Center for Radiation Oncology Research from UT MD Anderson Cancer Center.

  9. SU-E-J-153: Reconstructing 4D Cone Beam CT Images for Clinical QA of Lung SABR Treatments

    SciTech Connect

    Beaudry, J; Bergman, A; Cropp, R

    2015-06-15

    Purpose: To verify that the planned Primary Target Volume (PTV) and Internal Gross Tumor Volume (IGTV) fully enclose a moving lung tumor volume as visualized on a pre-SABR treatment verification 4D Cone Beam CT. Methods: Daily 3DCBCT image sets were acquired immediately prior to treatment for 10 SABR lung patients using the on-board imaging system integrated into a Varian TrueBeam (v1.6: no 4DCBCT module available). Respiratory information was acquired during the scan using the Varian RPM system. The CBCT projections were sorted into 8 bins offline, both by breathing phase and amplitude, using in-house software. An iterative algorithm based on total variation minimization, implemented in the open source reconstruction toolkit (RTK), was used to reconstruct the binned projections into 4DCBCT images. The relative tumor motion was quantified by tracking the centroid of the tumor volume from each 4DCBCT image. Following CT-CBCT registration, the planning CT volumes were compared to the location of the CBCT tumor volume as it moves along its breathing trajectory. An overlap metric quantified the ability of the planned PTV and IGTV to contain the tumor volume at treatment. Results: The 4DCBCT reconstructed images visibly show the tumor motion. The mean overlap between the planned PTV (IGTV) and the 4DCBCT tumor volumes was 100% (94%), with an uncertainty of 5% from the 4DCBCT tumor volume contours. Examination of the tumor motion and overlap metric verify that the IGTV drawn at the planning stage is a good representation of the tumor location at treatment. Conclusion: It is difficult to compare GTV volumes from a 4DCBCT and a planning CT due to image quality differences. However, it was possible to conclude the GTV remained within the PTV 100% of the time thus giving the treatment staff confidence that SABR lung treatements are being delivered accurately.

  10. Hybrid PET/MR Imaging and Brain Connectivity

    PubMed Central

    Aiello, Marco; Cavaliere, Carlo; Salvatore, Marco

    2016-01-01

    In recent years, brain connectivity is gaining ever-increasing interest from the interdisciplinary research community. The study of brain connectivity is characterized by a multifaceted approach providing both structural and functional evidence of the relationship between cerebral regions at different scales. Although magnetic resonance (MR) is the most established imaging modality for investigating connectivity in vivo, the recent advent of hybrid positron emission tomography (PET)/MR scanners paved the way for more comprehensive investigation of brain organization and physiology. Due to the high sensitivity and biochemical specificity of radiotracers, combining MR with PET imaging may enrich our ability to investigate connectivity by introducing the concept of metabolic connectivity and cometomics and promoting new insights on the physiological and molecular bases underlying high-level neural organization. This review aims to describe and summarize the main methods of analysis of brain connectivity employed in MR imaging and nuclear medicine. Moreover, it will discuss practical aspects and state-of-the-art techniques for exploiting hybrid PET/MR imaging to investigate the relationship of physiological processes and brain connectivity. PMID:26973446

  11. 4-D segmentation and normalization of 3He MR images for intrasubject assessment of ventilated lung volumes

    NASA Astrophysics Data System (ADS)

    Contrella, Benjamin; Tustison, Nicholas J.; Altes, Talissa A.; Avants, Brian B.; Mugler, John P., III; de Lange, Eduard E.

    2012-03-01

    Although 3He MRI permits compelling visualization of the pulmonary air spaces, quantitation of absolute ventilation is difficult due to confounds such as field inhomogeneity and relative intensity differences between image acquisition; the latter complicating longitudinal investigations of ventilation variation with respiratory alterations. To address these potential difficulties, we present a 4-D segmentation and normalization approach for intra-subject quantitative analysis of lung hyperpolarized 3He MRI. After normalization, which combines bias correction and relative intensity scaling between longitudinal data, partitioning of the lung volume time series is performed by iterating between modeling of the combined intensity histogram as a Gaussian mixture model and modulating the spatial heterogeneity tissue class assignments through Markov random field modeling. Evaluation of the algorithm was retrospectively applied to a cohort of 10 asthmatics between 19-25 years old in which spirometry and 3He MR ventilation images were acquired both before and after respiratory exacerbation by a bronchoconstricting agent (methacholine). Acquisition was repeated under the same conditions from 7 to 467 days (mean +/- standard deviation: 185 +/- 37.2) later. Several techniques were evaluated for matching intensities between the pre and post-methacholine images with the 95th percentile value histogram matching demonstrating superior correlations with spirometry measures. Subsequent analysis evaluated segmentation parameters for assessing ventilation change in this cohort. Current findings also support previous research that areas of poor ventilation in response to bronchoconstriction are relatively consistent over time.

  12. High resolution PET breast imager with improved detection efficiency

    DOEpatents

    Majewski, Stanislaw

    2010-06-08

    A highly efficient PET breast imager for detecting lesions in the entire breast including those located close to the patient's chest wall. The breast imager includes a ring of imaging modules surrounding the imaged breast. Each imaging module includes a slant imaging light guide inserted between a gamma radiation sensor and a photodetector. The slant light guide permits the gamma radiation sensors to be placed in close proximity to the skin of the chest wall thereby extending the sensitive region of the imager to the base of the breast. Several types of photodetectors are proposed for use in the detector modules, with compact silicon photomultipliers as the preferred choice, due to its high compactness. The geometry of the detector heads and the arrangement of the detector ring significantly reduce dead regions thereby improving detection efficiency for lesions located close to the chest wall.

  13. Longitudinal Monitoring of Hepatic Blood Flow before and after TIPS by Using 4D-Flow MR Imaging

    PubMed Central

    Bannas, Peter; Roldán-Alzate, Alejandro; Johnson, Kevin M.; Woods, Michael A.; Ozkan, Orhan; Motosugi, Utaroh; Wieben, Oliver; Reeder, Scott B.; Kramer, Harald

    2016-01-01

    Purpose To demonstrate the feasibility of four-dimensional (4D)– flow magnetic resonance (MR) imaging for noninvasive longitudinal hemodynamic monitoring of hepatic blood flow before and after transjugular intrahepatic portosystemic shunt (TIPS) placement. Materials and Methods The institutional review board approved this prospective Health Insurance Portability and Accountability Act compliant study with written informed consent. Four-dimensional–flow MR imaging was performed in seven patients with portal hypertension and refractory ascites before and 2 and 12 weeks after TIPS placement by using a time-resolved three-dimensional radial phase-contrast acquisition. Flow and peak velocity measurements were obtained in the superior mesenteric vein (SMV), splenic vein (SV), portal vein (PV), and the TIPS. Flow volumes and peak velocities in each vessel, as well as the ratio of in-stent to PV flow, were compared before and after TIPS placement by using analysis of variance. Results Flow volumes significantly increased in the SMV (0.24 L/ min; 95% confidence interval [CI]: 0.07, 0.41), SV (0.31 L/min; 95% CI: 0.07, 0.54), and PV (0.88 L/min; 95% CI: 0.06, 1.70) after TIPS placement (all P < .05), with no significant difference between the first and second post-TIPS placement acquisitions (all P > .11). Ascites resolved in six of seven patients. In those with resolved ascites, the TIPS-to-PV flow ratio was 0.8 ± 6 0.2 and 0.9 ± 0.2 at the two post-TIPS time points, respectively, while the observed ratios were 4.6 and 4.3 in the patient with refractory ascites at the two post-TIPS time points, respectively. In this patient, 4D-flow MR imaging demonstrated arterio-portal-venous shunting, with draining into the TIPS. Conclusion Four-dimensional–flow MR imaging is feasible for noninvasive longitudinal hemodynamic monitoring of hepatic blood flow before and after TIPS placement. PMID:27171019

  14. LOR-interleaving image reconstruction for PET imaging with fractional-crystal collimation

    NASA Astrophysics Data System (ADS)

    Li, Yusheng; Matej, Samuel; Karp, Joel S.; Metzler, Scott D.

    2015-01-01

    Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector’s intrinsic spatial resolution. To achieve images with better spatial resolution in a central region of interest (ROI), we have previously proposed using collimation in PET scanners. The collimator is designed to partially mask detector crystals to detect lines of response (LORs) within fractional crystals. A sequence of collimator-encoded LORs is measured with different collimation configurations. This novel collimated scanner geometry makes the reconstruction problem challenging, as both detector and collimator effects need to be modeled to reconstruct high-resolution images from collimated LORs. In this paper, we present a LOR-interleaving (LORI) algorithm, which incorporates these effects and has the advantage of reusing existing reconstruction software, to reconstruct high-resolution images for PET with fractional-crystal collimation. We also develop a 3D ray-tracing model incorporating both the collimator and crystal penetration for simulations and reconstructions of the collimated PET. By registering the collimator-encoded LORs with the collimator configurations, high-resolution LORs are restored based on the modeled transfer matrices using the non-negative least-squares method and EM algorithm. The resolution-enhanced images are then reconstructed from the high-resolution LORs using the MLEM or OSEM algorithm. For validation, we applied the LORI method to a small-animal PET scanner, A-PET, with a specially designed collimator. We demonstrate through simulated reconstructions with a hot-rod phantom and MOBY phantom that the LORI reconstructions can substantially improve spatial resolution and quantification compared to the uncollimated reconstructions. The LORI algorithm is crucial to improve overall image quality of collimated PET, which

  15. LOR-interleaving image reconstruction for PET imaging with fractional-crystal collimation

    PubMed Central

    Li, Yusheng; Matej, Samuel; Karp, Joel S.; Metzler, Scott D.

    2015-01-01

    Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector’s intrinsic spatial resolution. To achieve images with better spatial resolution in a central region of interest (ROI), we have previously proposed using collimation in PET scanner. The collimator is designed to partially mask detector crystals to detect lines of response (LORs) within fractional crystals. A sequence of collimator-encoded LORs is measured with different collimation configurations. This novel collimated scanner geometry makes the reconstruction problem challenging, as both detector and collimator effects need to be modeled to reconstruct high-resolution images from collimated LORs. In this paper, we present an LOR-interleaving (LORI) algorithm, which incorporates these effects and has the advantage of reusing existing reconstruction software, to reconstruct high-resolution images for PET with fractional-crystal collimation. We also develop a 3-D ray-tracing model incorporating both the collimator and crystal penetration for simulations and reconstructions of the collimated PET. By registering the collimator-encoded LORs with the collimator configurations, high-resolution LORs are restored based on the modeled transfer matrices using the nonnegative least-squares method and EM algorithm. The resolution-enhanced images are then reconstructed from the high-resolution LORs using the MLEM or OSEM algorithm. For validation, we applied the LORI method to a small-animal PET scanner, A-PET, with a specially designed collimator. We demonstrate through simulated reconstructions with a hot-rod phantom and MOBY phantom that the LORI reconstructions can substantially improve spatial resolution and quantification compared to the uncollimated reconstructions. The LORI algorithm is crucial to improve overall image quality of collimated PET, which

  16. Simultaneous acquisition of magnetic resonance spectroscopy (MRS) data and positron emission tomography (PET) images with a prototype MR-compatible, small animal PET imager

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Velan, S. Sendhil; Lemieux, Susan; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.

    2007-06-01

    Multi-modality imaging (such as PET-CT) is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET, fused with anatomical images created by MRI, allow the correlation of form with function. Perhaps more exciting than the combination of anatomical MRI with PET, is the melding of PET with MR spectroscopy (MRS). Thus, two aspects of physiology could be combined in novel ways to produce new insights into the physiology of normal and pathological processes. Our team is developing a system to acquire MRI images and MRS spectra, and PET images contemporaneously. The prototype MR-compatible PET system consists of two opposed detector heads (appropriate in size for small animal imaging), operating in coincidence mode with an active field-of-view of ˜14 cm in diameter. Each detector consists of an array of LSO detector elements coupled through a 2-m long fiber optic light guide to a single position-sensitive photomultiplier tube. The use of light guides allows these magnetic field-sensitive elements of the PET imager to be positioned outside the strong magnetic field of our 3T MRI scanner. The PET scanner imager was integrated with a 12-cm diameter, 12-leg custom, birdcage coil. Simultaneous MRS spectra and PET images were successfully acquired from a multi-modality phantom consisting of a sphere filled with 17 brain relevant substances and a positron-emitting radionuclide. There were no significant changes in MRI or PET scanner performance when both were present in the MRI magnet bore. This successful initial test demonstrates the potential for using such a multi-modality to obtain complementary MRS and PET data.

  17. Imaging quality of (44)Sc in comparison with five other PET radionuclides using Derenzo phantoms and preclinical PET.

    PubMed

    Bunka, Maruta; Müller, Cristina; Vermeulen, Christiaan; Haller, Stephanie; Türler, Andreas; Schibli, Roger; van der Meulen, Nicholas P

    2016-04-01

    PET is the favored nuclear imaging technique because of the high sensitivity and resolution it provides, as well as the possibility for quantification of accumulated radioactivity. (44)Sc (T1/2=3.97h, Eβ(+)=632keV) was recently proposed as a potentially interesting radionuclide for PET. The aim of this study was to investigate the image quality, which can be obtained with (44)Sc, and compare it with five other, frequently employed PET nuclides using Derenzo phantoms and a small-animal PET scanner. The radionuclides were produced at the medical cyclotron at CRS, ETH Zurich ((11)C, (18)F), at the Injector II research cyclotron at CRS, PSI ((64)Cu, (89)Zr, (44)Sc), as well as via a generator system ((68)Ga). Derenzo phantoms, containing solutions of each of these radionuclides, were scanned using a GE Healthcare eXplore VISTA small-animal PET scanner. The image resolution was determined for each nuclide by analysis of the intensity signal using the reconstructed PET data of a hole diameter of 1.3mm. The image quality of (44)Sc was compared to five frequently-used PET radionuclides. In agreement with the positron range, an increasing relative resolution was determined in the sequence of (68)Ga<(44)Sc<(89)Zr<(11)C<(64)Cu<(18)F. The performance of (44)Sc was in agreement with the theoretical expectations based on the energy of the emitted positrons.

  18. Phosphoramidate-based Peptidomimetic Prostate Cancer PET Imaging Agents

    DTIC Science & Technology

    2013-07-01

    develop a PET imaging agent based on modifying the peptidomimetic PSMA inhibitor which will result in improved tumor uptake and clearance mechanism...Different fluorination approaches were attempted with PSMA module compounds such as direct labeling, cupper free chemistry and the use of...labeling approaches are established, and then the labeling of the modified PSMA inhibitor analogues will be investigated in vitro as well as in vivo. 15

  19. Phosphoramidate-based Peptidomimetic Prostate Cancer PET Imaging Agents

    DTIC Science & Technology

    2013-11-01

    goal is to develop a PET imaging agent based on modifying the peptidomimetic PSMA inhibitor which will result in improved tumor uptake and clearance...mechanism. Different fluorination approaches were attempted with PSMA module compounds such as direct labeling, cupper free chemistry and the use of...the labeling approaches are established, and then the labeling of the modified PSMA inhibitor analogues will be investigated in vitro as well as in

  20. SU-D-207-03: Development of 4D-CBCT Imaging System with Dual Source KV X-Ray Tubes

    SciTech Connect

    Nakamura, M; Ishihara, Y; Matsuo, Y; Ueki, N; Iizuka, Y; Mizowaki, T; Hiraoka, M

    2015-06-15

    Purpose: The purposes of this work are to develop 4D-CBCT imaging system with orthogonal dual source kV X-ray tubes, and to determine the imaging doses from 4D-CBCT scans. Methods: Dual source kV X-ray tubes were used for the 4D-CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infrared marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X-ray dose distributions of 4D-CBCT imaging. The kV X-ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 x 2.5 x 2.5 mm. The dose covering a 2-cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed. Results: A moving object was well identified on 4D-CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X-ray imaging subsystems, both kV X-ray fields overlapped at a part of skin surface. The D2cc for the 4D-CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D-CBCT scans. Conclusion: We have developed 4D-CBCT imaging system with dual source kV X-ray tubes. The total imaging dose with 4D-CBCT scans was up to 105.4 mGy.

  1. Prediction of CT Substitutes from MR Images Based on Local Diffeomorphic Mapping for Brain PET Attenuation Correction.

    PubMed

    Wu, Yao; Yang, Wei; Lu, Lijun; Lu, Zhentai; Zhong, Liming; Huang, Meiyan; Feng, Yanqiu; Feng, Qianjin; Chen, Wufan

    2016-10-01

    Attenuation correction is important for PET reconstruction. In PET/MR, MR intensities are not directly related to attenuation coefficients that are needed in PET imaging. The attenuation coefficient map can be derived from CT images. Therefore, prediction of CT substitutes from MR images is desired for attenuation correction in PET/MR.

  2. PET Imaging with 89Zr: From Radiochemistry to the Clinic

    PubMed Central

    Deri, Melissa A.; Zeglis, Brian M.; Francesconi, Lynn C.; Lewis, Jason S.

    2012-01-01

    The advent of antibody-based cancer therapeutics has led to the concomitant rise in the development of companion diagnostics for these therapies, particularly nuclear imaging agents. A number of radioisotopes have been employed for antibody-based PET and SPECT imaging, notably 64Cu, 124I, 111In, and 99mTc; in recent years, however, the field has increasingly focused on 89Zr, a radiometal with near ideal physical and chemical properties for immunoPET imaging. In the review at hand, we seek to provide a comprehensive portrait of the current state of 89Zr radiochemical and imaging research, including work into the production and purification of the isotope, the synthesis of new chelators, the development of new bioconjugation strategies, the creation of novel 89Zr-based agents for preclinical imaging studies, and the translation of 89Zr-labeled radiopharmaceuticals to the clinic. Particular attention will also be dedicated to emerging trends in the field, 89Zr-based imaging applications using vectors other than antibodies, the comparative advantages and limitations of 89Zr-based imaging compared to that with other isotopes, and areas that would benefit from more extensive investigation. At bottom, it is hoped that this review will provide both the experienced investigator and new scientist with a full and critical overview of this exciting and fast-developing field. PMID:22998840

  3. Quantification of Lung PET Images: Challenges and Opportunities.

    PubMed

    Chen, Delphine L; Cheriyan, Joseph; Chilvers, Edwin R; Choudhury, Gourab; Coello, Christopher; Connell, Martin; Fisk, Marie; Groves, Ashley M; Gunn, Roger N; Holman, Beverley F; Hutton, Brian F; Lee, Sarah; MacNee, William; Mohan, Divya; Parr, David; Subramanian, Deepak; Tal-Singer, Ruth; Thielemans, Kris; van Beek, Edwin J R; Vass, Laurence; Wellen, Jeremy W; Wilkinson, Ian; Wilson, Frederick J

    2017-02-01

    Millions of people are affected by respiratory diseases, leading to a significant health burden globally. Because of the current insufficient knowledge of the underlying mechanisms that lead to the development and progression of respiratory diseases, treatment options remain limited. To overcome this limitation and understand the associated molecular changes, noninvasive imaging techniques such as PET and SPECT have been explored for biomarker development, with (18)F-FDG PET imaging being the most studied. The quantification of pulmonary molecular imaging data remains challenging because of variations in tissue, air, blood, and water fractions within the lungs. The proportions of these components further differ depending on the lung disease. Therefore, different quantification approaches have been proposed to address these variabilities. However, no standardized approach has been developed to date. This article reviews the data evaluating (18)F-FDG PET quantification approaches in lung diseases, focusing on methods to account for variations in lung components and the interpretation of the derived parameters. The diseases reviewed include acute respiratory distress syndrome, chronic obstructive pulmonary disease, and interstitial lung diseases such as idiopathic pulmonary fibrosis. Based on review of prior literature, ongoing research, and discussions among the authors, suggested considerations are presented to assist with the interpretation of the derived parameters from these approaches and the design of future studies.

  4. Image reconstruction for PET/CT scanners: past achievements and future challenges

    PubMed Central

    Tong, Shan; Alessio, Adam M; Kinahan, Paul E

    2011-01-01

    PET is a medical imaging modality with proven clinical value for disease diagnosis and treatment monitoring. The integration of PET and CT on modern scanners provides a synergy of the two imaging modalities. Through different mathematical algorithms, PET data can be reconstructed into the spatial distribution of the injected radiotracer. With dynamic imaging, kinetic parameters of specific biological processes can also be determined. Numerous efforts have been devoted to the development of PET image reconstruction methods over the last four decades, encompassing analytic and iterative reconstruction methods. This article provides an overview of the commonly used methods. Current challenges in PET image reconstruction include more accurate quantitation, TOF imaging, system modeling, motion correction and dynamic reconstruction. Advances in these aspects could enhance the use of PET/CT imaging in patient care and in clinical research studies of pathophysiology and therapeutic interventions. PMID:21339831

  5. Performance evaluation of the microPET P4: a PET system dedicated to animal imaging

    NASA Astrophysics Data System (ADS)

    Tai, Y. C.; Chatziioannou, A.; Siegel, S.; Young, J.; Newport, D.; Goble, R. N.; Nutt, R. E.; Cherry, S. R.

    2001-07-01

    The microPET Primate 4-ring system (P4) is an animal PET tomograph with a 7.8 cm axial extent, a 19 cm diameter transaxial field of view (FOV) and a 22 cm animal port. The system is composed of 168 detector modules, each with an 8×8 array of 2.2×2.2×10 mm3 lutetium oxyorthosilicate crystals, arranged as 32 crystal rings 26 cm in diameter. The detector crystals are coupled to a Hamamatsu R5900-C8 PS-PMT via a 10 cm long optical fibre bundle. The detectors have a timing resolution of 3.2 ns, an average energy resolution of 26%, and an average intrinsic spatial resolution of 1.75 mm. The system operates in 3D mode without inter-plane septa, acquiring data in list mode. The reconstructed image spatial resolution ranges from 1.8 mm at the centre to 3 mm at 4 cm radial offset. The tomograph has a peak system sensitivity of 2.25% at the centre of the FOV with a 250-750 keV energy window. The noise equivalent count rate peaks at 100-290 kcps for representative object sizes. Images from two phantoms and three different types of laboratory animal demonstrate the advantage of the P4 system over the original prototype microPET, including its threefold improvement in sensitivity and a large axial FOV sufficient to image an entire mouse in a single bed position.

  6. Optimizing modelling in iterative image reconstruction for preclinical pinhole PET

    NASA Astrophysics Data System (ADS)

    Goorden, Marlies C.; van Roosmalen, Jarno; van der Have, Frans; Beekman, Freek J.

    2016-05-01

    The recently developed versatile emission computed tomography (VECTor) technology enables high-energy SPECT and simultaneous SPECT and PET of small animals at sub-mm resolutions. VECTor uses dedicated clustered pinhole collimators mounted in a scanner with three stationary large-area NaI(Tl) gamma detectors. Here, we develop and validate dedicated image reconstruction methods that compensate for image degradation by incorporating accurate models for the transport of high-energy annihilation gamma photons. Ray tracing software was used to calculate photon transport through the collimator structures and into the gamma detector. Input to this code are several geometric parameters estimated from system calibration with a scanning 99mTc point source. Effects on reconstructed images of (i) modelling variable depth-of-interaction (DOI) in the detector, (ii) incorporating photon paths that go through multiple pinholes (‘multiple-pinhole paths’ (MPP)), and (iii) including various amounts of point spread function (PSF) tail were evaluated. Imaging 18F in resolution and uniformity phantoms showed that including large parts of PSFs is essential to obtain good contrast-noise characteristics and that DOI modelling is highly effective in removing deformations of small structures, together leading to 0.75 mm resolution PET images of a hot-rod Derenzo phantom. Moreover, MPP modelling reduced the level of background noise. These improvements were also clearly visible in mouse images. Performance of VECTor can thus be significantly improved by accurately modelling annihilation gamma photon transport.

  7. SU-D-201-06: Random Walk Algorithm Seed Localization Parameters in Lung Positron Emission Tomography (PET) Images

    SciTech Connect

    Soufi, M; Asl, A Kamali; Geramifar, P

    2015-06-15

    Purpose: The objective of this study was to find the best seed localization parameters in random walk algorithm application to lung tumor delineation in Positron Emission Tomography (PET) images. Methods: PET images suffer from statistical noise and therefore tumor delineation in these images is a challenging task. Random walk algorithm, a graph based image segmentation technique, has reliable image noise robustness. Also its fast computation and fast editing characteristics make it powerful for clinical purposes. We implemented the random walk algorithm using MATLAB codes. The validation and verification of the algorithm have been done by 4D-NCAT phantom with spherical lung lesions in different diameters from 20 to 90 mm (with incremental steps of 10 mm) and different tumor to background ratios of 4:1 and 8:1. STIR (Software for Tomographic Image Reconstruction) has been applied to reconstruct the phantom PET images with different pixel sizes of 2×2×2 and 4×4×4 mm{sup 3}. For seed localization, we selected pixels with different maximum Standardized Uptake Value (SUVmax) percentages, at least (70%, 80%, 90% and 100%) SUVmax for foreground seeds and up to (20% to 55%, 5% increment) SUVmax for background seeds. Also, for investigation of algorithm performance on clinical data, 19 patients with lung tumor were studied. The resulted contours from algorithm have been compared with nuclear medicine expert manual contouring as ground truth. Results: Phantom and clinical lesion segmentation have shown that the best segmentation results obtained by selecting the pixels with at least 70% SUVmax as foreground seeds and pixels up to 30% SUVmax as background seeds respectively. The mean Dice Similarity Coefficient of 94% ± 5% (83% ± 6%) and mean Hausdorff Distance of 1 (2) pixels have been obtained for phantom (clinical) study. Conclusion: The accurate results of random walk algorithm in PET image segmentation assure its application for radiation treatment planning and

  8. PET/SPECT imaging agents for neurodegenerative diseases

    PubMed Central

    Zhu, Lin; Ploessl, Karl; Kung, Hank F.

    2014-01-01

    Single photon emission computed tomography (SPECT) or positron emission computed tomography (PET) imaging agents for neurodegenerative disease have a significant impact on clinical diagnosis and patient care. The examples of Parkinson’s Disease (PD) and Alzheimer’s Disease (AD) imaging agents described in this paper provide a general view on how imaging agents, ie radioactive drugs, are selected, chemically prepared and applied in humans. Imaging the living human brain can provide unique information on the pathology and progression of neurodegenerative diseases, such as AD and PD. The imaging method will also facilitate preclinical and clinical trials of new drugs offering specific information related to drug binding sites in the brain. In the future, chemists will continue to play important roles in identifying specific targets, synthesizing target-specific probes for screening and ultimately testing them by in vitro and in vivo assays. PMID:24676152

  9. An MR image-guided, voxel-based partial volume correction method for PET images

    PubMed Central

    Wang, Hesheng; Fei, Baowei

    2012-01-01

    Purpose: Partial volume effect in positron emission tomography (PET) can cause incorrect quantification of radiopharmaceutical uptake in functional imaging. A PET partial volume correction method is presented to attenuate partial volume blurring and to yield voxel-based corrected PET images. Methods: By modeling partial volume effect as a convolution of point spread function of the PET scanner, the reconstructed PET images are corrected by iterative deconvolution with an edge-preserving smoothness constraint. The constraint is constructed to restore discontinuities extracted from coregistered MR images but maintains the smoothness in radioactivity distribution. The correction is implemented in a Bayesian deconvolution framework and is solved by a conjugate gradient method. The performance of the method was compared with the geometric transfer matrix (GTM) method on a simulated dataset. The method was evaluated on synthesized brain FDG–PET data and phantom MRI–PET experiments. Results: The true PET activity of objects with a size of greater than the full-width at half maximum of the point spread function has been effectively restored in the simulated data. The partial volume correction method is quantitatively comparable to the GTM method. For synthesized FDG–PET with true activity 0 μci/cc for cerebrospinal fluid (CSF), 228 μci/cc for white matter (WM), and 621 μci/cc for gray matter (GM), the method has improved the radioactivity quantification from 186 ± 16 μci/cc to 30 ± 7 μci/cc in CSF, 317 ± 15 μci/cc to 236 ± 10 μci/cc for WM, 438 ± 4 μci/cc to 592 ± 5 μci/cc for GM. Both visual and quantitative assessments show improvement of partial volume correction in the synthesized and phantom experiments. Conclusions: The partial volume correction method improves the quantification of PET images. The method is comparable to the GTM method but does not need MR image segmentation or prior tracer distribution information. The

  10. Microfluidics for Positron Emission Tomography (PET) Imaging Probe Development

    PubMed Central

    Wang, Ming-Wei; Lin, Wei-Yu; Liu, Kan; Masterman-Smith, Michael; Shen, Clifton Kwang-Fu

    2012-01-01

    Due to increased needs for Positron Emission Tomography (PET) scanning, high demands for a wide variety of radiolabeled compounds will have to be met by exploiting novel radiochemistry and engineering technologies to improve the production and development of PET probes. The application of microfluidic reactors to perform radiosyntheses is currently attracting a great deal of interest because of their potential to deliver many advantages over conventional labeling systems. Microfluidic-based radiochemistry can lead to the use of smaller quantities of precursors, accelerated reaction rates and easier purification processes with greater yield and higher specific activity of desired probes. Several ‘proof-of-principle’ examples, along with basics of device architecture and operation, and potential limitations of each design are discussed here. Along with the concept of radioisotope distribution from centralized cyclotron facilities to individual imaging centers and laboratories (“decentralized model”), an easy-to-use, standalone, flexible, fully-automated radiochemical microfluidic platform can open up to simpler and more cost-effective procedures for molecular imaging using PET. PMID:20643021

  11. Monte Carlo simulation of PET and SPECT imaging of {sup 90}Y

    SciTech Connect

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

    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 quantitatively 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

  12. Pretargeted PET Imaging Using a Site-Specifically Labeled Immunoconjugate.

    PubMed

    Cook, Brendon E; Adumeau, Pierre; Membreno, Rosemery; Carnazza, Kathryn E; Brand, Christian; Reiner, Thomas; Agnew, Brian J; Lewis, Jason S; Zeglis, Brian M

    2016-08-17

    In recent years, both site-specific bioconjugation techniques and bioorthogonal pretargeting strategies have emerged as exciting technologies with the potential to improve the safety and efficacy of antibody-based nuclear imaging. In the work at hand, we have combined these two approaches to create a pretargeted PET imaging strategy based on the rapid and bioorthogonal inverse electron demand Diels-Alder reaction between a (64)Cu-labeled tetrazine radioligand ((64)Cu-Tz-SarAr) and a site-specifically modified huA33-trans-cyclooctene immunoconjugate ((ss)huA33-PEG12-TCO). A bioconjugation strategy that harnesses enzymatic transformations and strain-promoted azide-alkyne click chemistry was used to site-specifically append PEGylated TCO moieties to the heavy chain glycans of the colorectal cancer-targeting huA33 antibody. Preclinical in vivo validation studies were performed in athymic nude mice bearing A33 antigen-expressing SW1222 human colorectal carcinoma xenografts. To this end, mice were administered (ss)huA33-PEG12-TCO via tail vein injection and-following accumulation intervals of 24 or 48 h-(64)Cu-Tz-SarAr. PET imaging and biodistribution studies reveal that this strategy clearly delineates tumor tissue as early as 1 h post-injection (6.7 ± 1.7%ID/g at 1 h p.i.), producing images with excellent contrast and high tumor-to-background activity concentration ratios (tumor:muscle = 21.5 ± 5.6 at 24 h p.i.). Furthermore, dosimetric calculations illustrate that this pretargeting approach produces only a fraction of the overall effective dose (0.0214 mSv/MBq; 0.079 rem/mCi) of directly labeled radioimmunoconjugates. Ultimately, this method effectively facilitates the high contrast pretargeted PET imaging of colorectal carcinoma using a site-specifically modified immunoconjugate.

  13. Investigation of optimization-based reconstruction with an image-total-variation constraint in PET

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Ye, Jinghan; Chen, Buxin; Perkins, Amy E.; Rose, Sean; Sidky, Emil Y.; Kao, Chien-Min; Xia, Dan; Tung, Chi-Hua; Pan, Xiaochuan

    2016-08-01

    Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations. Specifically, given an image-total-variation (TV) constraint, we investigated how the selection of different data divergences and associated parameters impacts the optimization-based reconstruction of PET images. The reconstruction robustness was explored also with respect to different data conditions and activity up-takes of practical relevance. A study was conducted particularly for image reconstruction from data collected by use of a PET configuration with sparsely populated detectors. Overall, the study demonstrates the robustness of the TV-constrained, optimization-based reconstruction for considerably different data conditions in PET imaging, as well as its potential to enable PET configurations with reduced numbers of detectors. Insights gained in the study may be exploited for developing algorithms for PET-image reconstruction and for enabling PET-configuration design of practical usefulness in preclinical and clinical applications.

  14. NEMA NU 4-2008 Comparison of Preclinical PET Imaging Systems

    PubMed Central

    Goertzen, Andrew L.; Bao, Qinan; Bergeron, Mélanie; Blankemeyer, Eric; Blinder, Stephan; Cañadas, Mario; Chatziioannou, Arion F.; Dinelle, Katherine; Elhami, Esmat; Jans, Hans-Sonke; Lage, Eduardo; Lecomte, Roger; Sossi, Vesna; Surti, Suleman; Tai, Yuan-Chuan; Vaquero, Juan José; Vicente, Esther; Williams, Darin A.; Laforest, Richard

    2014-01-01

    The National Electrical Manufacturers Association (NEMA) standard NU 4-2008 for performance measurements of small-animal tomographs was recently published. Before this standard, there were no standard testing procedures for preclinical PET systems, and manufacturers could not provide clear specifications similar to those available for clinical systems under NEMA NU 2-1994 and 2-2001. Consequently, performance evaluation papers used methods that were modified ad hoc from the clinical PET NEMA standard, thus making comparisons between systems difficult. Methods We acquired NEMA NU 4-2008 performance data for a collection of commercial animal PET systems manufactured since 2000: micro- PET P4, microPET R4, microPET Focus 120, microPET Focus 220, Inveon, ClearPET, Mosaic HP, Argus (formerly eXplore Vista), VrPET, LabPET 8, and LabPET 12. The data included spatial resolution, counting-rate performance, scatter fraction, sensitivity, and image quality and were acquired using settings for routine PET. Results The data showed a steady improvement in system performance for newer systems as compared with first-generation systems, with notable improvements in spatial resolution and sensitivity. Conclusion Variation in system design makes direct comparisons between systems from different vendors difficult. When considering the results from NEMA testing, one must also consider the suitability of the PET system for the specific imaging task at hand. PMID:22699999

  15. Bimodal Thrombus Imaging: Simultaneous PET/MR Imaging with a Fibrin-targeted Dual PET/MR Probe—Feasibility Study in Rat Model

    PubMed Central

    Uppal, Ritika; Catana, Ciprian; Ay, Ilknur; Benner, Thomas; Sorensen, A. Gregory

    2011-01-01

    Purpose: To image thrombus by using magnetic resonance (MR) imaging and positron emission tomography (PET) simultaneously in a rat arterial thrombus model with a dual PET/MR probe. Materials and Methods: Animal studies were approved by the institutional animal use committee. A dual PET/MR probe was synthesized by means of partial exchange of gadolinium for copper 64 (64Cu) in the fibrin-targeted MR probe EP-2104R. A preformed 25-mm thrombus was injected into the right internal carotid artery of a rat. Imaging was performed with a clinical 3.0-T MR imager with an MR-compatible human PET imager. Rats (n = 5) were imaged prior to and after systemic administration of the dual probe by using simultaneous PET/MR. The organ distribution of 64Cu and gadolinium was determined ex vivo (n = 8), 2 hours after injection by using well counting and inductively coupled plasma mass spectrometry, respectively. Signal intensity ratios (SIRs) between the thrombus-containing and contralateral vessel were computed from PET images and MR data before and after probe administration. Results: The dual probe was synthesized with greater than 98% radiochemical purity. Thrombus enhancement was observed in all five animals at both MR (SIR[postprobe]/SIR[preprobe] = 1.71 ± 0.35, P = .0053) and PET (SIR = 1.85 ± 0.48, P = .0087) after injection of the dual PET/MR probe. Ex vivo analysis at 2 hours after injection showed the highest 64Cu and gadolinium concentrations, after the excretory organs (kidney and liver), to be in the thrombus. Conclusion: A fibrin-targeted dual PET/MR probe enables simultaneous, direct MR and PET imaging of thrombus. © RSNA, 2010 PMID:21177389

  16. PET imaging of dopamine receptors in MPTP-induced parkinsonism

    SciTech Connect

    Larson, S.M.; DiChiro, G.; Burns, R.S.; Dannals, R.F.; Kopin, I.J.; Brooks, R.A.; Kessler, R.M.; Wagner, R.F.; Eckelman, W.C.; Margolin, R.A.

    1984-01-01

    MPTP(N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induces parkinsonism in animals and man by selectively destroying dopaminergic neurons in the pars compacta of the substantia nigra. The postsynaptic neurons (and presumably the dopamine receptors) are intact. The authors have imaged dopamine receptors in a patient with MPTP induced parkinsonism, using /sup 11/CMS (3-N(/sup 11/C) methylspiperone. Seven and 9 mCi's, respectively, were injected at one week intervals while the patient was first off, and then on, L-dopa. As measured by NeuroPET (NIH), putamen to cerebellum concentration ratios rose progressively to 5.5:1, by 90 min. after injection. At this time the concentration of /sup 11/CMS was 10 picomole/cc (off L-dopa), and 14 picomole/cc (on L-dopa). The Duvoisin scale was used to assess the severity of the patient's parkinsonism immediately prior and at the end of PET imaging. On both occasions, despite the small mass amount of /sup 11/CMS injected, (1.1 g/kg), a transient worsening of symptoms was seen. The effect of L-Dopa was almost completely reversed by the /sup 11/CMS. In contrast, off L-Dopa the patients severe basal state was worsened only slightly. The PET scans suggested that dopamine receptors are not reduced in MPTP-induced parkinsonism. The findings were consistent with the hypotheses that PET may identify patients who will benefit from L-Dopa, and that expression of parkinsonian symptoms reflects desaturation of dopamine receptors in striatum.

  17. MR-based motion correction for PET imaging using wired active MR microcoils in simultaneous PET-MR: Phantom study

    SciTech Connect

    Huang, Chuan; Brady, Thomas J.; El Fakhri, Georges; Ouyang, Jinsong; Ackerman, Jerome L.; Petibon, Yoann

    2014-04-15

    Purpose: Artifacts caused by head motion present a major challenge in brain positron emission tomography (PET) imaging. The authors investigated the feasibility of using wired active MR microcoils to track head motion and incorporate the measured rigid motion fields into iterative PET reconstruction. Methods: Several wired active MR microcoils and a dedicated MR coil-tracking sequence were developed. The microcoils were attached to the outer surface of an anthropomorphic{sup 18}F-filled Hoffman phantom to mimic a brain PET scan. Complex rotation/translation motion of the phantom was induced by a balloon, which was connected to a ventilator. PET list-mode and MR tracking data were acquired simultaneously on a PET-MR scanner. The acquired dynamic PET data were reconstructed iteratively with and without motion correction. Additionally, static phantom data were acquired and used as the gold standard. Results: Motion artifacts in PET images were effectively removed by wired active MR microcoil based motion correction. Motion correction yielded an activity concentration bias ranging from −0.6% to 3.4% as compared to a bias ranging from −25.0% to 16.6% if no motion correction was applied. The contrast recovery values were improved by 37%–156% with motion correction as compared to no motion correction. The image correlation (mean ± standard deviation) between the motion corrected (uncorrected) images of 20 independent noise realizations and static reference was R{sup 2} = 0.978 ± 0.007 (0.588 ± 0.010, respectively). Conclusions: Wired active MR microcoil based motion correction significantly improves brain PET quantitative accuracy and image contrast.

  18. Comparison between two super-resolution implementations in PET imaging.

    PubMed

    Chang, Guoping; Pan, Tinsu; Qiao, Feng; Clark, John W; Mawlawi, Osama R

    2009-04-01

    Super-resolution (SR) techniques are used in PET imaging to generate a high-resolution image by combining multiple low-resolution images that have been acquired from different points of view (POV). In this article, the authors propose a novel implementation of the SR technique whereby the required multiple low-resolution images are generated by shifting the reconstruction pixel grid during the image reconstruction process rather than being acquired from different POVs. The objective of this article is to compare the performances of the two SR implementations using theoretical and experimental studies. A mathematical framework is first provided to support the hypothesis that the two SR implementations have similar performance in current PET/CT scanners that use block detectors. Based on this framework, a simulation study, a point source study, and a NEMA/IEC phantom study were conducted to compare the performance of these two SR implementations with respect to contrast, resolution, noise, and SNR. For reference purposes, a comparison with a native reconstruction (NR) image using a high-resolution pixel grid was also performed. The mathematical framework showed that the two SR implementations are expected to achieve similar contrast and resolution but different noise contents. These results were confirmed by the simulation and experimental studies. The simulation study showed that the two SR implementations have an average contrast difference of 2.3%, while the point source study showed that their average differences in contrast and resolution were 0.5% and 1.2%, respectively. Comparisons between the SR and NR images for the point source study showed that the NR image exhibited averages of 30% and 8% lower contrast and resolution, respectively. The NEMA/IEC phantom study showed that the three images (two SR and NR) exhibited different noise structures. The SNR of the new SR implementation was, on average, 21.5% lower than the original implementation largely due to an

  19. Venous and Arterial Flow Quantification, are Equally Accurate and Precise with Parallel Imaging Compressed Sensing 4D Phase Contrast MRI

    PubMed Central

    Tariq, Umar; Hsiao, Albert; Alley, Marcus; Zhang, Tao; Lustig, Michael; Vasanawala, Shreyas S.

    2012-01-01

    Purpose To evaluate precision and accuracy of parallel-imaging compressed-sensing 4D phase contrast (PICS-4DPC) MRI venous flow quantification in children with patients referred for cardiac MRI at our children’s hospital. Materials and Methods With IRB approval and HIPAA compliance, 22 consecutive patients without shunts underwent 4DPC as part of clinical cardiac MRI examinations. Flow measurements were obtained in the superior and inferior vena cava, ascending and descending aorta and the pulmonary trunk. Conservation of flow to the upper, lower and whole body was used as an internal physiologic control. The arterial and venous flow rates at each location were compared with paired t-tests and F-tests to assess relative accuracy and precision. RESULTS Arterial and venous flow measurements were strongly correlated for the upper (ρ=0.89), lower (ρ=0.96) and whole body (ρ=0.97); net aortic and pulmonary trunk flow rates were also tightly correlated (ρ=0.97). There was no significant difference in the value or precision of arterial and venous flow measurements in upper, lower or whole body, though there was a trend toward improved precision with lower velocity-encoding settings. Conclusion With PICS-4DPC MRI, the accuracy and precision of venous flow quantification are comparable to that of arterial flow quantification at velocity-encodings appropriate for arterial vessels. PMID:23172846

  20. RGD-based PET tracers for imaging receptor integrin αv β3 expression.

    PubMed

    Cai, Hancheng; Conti, Peter S

    2013-05-15

    Positron emission tomography (PET) imaging of receptor integrin αv β3 expression may play a key role in the early detection of cancer and cardiovascular diseases, monitoring disease progression, evaluating therapeutic response, and aiding anti-angiogenic drugs discovery and development. The last decade has seen the development of new PET tracers for in vivo imaging of integrin αv β3 expression along with advances in PET chemistry. In this review, we will focus on the radiochemistry development of PET tracers based on arginine-glycine-aspartic acid (RGD) peptide, present an overview of general strategies for preparing RGD-based PET tracers, and review the recent advances in preparations of (18) F-labeled, (64) Cu-labeled, and (68) Ga-labeled RGD tracers, RGD-based PET multivalent probes, and RGD-based PET multimodality probes for imaging receptor integrin αv β3 expression.

  1. Iodine-124 as a label for pharmacological PET imaging.

    PubMed

    Belov, Vasily V; Bonab, Ali A; Fischman, Alan J; Heartlein, Michael; Calias, Pericles; Papisov, Mikhail I

    2011-06-06

    With the growing number of biotechnology products and drug delivery systems entering preclinical and clinical studies, pharmacological imaging studies with PET play an increasingly significant role. Such studies often require investigation of slow and complex pharmacokinetics (PK). This suggests labeling of the drug candidate with radionuclides that have long physical half-lives. Among the currently available PET positron emitters, ¹²⁴I has the longest physical half-life (4.2 days). This, combined with the well-investigated behavior of iodine in vivo, makes ¹²⁴I very attractive for pharmacological studies. However, the high energy of the positrons emitted by ¹²⁴I and the presence of single photons in the ¹²⁴I emission can potentially introduce limitations in the quantitative analysis of the images. The objective of this research was to determine whether the use of ¹²⁴I as a PET label provides data quality suitable for PK studies. The study was carried out using MicroPET P4 scanner (Siemens/Concorde Microsystems). Spatial resolution, count-rate performance, sensitivity and scatter fraction were measured using a line source and a cylindrical phantom. Model animal studies in rats and cynomolgus monkeys were carried out using human recombinant proteins. The proteins were labeled with ¹²⁴I, up to 185 MBq/mg. The transaxial and axial spatial resolutions in the center of the camera were satisfactory and higher for OSEM3D/MAP than FORE-2DFBP (FWHM 2.52 vs 3.31 mm, and 3.10 vs 3.69 mm). Linearity of the true coincidence count-rate was observed up to 44 MBq. Animal studies demonstrated excellent delineation and resolution of even very small organs. At optimal doses, 2-10 MBq per animal for rodents and 4-10 MBq per kg of body weight for larger animals, the quality of numerical data was appropriate for PK analysis in all experimental timeframes from minutes (dynamic studies) to 10 days. Overall, the data suggest that ¹²⁴I is an excellent label for

  2. PET Radiotracers for Imaging the Proliferative Status of Solid Tumors

    PubMed Central

    Mach, Robert H.; Dehdashti, Farrokh; Wheeler, Kenneth T.

    2009-01-01

    Synopsis Two different strategies have been developed for imaging the proliferative status of solid tumors with the functional imaging technique, Positron Emission Tomography (PET). The first strategy uses carbon-11 labeled thymidine and/or, more recently, fluorine-18 labeled thymidine analogs. These agents are a substrate for the enzyme thymidine kinase-1 (TK-1) and provide a pulse label of the number of cells in S phase. The second method for imaging the proliferative status of a tumor uses radiolabeled ligands that bind to the sigma-2 receptor which has a 10-fold higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells. This article compares and contrasts the two different strategies for imaging the proliferative status of solid tumors, and describes the strengths and weaknesses of each approach. PMID:20046891

  3. SU-E-J-28: Gantry Speed Significantly Affects Image Quality and Imaging Dose for 4D Cone-Beam Computed Tomography On the Varian Edge Platform

    SciTech Connect

    Santoso, A; Song, K; Gardner, S; Chetty, I; Wen, N

    2015-06-15

    Purpose: 4D-CBCT facilitates assessment of tumor motion at treatment position. We investigated the effect of gantry speed on 4D-CBCT image quality and dose using the Varian Edge On-Board Imager (OBI). Methods: A thoracic protocol was designed using a 125 kVp spectrum. Image quality parameters were obtained via 4D acquisition using a Catphan phantom with a gating system. A sinusoidal waveform was executed with a five second period and superior-inferior motion. 4D-CBCT scans were sorted into 4 and 10 phases. Image quality metrics included spatial resolution, contrast-to-noise ratio (CNR), uniformity index (UI), Hounsfield unit (HU) sensitivity, and RMS error (RMSE) of motion amplitude. Dosimetry was accomplished using Gafchromic XR-QA2 films within a CIRS Thorax phantom. This was placed on the gating phantom using the same motion waveform. Results: High contrast resolution decreased linearly from 5.93 to 4.18 lp/cm, 6.54 to 4.18 lp/cm, and 5.19 to 3.91 lp/cm for averaged, 4 phase, and 10 phase 4DCBCT volumes respectively as gantry speed increased from 1.0 to 6.0 degs/sec. CNRs decreased linearly from 4.80 to 1.82 as the gantry speed increased from 1.0 to 6.0 degs/sec, respectively. No significant variations in UIs, HU sensitivities, or RMSEs were observed with variable gantry speed. Ion chamber measurements compared to film yielded small percent differences in plastic water regions (0.1–9.6%), larger percent differences in lung equivalent regions (7.5–34.8%), and significantly larger percent differences in bone equivalent regions (119.1–137.3%). Ion chamber measurements decreased from 17.29 to 2.89 cGy with increasing gantry speed from 1.0 to 6.0 degs/sec. Conclusion: Maintaining technique factors while changing gantry speed changes the number of projections used for reconstruction. Increasing the number of projections by decreasing gantry speed decreases noise, however, dose is increased. The future of 4DCBCT’s clinical utility relies on further

  4. Physiological imaging with PET and SPECT in Dementia

    SciTech Connect

    Jagust, W.J. . Dept. of Neurology Lawrence Berkeley Lab., CA )

    1989-10-01

    Dementia is a medical problem of increasingly obvious importance. The most common cause of dementia, Alzheimer's disease (AD) accounts for at least 50% of all cases of dementia, with multi-infarct dementia the next most common cause of the syndrome. While the accuracy of diagnosis of AD may range from 80 to 90%, there is currently no laboratory test to confirm the diagnosis. Functional imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) offer diagnostic advantages since brain function is unequivocally disturbed in all dementing illnesses. Both PET and SPECT have been utilized in the study of dementia. While both techniques rely on principles of emission tomography to produce three dimensional maps of injected radiotracers, the differences between positron and single photon emission have important consequences for the practical applications of the two procedures. This briefly reviews the technical differences between PET and SPECT, and discusses how both techniques have been used in our laboratory to elucidate the pathophysiology of dementia. 32 refs., 2 figs.

  5. Detector Technologies for Sub-500um High-Sensitivity PET Imaging via a Novel PET Insert Approach

    SciTech Connect

    Tai, Yuan-Chuan

    2011-12-21

    The objective of this project was to develop detector technologies that would enable an ultrahigh resolution Virtual Pinhole (VP) PET insert device to provide sub-500 um resolution high-sensitivity PET imaging of a mouse in the future. To achieve this goal, we proposed to develop and characterize finely pixellated cadmium zinc telluride (CZT) detectors and the associated readout electronics with the following specific aims: 1. Develop pixellated CZT detectors with 350um pitches using 2-5 mm substrates; characterize their spatial, energy and timing performance through experiments; and optimize the anode design with steering grid if found necessary. 2. Develop a high-bandwidth readout system using a novel ASIC that can be directly bonded to CZT detectors with 2048 anodes of 350um pitches; optimize its overall performance for VP-PET applications considering the tradeoffs between spatial resolution (in 3D), count rate capability, timing and energy resolutions. 3. Evaluate the performance of a VP-PET insert based on the proposed detector technology through Monte Carlo simulation and experimental validation. Overall, we have completed all three specific aims and demonstrated that pixelated CZT detectors of 350um pitches, combined with VP-PET geometry, can provide PET image resolution of ~460 um FWHM for small animal imaging applications.

  6. MO-FG-207-00: Technological Advances in PET/MR Imaging

    SciTech Connect

    2015-06-15

    The use of integrated PET/MRI systems in clinical applications can best benefit from understanding their technological advances and limitations. The currently available clinical PET/MRI systems have their own characteristics. Thorough analyses of existing technical data and evaluation of necessary performance metrics for quality assurances could be conducted to optimize application-specific PET/MRI protocols. This Symposium will focus on technical advances and limitations of clinical PET/MRI systems, and how this exciting imaging modality can be utilized in applications that can benefit from both PET and MRI. Learning Objectives: To understand the technological advances of clinical PET/MRI systems To correctly identify clinical applications that can benefit from PET/MRI To understand ongoing work to further improve the current PET/MRI technology Floris Jansen is a GE Healthcare employee.

  7. Comparison of Imaging Characteristics of (124)I PET for Determination of Optimal Energy Window on the Siemens Inveon PET.

    PubMed

    Yu, A Ram; Kim, Hee-Joung; Lim, Sang Moo; Kim, Jin Su

    2016-01-01

    Purpose. (124)I has a half-life of 4.2 days, which makes it suitable for imaging over several days over its uptake and washout phases. However, it has a low positron branching ratio (23%), because of prompt gamma coincidence due to high-energy γ-photons (602 to 1,691 keV), which are emitted in cascade with positrons. Methods. In this study, we investigated the optimal PET energy window for (124)I PET based on image characteristics of reconstructed PET. Image characteristics such as nonuniformities, recovery coefficients (RCs), and the spillover ratios (SORs) of (124)I were measured as described in NEMA NU 4-2008 standards. Results. The maximum and minimum prompt gamma coincidence fraction (PGF) were 33% and 2% in 350~800 and 400~590 keV, respectively. The difference between best and worst uniformity in the various energy windows was less than 1%. The lowest SORs of (124)I were obtained at 350~750 keV in nonradioactive water compartment. Conclusion. Optimal energy window should be determined based on image characteristics. Our developed correction method would be useful for the correction of high-energy prompt gamma photon in (124)I PET. In terms of the image quality of (124)I PET, our findings indicate that an energy window of 350~750 keV would be optimal.

  8. Imaging performance of LabPET APD-based digital PET scanners for pre-clinical research

    NASA Astrophysics Data System (ADS)

    Bergeron, Mélanie; Cadorette, Jules; Tétrault, Marc-André; Beaudoin, Jean-François; Leroux, Jean-Daniel; Fontaine, Réjean; Lecomte, Roger

    2014-02-01

    The LabPET is an avalanche photodiode (APD) based digital PET scanner with quasi-individual detector read-out and highly parallel electronic architecture for high-performance in vivo molecular imaging of small animals. The scanner is based on LYSO and LGSO scintillation crystals (2×2×12/14 mm3), assembled side-by-side in phoswich pairs read out by an APD. High spatial resolution is achieved through the individual and independent read-out of an individual APD detector for recording impinging annihilation photons. The LabPET exists in three versions, LabPET4 (3.75 cm axial length), LabPET8 (7.5 cm axial length) and LabPET12 (11.4 cm axial length). This paper focuses on the systematic characterization of the three LabPET versions using two different energy window settings to implement a high-efficiency mode (250-650 keV) and a high-resolution mode (350-650 keV) in the most suitable operating conditions. Prior to measurements, a global timing alignment of the scanners and optimization of the APD operating bias have been carried out. Characteristics such as spatial resolution, absolute sensitivity, count rate performance and image quality have been thoroughly investigated following the NEMA NU 4-2008 protocol. Phantom and small animal images were acquired to assess the scanners' suitability for the most demanding imaging tasks in preclinical biomedical research. The three systems achieve the same radial FBP spatial resolution at 5 mm from the field-of-view center: 1.65/3.40 mm (FWHM/FWTM) for an energy threshold of 250 keV and 1.51/2.97 mm for an energy threshold of 350 keV. The absolute sensitivity for an energy window of 250-650 keV is 1.4%/2.6%/4.3% for LabPET4/8/12, respectively. The best count rate performance peaking at 362 kcps is achieved by the LabPET12 with an energy window of 250-650 keV and a mouse phantom (2.5 cm diameter) at an activity of 2.4 MBq ml-1. With the same phantom, the scatter fraction for all scanners is about 17% for an energy threshold of

  9. SU-F-207-13: Comparison of Four Dimensional Computed Tomography (4D CT) Versus Breath Hold Images to Determine Pulmonary Nodule Elasticity

    SciTech Connect

    Negahdar, M; Loo, B; Maxim, P

    2015-06-15

    Purpose: Elasticity may distinguish malignant from benign pulmonary nodules. To compare determining of malignant pulmonary nodule (MPN) elasticity from four dimensional computed tomography (4D CT) images versus inhale/exhale breath-hold CT images. Methods: We analyzed phase 00 and 50 of 4D CT and deep inhale and natural exhale of breath-hold CT images of 30 MPN treated with stereotactic ablative radiotherapy (SABR). The radius of the smallest MPN was 0.3 cm while the biggest one was 2.1 cm. An intensity based deformable image registration (DIR) workflow was applied to the 4D CT and breath-hold images to determine the volumes of the MPNs and a 1 cm ring of surrounding lung tissue (ring) in each state. Next, an elasticity parameter was derived by calculating the ratio of the volume changes of MPN (exhale:inhale or phase50:phase00) to that of a 1 cm ring of lung tissue surrounding the MPN. The proposed formulation of elasticity enables us to compare volume changes of two different MPN in two different locations of lung. Results: The calculated volume ratio of MPNs from 4D CT (phase50:phase00) and breath-hold images (exhale:inhale) was 1.00±0.23 and 0.95±0.11, respectively. It shows the stiffness of MPN and comparably bigger volume changes of MPN in breath-hold images because of the deeper degree of inhalation. The calculated elasticity of MPNs from 4D CT and breath-hold images was 1.12±0.22 and 1.23±0.26, respectively. For five patients who have had two MPN in their lung, calculated elasticity of tumor A and tumor B follows same trend in both 4D CT and breath-hold images. Conclusion: We showed that 4D CT and breath-hold images are comparable in the ability to calculate the elasticity of MPN. This study has been supported by Department of Defense LCRP 2011 #W81XWH-12-1-0286.

  10. SU-E-J-154: Image Quality Assessment of Contrast-Enhanced 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

    SciTech Connect

    Choi, W; Xue, M; Patel, K; Regine, W; Wang, J; D’Souza, W; Lu, W; Kang, M; Klahr, P

    2015-06-15

    Purpose: This study presents quantitative and qualitative assessment of the image qualities in contrast-enhanced (CE) 3D-CT, 4D-CT and CE 4D-CT to identify feasibility for replacing the clinical standard simulation with a single CE 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. Methods: Ten PDA patients were enrolled and underwent three CT scans: a clinical standard pair of CE 3D-CT immediately followed by a 4D-CT, and a CE 4D-CT one week later. Physicians qualitatively evaluated the general image quality and regional vessel definitions and gave a score from 1 to 5. Next, physicians delineated the contours of the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (CE 3D-CT, 50% phase for 4D-CT and CE 4D-CT), then high density areas were automatically removed by thresholding at 500 HU and morphological operations. The pancreatic tumor contrast-to-noise ratio (CNR), signal-tonoise ratio (SNR) and conspicuity (C, absolute difference of mean enhancement levels in P and T) were computed to quantitatively assess image quality. The Wilcoxon rank sum test was used to compare these quantities. Results: In qualitative evaluations, CE 3D-CT and CE 4D-CT scored equivalently (4.4±0.4 and 4.3±0.4) and both were significantly better than 4D-CT (3.1±0.6). In quantitative evaluations, the C values were higher in CE 4D-CT (28±19 HU, p=0.19 and 0.17) than the clinical standard pair of CE 3D-CT and 4D-CT (17±12 and 16±17 HU, p=0.65). In CE 3D-CT and CE 4D-CT, mean CNR (1.8±1.4 and 1.8±1.7, p=0.94) and mean SNR (5.8±2.6 and 5.5±3.2, p=0.71) both were higher than 4D-CT (CNR: 1.1±1.3, p<0.3; SNR: 3.3±2.1, p<0.1). The absolute enhancement levels for T and P were higher in CE 4D-CT (87, 82 HU) than in CE 3D-CT (60, 56) and 4DCT (53, 70). Conclusions: The individually optimized CE 4D-CT is feasible and achieved comparable image qualities to the clinical standard simulation. This study was supported in part by Philips Healthcare.

  11. PET Imaging and Biodistribution of Silicon Quantum Dots in Mice

    PubMed Central

    2011-01-01

    Investigation of nanomaterial disposition and fate in the body is critical before such material can be translated into clinical application. Herein a new macrocyclic ligand−64Cu2+ complex was synthesized and used to label dextran-coated silicon quantum dots (QD), with an average hydrodynamic diameter of 15.1 ± 7.6 nm. The chelate showed exceptional stability, demonstrated by no loss radiolabel under a ligand competition reaction with EDTA. The QDs’ biodistribution in mice was quantitatively evaluated by in vivo positron emission tomography (PET) imaging and ex vivo gamma counting. Results showed that they were excreted via renal filtration shortly postinjection and also accumulated in the liver. PMID:21546997

  12. Segmentation of dynamic PET images with kinetic spectral clustering

    NASA Astrophysics Data System (ADS)

    Mouysset, S.; Zbib, H.; Stute, S.; Girault, J. M.; Charara, J.; Noailles, J.; Chalon, S.; Buvat, I.; Tauber, C.

    2013-10-01

    Segmentation is often required for the analysis of dynamic positron emission tomography (PET) images. However, noise and low spatial resolution make it a difficult task and several supervised and unsupervised methods have been proposed in the literature to perform the segmentation based on semi-automatic clustering of the time activity curves of voxels. In this paper we propose a new method based on spectral clustering that does not require any prior information on the shape of clusters in the space in which they are identified. In our approach, the p-dimensional data, where p is the number of time frames, is first mapped into a high dimensional space and then clustering is performed in a low-dimensional space of the Laplacian matrix. An estimation of the bounds for the scale parameter involved in the spectral clustering is derived. The method is assessed using dynamic brain PET images simulated with GATE and results on real images are presented. We demonstrate the usefulness of the method and its superior performance over three other clustering methods from the literature. The proposed approach appears as a promising pre-processing tool before parametric map calculation or ROI-based quantification tasks.

  13. 4D-Imaging of the Lung: Reproducibility of Lesion Size and Displacement on Helical CT, MRI, and Cone Beam CT in a Ventilated Ex Vivo System

    SciTech Connect

    Biederer, Juergen Dinkel, Julien; Remmert, Gregor; Jetter, Siri; Nill, Simeon; Moser, Torsten; Bendl, Rolf; Thierfelder, Carsten; Fabel, Michael; Oelfke, Uwe; Bock, Michael; Plathow, Christian; Bolte, Hendrik; Welzel, Thomas; Hoffmann, Beata; Hartmann, Guenter; Schlegel, Wolfgang; Debus, Juergen; Heller, Martin

    2009-03-01

    Purpose: Four-dimensional (4D) imaging is a key to motion-adapted radiotherapy of lung tumors. We evaluated in a ventilated ex vivo system how size and displacement of artificial pulmonary nodules are reproduced with helical 4D-CT, 4D-MRI, and linac-integrated cone beam CT (CBCT). Methods and Materials: Four porcine lungs with 18 agarose nodules (mean diameters 1.3-1.9 cm), were ventilated inside a chest phantom at 8/min and subject to 4D-CT (collimation 24 x 1.2 mm, pitch 0.1, slice/increment 24x10{sup 2}/1.5/0.8 mm, pitch 0.1, temporal resolution 0.5 s), 4D-MRI (echo-shared dynamic three-dimensional-flash; repetition/echo time 2.13/0.72 ms, voxel size 2.7 x 2.7 x 4.0 mm, temporal resolution 1.4 s) and linac-integrated 4D-CBCT (720 projections, 3-min rotation, temporal resolution {approx}1 s). Static CT without respiration served as control. Three observers recorded lesion size (RECIST-diameters x/y/z) and axial displacement. Interobserver- and interphase-variation coefficients (IO/IP VC) of measurements indicated reproducibility. Results: Mean x/y/z lesion diameters in cm were equal on static and dynamic CT (1.88/1.87; 1.30/1.39; 1.71/1.73; p > 0.05), but appeared larger on MRI and CBCT (2.06/1.95 [p < 0.05 vs. CT]; 1.47/1.28 [MRI vs. CT/CBCT p < 0.05]; 1.86/1.83 [CT vs. CBCT p < 0.05]). Interobserver-VC for lesion sizes were 2.54-4.47% (CT), 2.29-4.48% (4D-CT); 5.44-6.22% (MRI) and 4.86-6.97% (CBCT). Interphase-VC for lesion sizes ranged from 2.28% (4D-CT) to 10.0% (CBCT). Mean displacement in cm decreased from static CT (1.65) to 4D-CT (1.40), CBCT (1.23) and MRI (1.16). Conclusions: Lesion sizes are exactly reproduced with 4D-CT but overestimated on 4D-MRI and CBCT with a larger variability due to limited temporal and spatial resolution. All 4D-modalities underestimate lesion displacement.

  14. Radiolabeling of Nanoparticles and Polymers for PET Imaging

    PubMed Central

    Stockhofe, Katharina; Postema, Johannes M.; Schieferstein, Hanno; Ross, Tobias L.

    2014-01-01

    Nanomedicine has become an emerging field in imaging and therapy of malignancies. Nanodimensional drug delivery systems have already been used in the clinic, as carriers for sensitive chemotherapeutics or highly toxic substances. In addition, those nanodimensional structures are further able to carry and deliver radionuclides. In the development process, non-invasive imaging by means of positron emission tomography (PET) represents an ideal tool for investigations of pharmacological profiles and to find the optimal nanodimensional architecture of the aimed-at drug delivery system. Furthermore, in a personalized therapy approach, molecular imaging modalities are essential for patient screening/selection and monitoring. Hence, labeling methods for potential drug delivery systems are an indispensable need to provide the radiolabeled analog. In this review, we describe and discuss various approaches and methods for the labeling of potential drug delivery systems using positron emitters. PMID:24699244

  15. A Novel Assessment of Various Bio-Imaging Methods for Lung Tumor Detection and Treatment by using 4-D and 2-D CT Images

    PubMed Central

    Judice A., Antony; Geetha, Dr. K. Parimala

    2013-01-01

    Lung Cancer is known as one of the most difficult cancer to cure, and the number of deaths that it causes generally increasing. A detection of the Lung Cancer in its early stage can be helpful for Medical treatment to limit the danger, but it is a challenging problem due to Cancer cell structure. Interpretation of Medical image is often difficult and time consuming, even for the experienced Physicians. The aid of image analysis Based on machine learning can make this process easier. This paper describes fully Automatic Decision Support system for Lung Cancer diagnostic from CT Lung images. Most traditional medical diagnosis systems are founded on huge quantity of training data and takes long processing time. However, on the occasion that very little volume of data is available, the traditional diagnosis systems derive defects such as larger error, Time complexity. Focused on the solution to this problem, a Medical Diagnosis System based on Hidden Markov Model (HMM) is presented. In this paper we describe a pre-processing stage involving some Noise removal techniques help to solve this problem, we preprocess an images (by Mean Error Square Filtering and Histogram analysis)obtained after scanning the Lung CT images. Secondly separate the lung areas from an image by a segmentation process (by Thresholding and region growing techniques). Finally we developed HMM for the classification of Cancer Nodule. Results are checked for 2D and 4D CT images. This automation process reduces the time complexity and increases the diagnosis confidence. PMID:23847454

  16. Effect of motion on tracer activity determination in CT attenuation corrected PET images: A lung phantom study

    SciTech Connect

    Pevsner, Alex; Nehmeh, Sadek A.; Humm, John L.; Mageras, Gig S.; Erdi, Yusuf E.

    2005-07-15

    Respiratory motion is known to affect the quantitation of {sup 18}FDG uptake in lung lesions. The aim of the study was to investigate the magnitude of errors in tracer activity determination due to motion, and its dependence upon CT attenuation at different phases of the motion cycle. To estimate these errors we have compared maximum activity concentrations determined from PET/CT images of a lung phantom at rest and under simulated respiratory motion. The NEMA 2001 IEC body phantom, containing six hollow spheres with diameters 37, 28, 22, 17, 13, and 10 mm, was used in this study. To mimic lung tissue density, the phantom (excluding spheres) was filled with low density polystyrene beads and water. The phantom spheres were filled with {sup 18}FDG solution setting the target-to-background activity concentration ratio at 8:1. PET/CT data were acquired with the phantom at rest, and while it was undergoing periodic motion along the longitudinal axis of the scanner with a range of displacement being 2 cm, and a period of 5 s. The phantom at rest and in motion was scanned using manufacturer provided standard helical/clinical protocol, a helical CT scan followed by a PET emission scan. The moving phantom was also scanned using a 4D-CT protocol that provides volume image sets at different phases of the motion cycle. To estimate the effect of motion on quantitation of activities in six spheres, we have examined the activity concentration data for (a) the stationary phantom, (b) the phantom undergoing simulated respiratory motion, and (c) a moving phantom acquired with PET/4D-CT protocol in which attenuation correction was performed with CT images acquired at different phases of motion cycle. The data for the phantom at rest and in motion acquired with the standard helical/clinical protocol showed that the activity concentration in the spheres can be underestimated by as much as 75%, depending on the sphere diameter. We have also demonstrated that fluctuations in sphere

  17. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    SciTech Connect

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J.; Kuncic, Zdenka

    2014-04-15

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  18. PET imaging of neurogenic activity in the adult brain: Toward in vivo imaging of human neurogenesis.

    PubMed

    Tamura, Yasuhisa; Kataoka, Yosky

    2017-01-01

    Neural stem cells are present in 2 neurogenic regions, the subventricular zone (SVZ) and the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG), and continue to generate new neurons throughout life. Adult hippocampal neurogenesis is linked to a variety of psychiatric disorders such as depression and anxiety, and to the therapeutic effects of antidepressants, as well as learning and memory. In vivo imaging for hippocampal neurogenic activity may be used to diagnose psychiatric disorders and evaluate the therapeutic efficacy of antidepressants. However, these imaging techniques remain to be established until now. Recently, we established a quantitative positron emission tomography (PET) imaging technique for neurogenic activity in the adult brain with 3'-deoxy-3'-[(18)F]fluoro-L-thymidine ([(18)F]FLT) and probenecid, a drug transporter inhibitor in blood-brain barrier. Moreover, we showed that this PET imaging technique can monitor alterations in neurogenic activity in the hippocampus of adult rats with depression and following treatment with an antidepressant. This PET imaging method may assist in diagnosing depression and in monitoring the therapeutic efficacy of antidepressants. In this commentary, we discuss the possibility of in vivo PET imaging for neurogenic activity in adult non-human primates and humans.

  19. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers.

    PubMed

    Matthews, Robert; Choi, Minsig

    2016-09-09

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it.

  20. Impact of motion and partial volume effects correction on PET myocardial perfusion imaging using simultaneous PET-MR

    PubMed Central

    Petibon, Yoann; Guehl, Nicolas J.; Reese, Timothy G.; Ebrahimi, Behzad; Normandin, Marc D.; Shoup, Timothy M.; Alpert, Nathaniel M.; El Fakhri, Georges; Ouyang, Jinsong

    2017-01-01

    PET is an established modality for myocardial perfusion imaging (MPI) which enables quantification of absolute myocardial blood flow (MBF) using dynamic imaging and kinetic modeling. However, heart motion and Partial Volume Effects (PVE) significantly limit the spatial resolution and quantitative accuracy of PET MPI. Simultaneous PET-MR offers a solution to the motion problem in PET by enabling MR-based motion correction of PET data. The aim of this study was to develop a motion and PVE correction methodology for PET MPI using simultaneous PET-MR, and to assess its impact on both static and dynamic PET MPI using 18F-Flurpiridaz, a novel 18F-labeled perfusion tracer. Two dynamic 18F-Flurpiridaz MPI scans were performed on healthy pigs using a PET-MR scanner. Cardiac motion was tracked using a dedicated tagged-MRI (tMR) sequence. Motion fields were estimated using non-rigid registration of tMR images and used to calculate motion-dependent attenuation maps. Motion correction of PET data was achieved by incorporating tMR-based motion fields and motion-dependent attenuation coefficients into image reconstruction. Dynamic and static PET datasets were created for each scan. Each dataset was reconstructed as (i) Ungated, (ii) Gated (end-diastolic phase), and (iii) Motion-Corrected (MoCo), each without and with point spread function (PSF) modeling for PVE correction. Myocardium-to-blood concentration ratios (MBR) and apparent wall thickness were calculated to assess image quality for static MPI. For dynamic MPI, segment- and voxel-wise myocardial blood flow (MBF) values were estimated by non-linear fitting of a 2-tissue compartment model to tissue time-activity-curves. MoCo and Gating respectively decreased mean apparent wall thickness by 15.1% and 14.4% and increased MBR by 20.3% and 13.6% compared to Ungated images (P<0.01). Combined motion and PSF correction (MoCo-PSF) yielded 30.9% (15.7%) lower wall thickness and 82.2% (20.5%) higher MBR compared to Ungated data

  1. Impact of motion and partial volume effects correction on PET myocardial perfusion imaging using simultaneous PET-MR

    NASA Astrophysics Data System (ADS)

    Petibon, Yoann; Guehl, Nicolas J.; Reese, Timothy G.; Ebrahimi, Behzad; Normandin, Marc D.; Shoup, Timothy M.; Alpert, Nathaniel M.; El Fakhri, Georges; Ouyang, Jinsong

    2017-01-01

    PET is an established modality for myocardial perfusion imaging (MPI) which enables quantification of absolute myocardial blood flow (MBF) using dynamic imaging and kinetic modeling. However, heart motion and partial volume effects (PVE) significantly limit the spatial resolution and quantitative accuracy of PET MPI. Simultaneous PET-MR offers a solution to the motion problem in PET by enabling MR-based motion correction of PET data. The aim of this study was to develop a motion and PVE correction methodology for PET MPI using simultaneous PET-MR, and to assess its impact on both static and dynamic PET MPI using 18F-Flurpiridaz, a novel 18F-labeled perfusion tracer. Two dynamic 18F-Flurpiridaz MPI scans were performed on healthy pigs using a PET-MR scanner. Cardiac motion was tracked using a dedicated tagged-MRI (tMR) sequence. Motion fields were estimated using non-rigid registration of tMR images and used to calculate motion-dependent attenuation maps. Motion correction of PET data was achieved by incorporating tMR-based motion fields and motion-dependent attenuation coefficients into image reconstruction. Dynamic and static PET datasets were created for each scan. Each dataset was reconstructed as (i) Ungated, (ii) Gated (end-diastolic phase), and (iii) Motion-Corrected (MoCo), each without and with point spread function (PSF) modeling for PVE correction. Myocardium-to-blood concentration ratios (MBR) and apparent wall thickness were calculated to assess image quality for static MPI. For dynamic MPI, segment- and voxel-wise MBF values were estimated by non-linear fitting of a 2-tissue compartment model to tissue time-activity-curves. MoCo and Gating respectively decreased mean apparent wall thickness by 15.1% and 14.4% and increased MBR by 20.3% and 13.6% compared to Ungated images (P  <  0.01). Combined motion and PSF correction (MoCo-PSF) yielded 30.9% (15.7%) lower wall thickness and 82.2% (20.5%) higher MBR compared to Ungated data reconstructed

  2. Development of PET imaging-based dose-painting prescriptions

    NASA Astrophysics Data System (ADS)

    Bowen, Stephen R.

    Historically, prescriptions in radiation therapy are based on physician experience drawn from the results of extensive clinical trials in order to establish standard-of-care guidelines. The doses of radiation are generally uniform across target volumes to reflect a fixed level of local neoplastic disease control of the population mean. However, inter-patient and intra-tumor variation in response to uniform doses can result in diminished tumor control and poor clinical outcome for certain patients. Recent research endeavors are emphasizing the need to individualize prescriptions by incorporating patient-specific biological markers with prognostic and predictive value. Quantitative imaging with positron emission tomography (PET) of tumor glucose metabolism, cell proliferation, and hypoxia has been suggested as a sensitive and specific technique to tailor patient prescriptions in a manner that may significantly improve clinical outcome. The concept of prescribing and delivering non-uniform dose based on molecular imaging, termed dose painting, hinges on the establishment of a dose-response relationship at the image voxel scale that optimizes a particular clinical endpoint. This doctoral thesis presented two methods of defining dose-painting prescriptions based on PET imaging: the first was a heuristic model derivation of hypoxia dose-painting prescriptions in head-and-neck cancer patients; the second was an empirical imaging surrogate endpoint derivation of prescriptions in veterinary sinonasal cancer patients. The clinical implementation of these dose painting prescriptions was investigated, which emphasized treatment planning and delivery solutions. Lastly, a summary and discussion of the future of dose painting to forge links between tumor biology and clinical outcome was presented. The compelling dose painting concept is fast becoming a clinical reality that may positively impact cancer patient lives.

  3. PET imaging predicts future body weight and cocaine preference

    SciTech Connect

    Michaelides M.; Wang G.; Michaelides M.; Thanos P.K. Kim R.; Cho J.; Ananth M.; Wang G.-J.; Volkow N.D.

    2011-08-28

    Deficits in dopamine D2/D3 receptor (D2R/D3R) binding availability using PET imaging have been reported in obese humans and rodents. Similar deficits have been reported in cocaine-addicts and cocaine-exposed primates. We found that D2R/D3R binding availability negatively correlated with measures of body weight at the time of scan (ventral striatum), at 1 (ventral striatum) and 2 months (dorsal and ventral striatum) post scan in rats. Cocaine preference was negatively correlated with D2R/D3R binding availability 2 months (ventral striatum) post scan. Our findings suggest that inherent deficits in striatal D2R/D3R signaling are related to obesity and drug addiction susceptibility and that ventral and dorsal striatum serve dissociable roles in maintaining weight gain and cocaine preference. Measuring D2R/D3R binding availability provides a way for assessing susceptibility to weight gain and cocaine abuse in rodents and given the translational nature of PET imaging, potentially primates and humans.

  4. Stereotactic PET atlas of the human brain: Aid for visual interpretation of functional brain images

    SciTech Connect

    Minoshima, S.; Koeppe, R.A.; Frey, A.; Ishihara, M.; Kuhl, D.E.

    1994-06-01

    In the routine analysis of functional brain images obtained by PET, subjective visual interpretation is often used for anatomic localization. To enhance the accuracy and consistency of the anatomic interpretation, a PET stereotactic atlas and localization approach was designed for functional brain images. The PET atlas was constructed from a high-resolution [{sup 18}F]fluorodeoxyglucose (FDG) image set of a normal volunteer (a 41-yr-ld woman). The image set was reoriented stereotactically, according to the intercommissural (anterior and posterior commissures) line and transformed to the standard stereotactic atlas coordinates. Cerebral structures were annotated on the transaxial planes using a proportional grid system and surface-rendered images. The stereotactic localization technique was applied to image sets from patients with Alzheimer`s disease, and areas of functional alteration were localized visually by referring to the PET atlas. Major brain structures were identified on both transaxial planes and surface-rendered images. In the stereotactic system, anatomic correspondence between the PET atlas and stereotactically reoriented individual image sets of patients with Alzheimer`s disease facilitated both indirect and direct localization of the cerebral structures. Because rapid stereotactic alignment methods for PET images are now available for routine use, the PET atlas will serve as an aid for visual interpretation of functional brain images in the stereotactic system. Widespread application of stereotactic localization may be used in functional brain images, not only in the research setting, but also in routine clinical situations. 41 refs., 3 figs.

  5. TU-F-17A-01: BEST IN PHYSICS (JOINT IMAGING-THERAPY) - An Automatic Toolkit for Efficient and Robust Analysis of 4D Respiratory Motion

    SciTech Connect

    Wei, J; Yuan, A; Li, G

    2014-06-15

    Purpose: To provide an automatic image analysis toolkit to process thoracic 4-dimensional computed tomography (4DCT) and extract patient-specific motion information to facilitate investigational or clinical use of 4DCT. Methods: We developed an automatic toolkit in MATLAB to overcome the extra workload from the time dimension in 4DCT. This toolkit employs image/signal processing, computer vision, and machine learning methods to visualize, segment, register, and characterize lung 4DCT automatically or interactively. A fully-automated 3D lung segmentation algorithm was designed and 4D lung segmentation was achieved in batch mode. Voxel counting was used to calculate volume variations of the torso, lung and its air component, and local volume changes at the diaphragm and chest wall to characterize breathing pattern. Segmented lung volumes in 12 patients are compared with those from a treatment planning system (TPS). Voxel conversion was introduced from CT# to other physical parameters, such as gravity-induced pressure, to create a secondary 4D image. A demon algorithm was applied in deformable image registration and motion trajectories were extracted automatically. Calculated motion parameters were plotted with various templates. Machine learning algorithms, such as Naive Bayes and random forests, were implemented to study respiratory motion. This toolkit is complementary to and will be integrated with the Computational Environment for Radiotherapy Research (CERR). Results: The automatic 4D image/data processing toolkit provides a platform for analysis of 4D images and datasets. It processes 4D data automatically in batch mode and provides interactive visual verification for manual adjustments. The discrepancy in lung volume calculation between this and the TPS is <±2% and the time saving is by 1–2 orders of magnitude. Conclusion: A framework of 4D toolkit has been developed to analyze thoracic 4DCT automatically or interactively, facilitating both investigational

  6. SU-E-J-200: A Dosimetric Analysis of 3D Versus 4D Image-Based Dose Calculation for Stereotactic Body Radiation Therapy in Lung Tumors

    SciTech Connect

    Ma, M; Rouabhi, O; Flynn, R; Xia, J; Bayouth, J

    2014-06-01

    Purpose: To evaluate the dosimetric difference between 3D and 4Dweighted dose calculation using patient specific respiratory trace and deformable image registration for stereotactic body radiation therapy in lung tumors. Methods: Two dose calculation techniques, 3D and 4D-weighed dose calculation, were used for dosimetric comparison for 9 lung cancer patients. The magnitude of the tumor motion varied from 3 mm to 23 mm. Breath-hold exhale CT was used for 3D dose calculation with ITV generated from the motion observed from 4D-CT. For 4D-weighted calculation, dose of each binned CT image from the ten breathing amplitudes was first recomputed using the same planning parameters as those used in the 3D calculation. The dose distribution of each binned CT was mapped to the breath-hold CT using deformable image registration. The 4D-weighted dose was computed by summing the deformed doses with the temporal probabilities calculated from their corresponding respiratory traces. Dosimetric evaluation criteria includes lung V20, mean lung dose, and mean tumor dose. Results: Comparing with 3D calculation, lung V20, mean lung dose, and mean tumor dose using 4D-weighted dose calculation were changed by −0.67% ± 2.13%, −4.11% ± 6.94% (−0.36 Gy ± 0.87 Gy), −1.16% ± 1.36%(−0.73 Gy ± 0.85 Gy) accordingly. Conclusion: This work demonstrates that conventional 3D dose calculation method may overestimate the lung V20, MLD, and MTD. The absolute difference between 3D and 4D-weighted dose calculation in lung tumor may not be clinically significant. This research is supported by Siemens Medical Solutions USA, Inc and Iowa Center for Research By Undergraduates.

  7. Polyglucose nanoparticles with renal elimination and macrophage avidity facilitate PET imaging in ischaemic heart disease

    PubMed Central

    Keliher, Edmund J.; Ye, Yu-Xiang; Wojtkiewicz, Gregory R.; Aguirre, Aaron D.; Tricot, Benoit; Senders, Max L.; Groenen, Hannah; Fay, Francois; Perez-Medina, Carlos; Calcagno, Claudia; Carlucci, Giuseppe; Reiner, Thomas; Sun, Yuan; Courties, Gabriel; Iwamoto, Yoshiko; Kim, Hye-Yeong; Wang, Cuihua; Chen, John W.; Swirski, Filip K.; Wey, Hsiao-Ying; Hooker, Jacob; Fayad, Zahi A.; Mulder, Willem J. M.; Weissleder, Ralph; Nahrendorf, Matthias

    2017-01-01

    Tissue macrophage numbers vary during health versus disease. Abundant inflammatory macrophages destruct tissues, leading to atherosclerosis, myocardial infarction and heart failure. Emerging therapeutic options create interest in monitoring macrophages in patients. Here we describe positron emission tomography (PET) imaging with 18F-Macroflor, a modified polyglucose nanoparticle with high avidity for macrophages. Due to its small size, Macroflor is excreted renally, a prerequisite for imaging with the isotope flourine-18. The particle's short blood half-life, measured in three species, including a primate, enables macrophage imaging in inflamed cardiovascular tissues. Macroflor enriches in cardiac and plaque macrophages, thereby increasing PET signal in murine infarcts and both mouse and rabbit atherosclerotic plaques. In PET/magnetic resonance imaging (MRI) experiments, Macroflor PET imaging detects changes in macrophage population size while molecular MRI reports on increasing or resolving inflammation. These data suggest that Macroflor PET/MRI could be a clinical tool to non-invasively monitor macrophage biology. PMID:28091604

  8. Task-based evaluation of a 4D MAP-RBI-EM image reconstruction method for gated myocardial perfusion SPECT using a human observer study

    NASA Astrophysics Data System (ADS)

    Lee, Taek-Soo; Higuchi, Takahiro; Lautamäki, Riikka; Bengel, Frank M.; Tsui, Benjamin M. W.

    2015-09-01

    We evaluated the performance of a new 4D image reconstruction method for improved 4D gated myocardial perfusion (MP) SPECT using a task-based human observer study. We used a realistic 4D NURBS-based Cardiac-Torso (NCAT) phantom that models cardiac beating motion. Half of the population was normal; the other half had a regional hypokinetic wall motion abnormality. Noise-free and noisy projection data with 16 gates/cardiac cycle were generated using an analytical projector that included the effects of attenuation, collimator-detector response, and scatter (ADS), and were reconstructed using the 3D FBP without and 3D OS-EM with ADS corrections followed by different cut-off frequencies of a 4D linear post-filter. A 4D iterative maximum a posteriori rescaled-block (MAP-RBI)-EM image reconstruction method with ADS corrections was also used to reconstruct the projection data using various values of the weighting factor for its prior. The trade-offs between bias and noise were represented by the normalized mean squared error (NMSE) and averaged normalized standard deviation (NSDav), respectively. They were used to select reasonable ranges of the reconstructed images for use in a human observer study. The observers were trained with the simulated cine images and were instructed to rate their confidence on the absence or presence of a motion defect on a continuous scale. We then applied receiver operating characteristic (ROC) analysis and used the area under the ROC curve (AUC) index. The results showed that significant differences in detection performance among the different NMSE-NSDav combinations were found and the optimal trade-off from optimized reconstruction parameters corresponded to a maximum AUC value. The 4D MAP-RBI-EM with ADS correction, which had the best trade-off among the tested reconstruction methods, also had the highest AUC value, resulting in significantly better human observer detection performance when detecting regional myocardial wall motion

  9. Abdominal 4D Flow MR Imaging in a Breath Hold: Combination of Spiral Sampling and Dynamic Compressed Sensing for Highly Accelerated Acquisition

    PubMed Central

    Knight-Greenfield, Ashley; Jajamovich, Guido; Besa, Cecilia; Cui, Yong; Stalder, Aurélien; Markl, Michael; Taouli, Bachir

    2015-01-01

    Purpose To develop a highly accelerated phase-contrast cardiac-gated volume flow measurement (four-dimensional [4D] flow) magnetic resonance (MR) imaging technique based on spiral sampling and dynamic compressed sensing and to compare this technique with established phase-contrast imaging techniques for the quantification of blood flow in abdominal vessels. Materials and Methods This single-center prospective study was compliant with HIPAA and approved by the institutional review board. Ten subjects (nine men, one woman; mean age, 51 years; age range, 30–70 years) were enrolled. Seven patients had liver disease. Written informed consent was obtained from all participants. Two 4D flow acquisitions were performed in each subject, one with use of Cartesian sampling with respiratory tracking and the other with use of spiral sampling and a breath hold. Cartesian two-dimensional (2D) cine phase-contrast images were also acquired in the portal vein. Two observers independently assessed vessel conspicuity on phase-contrast three-dimensional angiograms. Quantitative flow parameters were measured by two independent observers in major abdominal vessels. Intertechnique concordance was quantified by using Bland-Altman and logistic regression analyses. Results There was moderate to substantial agreement in vessel conspicuity between 4D flow acquisitions in arteries and veins (κ = 0.71 and 0.61, respectively, for observer 1; κ = 0.71 and 0.44 for observer 2), whereas more artifacts were observed with spiral 4D flow (κ = 0.30 and 0.20). Quantitative measurements in abdominal vessels showed good equivalence between spiral and Cartesian 4D flow techniques (lower bound of the 95% confidence interval: 63%, 77%, 60%, and 64% for flow, area, average velocity, and peak velocity, respectively). For portal venous flow, spiral 4D flow was in better agreement with 2D cine phase-contrast flow (95% limits of agreement: −8.8 and 9.3 mL/sec, respectively) than was Cartesian 4D flow (95

  10. Task-Based Evaluation of a 4D MAP-RBI-EM Image Reconstruction Method for Gated Myocardial Perfusion SPECT using a Human Observer Study

    PubMed Central

    Lee, Taek-Soo; Higuchi, Takahiro; Lautamäki, Riikka; Bengel, Frank M.; Tsui, Benjamin M. W.

    2015-01-01

    We evaluated the performance of a new 4D image reconstruction method for improved 4D gated myocardial perfusion (MP) SPECT using a task-based human observer study. We used a realistic 4D NURBS-based Cardiac-Torso (NCAT) phantom that models cardiac beating motion. Half of the population was normal; the other half had a regional hypokinetic wall motion abnormality. Noise-free and noisy projection data with 16 gates/cardiac cycle were generated using an analytical projector that included the effects of attenuation, collimator-detector response, and scatter (ADS), and were reconstructed using the 3D FBP without and 3D OS-EM with ADS corrections followed by different cut-off frequencies of a 4D linear post-filter. A 4D iterative maximum a posteriori rescaled-block (MAP-RBI)-EM image reconstruction method with ADS corrections was also used to reconstruct the projection data using various values of the weighting factor for its prior. The trade-offs between bias and noise were represented by the normalized mean squared error (NMSE) and averaged normalized standard deviation (NSDav), respectively. They were used to select reasonable ranges of the reconstructed images for use in a human observer study. The observers were trained with the simulated cine images and were instructed to rate their confidence on the absence or presence of a motion defect on a continuous scale. We then applied receiver operating characteristic (ROC) analysis and used the area under the ROC curve (AUC) index. The results showed that significant differences in detection performance among the different NMSE-NSDav combinations were found and the optimal trade-off from optimized reconstruction parameters corresponded to a maximum AUC value. The 4D MAP-RBI-EM with ADS correction, which had the best trade-off among the tested reconstruction methods, also had the highest AUC value, resulting in significantly better human observer detection performance when detecting regional myocardial wall motion

  11. Local respiratory motion correction for PET/CT imaging: Application to lung cancer

    SciTech Connect

    Lamare, F. Fernandez, P.; Fayad, H.; Visvikis, D.

    2015-10-15

    Purpose: Despite multiple methodologies already proposed to correct respiratory motion in the whole PET imaging field of view (FOV), such approaches have not found wide acceptance in clinical routine. An alternative can be the local respiratory motion correction (LRMC) of data corresponding to a given volume of interest (VOI: organ or tumor). Advantages of LRMC include the use of a simple motion model, faster execution times, and organ specific motion correction. The purpose of this study was to evaluate the performance of LMRC using various motion models for oncology (lung lesion) applications. Methods: Both simulated (NURBS based 4D cardiac-torso phantom) and clinical studies (six patients) were used in the evaluation of the proposed LRMC approach. PET data were acquired in list-mode and synchronized with respiration. The implemented approach consists first in defining a VOI on the reconstructed motion average image. Gated PET images of the VOI are subsequently reconstructed using only lines of response passing through the selected VOI and are used in combination with a center of gravity or an affine/elastic registration algorithm to derive the transformation maps corresponding to the respiration effects. Those are finally integrated in the reconstruction process to produce a motion free image over the lesion regions. Results: Although the center of gravity or affine algorithm achieved similar performance for individual lesion motion correction, the elastic model, applied either locally or to the whole FOV, led to an overall superior performance. The spatial tumor location was altered by 89% and 81% for the elastic model applied locally or to the whole FOV, respectively (compared to 44% and 39% for the center of gravity and affine models, respectively). This resulted in similar associated overall tumor volume changes of 84% and 80%, respectively (compared to 75% and 71% for the center of gravity and affine models, respectively). The application of the nonrigid

  12. Positron emitting magnetic nanoconstructs for PET/MR imaging.

    PubMed

    Aryal, Santosh; Key, Jaehong; Stigliano, Cinzia; Landis, Melissa D; Lee, Daniel Y; Decuzzi, Paolo

    2014-07-09

    Hybrid PET/MRI scanners have the potential to provide fundamental molecular, cellular, and anatomic information essential for optimizing therapeutic and surgical interventions. However, their full utilization is currently limited by the lack of truly multi-modal contrast agents capable of exploiting the strengths of each modality. Here, we report on the development of long-circulating positron-emitting magnetic nanoconstructs (PEM) designed to image solid tumors for combined PET/MRI. PEMs are synthesized by a modified nano-precipitation method mixing poly(lactic-co-glycolic acid) (PLGA), lipids, and polyethylene glycol (PEG) chains with 5 nm iron oxide nanoparticles (USPIOs). PEM lipids are coupled with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and subsequently chelated to (64)Cu. PEMs show a diameter of 140 ± 7 nm and a transversal relaxivity r2 of 265.0 ± 10.0 (mM × s)(-1), with a r2/r1 ratio of 123. Using a murine xenograft model bearing human breast cancer cell line (MDA-MB-231), intravenously administered PEMs progressively accumulate in tumors reaching a maximum of 3.5 ± 0.25% ID/g tumor at 20 h post-injection. Correlation of PET and MRI signals revealed non-uniform intratumoral distribution of PEMs with focal areas of accumulation at the tumor periphery. These long-circulating PEMs with high transversal relaxivity and tumor accumulation may allow for detailed interrogation over multiple scales in a clinically relevant setting.

  13. Quantitative image reconstruction for total-body PET imaging using the 2-meter long EXPLORER scanner.

    PubMed

    Zhang, Xuezhu; Zhou, Jian; Cherry, Simon R; Badawi, Ramsey D; Qi, Jinyi

    2017-03-21

    The EXPLORER project aims to build a 2 meter long total-body PET scanner, which will provide extremely high sensitivity for imaging the entire human body. It will possess a range of capabilities currently unavailable to state-of-the-art clinical PET scanners with a limited axial field-of-view. The huge number of lines-of-response (LORs) of the EXPLORER poses a challenge to the data handling and image reconstruction. The objective of this study is to develop a quantitative image reconstruction method for the EXPLORER and compare its performance with current whole-body scanners. Fully 3D image reconstruction was performed using time-of-flight list-mode data with parallel computation. To recover the resolution loss caused by the parallax error between crystal pairs at a large axial ring difference or transaxial radial offset, we applied an image domain resolution model estimated from point source data. To evaluate the image quality, we conducted computer simulations using the SimSET Monte-Carlo toolkit and XCAT 2.0 anthropomorphic phantom to mimic a 20 min whole-body PET scan with an injection of 25 MBq (18)F-FDG. We compare the performance of the EXPLORER with a current clinical scanner that has an axial FOV of 22 cm. The comparison results demonstrated superior image quality from the EXPLORER with a 6.9-fold reduction in noise standard deviation comparing with multi-bed imaging using the clinical scanner.

  14. Quantitative image reconstruction for total-body PET imaging using the 2-meter long EXPLORER scanner

    NASA Astrophysics Data System (ADS)

    Zhang, Xuezhu; Zhou, Jian; Cherry, Simon R.; Badawi, Ramsey D.; Qi, Jinyi

    2017-03-01

    The EXPLORER project aims to build a 2 meter long total-body PET scanner, which will provide extremely high sensitivity for imaging the entire human body. It will possess a range of capabilities currently unavailable to state-of-the-art clinical PET scanners with a limited axial field-of-view. The huge number of lines-of-response (LORs) of the EXPLORER poses a challenge to the data handling and image reconstruction. The objective of this study is to develop a quantitative image reconstruction method for the EXPLORER and compare its performance with current whole-body scanners. Fully 3D image reconstruction was performed using time-of-flight list-mode data with parallel computation. To recover the resolution loss caused by the parallax error between crystal pairs at a large axial ring difference or transaxial radial offset, we applied an image domain resolution model estimated from point source data. To evaluate the image quality, we conducted computer simulations using the SimSET Monte–Carlo toolkit and XCAT 2.0 anthropomorphic phantom to mimic a 20 min whole-body PET scan with an injection of 25 MBq 18F-FDG. We compare the performance of the EXPLORER with a current clinical scanner that has an axial FOV of 22 cm. The comparison results demonstrated superior image quality from the EXPLORER with a 6.9-fold reduction in noise standard deviation comparing with multi-bed imaging using the clinical scanner.

  15. In Vivo Imaging of GLP-1R with a Targeted Bimodal PET/Fluorescence Imaging Agent

    PubMed Central

    2015-01-01

    Accurate visualization and quantification of β-cell mass is critical for the improved understanding, diagnosis, and treatment of both type 1 diabetes (T1D) and insulinoma. Here, we describe the synthesis of a bimodal imaging probe (PET/fluorescence) for imaging GLP-1R expression in the pancreas and in pancreatic islet cell tumors. The conjugation of a bimodal imaging tag containing a near-infrared fluorescent dye, and the copper chelator sarcophagine to the GLP-1R targeting peptide exendin-4 provided the basis for the bimodal imaging probe. Conjugation was performed via a novel sequential one-pot synthetic procedure including 64Cu radiolabeling and copper-catalyzed click-conjugation. The bimodal imaging agent 64Cu-E4-Fl was synthesized in good radiochemical yield and specific activity (RCY = 36%, specific activity: 141 μCi/μg, >98% radiochemical purity). The agent showed good performance in vivo and ex vivo, visualizing small xenografts (<2 mm) with PET and pancreatic β-cell mass by phosphor autoradiography. Using the fluorescent properties of the probe, we were able to detect individual pancreatic islets, confirming specific binding to GLP-1R and surpassing the sensitivity of the radioactive label. The use of bimodal PET/fluorescent imaging probes is promising for preoperative imaging and fluorescence-assisted analysis of patient tissues. We believe that our procedure could become relevant as a protocol for the development of bimodal imaging agents. PMID:24856928

  16. Nonrigid Image Registration for Head and Neck Cancer Radiotherapy Treatment Planning With PET/CT

    SciTech Connect

    Ireland, Rob H. . E-mail: r.ireland@sheffield.ac.uk; Dyker, Karen E.; Barber, David C.; Wood, Steven M.; Hanney, Michael B.; Tindale, Wendy B.; Woodhouse, Neil; Hoggard, Nigel; Conway, John; Robinson, Martin H.

    2007-07-01

    Purpose: Head and neck radiotherapy planning with positron emission tomography/computed tomography (PET/CT) requires the images to be reliably registered with treatment planning CT. Acquiring PET/CT in treatment position is problematic, and in practice for some patients it may be beneficial to use diagnostic PET/CT for radiotherapy planning. Therefore, the aim of this study was first to quantify the image registration accuracy of PET/CT to radiotherapy CT and, second, to assess whether PET/CT acquired in diagnostic position can be registered to planning CT. Methods and Materials: Positron emission tomography/CT acquired in diagnostic and treatment position for five patients with head and neck cancer was registered to radiotherapy planning CT using both rigid and nonrigid image registration. The root mean squared error for each method was calculated from a set of anatomic landmarks marked by four independent observers. Results: Nonrigid and rigid registration errors for treatment position PET/CT to planning CT were 2.77 {+-} 0.80 mm and 4.96 {+-} 2.38 mm, respectively, p = 0.001. Applying the nonrigid registration to diagnostic position PET/CT produced a more accurate match to the planning CT than rigid registration of treatment position PET/CT (3.20 {+-} 1.22 mm and 4.96 {+-} 2.38 mm, respectively, p = 0.012). Conclusions: Nonrigid registration provides a more accurate registration of head and neck PET/CT to treatment planning CT than rigid registration. In addition, nonrigid registration of PET/CT acquired with patients in a standardized, diagnostic position can provide images registered to planning CT with greater accuracy than a rigid registration of PET/CT images acquired in treatment position. This may allow greater flexibility in the timing of PET/CT for head and neck cancer patients due to undergo radiotherapy.

  17. Feasibility of a semi-automated contrast-oriented algorithm for tumor segmentation in retrospectively gated PET images: phantom and clinical validation.

    PubMed

    Carles, Montserrat; Fechter, Tobias; Nemer, Ursula; Nanko, Norbert; Mix, Michael; Nestle, Ursula; Schaefer, Andrea

    2015-12-21

    PET/CT plays an important role in radiotherapy planning for lung tumors. Several segmentation algorithms have been proposed for PET tumor segmentation. However, most of them do not take into account respiratory motion and are not well validated. The aim of this work was to evaluate a semi-automated contrast-oriented algorithm (COA) for PET tumor segmentation adapted to retrospectively gated (4D) images. The evaluation involved a wide set of 4D-PET/CT acquisitions of dynamic experimental phantoms and lung cancer patients. In addition, segmentation accuracy of 4D-COA was compared with four other state-of-the-art algorithms. In phantom evaluation, the physical properties of the objects defined the gold standard. In clinical evaluation, the ground truth was estimated by the STAPLE (Simultaneous Truth and Performance Level Estimation) consensus of three manual PET contours by experts. Algorithm evaluation with phantoms resulted in: (i) no statistically significant diameter differences for different targets and movements (Δφ = 0.3 ± 1.6 mm); (ii) reproducibility for heterogeneous and irregular targets independent of user initial interaction and (iii) good segmentation agreement for irregular targets compared to manual CT delineation in terms of Dice Similarity Coefficient (DSC = 0.66 ± 0.04), Positive Predictive Value (PPV  = 0.81 ± 0.06) and Sensitivity (Sen. = 0.49 ± 0.05). In clinical evaluation, the segmented volume was in reasonable agreement with the consensus volume (difference in volume (%Vol) = 40 ± 30, DSC = 0.71 ± 0.07 and PPV = 0.90 ± 0.13). High accuracy in target tracking position (ΔME) was obtained for experimental and clinical data (ΔME(exp) = 0 ± 3 mm; ΔME(clin) 0.3 ± 1.4 mm). In the comparison with other lung segmentation methods, 4D-COA has shown the highest volume accuracy in both experimental and clinical data. In conclusion, the accuracy in volume delineation, position tracking and its robustness on highly irregular target movements

  18. Feasibility of a semi-automated contrast-oriented algorithm for tumor segmentation in retrospectively gated PET images: phantom and clinical validation

    NASA Astrophysics Data System (ADS)

    Carles, Montserrat; Fechter, Tobias; Nemer, Ursula; Nanko, Norbert; Mix, Michael; Nestle, Ursula; Schaefer, Andrea

    2015-12-01

    PET/CT plays an important role in radiotherapy planning for lung tumors. Several segmentation algorithms have been proposed for PET tumor segmentation. However, most of them do not take into account respiratory motion and are not well validated. The aim of this work was to evaluate a semi-automated contrast-oriented algorithm (COA) for PET tumor segmentation adapted to retrospectively gated (4D) images. The evaluation involved a wide set of 4D-PET/CT acquisitions of dynamic experimental phantoms and lung cancer patients. In addition, segmentation accuracy of 4D-COA was compared with four other state-of-the-art algorithms. In phantom evaluation, the physical properties of the objects defined the gold standard. In clinical evaluation, the ground truth was estimated by the STAPLE (Simultaneous Truth and Performance Level Estimation) consensus of three manual PET contours by experts. Algorithm evaluation with phantoms resulted in: (i) no statistically significant diameter differences for different targets and movements (Δ φ =0.3+/- 1.6 mm); (ii) reproducibility for heterogeneous and irregular targets independent of user initial interaction and (iii) good segmentation agreement for irregular targets compared to manual CT delineation in terms of Dice Similarity Coefficient (DSC  =  0.66+/- 0.04 ), Positive Predictive Value (PPV  =  0.81+/- 0.06 ) and Sensitivity (Sen.  =  0.49+/- 0.05 ). In clinical evaluation, the segmented volume was in reasonable agreement with the consensus volume (difference in volume (%Vol)  =  40+/- 30 , DSC  =  0.71+/- 0.07 and PPV  =  0.90+/- 0.13 ). High accuracy in target tracking position (Δ ME) was obtained for experimental and clinical data (Δ ME{{}\\text{exp}}=0+/- 3 mm; Δ ME{{}\\text{clin}}=0.3+/- 1.4 mm). In the comparison with other lung segmentation methods, 4D-COA has shown the highest volume accuracy in both experimental and clinical data. In conclusion, the accuracy in volume

  19. A proposed framework for consensus-based lung tumour volume auto-segmentation in 4D computed tomography imaging

    NASA Astrophysics Data System (ADS)

    Martin, Spencer; Brophy, Mark; Palma, David; Louie, Alexander V.; Yu, Edward; Yaremko, Brian; Ahmad, Belal; Barron, John L.; Beauchemin, Steven S.; Rodrigues, George; Gaede, Stewart

    2015-02-01

    This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs) based on GT estimates (STAPLE) from each respiratory phase of the 4D-CT dataset. Accuracy assessment of auto-segmentation employed graph cuts for 3D-shape reconstruction and point-set registration-based analysis yielding volumetric and distance-based measures. STAPLE-based auto-segmented GTV accuracy ranged from (81.51  ±  1.92) to (97.27  ±  0.28)% volumetric overlap of the estimated ground truth. IGTV auto-segmentation showed significantly improved accuracies with reduced variance for all patients ranging from 90.87 to 98.57% volumetric overlap of the ground truth volume. Additional metrics supported these observations with statistical significance. Accuracy of auto-segmentation was shown to be largely independent of selection of the initial propagation phase. IGTV construction based on auto-segmented GTVs within the 4D-CT dataset provided accurate and reliable target volumes compared to manual segmentation-based GT estimates. While inter-/intra-observer effects were largely mitigated, the proposed segmentation workflow is more complex than that of current clinical practice and requires further development.

  20. Transformation of light double cones in the human retina: the origin of trichromatism, of 4D-spatiotemporal vision, and of patchwise 4D Fourier transformation in Talbot imaging

    NASA Astrophysics Data System (ADS)

    Lauinger, Norbert

    1997-09-01

    The interpretation of the 'inverted' retina of primates as an 'optoretina' (a light cones transforming diffractive cellular 3D-phase grating) integrates the functional, structural, and oscillatory aspects of a cortical layer. It is therefore relevant to consider prenatal developments as a basis of the macro- and micro-geometry of the inner eye. This geometry becomes relevant for the postnatal trichromatic synchrony organization (TSO) as well as the adaptive levels of human vision. It is shown that the functional performances, the trichromatism in photopic vision, the monocular spatiotemporal 3D- and 4D-motion detection, as well as the Fourier optical image transformation with extraction of invariances all become possible. To transform light cones into reciprocal gratings especially the spectral phase conditions in the eikonal of the geometrical optical imaging before the retinal 3D-grating become relevant first, then in the von Laue resp. reciprocal von Laue equation for 3D-grating optics inside the grating and finally in the periodicity of Talbot-2/Fresnel-planes in the near-field behind the grating. It is becoming possible to technically realize -- at least in some specific aspects -- such a cortical optoretina sensor element with its typical hexagonal-concentric structure which leads to these visual functions.

  1. Quantification of accuracy of the automated nonlinear image matching and anatomical labeling (ANIMAL) nonlinear registration algorithm for 4D CT images of lung.

    PubMed

    Heath, E; Collins, D L; Keall, P J; Dong, L; Seuntjens, J

    2007-11-01

    The performance of the ANIMAL (Automated Nonlinear Image Matching and Anatomical Labeling) nonlinear registration algorithm for registration of thoracic 4D CT images was investigated. The algorithm was modified to minimize the incidence of deformation vector discontinuities that occur during the registration of lung images. Registrations were performed between the inhale and exhale phases for five patients. The registration accuracy was quantified by the cross-correlation of transformed and target images and distance to agreement (DTA) measured based on anatomical landmarks and triangulated surfaces constructed from manual contours. On average, the vector DTA between transformed and target landmarks was 1.6 mm. Comparing transformed and target 3D triangulated surfaces derived from planning contours, the average target volume (GTV) center-of-mass shift was 2.0 mm and the 3D DTA was 1.6 mm. An average DTA of 1.8 mm was obtained for all planning structures. All DTA metrics were comparable to inter observer uncertainties established for landmark identification and manual contouring.

  2. Optimising rigid motion compensation for small animal brain PET imaging

    NASA Astrophysics Data System (ADS)

    Spangler-Bickell, Matthew G.; Zhou, Lin; Kyme, Andre Z.; De Laat, Bart; Fulton, Roger R.; Nuyts, Johan

    2016-10-01

    Motion compensation (MC) in PET brain imaging of awake small animals is attracting increased attention in preclinical studies since it avoids the confounding effects of anaesthesia and enables behavioural tests during the scan. A popular MC technique is to use multiple external cameras to track the motion of the animal’s head, which is assumed to be represented by the motion of a marker attached to its forehead. In this study we have explored several methods to improve the experimental setup and the reconstruction procedures of this method: optimising the camera-marker separation; improving the temporal synchronisation between the motion tracker measurements and the list-mode stream; post-acquisition smoothing and interpolation of the motion data; and list-mode reconstruction with appropriately selected subsets. These techniques have been tested and verified on measurements of a moving resolution phantom and brain scans of an awake rat. The proposed techniques improved the reconstructed spatial resolution of the phantom by 27% and of the rat brain by 14%. We suggest a set of optimal parameter values to use for awake animal PET studies and discuss the relative significance of each parameter choice.

  3. Brain tissue segmentation in PET-CT images using probabilistic atlas and variational Bayes inference.

    PubMed

    Xia, Yong; Wang, Jiabin; Eberl, Stefan; Fulham, Michael; Feng, David Dagan

    2011-01-01

    PET-CT provides aligned anatomical (CT) and functional (PET) images in a single scan, and has the potential to improve brain PET image segmentation, which can in turn improve quantitative clinical analyses. We propose a statistical segmentation algorithm that incorporates the prior anatomical knowledge represented by probabilistic brain atlas into the variational Bayes inference to delineate gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) in brain PET-CT images. Our approach adds an additional novel aspect by allowing voxels to have variable and adaptive prior probabilities of belonging to each class. We compared our algorithm to the segmentation approaches implemented in the expectation maximization segmentation (EMS) and statistical parametric mapping (SPM8) packages in 26 clinical cases. The results show that our algorithm improves the accuracy of brain PET-CT image segmentation.

  4. Effects of injected dose, BMI and scanner type on NECR and image noise in PET imaging.

    PubMed

    Chang, Tingting; Chang, Guoping; Kohlmyer, Steve; Clark, John W; Rohren, Eric; Mawlawi, Osama R

    2011-08-21

    Noise equivalent count rate (NECR) and image noise are two different but related metrics that have been used to predict and assess image quality, respectively. The aim of this study is to investigate, using patient studies, the relationships between injected dose (ID), body mass index (BMI) and scanner type on NECR and image noise measurements in PET imaging. Two groups of 90 patients each were imaged on a GE DSTE and a DRX PET/CT scanner, respectively. The patients in each group were divided into nine subgroups according to three BMI (20-24.9, 25-29.9, 30-45 kg m(-2)) and three ID (296-444, 444-555, 555-740 MBq) ranges, resulting in ten patients/subgroup. All PET data were acquired in 3D mode and reconstructed using the VuePoint HD® fully 3D OSEM algorithm (2 iterations, 21(DRX) or 20 (DSTE) subsets). NECR and image noise measurements for bed positions covering the liver were calculated for each patient. NECR was calculated from the trues, randoms and scatter events recorded in the DICOM header of each patient study, while image noise was determined as the standard deviation of 50 non-neighboring voxels in the liver of each patient. A t-test compared the NECR and image noise for different scanners but with the same BMI and ID. An ANOVA test on the other hand was used to compare the results of patients with different BMI but the same ID and scanner type as well as different ID but the same BMI and scanner type. As expected the t-test showed a significant difference in NECR between the two scanners for all BMI and ID subgroups. However, contrary to what is expected no such findings were observed for image noise measurement. The ANOVA results showed a statistically significant difference in both NECR and image noise among the different BMI for each ID and scanner subgroup. However, there was no statistically significant difference in NECR and image noise across different ID for each BMI and scanner subgroup. Although the GE DRX PET/CT scanner has better count rate

  5. Heterogeneity in stabilization phenomena in FLT PET images of canines

    PubMed Central

    Simoncic, Urban; Jeraj, Robert

    2014-01-01

    3′-(18F)fluoro-3′-deoxy-L-thymidine (FLT) is a PET marker of cellular proliferation. Its tissue uptake rate is often quantified with a Standardized Uptake Value (SUV), although kinetic analysis provides a more accurate quantification. The purpose of this study is to investigate the heterogeneity in FLT stabilization phenomena. The study was done on 15 canines with spontaneously occurring sinonasal tumours. They were imaged dynamically for 90 min with FLT PET/CT twice; before and during the radiotherapy. Images were analyzed for kinetics on a voxel basis through compartmental analysis. Stabilization curves were calculated as a time-dependant correlation between the time-dependant SUV and the kinetic parameters (voxel values within the tumour were correlated). Stabilization curves were analyzed for stabilization speed, maximal correlation and correlation decrease following the maximal correlation. These stabilization parameters were correlated with the region-averaged kinetic parameters. The FLT SUV was highly correlated with vasculature fraction immediately post-injection, followed by maximum in correlation with the perfusion/permeability. At later times post-injection the FLT SUV was highly correlated (Pearson correlation coefficient above 0.95) with the FLT influx parameter for cases with tumour-averaged SUV30–50min above 2, while others were indeterminate (correlation coefficients from 0.1 to 0.97). All cases with highly correlated SUV and FLT influx parameter had correlation coefficient within 0.5% of its maximum in the period of 30–50 min post-injection. Stabilization time was inversely proportional to the FLT influx rate. Correlation between the FLT SUV and FLT influx parameter dropped at later times post-injection with drop being proportional to the dephosphorylation rate. The FLT was found to be metabolically stable in canines. FLT PET imaging protocol should define minimal and maximal FLT uptake period, which would be 30–50 min for our patients

  6. Towards integration of PET/MR hybrid imaging into radiation therapy treatment planning

    SciTech Connect

    Paulus, Daniel H.; Thorwath, Daniela; Schmidt, Holger; Quick, Harald H.

    2014-07-15

    Purpose: Multimodality imaging has become an important adjunct of state-of-the-art radiation therapy (RT) treatment planning. Recently, simultaneous PET/MR hybrid imaging has become clinically available and may also contribute to target volume delineation and biological individualization in RT planning. For integration of PET/MR hybrid imaging into RT treatment planning, compatible dedicated RT devices are required for accurate patient positioning. In this study, prototype RT positioning devices intended for PET/MR hybrid imaging are introduced and tested toward PET/MR compatibility and image quality. Methods: A prototype flat RT table overlay and two radiofrequency (RF) coil holders that each fix one flexible body matrix RF coil for RT head/neck imaging have been evaluated within this study. MR image quality with the RT head setup was compared to the actual PET/MR setup with a dedicated head RF coil. PET photon attenuation and CT-based attenuation correction (AC) of the hardware components has been quantitatively evaluated by phantom scans. Clinical application of the new RT setup in PET/MR imaging was evaluated in anin vivo study. Results: The RT table overlay and RF coil holders are fully PET/MR compatible. MR phantom and volunteer imaging with the RT head setup revealed high image quality, comparable to images acquired with the dedicated PET/MR head RF coil, albeit with 25% reduced SNR. Repositioning accuracy of the RF coil holders was below 1 mm. PET photon attenuation of the RT table overlay was calculated to be 3.8% and 13.8% for the RF coil holders. With CT-based AC of the devices, the underestimation error was reduced to 0.6% and 0.8%, respectively. Comparable results were found within the patient study. Conclusions: The newly designed RT devices for hybrid PET/MR imaging are PET and MR compatible. The mechanically rigid design and the reproducible positioning allow for straightforward CT-based AC. The systematic evaluation within this study provides the

  7. PET Imaging of Skeletal Metastases and Its Role in Personalizing Further Management.

    PubMed

    Mahajan, Abhishek; Azad, Gurdip Kaur; Cook, Gary J

    2016-07-01

    In oncology, the skeleton is one of the most frequently encountered sites for metastatic disease and thus early detection not only has an impact on an individual patient's management but also on the overall outcome. Multiparametric and multimodal hybrid PET/computed tomography and PET/MR imaging have revolutionized imaging for bone metastases, but irrespective of tumor biology or morphology of the bone lesion it remains unclear which imaging modality is the most clinically relevant to guide individualized cancer care. In this review, we highlight the current clinical challenges of PET imaging in evaluation and quantification of skeletal tumor burden and its impact on personalized cancer management.

  8. EXPLORER: Changing the molecular imaging paradigm with total-body PET/CT (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cherry, Simon R.; Badawi, Ramsey D.; Jones, Terry

    2016-04-01

    Positron emission tomography (PET) is the highest sensitivity technique for human whole-body imaging studies. However, current clinical PET scanners do not make full use of the available signal, as they only permit imaging of a 15-25 cm segment of the body at one time. Given the limited sensitive region, whole-body imaging with clinical PET scanners requires relatively long scan times and subjects the patient to higher than necessary radiation doses. The EXPLORER initiative aims to build a 2-meter axial length PET scanner to allow imaging the entire subject at once, capturing nearly the entire available PET signal. EXPLORER will acquire data with ~40-fold greater sensitivity leading to a six-fold increase in reconstructed signal-to-noise ratio for imaging the total body. Alternatively, total-body images with the EXPLORER scanner will be able to be acquired in ~30 seconds or with ~0.15 mSv injected dose, while maintaining current PET image quality. The superior sensitivity will open many new avenues for biomedical research. Specifically for cancer applications, high sensitivity PET will enable detection of smaller lesions. Additionally, greater sensitivity will allow imaging out to 10 half-lives of positron emitting radiotracers. This will enable 1) metabolic ultra-staging with FDG by extending the uptake and clearance time to 3-5 hours to significantly improve contrast and 2) improved kinetic imaging with short-lived radioisotopes such as C-11, crucial for drug development studies. Frequent imaging studies of the same subject to study disease progression or to track response to therapy will be possible with the low dose capabilities of the EXPLORER scanner. The low dose capabilities will also open up new imaging possibilities in pediatrics and adolescents to better study developmental disorders. This talk will review the basis for developing total-body PET, potential applications, and review progress to date in developing EXPLORER, the first total-body PET scanner.

  9. Respiration-Averaged CT for Attenuation Correction of PET Images – Impact on PET Texture Features in Non-Small Cell Lung Cancer Patients

    PubMed Central

    Cheng, Nai-Ming; Fang, Yu-Hua Dean; Tsan, Din-Li

    2016-01-01

    Purpose We compared attenuation correction of PET images with helical CT (PET/HCT) and respiration-averaged CT (PET/ACT) in patients with non-small-cell lung cancer (NSCLC) with the goal of investigating the impact of respiration-averaged CT on 18F FDG PET texture parameters. Materials and Methods A total of 56 patients were enrolled. Tumors were segmented on pretreatment PET images using the adaptive threshold. Twelve different texture parameters were computed: standard uptake value (SUV) entropy, uniformity, entropy, dissimilarity, homogeneity, coarseness, busyness, contrast, complexity, grey-level nonuniformity, zone-size nonuniformity, and high grey-level large zone emphasis. Comparisons of PET/HCT and PET/ACT were performed using Wilcoxon signed-rank tests, intraclass correlation coefficients, and Bland-Altman analysis. Receiver operating characteristic (ROC) curves as well as univariate and multivariate Cox regression analyses were used to identify the parameters significantly associated with disease-specific survival (DSS). A fixed threshold at 45% of the maximum SUV (T45) was used for validation. Results SUV maximum and total lesion glycolysis (TLG) were significantly higher in PET/ACT. However, texture parameters obtained with PET/ACT and PET/HCT showed a high degree of agreement. The lowest levels of variation between the two modalities were observed for SUV entropy (9.7%) and entropy (9.8%). SUV entropy, entropy, and coarseness from both PET/ACT and PET/HCT were significantly associated with DSS. Validation analyses using T45 confirmed the usefulness of SUV entropy and entropy in both PET/HCT and PET/ACT for the prediction of DSS, but only coarseness from PET/ACT achieved the statistical significance threshold. Conclusions Our results indicate that 1) texture parameters from PET/ACT are clinically useful in the prediction of survival in NSCLC patients and 2) SUV entropy and entropy are robust to attenuation correction methods. PMID:26930211

  10. Automatic co-segmentation of lung tumor based on random forest in PET-CT images

    NASA Astrophysics Data System (ADS)

    Jiang, Xueqing; Xiang, Dehui; Zhang, Bin; Zhu, Weifang; Shi, Fei; Chen, Xinjian

    2016-03-01

    In this paper, a fully automatic method is proposed to segment the lung tumor in clinical 3D PET-CT images. The proposed method effectively combines PET and CT information to make full use of the high contrast of PET images and superior spatial resolution of CT images. Our approach consists of three main parts: (1) initial segmentation, in which spines are removed in CT images and initial connected regions achieved by thresholding based segmentation in PET images; (2) coarse segmentation, in which monotonic downhill function is applied to rule out structures which have similar standardized uptake values (SUV) to the lung tumor but do not satisfy a monotonic property in PET images; (3) fine segmentation, random forests method is applied to accurately segment the lung tumor by extracting effective features from PET and CT images simultaneously. We validated our algorithm on a dataset which consists of 24 3D PET-CT images from different patients with non-small cell lung cancer (NSCLC). The average TPVF, FPVF and accuracy rate (ACC) were 83.65%, 0.05% and 99.93%, respectively. The correlation analysis shows our segmented lung tumor volumes has strong correlation ( average 0.985) with the ground truth 1 and ground truth 2 labeled by a clinical expert.

  11. Performance of three-photon PET imaging: Monte Carlo simulations.

    PubMed

    Kacperski, Krzysztof; Spyrou, Nicholas M

    2005-12-07

    We have recently introduced the idea of making use of three-photon positron annihilations in positron emission tomography. In this paper, the basic characteristics of the three-gamma imaging in PET are studied by means of Monte Carlo simulations and analytical computations. Two typical configurations of human and small animal scanners are considered. Three-photon imaging requires high-energy resolution detectors. Parameters currently attainable by CdZnTe semiconductor detectors, the technology of choice for the future development of radiation imaging, are assumed. Spatial resolution is calculated as a function of detector energy resolution and size, position in the field of view, scanner size and the energies of the three-gamma annihilation photons. Possible ways to improve the spatial resolution obtained for nominal parameters, 1.5 cm and 3.2 mm FWHM for human and small animal scanners, respectively, are indicated. Counting rates of true and random three-photon events for typical human and small animal scanning configurations are assessed. A simple formula for minimum size of lesions detectable in the three-gamma based images is derived. Depending on the contrast and total number of registered counts, lesions of a few mm size for human and sub mm for small animal scanners can be detected.

  12. Development of [F-18]-Labeled Amyloid Imaging Agents for PET

    SciTech Connect

    Mathis, CA

    2007-05-09

    The applicant proposes to design and synthesize a series of fluorine-18-labeled radiopharmaceuticals to be used as amyloid imaging agents for positron emission tomography (PET). The investigators will conduct comprehensive iterative in vitro and in vivo studies based upon well defined acceptance criteria in order to identify lead agents suitable for human studies. The long term goals are to apply the selected radiotracers as potential diagnostic agents of Alzheimer's disease (AD), as surrogate markers of amyloid in the brain to determine the efficacy of anti-amyloid therapeutic drugs, and as tools to help address basic scientific questions regarding the progression of the neuropathology of AD, such as testing the "amyloid cascade hypothesis" which holds that amyloid accumulation is the primary cause of AD.

  13. Comparison of bootstrap resampling methods for 3-D PET imaging.

    PubMed

    Lartizien, C; Aubin, J-B; Buvat, I

    2010-07-01

    Two groups of bootstrap methods have been proposed to estimate the statistical properties of positron emission tomography (PET) images by generating multiple statistically equivalent data sets from few data samples. The first group generates resampled data based on a parametric approach assuming that data from which resampling is performed follows a Poisson distribution while the second group consists of nonparametric approaches. These methods either require a unique original sample or a series of statistically equivalent data that can be list-mode files or sinograms. Previous reports regarding these bootstrap approaches suggest different results. This work compares the accuracy of three of these bootstrap methods for 3-D PET imaging based on simulated data. Two methods are based on a unique file, namely a list-mode based nonparametric (LMNP) method and a sinogram based parametric (SP) method. The third method is a sinogram-based nonparametric (SNP) method. Another original method (extended LMNP) was also investigated, which is an extension of the LMNP methods based on deriving a resampled list-mode file by drawings events from multiple original list-mode files. Our comparison is based on the analysis of the statistical moments estimated on the repeated and resampled data. This includes the probability density function and the moments of order 1 and 2. Results show that the two methods based on multiple original data (SNP and extended LMNP) are the only methods that correctly estimate the statistical parameters. Performances of the LMNP and SP methods are variable. Simulated data used in this study were characterized by a high noise level. Differences among the tested strategies might be reduced with clinical data sets with lower noise.

  14. Combined SPECT/CT and PET/CT for breast imaging

    NASA Astrophysics Data System (ADS)

    Russo, Paolo; Larobina, Michele; Di Lillo, Francesca; Del Vecchio, Silvana; Mettivier, Giovanni

    2016-02-01

    In the field of nuclear medicine imaging, breast imaging for cancer diagnosis is still mainly based on 2D imaging techniques. Three-dimensional tomographic imaging with whole-body PET or SPECT scanners, when used for imaging the breast, has performance limits in terms of spatial resolution and sensitivity, which can be overcome only with a dedicated instrumentation. However, only few hybrid imaging systems for PET/CT or SPECT/CT dedicated to the breast have been developed in the last decade, providing complementary functional and anatomical information on normal breast tissue and lesions. These systems are still under development and clinical trials on just few patients have been reported; no commercial dedicated breast PET/CT or SPECT/CT is available. This paper reviews combined dedicated breast PET/CT and SPECT/CT scanners described in the recent literature, with focus on their technological aspects.

  15. In Vivo ¹⁸F-FDG-PET Imaging in Mouse Atherosclerosis.

    PubMed

    Mateo, Jesús; Bilbao, Izaskun; Vaquero, Juan José; Ruiz-Cabello, Jesús; España, Samuel

    2015-01-01

    Positron emission tomography (PET) is an important technique in cardiovascular research. Vascular inflammation detected by fluorodeoxyglucose (FDG)-PET has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. The use of PET imaging in mouse models of atherosclerosis is challenged by the reduced size of the scanned organs. However, the last generation of dedicated PET scanners has an improved spatial resolution (<1 mm) and increased sensitivity allowing those studies to be performed. Here, we describe a procedure to perform FDG-PET experiments in atherosclerosis mouse models, the required equipment for animal handling and imaging, and the tools and procedures for image analysis and validation of the results.

  16. Antibody-based PET imaging of amyloid beta in mouse models of Alzheimer's disease

    PubMed Central

    Sehlin, Dag; Fang, Xiaotian T.; Cato, Linda; Antoni, Gunnar; Lannfelt, Lars; Syvänen, Stina

    2016-01-01

    Owing to their specificity and high-affinity binding, monoclonal antibodies have potential as positron emission tomography (PET) radioligands and are currently used to image various targets in peripheral organs. However, in the central nervous system, antibody uptake is limited by the blood–brain barrier (BBB). Here we present a PET ligand to be used for diagnosis and evaluation of treatment effects in Alzheimer's disease. The amyloid β (Aβ) antibody mAb158 is radiolabelled and conjugated to a transferrin receptor antibody to enable receptor-mediated transcytosis across the BBB. PET imaging of two different mouse models with Aβ pathology clearly visualize Aβ in the brain. The PET signal increases with age and correlates closely with brain Aβ levels. Thus, we demonstrate that antibody-based PET ligands can be successfully used for brain imaging. PMID:26892305

  17. Molecular Imaging and Precision Medicine: PET/Computed Tomography and Therapy Response Assessment in Oncology.

    PubMed

    Sheikhbahaei, Sara; Mena, Esther; Pattanayak, Puskar; Taghipour, Mehdi; Solnes, Lilja B; Subramaniam, Rathan M

    2017-01-01

    A variety of methods have been developed to assess tumor response to therapy. Standardized qualitative criteria based on 18F-fluoro-deoxyglucose PET/computed tomography have been proposed to evaluate the treatment effectiveness in specific cancers and these allow more accurate therapy response assessment and survival prognostication. Multiple studies have addressed the utility of the volumetric PET biomarkers as prognostic indicators but there is no consensus about the preferred segmentation methodology for these metrics. Heterogeneous intratumoral uptake was proposed as a novel PET metric for therapy response assessment. PET imaging techniques will be used to study the biological behavior of cancers during therapy.

  18. Impact of metal artefacts due to EEG electrodes in brain PET/CT imaging

    NASA Astrophysics Data System (ADS)

    Lemmens, Catherine; Montandon, Marie-Louise; Nuyts, Johan; Ratib, Osman; Dupont, Patrick; Zaidi, Habib

    2008-08-01

    The goal of this study is to investigate the impact of electroencephalogram (EEG) electrodes on the visual quality and quantification of 18F-FDG PET images in neurological PET/CT examinations. For this purpose, the scans of 20 epilepsy patients with EEG monitoring were used. The CT data were reconstructed with filtered backprojection (FBP) and with a metal artefact reduction (MAR) algorithm. Both data sets were used for CT-based attenuation correction (AC) of the PET data. Also, a calculated AC (CALC) technique was considered. A volume of interest (VOI)-based analysis and a voxel-based quantitative analysis were performed to compare the different AC methods. Images were also evaluated visually by two observers. It was shown with simulations and phantom measurements that from the considered AC methods, the MAR-AC can be used as the reference in this setting. The visual assessment of PET images showed local hot spots outside the brain corresponding to the locations of the electrodes when using FBP-AC. In the brain, no abnormalities were observed. The quantitative analysis showed a very good correlation between PET-FBP-AC and PET-MAR-AC, with a statistically significant positive bias in the PET-FBP-AC images of about 5-7% in most brain voxels. There was also good correlation between PET-CALC-AC and PET-MAR-AC, but in the PET-CALC-AC images, regions with both a significant positive and negative bias were observed. EEG electrodes give rise to local hot spots outside the brain and a positive quantification bias in the brain. However, when diagnosis is made by mere visual assessment, the presence of EEG electrodes does not seem to alter the diagnosis. When quantification is performed, the bias becomes an issue especially when comparing brain images with and without EEG monitoring.

  19. New targets for the development of PET tracers for imaging neurodegeneration in Alzheimer disease.

    PubMed

    Mach, Robert H

    2014-08-01

    The field of molecular imaging has experienced significant advances in the area of Alzheimer disease (AD), the most significant being the development of PET radiotracers for imaging β-amyloid burden in the brain of individuals at risk for or in the early stages of AD. More recent advances include the development of PET radiotracers for imaging aggregates of hyperphosphorylated tau protein in neurofibrillary tangles, a process that occurs late in the disease process. This article highlights advances in the neurobiology of AD and describes how PET can be used to study the mechanisms of neurodegeneration in AD.

  20. Transmission imaging for integrated PET-MR systems

    NASA Astrophysics Data System (ADS)

    Bowen, Spencer L.; Fuin, Niccolò; Levine, Michael A.; Catana, Ciprian

    2016-08-01

    Attenuation correction for PET-MR systems continues to be a challenging problem, particularly for body regions outside the head. The simultaneous acquisition of transmission scan based μ-maps and MR images on integrated PET-MR systems may significantly increase the performance of and offer validation for new MR-based μ-map algorithms. For the Biograph mMR (Siemens Healthcare), however, use of conventional transmission schemes is not practical as the patient table and relatively small diameter scanner bore significantly restrict radioactive source motion and limit source placement. We propose a method for emission-free coincidence transmission imaging on the Biograph mMR. The intended application is not for routine subject imaging, but rather to improve and validate MR-based μ-map algorithms; particularly for patient implant and scanner hardware attenuation correction. In this study we optimized source geometry and assessed the method’s performance with Monte Carlo simulations and phantom scans. We utilized a Bayesian reconstruction algorithm, which directly generates μ-map estimates from multiple bed positions, combined with a robust scatter correction method. For simulations with a pelvis phantom a single torus produced peak noise equivalent count rates (34.8 kcps) dramatically larger than a full axial length ring (11.32 kcps) and conventional rotating source configurations. Bias in reconstructed μ-maps for head and pelvis simulations was  ⩽4% for soft tissue and  ⩽11% for bone ROIs. An implementation of the single torus source was filled with 18F-fluorodeoxyglucose and the proposed method quantified for several test cases alone or in comparison with CT-derived μ-maps. A volume average of 0.095 cm-1 was recorded for an experimental uniform cylinder phantom scan, while a bias of  <2% was measured for the cortical bone equivalent insert of the multi-compartment phantom. Single torus μ-maps of a hip implant phantom showed significantly less

  1. Transmission imaging for integrated PET-MR systems.

    PubMed

    Bowen, Spencer L; Fuin, Niccolò; Levine, Michael A; Catana, Ciprian

    2016-08-07

    Attenuation correction for PET-MR systems continues to be a challenging problem, particularly for body regions outside the head. The simultaneous acquisition of transmission scan based μ-maps and MR images on integrated PET-MR systems may significantly increase the performance of and offer validation for new MR-based μ-map algorithms. For the Biograph mMR (Siemens Healthcare), however, use of conventional transmission schemes is not practical as the patient table and relatively small diameter scanner bore significantly restrict radioactive source motion and limit source placement. We propose a method for emission-free coincidence transmission imaging on the Biograph mMR. The intended application is not for routine subject imaging, but rather to improve and validate MR-based μ-map algorithms; particularly for patient implant and scanner hardware attenuation correction. In this study we optimized source geometry and assessed the method's performance with Monte Carlo simulations and phantom scans. We utilized a Bayesian reconstruction algorithm, which directly generates μ-map estimates from multiple bed positions, combined with a robust scatter correction method. For simulations with a pelvis phantom a single torus produced peak noise equivalent count rates (34.8 kcps) dramatically larger than a full axial length ring (11.32 kcps) and conventional rotating source configurations. Bias in reconstructed μ-maps for head and pelvis simulations was  ⩽4% for soft tissue and  ⩽11% for bone ROIs. An implementation of the single torus source was filled with (18)F-fluorodeoxyglucose and the proposed method quantified for several test cases alone or in comparison with CT-derived μ-maps. A volume average of 0.095 cm(-1) was recorded for an experimental uniform cylinder phantom scan, while a bias of  <2% was measured for the cortical bone equivalent insert of the multi-compartment phantom. Single torus μ-maps of a hip implant phantom showed significantly

  2. What Does PET Imaging Add to Conventional Staging of Head and Neck Cancer Patients?

    SciTech Connect

    Pohar, Surjeet . E-mail: poharss@evms.edu; Brown, Robert B.S.; Newman, Nancy; Koniarczyk, Michael; Hsu, Jack; Feiglin, David

    2007-06-01

    Purpose: To determine the value of PET scans in the staging of patients with head and neck carcinoma. Methods and Materials: The charts of 25 patients who underwent neck dissection, computed tomography (CT) scan, and F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging as part of their initial work-up for a head and neck squamous cell cancer between 2000-2003 were reviewed. All patients underwent clinical examination, triple endoscopy, and chest radiograph as part of their clinical staging, adhering to American Joint Commission for Cancer criteria. In addition to the clinical nodal (N) stage, PET findings were incorporated to determine a second type of N staging: clinical N + PET stage. The number of neck sides and nodal levels involved on CT or PET and on pathologic examination were recorded. Results: The sensitivity and specificity for detection of nodal disease were similar for CT and FDG-PET. Positive and negative likelihood ratios were similar for both diagnostic tests. None of our 25 patients had unsuspected distant disease detected by PET. Conclusion: The addition of PET imaging did not improve diagnostic accuracy in our patients compared with CT. PET scanning did not alter clinical management in any of the patients.

  3. TU-AB-BRA-06: Texture Feature Reproducibility Between PET/CT and PET/MR Imaging Modalities

    SciTech Connect

    Galavis, P; Friedman, K; Chandarana, H; Jackson, K

    2015-06-15

    Purpose: Radiomics involves the extraction of texture features from different imaging modalities with the purpose of developing models to predict patient treatment outcomes. The purpose of this study is to investigate texture feature reproducibility across [18F]FDG PET/CT and [18F]FDG PET/MR imaging in patients with primary malignancies. Methods: Twenty five prospective patients with solid tumors underwent clinical [18F]FDG PET/CT scan followed by [18F]FDG PET/MR scans. In all patients the lesions were identified using nuclear medicine reports. The images were co-registered and segmented using an in-house auto-segmentation method. Fifty features, based on the intensity histogram, second and high order matrices, were extracted from the segmented regions from both image data sets. One-way random-effects ANOVA model of the intra-class correlation coefficient (ICC) was used to establish texture feature correlations between both data sets. Results: Fifty features were classified based on their ICC values, which were found in the range from 0.1 to 0.86, in three categories: high, intermediate, and low. Ten features extracted from second and high-order matrices showed large ICC ≥ 0.70. Seventeen features presented intermediate 0.5 ≤ ICC ≤ 0.65 and the remaining twenty three presented low ICC ≤ 0.45. Conclusion: Features with large ICC values could be reliable candidates for quantification as they lead to similar results from both imaging modalities. Features with small ICC indicates a lack of correlation. Therefore, the use of these features as a quantitative measure will lead to different assessments of the same lesion depending on the imaging modality from where they are extracted. This study shows the importance of the need for further investigation and standardization of features across multiple imaging modalities.

  4. IMRT treatment plans and functional planning with functional lung imaging from 4D-CT for thoracic cancer patients

    PubMed Central

    2013-01-01

    Background and purpose Currently, the inhomogeneity of the pulmonary function is not considered when treatment plans are generated in thoracic cancer radiotherapy. This study evaluates the dose of treatment plans on highly-functional volumes and performs functional treatment planning by incorporation of ventilation data from 4D-CT. Materials and methods Eleven patients were included in this retrospective study. Ventilation was calculated using 4D-CT. Two treatment plans were generated for each case, the first one without the incorporation of the ventilation and the second with it. The dose of the first plans was overlapped with the ventilation and analyzed. Highly-functional regions were avoided in the second treatment plans. Results For small targets in the first plans (PTV < 400 cc, 6 cases), all V5, V20 and the mean lung dose values for the highly-functional regions were lower than that of the total lung. For large targets, two out of five cases had higher V5 and V20 values for the highly-functional regions. All the second plans were within constraints. Conclusion Radiation treatments affect functional lung more seriously in large tumor cases. With compromise of dose to other critical organs, functional treatment planning to reduce dose in highly-functional lung volumes can be achieved PMID:23281734

  5. Comparison of two respiration monitoring systems for 4D imaging with a Siemens CT using a new dynamic breathing phantom.

    PubMed

    Vásquez, A C; Runz, A; Echner, G; Sroka-Perez, G; Karger, C P

    2012-05-07

    Four-dimensional computed tomography (4D-CT) requires breathing information from the patient, and for this, several systems are available. Testing of these systems, under realistic conditions, requires a phantom with a moving target and an expandable outer contour. An anthropomorphic phantom was developed to simulate patient breathing as well as lung tumor motion. Using the phantom, an optical camera system (GateCT) and a pressure sensor (AZ-733V) were simultaneously operated, and 4D-CTs were reconstructed with a Siemens CT using the provided local-amplitude-based sorting algorithm. The comparison of the tumor trajectories of both systems revealed discrepancies up to 9.7 mm. Breathing signal differences, such as baseline drift, temporal resolution and noise level were shown not to be the reason for this. Instead, the variability of the sampling interval and the accuracy of the sampling rate value written on the header of the GateCT-signal file were identified as the cause. Interpolation to regular sampling intervals and correction of the sampling rate to the actual value removed the observed discrepancies. Consistently, the introduction of sampling interval variability and inaccurate sampling rate values into the header of the AZ-733V file distorted the tumor trajectory for this system. These results underline the importance of testing new equipment thoroughly, especially if components of different manufacturers are combined.

  6. Segmentation of brain PET-CT images based on adaptive use of complementary information

    NASA Astrophysics Data System (ADS)

    Xia, Yong; Wen, Lingfeng; Eberl, Stefan; Fulham, Michael; Feng, Dagan

    2009-02-01

    Dual modality PET-CT imaging provides aligned anatomical (CT) and functional (PET) images in a single scanning session, which can potentially be used to improve image segmentation of PET-CT data. The ability to distinguish structures for segmentation is a function of structure and modality and varies across voxels. Thus optimal contribution of a particular modality to segmentation is spatially variant. Existing segmentation algorithms, however, seldom account for this characteristic of PET-CT data and the results using these algorithms are not optimal. In this study, we propose a relative discrimination index (RDI) to characterize the relative abilities of PET and CT to correctly classify each voxel into the correct structure for segmentation. The definition of RDI is based on the information entropy of the probability distribution of the voxel's class label. If the class label derived from CT data for a particular voxel has more certainty than that derived from PET data, the corresponding RDI will have a higher value. We applied the RDI matrix to balance adaptively the contributions of PET and CT data to segmentation of brain PET-CT images on a voxel-by-voxel basis, with the aim to give the modality with higher discriminatory power a larger weight. The resultant segmentation approach is distinguished from traditional approaches by its innovative and adaptive use of the dual-modality information. We compared our approach to the non-RDI version and two commonly used PET-only based segmentation algorithms for simulation and clinical data. Our results show that the RDI matrix markedly improved PET-CT image segmentation.

  7. Positron Emission Tomography (PET)

    DOE R&D Accomplishments Database

    Welch, M. J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

  8. Positron Emission Tomography (PET)

    SciTech Connect

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  9. MR-PET image coregistration for quantitation of striatal dopamine D{sub 2} receptors

    SciTech Connect

    Wang, G.J.; Volkow, N.D.; Levy, A.V.

    1996-05-01

    Our goal was to assess the utility of MR-PET image coregistration to quantify dopamine D{sub 2} receptors in striatum. Twenty-nine normal subjects were investigated with PET and [{sup 11}C]raclopride and with MRI. D{sub 2} receptors were quantified using the ratio of the distribution volume in striatum to that in cerebellum. Measures obtained using regions selected directly from the PET images were compared with those obtained from MR images and then projected to coregistered PET images. There were no differences between measures selected from the PET images (3.9 {+-} 0.5) and those from the MR images (3.9 {+-} 0.65). The values for these two measures were significantly correlated and corresponded to r = 0.9, P < 0.0001. Regions of interest selected directly from PET images, where there is a large contrast between the region of interest and background, as for the case of dopamine D{sub 2} ligands, are almost identical to those obtained from coregistered MR images. 24 refs., 4 figs., 1 tab.

  10. TH-E-202-01: Pitfalls and Remedies in PET/CT Imaging for RT Planning.

    PubMed

    Pan, T

    2016-06-01

    PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: 1. Pitfalls and remedies in PET/CT imaging for RT planning 2. The use of hypoxia PET imaging for radiotherapy 3. PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy. The second presentation will discuss the use of hypoxia PET Imaging for radiation therapy. We will discuss various hypoxia radiotracers, the choice of clinical acquisition protocol (in particular a single late static acquisition versus a dynamic acquisition), and the compartmental modeling with different transfer rate constants explained. We will demonstrate applications of hypoxia imaging for dose escalation/de-escalation in clinical trials. The last presentation will discuss the use of PET/CT for tumor response evaluation. We will discuss anatomic response assessment vs. metabolic response assessment, visual evaluation and semi-quantitative evaluation, and limitations of current PET/CT assessment. We will summarize clinical trials using PET response in guiding adaptive radiotherapy. Finally, we will summarize recent advancements in PET/CT radiomics and non-FDG PET tracers for response assessment.

  11. A Survey of FDG- and Amyloid-PET Imaging in Dementia and GRADE Analysis

    PubMed Central

    Daniela, Perani; Orazio, Schillaci; Alessandro, Padovani; Mariano, Nobili Flavio; Leonardo, Iaccarino; Pasquale Anthony, Della Rosa; Giovanni, Frisoni; Carlo, Caltagirone

    2014-01-01

    PET based tools can improve the early diagnosis of Alzheimer's disease (AD) and differential diagnosis of dementia. The importance of identifying individuals at risk of developing dementia among people with subjective cognitive complaints or mild cognitive impairment has clinical, social, and therapeutic implications. Within the two major classes of AD biomarkers currently identified, that is, markers of pathology and neurodegeneration, amyloid- and FDG-PET imaging represent decisive tools for their measurement. As a consequence, the PET tools have been recognized to be of crucial value in the recent guidelines for the early diagnosis of AD and other dementia conditions. The references based recommendations, however, include large PET imaging literature based on visual methods that greatly reduces sensitivity and specificity and lacks a clear cut-off between normal and pathological findings. PET imaging can be assessed using parametric or voxel-wise analyses by comparing the subject's scan with a normative data set, significantly increasing the diagnostic accuracy. This paper is a survey of the relevant literature on FDG and amyloid-PET imaging aimed at providing the value of quantification for the early and differential diagnosis of AD. This allowed a meta-analysis and GRADE analysis revealing high values for PET imaging that might be useful in considering recommendations. PMID:24772437

  12. A survey of FDG- and amyloid-PET imaging in dementia and GRADE analysis.

    PubMed

    Perani, Daniela; Daniela, Perani; Schillaci, Orazio; Orazio, Schillaci; Padovani, Alessandro; Alessandro, Padovani; Nobili, Flavio Mariano; Mariano, Nobili Flavio; Iaccarino, Leonardo; Leonardo, Iaccarino; Della Rosa, Pasquale Anthony; Pasquale Anthony, Della Rosa; Frisoni, Giovanni; Giovanni, Frisoni; Caltagirone, Carlo; Carlo, Caltagirone

    2014-01-01

    PET based tools can improve the early diagnosis of Alzheimer's disease (AD) and differential diagnosis of dementia. The importance of identifying individuals at risk of developing dementia among people with subjective cognitive complaints or mild cognitive impairment has clinical, social, and therapeutic implications. Within the two major classes of AD biomarkers currently identified, that is, markers of pathology and neurodegeneration, amyloid- and FDG-PET imaging represent decisive tools for their measurement. As a consequence, the PET tools have been recognized to be of crucial value in the recent guidelines for the early diagnosis of AD and other dementia conditions. The references based recommendations, however, include large PET imaging literature based on visual methods that greatly reduces sensitivity and specificity and lacks a clear cut-off between normal and pathological findings. PET imaging can be assessed using parametric or voxel-wise analyses by comparing the subject's scan with a normative data set, significantly increasing the diagnostic accuracy. This paper is a survey of the relevant literature on FDG and amyloid-PET imaging aimed at providing the value of quantification for the early and differential diagnosis of AD. This allowed a meta-analysis and GRADE analysis revealing high values for PET imaging that might be useful in considering recommendations.

  13. (68)Ga-PSMA PET/MR with multimodality image analysis for primary prostate cancer.

    PubMed

    Eiber, Matthias; Nekolla, Stephan G; Maurer, Tobias; Weirich, Gregor; Wester, Hans-Jürgen; Schwaiger, Markus

    2015-08-01

    Current imaging procedures for prostate cancer including positron emission tomography (PET) exhibit considerable limitations and are not always able to meet the diagnostic needs. Recently, a (68)Gallium-labeled ligand of the prostate-specific membrane antigen ((68)Ga-PSMA) has been introduced in PET-imaging of prostate cancer with first promising results. Due to relatively exclusive expression of PSMA in prostatic tissue as well as increased expression in prostate cancer, 68 Ga-PSMA was reported to exhibit a favorable lesion to background ratio. Together with the novel development of combined PET/MRI, the combination of excellent morphological detail, multiparametric functional information, and molecular PET data might lead to a significant improvement in detection of prostate cancer. We present an exemplarily case of primary staging using multiparametric (68)Ga-PSMA PET/MR by combining molecular and structural information.

  14. The use of PET imaging in studying cognition, genetics and pharmacotherapeutic interventions in schizophrenia.

    PubMed

    Vyas, Nora S; Patel, Neva H; Nijran, Kuldip S; Al-Nahhas, Adil; Puri, Basant K

    2011-01-01

    Positron emission tomography (PET) offers a strategic imaging platform to provide a map of functional neural correlates associated with the underlying cognitive deficits in schizophrenia. It enables regional cerebral glucose metabolism and dopaminergic and serotonergic receptor function to be studied. PET neuroimaging can therefore be used in drug development and to study putative treatments. Recent PET studies of the first-generation antipsychotics flupentixol and haloperidol, and of the second-generation antipsychotics risperidone, aripiprazole, quetiapine, sertindole, ziprasidone, paliperidone and olanzapine, have been carried out; modulation of limbic circuitry has been found to be a predictor of treatment response. PET can also be used to predict and monitor likely extrapyramidal side effects from antipsychotic treatment. PET and neuropsychological testing can together also allow the study of putative molecular genetic changes associated with schizophrenia. Advances in the imaging, cognition and molecular genetics are likely to lead to the development of future diagnostics, treatments and novel pharmacological agents.

  15. Quantitative Evaluation of Atlas-based Attenuation Correction for Brain PET in an Integrated Time-of-Flight PET/MR Imaging System.

    PubMed

    Yang, Jaewon; Jian, Yiqiang; Jenkins, Nathaniel; Behr, Spencer C; Hope, Thomas A; Larson, Peder E Z; Vigneron, Daniel; Seo, Youngho

    2017-02-23

    Purpose To assess the patient-dependent accuracy of atlas-based attenuation correction (ATAC) for brain positron emission tomography (PET) in an integrated time-of-flight (TOF) PET/magnetic resonance (MR) imaging system. Materials and Methods Thirty recruited patients provided informed consent in this institutional review board-approved study. All patients underwent whole-body fluorodeoxyglucose PET/computed tomography (CT) followed by TOF PET/MR imaging. With use of TOF PET data, PET images were reconstructed with four different attenuation correction (AC) methods: PET with patient CT-based AC (CTAC), PET with ATAC (air and bone from an atlas), PET with ATACpatientBone (air and tissue from the atlas with patient bone), and PET with ATACboneless (air and tissue from the atlas without bone). For quantitative evaluation, PET mean activity concentration values were measured in 14 1-mL volumes of interest (VOIs) distributed throughout the brain and statistical significance was tested with a paired t test. Results The mean overall difference (±standard deviation) of PET with ATAC compared with PET with CTAC was -0.69 kBq/mL ± 0.60 (-4.0% ± 3.2) (P < .001). The results were patient dependent (range, -9.3% to 0.57%) and VOI dependent (range, -5.9 to -2.2). In addition, when bone was not included for AC, the overall difference of PET with ATACboneless (-9.4% ± 3.7) was significantly worse than that of PET with ATAC (-4.0% ± 3.2) (P < .001). Finally, when patient bone was used for AC instead of atlas bone, the overall difference of PET with ATACpatientBone (-1.5% ± 1.5) improved over that of PET with ATAC (-4.0% ± 3.2) (P < .001). Conclusion ATAC in PET/MR imaging achieves similar quantification accuracy to that from CTAC by means of atlas-based bone compensation. However, patient-specific anatomic differences from the atlas causes bone attenuation differences and misclassified sinuses, which result in patient-dependent performance variation of ATAC. (©) RSNA, 2017

  16. Characterization of a PET Camera Optimized for ProstateImaging

    SciTech Connect

    Huber, Jennifer S.; Choong, Woon-Seng; Moses, William W.; Qi,Jinyi; Hu, Jicun; Wang, G.C.; Wilson, David; Oh, Sang; Huesman, RonaldH.; Derenzo, Stephen E.

    2005-11-11

    We present the characterization of a positron emission tomograph for prostate imaging that centers a patient between a pair of external curved detector banks (ellipse: 45 cm minor, 70 cm major axis). The distance between detector banks adjusts to allow patient access and to position the detectors as closely as possible for maximum sensitivity with patients of various sizes. Each bank is composed of two axial rows of 20 HR+ block detectors for a total of 80 detectors in the camera. The individual detectors are angled in the transaxial plane to point towards the prostate to reduce resolution degradation in that region. The detectors are read out by modified HRRT data acquisition electronics. Compared to a standard whole-body PET camera, our dedicated-prostate camera has the same sensitivity and resolution, less background (less randoms and lower scatter fraction) and a lower cost. We have completed construction of the camera. Characterization data and reconstructed images of several phantoms are shown. Sensitivity of a point source in the center is 946 cps/mu Ci. Spatial resolution is 4 mm FWHM in the central region.

  17. A pretargeting system for tumor PET imaging and radioimmunotherapy

    PubMed Central

    Kraeber-Bodéré, Françoise; Rousseau, Caroline; Bodet-Milin, Caroline; Frampas, Eric; Faivre-Chauvet, Alain; Rauscher, Aurore; Sharkey, Robert M.; Goldenberg, David M.; Chatal, Jean-François; Barbet, Jacques

    2015-01-01

    Labeled antibodies, as well as their fragments and antibody-derived recombinant constructs, have long been proposed as general vectors to target radionuclides to tumor lesions for imaging and therapy. They have indeed shown promise in both imaging and therapeutic applications, but they have not fulfilled the original expectations of achieving sufficient image contrast for tumor detection or sufficient radiation dose delivered to tumors for therapy. Pretargeting was originally developed for tumor immunoscintigraphy. It was assumed that directly-radiolabled antibodies could be replaced by an unlabeled immunoconjugate capable of binding both a tumor-specific antigen and a small molecular weight molecule. The small molecular weight molecule would carry the radioactive payload and would be injected after the bispecific immunoconjugate. It has been demonstrated that this approach does allow for both antibody-specific recognition and fast clearance of the radioactive molecule, thus resulting in improved tumor-to-normal tissue contrast ratios. It was subsequently shown that pretargeting also held promise for tumor therapy, translating improved tumor-to-normal tissue contrast ratios into more specific delivery of absorbed radiation doses. Many technical approaches have been proposed to implement pretargeting, and two have been extensively documented. One is based on the avidin-biotin system, and the other on bispecific antibodies binding a tumor-specific antigen and a hapten. Both have been studied in preclinical models, as well as in several clinical studies, and have shown improved targeting efficiency. This article reviews the historical and recent preclinical and clinical advances in the use of bispecific-antibody-based pretargeting for radioimmunodetection and radioimmunotherapy of cancer. The results of recent evaluation of pretargeting in PET imaging also are discussed. PMID:25873896

  18. A novel CT-FFR method for the coronary artery based on 4D-CT image analysis and structural and fluid analysis

    NASA Astrophysics Data System (ADS)

    Hirohata, K.; Kano, A.; Goryu, A.; Ooga, J.; Hongo, T.; Higashi, S.; Fujisawa, Y.; Wakai, S.; Arakita, K.; Ikeda, Y.; Kaminaga, S.; Ko, B. S.; Seneviratne, S. K.

    2015-03-01

    Non invasive fractional flow reserve derived from CT coronary angiography (CT-FFR) has to date been typically performed using the principles of fluid analysis in which a lumped parameter coronary vascular bed model is assigned to represent the impedance of the downstream coronary vascular networks absent in the computational domain for each coronary outlet. This approach may have a number of limitations. It may not account for the impact of the myocardial contraction and relaxation during the cardiac cycle, patient-specific boundary conditions for coronary artery outlets and vessel stiffness. We have developed a novel approach based on 4D-CT image tracking (registration) and structural and fluid analysis, to address these issues. In our approach, we analyzed the deformation variation of vessels and the volume variation of vessels, primarily from 70% to 100% of cardiac phase, to better define boundary conditions and stiffness of vessels. We used a statistical estimation method based on a hierarchical Bayes model to integrate 4D-CT measurements and structural and fluid analysis data. Under these analysis conditions, we performed structural and fluid analysis to determine pressure, flow rate and CT-FFR. The consistency of this method has been verified by a comparison of 4D-CTFFR analysis results derived from five clinical 4D-CT datasets with invasive measurements of FFR. Additionally, phantom experiments of flexible tubes with/without stenosis using pulsating pumps, flow sensors and pressure sensors were performed. Our results show that the proposed 4D-CT-FFR analysis method has the potential to accurately estimate the effect of coronary artery stenosis on blood flow.

  19. Metal artifact reduction strategies for improved attenuation correction in hybrid PET/CT imaging

    SciTech Connect

    Abdoli, Mehrsima; Dierckx, Rudi A. J. O.; Zaidi, Habib

    2012-06-15

    Metallic implants are known to generate bright and dark streaking artifacts in x-ray computed tomography (CT) images, which in turn propagate to corresponding functional positron emission tomography (PET) images during the CT-based attenuation correction procedure commonly used on hybrid clinical PET/CT scanners. Therefore, visual artifacts and overestimation and/or underestimation of the tracer uptake in regions adjacent to metallic implants are likely to occur and as such, inaccurate quantification of the tracer uptake and potential erroneous clinical interpretation of PET images is expected. Accurate quantification of PET data requires metal artifact reduction (MAR) of the CT images prior to the application of the CT-based attenuation correction procedure. In this review, the origins of metallic artifacts and their impact on clinical PET/CT imaging are discussed. Moreover, a brief overview of proposed MAR methods and their advantages and drawbacks is presented. Although most of the presented MAR methods are mainly developed for diagnostic CT imaging, their potential application in PET/CT imaging is highlighted. The challenges associated with comparative evaluation of these methods in a clinical environment in the absence of a gold standard are also discussed.

  20. Initial Characterization of a Dedicated Breast PET/CT Scanner During Human Imaging

    PubMed Central

    Bowen, Spencer L.; Wu, Yibao; Chaudhari, Abhijit J.; Fu, Lin; Packard, Nathan J.; Burkett, George W.; Yang, Kai; Lindfors, Karen K.; Shelton, David K.; Hagge, Rosalie; Borowsky, Alexander D.; Martinez, Steve R.; Qi, Jinyi; Boone, John M.; Cherry, Simon R.; Badawi, Ramsey D.

    2010-01-01

    We have constructed a dedicated breast PET/CT scanner capable of high-resolution functional and anatomic imaging. Here, we present an initial characterization of scanner performance during patient imaging. Methods The system consisted of a lutetium oxyorthosilicate–based dual–planar head PET camera (crystal size, 3 × 3 × 20 mm) and 768-slice cone-beam CT. The position of the PET heads (separation and height) could be adjusted for varying breast dimensions. For scanning, the patient lay prone on a specialized bed and inserted a single pendent breast through an aperture in the table top. Compression of the breast as used in mammography is not required. PET and CT systems rotate in the coronal plane underneath the patient sequentially to collect fully tomographic datasets. PET images were reconstructed with the fully 3-dimensional maximum a posteriori method, and CT images were reconstructed with the Feldkamp algorithm, then spatially registered and fused for display. Phantom scans were obtained to assess the registration accuracy between PET and CT images and the influence of PET electronics and activity on CT image quality. We imaged 4 women with mammographic findings highly suggestive of breast cancer (breast imaging reporting and data system, category 5) in an ongoing clinical trial. Patients were injected with 18F-FDG and imaged for 12.5 min per breast. From patient data, noise-equivalent counting rates and the singles-to-trues ratio (a surrogate for the randoms fraction) were calculated. Results The average registration error between PET and CT images was 0.18 mm. PET electronics and activity did not significantly affect CT image quality. For the patient trial, biopsy-confirmed cancers were visualized on dedicated breast PET/CT on all patient scans, including the detection of ductal carcinoma in situ in 1 case. The singles-to-trues ratio was found to be inversely correlated with breast volume in the field of view, suggesting that larger breasts trend

  1. DigiPET: sub-millimeter spatial resolution small-animal PET imaging using thin monolithic scintillators

    NASA Astrophysics Data System (ADS)

    España, Samuel; Marcinkowski, Radoslaw; Keereman, Vincent; Vandenberghe, Stefaan; Van Holen, Roel

    2014-07-01

    A new preclinical PET system based on dSiPMs, called DigiPET, is presented. The system is based on thin monolithic scintillation crystals and exhibits superior spatial resolution at low-cost compared to systems based on pixelated crystals. Current dedicated small-rodent PET scanners have a spatial resolution in the order of 1 mm. Most of them have a large footprint, requiring considerable laboratory space. For rodent brain imaging, a PET scanner with sub-millimeter resolution is desired. To achieve this, crystals with a pixel pitch down to 0.5 mm have been used. However, fine pixels are difficult to produce and will render systems expensive. In this work, we present the first results with a high-resolution preclinical PET scanner based on thin monolithic scintillators and a large solid angle. The design is dedicated to rat-brain imaging and therefore has a very compact geometry. Four detectors were placed in a square arrangement with a distance of 34.5 mm between two opposing detector modules, defining a field of view (FOV) of 32 × 32 × 32 mm3. Each detector consists of a thin monolithic LYSO crystal of 32 × 32 × 2 mm3 optically coupled to a digital silicon photomultiplier (dSiPM). Event positioning within each detector was obtained using the maximum likelihood estimation (MLE) method. To evaluate the system performance, we measured the energy resolution, coincidence resolving time (CRT), sensitivity and spatial resolution. The image quality was evaluated by acquiring a hot-rod phantom filled with 18F-FDG and a rat head one hour after an 18F-FDG injection. The MLE yielded an average intrinsic spatial resolution on the detector of 0.54 mm FWHM. We obtained a CRT of 680 ps and an energy resolution of 18% FWHM at 511 keV. The sensitivity and spatial resolution obtained at the center of the FOV were 6.0 cps kBq-1 and 0.7 mm, respectively. In the reconstructed images of the hot-rod phantom, hot rods down to 0.7 mm can be discriminated. In conclusion, a compact PET

  2. Feasibility study of small animal imaging using clinical PET/CT scanner

    NASA Astrophysics Data System (ADS)

    Hsu, Wen-Lin; Chen, Chia-Lin; Wang, Ze-Jing; Wu, Tung-Hsin; Liu, Dai-Wei; Lee, Jason J. S.

    2007-02-01

    The feasibility of small animal imaging using a clinical positron emission tomography/computed tomography (PET/CT) scanner with [F-18]-fluoro-2-deoxy- D-glucose (FDG) was evaluated. Two protocols in PET/CT system, single-mouse high-resolution mode (SHR) and multi-mouse high throughput mode (MHT) protocol were employed to investigate the ability of the scanner and also explored the performance differences between microPET and clinical PET/CT. In this study, we have found that even the clinical PET/CT scanner could not compete with the microPET scanner, especially in spatial resolution; the high-resolution CT image could advance the anatomical information to sub-millimeter level. Besides, CT-based attenuation correction can improve the image uniformity characteristics and quantification accuracy, and the large bore of a human whole-body scanner broadens the possibility of high throughput studies. Considering all the benefits, clinical PET/CT imaging might be a potential alternative for small animal study.

  3. Optimal Co-segmentation of Tumor in PET-CT Images with Context Information

    PubMed Central

    Song, Qi; Bai, Junjie; Han, Dongfeng; Bhatia, Sudershan; Sun, Wenqing; Rockey, William; Bayouth, John E.; Buatti, John M.

    2014-01-01

    PET-CT images have been widely used in clinical practice for radiotherapy treatment planning of the radiotherapy. Many existing segmentation approaches only work for a single imaging modality, which suffer from the low spatial resolution in PET or low contrast in CT. In this work we propose a novel method for the co-segmentation of the tumor in both PET and CT images, which makes use of advantages from each modality: the functionality information from PET and the anatomical structure information from CT. The approach formulates the segmentation problem as a minimization problem of a Markov Random Field (MRF) model, which encodes the information from both modalities. The optimization is solved using a graph-cut based method. Two sub-graphs are constructed for the segmentation of the PET and the CT images, respectively. To achieve consistent results in two modalities, an adaptive context cost is enforced by adding context arcs between the two subgraphs. An optimal solution can be obtained by solving a single maximum flow problem, which leads to simultaneous segmentation of the tumor volumes in both modalities. The proposed algorithm was validated in robust delineation of lung tumors on 23 PET-CT datasets and two head-and-neck cancer subjects. Both qualitative and quantitative results show significant improvement compared to the graph cut methods solely using PET or CT. PMID:23693127

  4. Evolution of bombesin conjugates for targeted PET imaging of tumors.

    PubMed

    Zhang, Hanwen; Abiraj, Keelara; Thorek, Daniel L J; Waser, Beatrice; Smith-Jones, Peter M; Honer, Michael; Reubi, Jean Claude; Maecke, Helmut R

    2012-01-01

    Bombesin receptors are under intense investigation as molecular targets since they are overexpressed in several prevalent solid tumors. We rationally designed and synthesized a series of modified bombesin (BN) peptide analogs to study the influence of charge and spacers at the N-terminus, as well as amino acid substitutions, on both receptor binding affinity and pharmacokinetics. This enabled development of a novel (64/67)Cu-labeled BN peptide for PET imaging and targeted radiotherapy of BN receptor-positive tumors. Our results show that N-terminally positively charged peptide ligands had significantly higher affinity to human gastrin releasing peptide receptor (GRPr) than negatively charged or uncharged ligands (IC(50): 3.2±0.5 vs 26.3±3.5 vs 41.5±2.5 nM). The replacement of Nle(14) by Met, and deletion of D-Tyr(6), further resulted in 8-fold higher affinity. Contrary to significant changes to human GRPr binding, modifications at the N-terminal and at the 6(th), 11(th), and 14(th) position of BN induced only slight influences on affinity to mouse GRPr. [Cu(II)]-CPTA-[βAla(11)] BN(7-14) ([Cu(II)]-BZH7) showed the highest internalization rate into PC-3 cells with relatively slow efflux because of its subnanomolar affinity to GRPr. Interestingly, [(64/67)Cu]-BZH7 also displayed similar affinities to the other 2 human BN receptor subtypes. In vivo studies showed that [(64/67)Cu]-BZH7 had a high accumulation in PC-3 xenografts and allowed for clear-cut visualization of the tumor in PET imaging. In addition, a CPTA-glycine derivative, forming a hippurane-type spacer, enhanced kidney clearance of the radiotracer. These data indicate that the species variation of BN receptor plays an important role in screening radiolabeled BN. As well, the positive charge from the metallated complex at the N-terminal significantly increases affinity to human GRPr. Application of these observations enabled the novel ligand [(64/67)Cu]-BZH7 to clearly visualize PC-3 tumors in vivo

  5. MRI-guided brain PET image filtering and partial volume correction.

    PubMed

    Yan, Jianhua; Lim, Jason Chu-Shern; Townsend, David W

    2015-02-07

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and (18)F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  6. MRI-guided brain PET image filtering and partial volume correction

    NASA Astrophysics Data System (ADS)

    Yan, Jianhua; Chu-Shern Lim, Jason; Townsend, David W.

    2015-02-01

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and 18F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  7. 68Ga-PSMA PET/CT Imaging in Multiple Myeloma.

    PubMed

    Sasikumar, Arun; Joy, Ajith; Pillai, M R A; Nanabala, Raviteja; Thomas, Boben

    2017-02-01

    The potential applications of Ga-labeled prostate-specific membrane antigen (PSMA) PET/CT in the imaging of prostate cancer are now well established. A few case reports regarding the potential use of Ga-PSMA PET/CT in nonprostate cancer malignancies are also published. Apparently, the tumor neoangiogenesis is the mechanism attributed to increased Ga-PSMA uptake in the tumor sites in nonprostatic malignancies. We describe the use of Ga-PSMA PET/CT in imaging multiple myeloma. The intense Ga-PSMA avidity of the lesions also opens up the possibility of theranostics with Lu-PSMA.

  8. Simultaneous reconstruction of the activity image and registration of the CT image in TOF-PET

    NASA Astrophysics Data System (ADS)

    Rezaei, Ahmadreza; Michel, Christian; Casey, Michael E.; Nuyts, Johan

    2016-02-01

    Previously, maximum-likelihood methods have been proposed to jointly estimate the activity image and the attenuation image or the attenuation sinogram from time-of-flight (TOF) positron emission tomography (PET) data. In this contribution, we propose a method that addresses the possible alignment problem of the TOF-PET emission data and the computed tomography (CT) attenuation data, by combining reconstruction and registration. The method, called MLRR, iteratively reconstructs the activity image while registering the available CT-based attenuation image, so that the pair of activity and attenuation images maximise the likelihood of the TOF emission sinogram. The algorithm is slow to converge, but some acceleration could be achieved by using Nesterov’s momentum method and by applying a multi-resolution scheme for the non-rigid displacement estimation. The latter also helps to avoid local optima, although convergence to the global optimum cannot be guaranteed. The results are evaluated on 2D and 3D simulations as well as a respiratory gated clinical scan. Our experiments indicate that the proposed method is able to correct for possible misalignment of the CT-based attenuation image, and is therefore a very promising approach to suppressing attenuation artefacts in clinical PET/CT. When applied to respiratory gated data of a patient scan, it produced deformations that are compatible with breathing motion and which reduced the well known attenuation artefact near the dome of the liver. Since the method makes use of the energy-converted CT attenuation image, the scale problem of joint reconstruction is automatically solved.

  9. 4-D OCT in Developmental Cardiology

    NASA Astrophysics Data System (ADS)

    Jenkins, Michael W.; Rollins, Andrew M.

    Although strong evidence exists to suggest that altered cardiac function can lead to CHDs, few studies have investigated the influential role of cardiac function and biophysical forces on the development of the cardiovascular system due to a lack of proper in vivo imaging tools. 4-D imaging is needed to decipher the complex spatial and temporal patterns of biomechanical forces acting upon the heart. Numerous solutions over the past several years have demonstrated 4-D OCT imaging of the developing cardiovascular system. This chapter will focus on these solutions and explain their context in the evolution of 4-D OCT imaging. The first sections describe the relevant techniques (prospective gating, direct 4-D imaging, retrospective gating), while later sections focus on 4-D Doppler imaging and measurements of force implementing 4-D OCT Doppler. Finally, the techniques are summarized, and some possible future directions are discussed.

  10. Algorithm for lung cancer detection based on PET/CT images

    NASA Astrophysics Data System (ADS)

    Saita, Shinsuke; Ishimatsu, Keita; Kubo, Mitsuru; Kawata, Yoshiki; Niki, Noboru; Ohtsuka, Hideki; Nishitani, Hiromu; Ohmatsu, Hironobu; Eguchi, Kenji; Kaneko, Masahiro; Moriyama, Noriyuki

    2009-02-01

    The five year survival rate of the lung cancer is low with about twenty-five percent. In addition it is an obstinate lung cancer wherein three out of four people die within five years. Then, the early stage detection and treatment of the lung cancer are important. Recently, we can obtain CT and PET image at the same time because PET/CT device has been developed. PET/CT is possible for a highly accurate cancer diagnosis because it analyzes quantitative shape information from CT image and FDG distribution from PET image. However, neither benign-malignant classification nor staging intended for lung cancer have been established still enough by using PET/CT images. In this study, we detect lung nodules based on internal organs extracted from CT image, and we also develop algorithm which classifies benignmalignant and metastatic or non metastatic lung cancer using lung structure and FDG distribution(one and two hour after administering FDG). We apply the algorithm to 59 PET/CT images (malignant 43 cases [Ad:31, Sq:9, sm:3], benign 16 cases) and show the effectiveness of this algorithm.

  11. Magnetic Particle / Magnetic Resonance Imaging: In-Vitro MPI-Guided Real Time Catheter Tracking and 4D Angioplasty Using a Road Map and Blood Pool Tracer Approach

    PubMed Central

    Jung, Caroline; Kaul, Michael Gerhard; Werner, Franziska; Them, Kolja; Reimer, Rudolph; Nielsen, Peter; vom Scheidt, Annika; Adam, Gerhard; Knopp, Tobias; Ittrich, Harald

    2016-01-01

    Purpose In-vitro evaluation of the feasibility of 4D real time tracking of endovascular devices and stenosis treatment with a magnetic particle imaging (MPI) / magnetic resonance imaging (MRI) road map approach and an MPI-guided approach using a blood pool tracer. Materials and Methods A guide wire and angioplasty-catheter were labeled with a thin layer of magnetic lacquer. For real time MPI a custom made software framework was developed. A stenotic vessel phantom filled with saline or superparamagnetic iron oxide nanoparticles (MM4) was equipped with bimodal fiducial markers for co-registration in preclinical 7T MRI and MPI. In-vitro angioplasty was performed inflating the balloon with saline or MM4. MPI data were acquired using a field of view of 37.3×37.3×18.6 mm3 and a frame rate of 46 volumes/sec. Analysis of the magnetic lacquer-marks on the devices were performed with electron microscopy, atomic absorption spectrometry and micro-computed tomography. Results Magnetic marks allowed for MPI/MRI guidance of interventional devices. Bimodal fiducial markers enable MPI/MRI image fusion for MRI based roadmapping. MRI roadmapping and the blood pool tracer approach facilitate MPI real time monitoring of in-vitro angioplasty. Successful angioplasty was verified with MPI and MRI. Magnetic marks consist of micrometer sized ferromagnetic plates mainly composed of iron and iron oxide. Conclusions 4D real time MP imaging, tracking and guiding of endovascular instruments and in-vitro angioplasty is feasible. In addition to an approach that requires a blood pool tracer, MRI based roadmapping might emerge as a promising tool for radiation free 4D MPI-guided interventions. PMID:27249022

  12. Contribution of nonattenuation-corrected images on FDG-PET/CT in the assessment of solitary pulmonary nodules.

    PubMed

    Şahin, Ertan; Kara, Ahmet; Elboğa, Umut

    2016-12-01

    In this study, we aim to determine the diagnostic performance of nonattenuation-corrected (NAC) and attenuation-corrected (AC) FDG-PET/CT images in the assessment of solitary pulmonary nodule (SPN). We reviewed the images of 41 patients who underwent FDG-PET/CT to diagnose SPNs. The visual analysis of FDG uptake intensity in SPN on AC and NAC PET images was made using a four-point score from 1 to 4 on both AC and NAC PET images. The cutoff value of SUVmax and visual uptake scores for malignancy were defined as ≥2.5 and ≥3, respectively. The significant visual uptake (≥2 visual point score) on AC and NAC PET images was considered to be positive 18F-FDG PET findings for lesion detectability. The sensitivity, specificity and diagnostic accuracy were calculated for AC and NAC PET images. Based on the histopathology and imaging data, 22 of the SPNs (54 %) were malignant and 19 of them (46 %) were benign. The sensitivity and NPV were found to be 100 % in the detection of SPNs for AC and NAC PET images. For all SPNs and SPNs ≤2 cm, NAC PET image had a higher diagnostic performance for the SPN characterization as malignant or benign, when compared with AC PET image. The success rates of AC and NAC PET images were found to be similar for the detection of SPNs. NAC PET image had a higher diagnostic performance for the SPN characterization. It is thought that NAC PET image may provide additional contributions for characterization of SPNs.

  13. Image Quality Performance Measurement of the microPET Focus 120

    NASA Astrophysics Data System (ADS)

    Ballado, Fernando Trejo; López, Nayelli Ortega; Flores, Rafael Ojeda; Ávila-Rodríguez, Miguel A.

    2010-12-01

    The aim of this work is to evaluate the characteristics involved in the image reconstruction of the microPET Focus 120. For this evaluation were used two different phantoms; a miniature hot-rod Derenzo phantom and a National Electrical Manufacturers Association (NEMA) NU4-2008 image quality (IQ) phantom. The best image quality was obtained when using OSEM3D as the reconstruction method reaching a spatial resolution of 1.5 mm with the Derenzo phantom filled with 18F. Image quality test results indicate a superior image quality for the Focus 120 when compared to previous microPET models.

  14. MO-C-17A-02: A Novel Method for Evaluating Hepatic Stiffness Based On 4D-MRI and Deformable Image Registration

    SciTech Connect

    Cui, T; Liang, X; Czito, B; Palta, M; Bashir, M; Yin, F; Cai, J

    2014-06-15

    Purpose: Quantitative imaging of hepatic stiffness has significant potential in radiation therapy, ranging from treatment planning to response assessment. This study aims to develop a novel, noninvasive method to quantify liver stiffness with 3D strains liver maps using 4D-MRI and deformable image registration (DIR). Methods: Five patients with liver cancer were imaged with an institutionally developed 4D-MRI technique under an IRB-approved protocol. Displacement vector fields (DVFs) across the liver were generated via DIR of different phases of 4D-MRI. Strain tensor at each voxel of interest (VOI) was computed from the relative displacements between the VOI and each of the six adjacent voxels. Three principal strains (E{sub 1}, E{sub 2} and E{sub 3}) of the VOI were derived as the eigenvalue of the strain tensor, which represent the magnitudes of the maximum and minimum stretches. Strain tensors for two regions of interest (ROIs) were calculated and compared for each patient, one within the tumor (ROI{sub 1}) and the other in normal liver distant from the heart (ROI{sub 2}). Results: 3D strain maps were successfully generated fort each respiratory phase of 4D-MRI for all patients. Liver deformations induced by both respiration and cardiac motion were observed. Differences in strain values adjacent to the distant from the heart indicate significant deformation caused by cardiac expansion during diastole. The large E{sub 1}/E{sub 2} (∼2) and E{sub 1}/E{sub 2} (∼10) ratios reflect the predominance of liver deformation in the superior-inferior direction. The mean E{sub 1} in ROI{sub 1} (0.12±0.10) was smaller than in ROI{sub 2} (0.15±0.12), reflecting a higher degree of stiffness of the cirrhotic tumor. Conclusion: We have successfully developed a novel method for quantitatively evaluating regional hepatic stiffness based on DIR of 4D-MRI. Our initial findings indicate that liver strain is heterogeneous, and liver tumors may have lower principal strain values

  15. PET imaging with the non-pure positron emitters: 55Co, 86Y and 124I

    NASA Astrophysics Data System (ADS)

    Braad, P. E. N.; Hansen, S. B.; Thisgaard, H.; Høilund-Carlsen, P. F.

    2015-05-01

    PET/CT with non-pure positron emitters is a highly valuable tool in immuno-PET and for pretherapeutic dosimetry. However, imaging is complicated by prompt gamma coincidences (PGCs) that add an undesired background activity to the images. Time-of-flight (TOF) reconstruction improves lesion detectability in 18F-PET and can potentially also improve the signal-to-noise ratio in images acquired with non-pure positron emitters. Using the GE Discovery 690 PET/CT system, we evaluated the image quality with 55Co, 86Y and 124I, and the effect of PGC-correction and TOF-reconstruction on image quality and quantitation in a series of phantom studies. PET image quality and quantitation for all isotopes were significantly affected by PGCs. The effect was most severe with 86Y, and less, but comparable, with 55Co and 124I. PGC-correction improved the image quality and the quantitation accuracy dramatically for all isotopes, especially when the activity was limited to a few hot lesions in a warm background. In imaging situations, where high levels of activity were present in the background, activity concentrations were overestimated. TOF-reconstruction improved image quality in isolated lesions but worsened the accuracy of quantitation and uniformity in homogeneous activity distributions. Better modelling of PGCs in the scatter correction can potentially improve the situation.

  16. Imaging 4-D hydrogeologic processes with geophysics: an example using crosswell electrical measurements to characterize a tracer plume

    NASA Astrophysics Data System (ADS)

    Singha, K.; Gorelick, S. M.

    2005-05-01

    Geophysical methods provide an inexpensive way to collect spatially exhaustive data about hydrogeologic, mechanical or geochemical parameters. In the presence of heterogeneity over multiple scales of these parameters at most field sites, geophysical data can contribute greatly to our understanding about the subsurface by providing important data we would otherwise lack without extensive, and often expensive, direct sampling. Recent work has highlighted the use of time-lapse geophysical data to help characterize hydrogeologic processes. We investigate the potential for making quantitative assessments of sodium-chloride tracer transport using 4-D crosswell electrical resistivity tomography (ERT) in a sand and gravel aquifer at the Massachusetts Military Reservation on Cape Cod. Given information about the relation between electrical conductivity and tracer concentration, we can estimate spatial moments from the 3-D ERT inversions, which give us information about tracer mass, center of mass, and dispersivity through time. The accuracy of these integrated measurements of tracer plume behavior is dependent on spatially variable resolution. The ERT inversions display greater apparent dispersion than tracer plumes estimated by 3D advective-dispersive simulation. This behavior is attributed to reduced measurement sensitivity to electrical conductivity values with distance from the electrodes and differential smoothing from tomographic inversion. The latter is a problem common to overparameterized inverse problems, which often occur when real-world budget limitations preclude extensive well-drilling or additional data collection. These results prompt future work on intelligent methods for reparameterizing the inverse problem and coupling additional disparate data sets.

  17. TU-G-BRA-04: Changes in Regional Lung Function Measured by 4D-CT Ventilation Imaging for Thoracic Radiotherapy

    SciTech Connect

    Nakajima, Y; Kadoya, N; Kabus, S; Loo, B; Keall, P; Yamamoto, T

    2015-06-15

    Purpose: To test the hypothesis: 4D-CT ventilation imaging can show the known effects of radiotherapy on lung function: (1) radiation-induced ventilation reductions, and (2) ventilation increases caused by tumor regression. Methods: Repeat 4D-CT scans (pre-, mid- and/or post-treatment) were acquired prospectively for 11 thoracic cancer patients in an IRB-approved clinical trial. A ventilation image for each time point was created using deformable image registration and the Hounsfield unit (HU)-based or Jacobian-based metric. The 11 patients were divided into two subgroups based on tumor volume reduction using a threshold of 5 cm{sup 3}. To quantify radiation-induced ventilation reduction, six patients who showed a small tumor volume reduction (<5 cm{sup 3}) were analyzed for dose-response relationships. To investigate ventilation increase caused by tumor regression, two of the other five patients were analyzed to compare ventilation changes in the lung lobes affected and unaffected by the tumor. The remaining three patients were excluded because there were no unaffected lobes. Results: Dose-dependent reductions of HU-based ventilation were observed in a majority of the patient-specific dose-response curves and in the population-based dose-response curve, whereas no clear relationship was seen for Jacobian-based ventilation. The post-treatment population-based dose-response curve of HU-based ventilation demonstrated the average ventilation reductions of 20.9±7.0% at 35–40 Gy (equivalent dose in 2-Gy fractions, EQD2), and 40.6±22.9% at 75–80 Gy EQD2. Remarkable ventilation increases in the affected lobes were observed for the two patients who showed an average tumor volume reduction of 37.1 cm{sup 3} and re-opening airways. The mid-treatment increase in HU-based ventilation of patient 3 was 100.4% in the affected lobes, which was considerably greater than 7.8% in the unaffected lobes. Conclusion: This study has demonstrated that 4D-CT ventilation imaging shows

  18. OpenPET: A Flexible Electronics System for Radiotracer Imaging

    PubMed Central

    Moses, W. W.; Buckley, S.; Vu, C.; Peng, Q.; Pavlov, N.; Choong, W.-S.; Wu, J.; Jackson, C.

    2011-01-01

    We present the design for OpenPET, an electronics readout system designed for prototype radiotracer imaging instruments. The critical requirements are that it has sufficient performance, channel count, channel density, and power consumption to service a complete camera, and yet be simple, flexible, and customizable enough to be used with almost any detector or camera design. An important feature of this system is that each analog input is processed independently. Each input can be configured to accept signals of either polarity as well as either differential or ground referenced signals. Each signal is digitized by a continuously sampled ADC, which is processed by an FPGA to extract pulse height information. A leading edge discriminator creates a timing edge that is “time stamped” by a TDC implemented inside the FPGA. This digital information from each channel is sent to an FPGA that services 16 analog channels, and information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc. As all of this processing is controlled by firmware and software, it can be modified / customized easily. The system is open source, meaning that all technical data (specifications, schematics and board layout files, source code, and instructions) will be publicly available. PMID:21297894

  19. Current status of PET in breast cancer imaging, staging, and therapy.

    PubMed

    Wahl, R L

    2001-07-01

    The exact roles of PET in the imaging management of patients with known or suspected breast cancer are still in evolution. For assessing primary lesions, it is sometimes possible with PET to detect cancers occult on standard methods. This could be useful in high-risk patient populations, but in dense breasts, background FDG uptake is often higher than in women with fatty breasts, making identification of lesions < 1 cm in size improbable with current technologies. Distinguishing malignant from benign primary breast disease would seem better addressed by biopsy. With a positive predictive value of FDG PET for cancer over 96%, any FDG-avid breast lesion is highly suspicious and merits biopsy. Although PET in theory should be useful for depicting multifocal disease before surgery, the limitations in detecting small lesions in the breast limit the contribution of PET at present. It is most likely that PET will have a greater role in depicting primary breast lesions as dedicated PET imaging devices for the breast evolve. For axillary and internal mammary nodal staging, results with FDG PET are variable. Small nodal metastases < or = 5 mm will be missed by PET, whereas larger ones are more likely to be detected. PET can depict internal mammary nodes, but the accuracy of the method in this setting is not known, nor is there consensus on how identifying internal mammary node metastases will change treatment. Based on the available data, for pT1 breast lesions, PET, if negative, is not an adequate replacement for sentinel node surgery or axillary dissection. Results from the multicenter trial will be of great interest. Clearly PET can stage metastatic disease well. Bone scans with 18F- are exquisitely sensitive for metastases, and FDG is also very good. However, FDG PET can miss some blastic metastases to bone so at present FDG is not capable of excluding the presence of bone metastases. PET seems very well suited to detecting recurrences in soft tissues and the brachial

  20. 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.

  1. A finite element updating approach for identification of the anisotropic hyperelastic properties of normal and diseased aortic walls from 4D ultrasound strain imaging.

    PubMed

    Wittek, Andreas; Derwich, Wojciech; Karatolios, Konstantinos; Fritzen, Claus Peter; Vogt, Sebastian; Schmitz-Rixen, Thomas; Blase, Christopher

    2016-05-01

    Computational analysis of the biomechanics of the vascular system aims at a better understanding of its physiology and pathophysiology and eventually at diagnostic clinical use. Because of great inter-individual variations, such computational models have to be patient-specific with regard to geometry, material properties and applied loads and boundary conditions. Full-field measurements of heterogeneous displacement or strain fields can be used to improve the reliability of parameter identification based on a reduced number of observed load cases as is usually given in an in vivo setting. Time resolved 3D ultrasound combined with speckle tracking (4D US) is an imaging technique that provides full field information of heterogeneous aortic wall strain distributions in vivo. In a numerical verification experiment, we have shown the feasibility of identifying nonlinear and orthotropic constitutive behaviour based on the observation of just two load cases, even though the load free geometry is unknown, if heterogeneous strain fields are available. Only clinically available 4D US measurements of wall motion and diastolic and systolic blood pressure are required as input for the inverse FE updating approach. Application of the developed inverse approach to 4D US data sets of three aortic wall segments from volunteers of different age and pathology resulted in the reproducible identification of three distinct and (patho-) physiologically reasonable constitutive behaviours. The use of patient-individual material properties in biomechanical modelling of AAAs is a step towards more personalized rupture risk assessment.

  2. Prenatal diagnosis of a patent urachus cyst with the use of 2D, 3D, 4D ultrasound and fetal magnetic resonance imaging.

    PubMed

    Fuchs, F; Picone, O; Levaillant, J M; Mabille, M; Mas, A E; Frydman, R; Senat, M V

    2008-01-01

    Patent urachus cyst is a rare umbilical anomaly, which is poorly detected prenatally and frequently confounded with pseudo bladder exstrophy or omphalocele. A 27-year-old woman was referred to our prenatal diagnosis centre at 18 weeks of gestation after diagnosis of a megabladder and 2 umbilical cord cysts. Subsequent 2D, 3D and 4D ultrasound examinations and fetal magnetic resonance imaging (MRI) revealed a typical umbilical cyst and an extra-abdominal cyst, communicating with the vertex of the fetal bladder through a small channel that increased in size when the fetus voided urine. Termination of pregnancy occured at 31 weeks because of associated cerebral septal agenesis, and autopsy confirmed the prenatal diagnosis of urachus cyst. Few cases of urachus cyst diagnosed prenatally are reported in literature, but none were associated with other extra-abdominal disorders and none used 3D, 4D and fetal MRI. Our case illustrated the efficiency in prenatal diagnosis of 3D and 4D ultrasound examinations. This could help pediatrician surgeons to explain to a couple about neonatal surgical repair and plastic reconstruction in the prenatal period.

  3. The Role of 18F-FDG PET/CT Integrated Imaging in Distinguishing Malignant from Benign Pleural Effusion

    PubMed Central

    Sun, Yajuan; Yu, Hongjuan; Ma, Jingquan

    2016-01-01

    Objective The aim of our study was to evaluate the role of 18F-FDG PET/CT integrated imaging in differentiating malignant from benign pleural effusion. Methods A total of 176 patients with pleural effusion who underwent 18F-FDG PET/CT examination to differentiate malignancy from benignancy were retrospectively researched. The images of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging were visually analyzed. The suspected malignant effusion was characterized by the presence of nodular or irregular pleural thickening on CT imaging. Whereas on PET imaging, pleural 18F-FDG uptake higher than mediastinal activity was interpreted as malignant effusion. Images of 18F-FDG PET/CT integrated imaging were interpreted by combining the morphologic feature of pleura on CT imaging with the degree and form of pleural 18F-FDG uptake on PET imaging. Results One hundred and eight patients had malignant effusion, including 86 with pleural metastasis and 22 with pleural mesothelioma, whereas 68 patients had benign effusion. The sensitivities of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging in detecting malignant effusion were 75.0%, 91.7% and 93.5%, respectively, which were 69.8%, 91.9% and 93.0% in distinguishing metastatic effusion. The sensitivity of 18F-FDG PET/CT integrated imaging in detecting malignant effusion was higher than that of CT imaging (p = 0.000). For metastatic effusion, 18F-FDG PET imaging had higher sensitivity (p = 0.000) and better diagnostic consistency with 18F-FDG PET/CT integrated imaging compared with CT imaging (Kappa = 0.917 and Kappa = 0.295, respectively). The specificities of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging were 94.1%, 63.2% and 92.6% in detecting benign effusion. The specificities of CT imaging and 18F-FDG PET/CT integrated imaging were higher than that of 18F-FDG PET imaging (p = 0.000 and p = 0.000, respectively), and CT imaging had better diagnostic consistency with

  4. Twelve automated thresholding methods for segmentation of PET images: a phantom study

    NASA Astrophysics Data System (ADS)

    Prieto, Elena; Lecumberri, Pablo; Pagola, Miguel; Gómez, Marisol; Bilbao, Izaskun; Ecay, Margarita; Peñuelas, Iván; Martí-Climent, Josep M.

    2012-06-01

    Tumor volume delineation over positron emission tomography (PET) images is of great interest for proper diagnosis and therapy planning. However, standard segmentation techniques (manual or semi-automated) are operator dependent and time consuming while fully automated procedures are cumbersome or require complex mathematical development. The aim of this study was to segment PET images in a fully automated way by implementing a set of 12 automated thresholding algorithms, classical in the fields of optical character recognition, tissue engineering or non-destructive testing images in high-tech structures. Automated thresholding algorithms select a specific threshold for each image without any a priori spatial information of the segmented object or any special calibration of the tomograph, as opposed to usual thresholding methods for PET. Spherical 18F-filled objects of different volumes were acquired on clinical PET/CT and on a small animal PET scanner, with three different signal-to-background ratios. Images were segmented with 12 automatic thresholding algorithms and results were compared with the standard segmentation reference, a threshold at 42% of the maximum uptake. Ridler and Ramesh thresholding algorithms based on clustering and histogram-shape information, respectively, provided better results that the classical 42%-based threshold (p < 0.05). We have herein demonstrated that fully automated thresholding algorithms can provide better results than classical PET segmentation tools.

  5. Twelve automated thresholding methods for segmentation of PET images: a phantom study.

    PubMed

    Prieto, Elena; Lecumberri, Pablo; Pagola, Miguel; Gómez, Marisol; Bilbao, Izaskun; Ecay, Margarita; Peñuelas, Iván; Martí-Climent, Josep M

    2012-06-21

    Tumor volume delineation over positron emission tomography (PET) images is of great interest for proper diagnosis and therapy planning. However, standard segmentation techniques (manual or semi-automated) are operator dependent and time consuming while fully automated procedures are cumbersome or require complex mathematical development. The aim of this study was to segment PET images in a fully automated way by implementing a set of 12 automated thresholding algorithms, classical in the fields of optical character recognition, tissue engineering or non-destructive testing images in high-tech structures. Automated thresholding algorithms select a specific threshold for each image without any a priori spatial information of the segmented object or any special calibration of the tomograph, as opposed to usual thresholding methods for PET. Spherical (18)F-filled objects of different volumes were acquired on clinical PET/CT and on a small animal PET scanner, with three different signal-to-background ratios. Images were segmented with 12 automatic thresholding algorithms and results were compared with the standard segmentation reference, a threshold at 42% of the maximum uptake. Ridler and Ramesh thresholding algorithms based on clustering and histogram-shape information, respectively, provided better results that the classical 42%-based threshold (p < 0.05). We have herein demonstrated that fully automated thresholding algorithms can provide better results than classical PET segmentation tools.

  6. Positron emission tomography (PET) imaging with 18F-based radiotracers

    PubMed Central

    Alauddin, Mian M

    2012-01-01

    Positron Emission Tomography (PET) is a nuclear medicine imaging technique that is widely used in early detection and treatment follow up of many diseases, including cancer. This modality requires positron-emitting isotope labeled biomolecules, which are synthesized prior to perform imaging studies. Fluorine-18 is one of the several isotopes of fluorine that is routinely used in radiolabeling of biomolecules for PET; because of its positron emitting property and favorable half-life of 109.8 min. The biologically active molecule most commonly used for PET is 2-deoxy-2-18F-fluoro-β-D-glucose (18F-FDG), an analogue of glucose, for early detection of tumors. The concentrations of tracer accumulation (PET image) demonstrate the metabolic activity of tissues in terms of regional glucose metabolism and accumulation. Other tracers are also used in PET to image the tissue concentration. In this review, information on fluorination and radiofluorination reactions, radiofluorinating agents, and radiolabeling of various compounds and their application in PET imaging is presented. PMID:23133802

  7. Application of 18F-FDG PET and diffusion weighted imaging (DWI) in multiple myeloma: comparison of functional imaging modalities

    PubMed Central

    Sachpekidis, Christos; Mosebach, Jennifer; Freitag, Martin T; Wilhelm, Thomas; Mai, Elias K; Goldschmidt, Hartmut; Haberkorn, Uwe; Schlemmer, Heinz-Peter; Delorme, Stefan; Dimitrakopoulou-Strauss, Antonia

    2015-01-01

    Aim of this prospective study was to assess the sensitivity of positron emission tomography (PET) and diffusion-weighted imaging (DWI) in detecting multiple myeloma (MM) lesions, using the well-established morphologic modalities magnetic resonance imaging (MRI) and computed tomography (CT) as the standard of reference (RS). The study included 24 MM patients (15 newly diagnosed, 9 pre-treated). All underwent 18F-FDG PET/CT and wholebody DWI. The findings in PET and DWI were compared to matching imaging findings in combined non-enhanced T1w, fat-saturated T2w (TIRM)- MRI, and low-dose CT. Patient-based analysis revealed that 15/24 patients (10 primary MM, 5 pre-treated) had myeloma lesions according to our RS. PET was positive in 13/24 patients (11 primary MM, 2 pre-treated) and DWI in 18/24 patients (12 primary MM, 6 pre-treated). Lesion-based analysis demonstrated 128 MM lesions, of which PET depicted 60/128 lesions (sensitivity 47%), while DWI depicted 99/128 lesions (sensitivity 77%). Further analysis including only the 15 untreated MM patients revealed a sensitivity of 90% for both PET and DWI and an overall concordance of PET and DWI of 72%. In conclusion, DWI was more sensitive than 18F-FDG PET in detecting myeloma lesions in a mixed population of primary and pre-treated MM patients. However, 18F-FDG PET and DWI demonstrated equivalent sensitivities in the sub-population of primary, untreated MM patients. This higher sensitivity of DWI in pre-treated patients may be due to the fact that 18F-FDG PET becomes negative earlier in the course of treatment in contrary to MRI, in which already treated lesions can remain visible. PMID:26550539

  8. Dual-modality brain PET-CT image segmentation based on adaptive use of functional and anatomical information.

    PubMed

    Xia, Yong; Eberl, Stefan; Wen, Lingfeng; Fulham, Michael; Feng, David Dagan

    2012-01-01

    Dual medical imaging modalities, such as PET-CT, are now a routine component of clinical practice. Medical image segmentation methods, however, have generally only been applied to single modality images. In this paper, we propose the dual-modality image segmentation model to segment brain PET-CT images into gray matter, white matter and cerebrospinal fluid. This model converts PET-CT image segmentation into an optimization process controlled simultaneously by PET and CT voxel values and spatial constraints. It is innovative in the creation and application of the modality discriminatory power (MDP) coefficient as a weighting scheme to adaptively combine the functional (PET) and anatomical (CT) information on a voxel-by-voxel basis. Our approach relies upon allowing the modality with higher discriminatory power to play a more important role in the segmentation process. We compared the proposed approach to three other image segmentation strategies, including PET-only based segmentation, combination of the results of independent PET image segmentation and CT image segmentation, and simultaneous segmentation of joint PET and CT images without an adaptive weighting scheme. Our results in 21 clinical studies showed that our approach provides the most accurate and reliable segmentation for brain PET-CT images.

  9. Assessing Cardiac Injury in Mice With Dual Energy-MicroCT, 4D-MicroCT, and MicroSPECT Imaging After Partial Heart Irradiation

    SciTech Connect

    Lee, Chang-Lung; Min, Hooney; Befera, Nicholas; Clark, Darin; Qi, Yi; Das, Shiva; Johnson, G. Allan; Badea, Cristian T.; Kirsch, David G.

    2014-03-01

    Purpose: To develop a mouse model of cardiac injury after partial heart irradiation (PHI) and to test whether dual energy (DE)-microCT and 4-dimensional (4D)-microCT can be used to assess cardiac injury after PHI to complement myocardial perfusion imaging using micro-single photon emission computed tomography (SPECT). Methods and Materials: To study cardiac injury from tangent field irradiation in mice, we used a small-field biological irradiator to deliver a single dose of 12 Gy x-rays to approximately one-third of the left ventricle (LV) of Tie2Cre; p53{sup FL/+} and Tie2Cre; p53{sup FL/−} mice, where 1 or both alleles of p53 are deleted in endothelial cells. Four and 8 weeks after irradiation, mice were injected with gold and iodinated nanoparticle-based contrast agents, and imaged with DE-microCT and 4D-microCT to evaluate myocardial vascular permeability and cardiac function, respectively. Additionally, the same mice were imaged with microSPECT to assess myocardial perfusion. Results: After PHI with tangent fields, DE-microCT scans showed a time-dependent increase in accumulation of gold nanoparticles (AuNp) in the myocardium of Tie2Cre; p53{sup FL/−} mice. In Tie2Cre; p53{sup FL/−} mice, extravasation of AuNp was observed within the irradiated LV, whereas in the myocardium of Tie2Cre; p53{sup FL/+} mice, AuNp were restricted to blood vessels. In addition, data from DE-microCT and microSPECT showed a linear correlation (R{sup 2} = 0.97) between the fraction of the LV that accumulated AuNp and the fraction of LV with a perfusion defect. Furthermore, 4D-microCT scans demonstrated that PHI caused a markedly decreased ejection fraction, and higher end-diastolic and end-systolic volumes, to develop in Tie2Cre; p53{sup FL/−} mice, which were associated with compensatory cardiac hypertrophy of the heart that was not irradiated. Conclusions: Our results show that DE-microCT and 4D-microCT with nanoparticle-based contrast agents are novel imaging approaches

  10. Perfusion-weighted imaging and dynamic 4D angiograms for the estimation of collateral blood flow in lacunar infarction.

    PubMed

    Förster, Alex; Mürle, Bettina; Böhme, Johannes; Al-Zghloul, Mansour; Kerl, Hans U; Wenz, Holger; Groden, Christoph

    2016-10-01

    Although lacunar infarction accounts for approximately 25% of ischemic strokes, collateral blood flow through anastomoses is not well evaluated in lacunar infarction. In 111 lacunar infarction patients, we analyzed diffusion-weighted images, perfusion-weighted images, and blood flow on dynamic four-dimensional angiograms generated by use of Signal Processing In NMR-Software. Blood flow was classified as absent (type 1), from periphery to center (type 2), from center to periphery (type 3), and combination of type 2 and 3 (type 4). On diffusion-weighted images, lacunar infarction was found in the basal ganglia (11.7%), internal capsule (24.3%), corona radiata (30.6%), thalamus (24.3%), and brainstem (9.0%). In 58 (52.2%) patients, perfusion-weighted image showed a circumscribed hypoperfusion, in one (0.9%) a circumscribed hyperperfusion, whereas the remainder was normal. In 36 (62.1%) patients, a larger perfusion deficit (>7 mm) was observed. In these, blood flow was classified type 1 in four (11.1%), 2 in 17 (47.2%), 3 in 9 (25.0%), and 4 in six (16.7%) patients. Patients with lacunar infarction in the posterior circulation more often demonstrated blood flow type 2 and less often type 3 (p = 0.01). Detailed examination and graduation of blood flow in lacunar infarction by use of dynamic four-dimensional angiograms is feasible and may serve for a better characterization of this stroke subtype.

  11. An automated landmark-based elastic registration technique for large deformation recovery from 4-D CT lung images

    NASA Astrophysics Data System (ADS)

    Negahdar, Mohammadreza; Zacarias, Albert; Milam, Rebecca A.; Dunlap, Neal; Woo, Shiao Y.; Amini, Amir A.

    2012-03-01

    The treatment plan evaluation for lung cancer patients involves pre-treatment and post-treatment volume CT imaging of the lung. However, treatment of the tumor volume lung results in structural changes to the lung during the course of treatment. In order to register the pre-treatment volume to post-treatment volume, there is a need to find robust and homologous features which are not affected by the radiation treatment along with a smooth deformation field. Since airways are well-distributed in the entire lung, in this paper, we propose use of airway tree bifurcations for registration of the pre-treatment volume to the post-treatment volume. A dedicated and automated algorithm has been developed that finds corresponding airway bifurcations in both images. To derive the 3-D deformation field, a B-spline transformation model guided by mutual information similarity metric was used to guarantee the smoothness of the transformation while combining global information from bifurcation points. Therefore, the approach combines both global statistical intensity information with local image feature information. Since during normal breathing, the lung undergoes large nonlinear deformations, it is expected that the proposed method would also be applicable to large deformation registration between maximum inhale and maximum exhale images in the same subject. The method has been evaluated by registering 3-D CT volumes at maximum exhale data to all the other temporal volumes in the POPI-model data.

  12. Approaches using molecular imaging technology -- use of PET in clinical microdose studies.

    PubMed

    Wagner, Claudia C; Langer, Oliver

    2011-06-19

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nervous system pharmaceuticals and is extending its range of application to many other fields of pharmaceutical medicine. Although requirements for preclinical safety testing for microdose studies have been cut down by regulatory authorities, radiopharmaceuticals increasingly need to be produced under good manufacturing practice (GMP) conditions, which increases the costs of PET microdosing studies. Further challenges in PET microdosing include combining PET with other ultrasensitive analytical methods, such as accelerator mass spectrometry (AMS), to gain plasma PK data of drugs, beyond the short PET examination periods. Finally, conducting clinical PET studies with radiolabeled drugs both at micro- and therapeutic doses is encouraged to answer the question of dose linearity in clinical microdosing.

  13. Approaches using molecular imaging technology - use of PET in clinical microdose studies§

    PubMed Central

    Wagner, Claudia C; Langer, Oliver

    2013-01-01

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nerv