Optimization of intra-voxel incoherent motion imaging at 3.0 Tesla for fast liver examination.

PubMed

Leporq, Benjamin; Saint-Jalmes, Hervé; Rabrait, Cecile; Pilleul, Frank; Guillaud, Olivier; Dumortier, Jérôme; Scoazec, Jean-Yves; Beuf, Olivier

2015-05-01

Optimization of multi b-values MR protocol for fast intra-voxel incoherent motion imaging of the liver at 3.0 Tesla. A comparison of four different acquisition protocols were carried out based on estimated IVIM (DSlow , DFast , and f) and ADC-parameters in 25 healthy volunteers. The effects of respiratory gating compared with free breathing acquisition then diffusion gradient scheme (simultaneous or sequential) and finally use of weighted averaging for different b-values were assessed. An optimization study based on Cramer-Rao lower bound theory was then performed to minimize the number of b-values required for a suitable quantification. The duration-optimized protocol was evaluated on 12 patients with chronic liver diseases No significant differences of IVIM parameters were observed between the assessed protocols. Only four b-values (0, 12, 82, and 1310 s.mm(-2) ) were found mandatory to perform a suitable quantification of IVIM parameters. DSlow and DFast significantly decreased between nonadvanced and advanced fibrosis (P < 0.05 and P < 0.01) whereas perfusion fraction and ADC variations were not found to be significant. Results showed that IVIM could be performed in free breathing, with a weighted-averaging procedure, a simultaneous diffusion gradient scheme and only four optimized b-values (0, 10, 80, and 800) reducing scan duration by a factor of nine compared with a nonoptimized protocol. Preliminary results have shown that parameters such as DSlow and DFast based on optimized IVIM protocol can be relevant biomarkers to distinguish between nonadvanced and advanced fibrosis. © 2014 Wiley Periodicals, Inc.

Optimized protocols for cardiac magnetic resonance imaging in patients with thoracic metallic implants.

PubMed

Olivieri, Laura J; Cross, Russell R; O'Brien, Kendall E; Ratnayaka, Kanishka; Hansen, Michael S

2015-09-01

Cardiac magnetic resonance (MR) imaging is a valuable tool in congenital heart disease; however patients frequently have metal devices in the chest from the treatment of their disease that complicate imaging. Methods are needed to improve imaging around metal implants near the heart. Basic sequence parameter manipulations have the potential to minimize artifact while limiting effects on image resolution and quality. Our objective was to design cine and static cardiac imaging sequences to minimize metal artifact while maintaining image quality. Using systematic variation of standard imaging parameters on a fluid-filled phantom containing commonly used metal cardiac devices, we developed optimized sequences for steady-state free precession (SSFP), gradient recalled echo (GRE) cine imaging, and turbo spin-echo (TSE) black-blood imaging. We imaged 17 consecutive patients undergoing routine cardiac MR with 25 metal implants of various origins using both standard and optimized imaging protocols for a given slice position. We rated images for quality and metal artifact size by measuring metal artifact in two orthogonal planes within the image. All metal artifacts were reduced with optimized imaging. The average metal artifact reduction for the optimized SSFP cine was 1.5+/-1.8 mm, and for the optimized GRE cine the reduction was 4.6+/-4.5 mm (P < 0.05). Quality ratings favored the optimized GRE cine. Similarly, the average metal artifact reduction for the optimized TSE images was 1.6+/-1.7 mm (P < 0.05), and quality ratings favored the optimized TSE imaging. Imaging sequences tailored to minimize metal artifact are easily created by modifying basic sequence parameters, and images are superior to standard imaging sequences in both quality and artifact size. Specifically, for optimized cine imaging a GRE sequence should be used with settings that favor short echo time, i.e. flow compensation off, weak asymmetrical echo and a relatively high receiver bandwidth. For static black-blood imaging, a TSE sequence should be used with fat saturation turned off and high receiver bandwidth.

Optimization of image quality in pulmonary CT angiography with low dose of contrast material

NASA Astrophysics Data System (ADS)

Assi, Abed Al Nasser; Abu Arra, Ali

2017-06-01

Aim: The aim of this study was to compare objective image quality data for patient pulmonary embolism between a conventional pulmonary CTA protocol with respect to a novel acquisition protocol performed with optimize radiation dose and less amount of iodinated contrast medium injected to the patients during PE scanning. Materials and Methods: Sixty- four patients with Pulmonary Embolism (PE) possibility, were examined using angio-CT protocol. Patients were randomly assigned to two groups: A (16 women and 16 men, with age ranging from 19-89 years) mean age, 62 years with standard deviation 16; range, 19-89 years) - injected contrast agent: 35-40 ml. B (16 women and 16 men, with age ranging from 28-86 years) - injected contrast agent: 70-80 ml. Other scanning parameters were kept constant. Pulmonary vessel enhancement and image noise were quantified; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective vessel contrast was assessed by two radiologists in consensus. Result: A total of 14 cases of PE (22 %) were found in the evaluated of subjects (nine in group A, and five in group B). All PE cases were detected by the two readers. There was no significant difference in the size or location of the PEs between the two groups, the average image noise was 14 HU for group A and 19 HU for group B. The difference was not statistically significant (p = 0.09). Overall, the SNR and CNR were slightly higher on group B (24.4 and 22.5 respectively) compared with group A (19.4 and 16.4 respectively), but those differences were not statistically significant (p = 0.71 and p = 0.35, respectively). Conclusion and Discussion: Both groups that had been evaluated by pulmonary CTA protocol allow similar image quality to be achieved as compared with each other's, with optimize care dose for both protocol and contrast volume were reduced by 50 % in new protocol comparing to the conventional protocol.

Optimized imaging of the midface and orbits

PubMed Central

Langner, Sönke

2015-01-01

A variety of imaging techniques are available for imaging the midface and orbits. This review article describes the different imaging techniques based on the recent literature and discusses their impact on clinical routine imaging. Imaging protocols are presented for different diseases and the different imaging modalities. PMID:26770279

Optimization of a protocol for myocardial perfusion scintigraphy by using an anthropomorphic phantom.

PubMed

Ramos, Susie Medeiros Oliveira; Glavam, Adriana Pereira; Kubo, Tadeu Takao Almodovar; de Sá, Lidia Vasconcellos

2014-01-01

To develop a study aiming at optimizing myocardial perfusion imaging. Imaging of an anthropomorphic thorax phantom with a GE SPECT Ventri gamma camera, with varied activities and acquisition times, in order to evaluate the influence of these parameters on the quality of the reconstructed medical images. The (99m)Tc-sestamibi radiotracer was utilized, and then the images were clinically evaluated on the basis of data such as summed stress score, and on the technical image quality and perfusion. The software ImageJ was utilized in the data quantification. The results demonstrated that for the standard acquisition time utilized in the procedure (15 seconds per angle), the injected activity could be reduced by 33.34%. Additionally, even if the standard scan time is reduced by 53.34% (7 seconds per angle), the standard injected activity could still be reduced by 16.67%, without impairing the image quality and the diagnostic reliability. The described method and respective results provide a basis for the development of a clinical trial of patients in an optimized protocol.

Optimization of a protocol for myocardial perfusion scintigraphy by using an anthropomorphic phantom*

PubMed Central

Ramos, Susie Medeiros Oliveira; Glavam, Adriana Pereira; Kubo, Tadeu Takao Almodovar; de Sá, Lidia Vasconcellos

2014-01-01

Objective To develop a study aiming at optimizing myocardial perfusion imaging. Materials and Methods Imaging of an anthropomorphic thorax phantom with a GE SPECT Ventri gamma camera, with varied activities and acquisition times, in order to evaluate the influence of these parameters on the quality of the reconstructed medical images. The 99mTc-sestamibi radiotracer was utilized, and then the images were clinically evaluated on the basis of data such as summed stress score, and on the technical image quality and perfusion. The software ImageJ was utilized in the data quantification. Results The results demonstrated that for the standard acquisition time utilized in the procedure (15 seconds per angle), the injected activity could be reduced by 33.34%. Additionally, even if the standard scan time is reduced by 53.34% (7 seconds per angle), the standard injected activity could still be reduced by 16.67%, without impairing the image quality and the diagnostic reliability. Conclusion The described method and respective results provide a basis for the development of a clinical trial of patients in an optimized protocol. PMID:25741088

Comparison of different tissue clearing methods and 3D imaging techniques for visualization of GFP-expressing mouse embryos and embryonic hearts.

PubMed

Kolesová, Hana; Čapek, Martin; Radochová, Barbora; Janáček, Jiří; Sedmera, David

2016-08-01

Our goal was to find an optimal tissue clearing protocol for whole-mount imaging of embryonic and adult hearts and whole embryos of transgenic mice that would preserve green fluorescent protein GFP fluorescence and permit comparison of different currently available 3D imaging modalities. We tested various published organic solvent- or water-based clearing protocols intended to preserve GFP fluorescence in central nervous system: tetrahydrofuran dehydration and dibenzylether protocol (DBE), SCALE, CLARITY, and CUBIC and evaluated their ability to render hearts and whole embryos transparent. DBE clearing protocol did not preserve GFP fluorescence; in addition, DBE caused considerable tissue-shrinking artifacts compared to the gold standard BABB protocol. The CLARITY method considerably improved tissue transparency at later stages, but also decreased GFP fluorescence intensity. The SCALE clearing resulted in sufficient tissue transparency up to ED12.5; at later stages the useful depth of imaging was limited by tissue light scattering. The best method for the cardiac specimens proved to be the CUBIC protocol, which preserved GFP fluorescence well, and cleared the specimens sufficiently even at the adult stages. In addition, CUBIC decolorized the blood and myocardium by removing tissue iron. Good 3D renderings of whole fetal hearts and embryos were obtained with optical projection tomography and selective plane illumination microscopy, although at resolutions lower than with a confocal microscope. Comparison of five tissue clearing protocols and three imaging methods for study of GFP mouse embryos and hearts shows that the optimal method depends on stage and level of detail required.

Physics of cardiac imaging with multiple-row detector CT.

PubMed

Mahesh, Mahadevappa; Cody, Dianna D

2007-01-01

Cardiac imaging with multiple-row detector computed tomography (CT) has become possible due to rapid advances in CT technologies. Images with high temporal and spatial resolution can be obtained with multiple-row detector CT scanners; however, the radiation dose associated with cardiac imaging is high. Understanding the physics of cardiac imaging with multiple-row detector CT scanners allows optimization of cardiac CT protocols in terms of image quality and radiation dose. Knowledge of the trade-offs between various scan parameters that affect image quality--such as temporal resolution, spatial resolution, and pitch--is the key to optimized cardiac CT protocols, which can minimize the radiation risks associated with these studies. Factors affecting temporal resolution include gantry rotation time, acquisition mode, and reconstruction method; factors affecting spatial resolution include detector size and reconstruction interval. Cardiac CT has the potential to become a reliable tool for noninvasive diagnosis and prevention of cardiac and coronary artery disease. (c) RSNA, 2007.

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

PubMed Central

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

2017-01-01

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

Impact of imaging approach on radiation dose and associated cancer risk in children undergoing cardiac catheterization

PubMed Central

Einstein, Andrew J.; Januzis, Natalie; Nguyen, Giao; Li, Jennifer S.; Fleming, Gregory A.; Yoshizumi, Terry K.

2016-01-01

Objectives To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Background Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, anti-scatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. Methods We used anthropomorphic phantoms (ages: newborn and 5-years-old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies’ Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. Results For the newborn and 5-year-old phantoms respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20cm increase in source-to-image-distance; −42% and −48% with addition of 1-inch periphery collimation; −31% and −46% with removal of the anti-scatter grid. Compared to an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and 4-fold (5-year-old). Estimated cancer LAR from 30-minutes of postero-anterior fluoroscopy using optimized versus sub-optimal imaging respectively was: 0.42% versus 1.23% (newborn female), 0.20% vs 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% vs 0.69% (5-year-old male). Conclusions Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. PMID:27315598

Optimization and comparison of simultaneous and separate acquisition protocols for dual isotope myocardial perfusion SPECT

PubMed Central

Ghaly, Michael; Links, Jonathan M; Frey, Eric C

2015-01-01

Dual-isotope simultaneous-acquisition (DISA) rest-stress myocardial perfusion SPECT (MPS) protocols offer a number of advantages over separate acquisition. However, crosstalk contamination due to scatter in the patient and interactions in the collimator degrade image quality. Compensation can reduce the effects of crosstalk, but does not entirely eliminate image degradations. Optimizing acquisition parameters could further reduce the impact of crosstalk. In this paper we investigate the optimization of the rest Tl-201 energy window width and relative injected activities using the ideal observer (IO), a realistic digital phantom population and Monte Carlo (MC) simulated Tc-99m and Tl-201 projections as a means to improve image quality. We compared performance on a perfusion defect detection task for Tl-201 acquisition energy window widths varying from 4 to 40 keV centered at 72 keV for a camera with a 9% energy resolution. We also investigated 7 different relative injected activities, defined as the ratio of Tc-99m and Tl-201 activities, while keeping the total effective dose constant at 13.5 mSv. For each energy window and relative injected activity, we computed the IO test statistics using a Markov chain Monte Carlo (MCMC) method for an ensemble of 1,620 triplets of fixed and reversible defect-present, and defect-absent noisy images modeling realistic background variations. The volume under the 3-class receiver operating characteristic (ROC) surface (VUS) was estimated and served as the figure of merit. For simultaneous acquisition, the IO suggested that relative Tc-to-Tl injected activity ratios of 2.6–5 and acquisition energy window widths of 16–22% were optimal. For separate acquisition, we observed a broad range of optimal relative injected activities from 2.6 to 12.1 and acquisition energy window of widths 16–22%. A negative correlation between Tl-201 injected activity and the width of the Tl-201 energy window was observed in these ranges. The results also suggested that DISA methods could potentially provide image quality as good as that obtained with separate acquisition protocols. We compared observer performance for the optimized protocols and the current clinical protocol using separate acquisition. The current clinical protocols provided better performance at a cost of injecting the patient with approximately double the injected activity of Tc-99m and Tl-201, resulting in substantially increased radiation dose. PMID:26083239

Optimization of dose and image quality in adult and pediatric computed tomography scans

NASA Astrophysics Data System (ADS)

Chang, Kwo-Ping; Hsu, Tzu-Kun; Lin, Wei-Ting; Hsu, Wen-Lin

2017-11-01

Exploration to maximize CT image and reduce radiation dose was conducted while controlling for multiple factors. The kVp, mAs, and iteration reconstruction (IR), affect the CT image quality and radiation dose absorbed. The optimal protocols (kVp, mAs, IR) are derived by figure of merit (FOM) based on CT image quality (CNR) and CT dose index (CTDIvol). CT image quality metrics such as CT number accuracy, SNR, low contrast materials' CNR and line pair resolution were also analyzed as auxiliary assessments. CT protocols were carried out with an ACR accreditation phantom and a five-year-old pediatric head phantom. The threshold values of the adult CT scan parameters, 100 kVp and 150 mAs, were determined from the CT number test and line pairs in ACR phantom module 1and module 4 respectively. The findings of this study suggest that the optimal scanning parameters for adults be set at 100 kVp and 150-250 mAs. However, for improved low- contrast resolution, 120 kVp and 150-250 mAs are optimal. Optimal settings for pediatric head CT scan were 80 kVp/50 mAs, for maxillary sinus and brain stem, while 80 kVp /300 mAs for temporal bone. SNR is not reliable as the independent image parameter nor the metric for determining optimal CT scan parameters. The iteration reconstruction (IR) approach is strongly recommended for both adult and pediatric CT scanning as it markedly improves image quality without affecting radiation dose.

Thick tissue diffusion model with binding to optimize topical staining in fluorescence breast cancer margin imaging

NASA Astrophysics Data System (ADS)

Xu, Xiaochun; Kang, Soyoung; Navarro-Comes, Eric; Wang, Yu; Liu, Jonathan T. C.; Tichauer, Kenneth M.

2018-03-01

Intraoperative tumor/surgical margin assessment is required to achieve higher tumor resection rate in breast-conserving surgery. Though current histology provides incomparable accuracy in margin assessment, thin tissue sectioning and the limited field of view of microscopy makes histology too time-consuming for intraoperative applications. If thick tissue, wide-field imaging can provide an acceptable assessment of tumor cells at the surface of resected tissues, an intraoperative protocol can be developed to guide the surgery and provide immediate feedback for surgeons. Topical staining of margins with cancer-targeted molecular imaging agents has the potential to provide the sensitivity needed to see microscopic cancer on a wide-field image; however, diffusion and nonspecific retention of imaging agents in thick tissue can significantly diminish tumor contrast with conventional methods. Here, we present a mathematical model to accurately simulate nonspecific retention, binding, and diffusion of imaging agents in thick tissue topical staining to guide and optimize future thick tissue staining and imaging protocol. In order to verify the accuracy and applicability of the model, diffusion profiles of cancer targeted and untargeted (control) nanoparticles at different staining times in A431 tumor xenografts were acquired for model comparison and tuning. The initial findings suggest the existence of nonspecific retention in the tissue, especially at the tissue surface. The simulator can be used to compare the effect of nonspecific retention, receptor binding and diffusion under various conditions (tissue type, imaging agent) and provides optimal staining and imaging protocols for targeted and control imaging agent.

Optimization of the scan protocols for CT-based material extraction in small animal PET/CT studies

NASA Astrophysics Data System (ADS)

Yang, Ching-Ching; Yu, Jhih-An; Yang, Bang-Hung; Wu, Tung-Hsin

2013-12-01

We investigated the effects of scan protocols on CT-based material extraction to minimize radiation dose while maintaining sufficient image information in small animal studies. The phantom simulation experiments were performed with the high dose (HD), medium dose (MD) and low dose (LD) protocols at 50, 70 and 80 kVp with varying mA s. The reconstructed CT images were segmented based on Hounsfield unit (HU)-physical density (ρ) calibration curves and the dual-energy CT-based (DECT) method. Compared to the (HU;ρ) method performed on CT images acquired with the 80 kVp HD protocol, a 2-fold improvement in segmentation accuracy and a 7.5-fold reduction in radiation dose were observed when the DECT method was performed on CT images acquired with the 50/80 kVp LD protocol, showing the possibility to reduce radiation dose while achieving high segmentation accuracy.

Optimized Setup and Protocol for Magnetic Domain Imaging with In Situ Hysteresis Measurement.

PubMed

Liu, Jun; Wilson, John; Davis, Claire; Peyton, Anthony

2017-11-07

This paper elaborates the sample preparation protocols required to obtain optimal domain patterns using the Bitter method, focusing on the extra steps compared to standard metallographic sample preparation procedures. The paper proposes a novel bespoke rig for dynamic domain imaging with in situ BH (magnetic hysteresis) measurements and elaborates the protocols for the sensor preparation and the use of the rig to ensure accurate BH measurement. The protocols for static and ordinary dynamic domain imaging (without in situ BH measurements) are also presented. The reported method takes advantage of the convenience and high sensitivity of the traditional Bitter method and enables in situ BH measurement without interrupting or interfering with the domain wall movement processes. This facilitates establishing a direct and quantitative link between the domain wall movement processes-microstructural feature interactions in ferritic steels with their BH loops. This method is anticipated to become a useful tool for the fundamental study of microstructure-magnetic property relationships in steels and to help interpret the electromagnetic sensor signals for non-destructive evaluation of steel microstructures.

Optimized Setup and Protocol for Magnetic Domain Imaging with In Situ Hysteresis Measurement

PubMed Central

Liu, Jun; Wilson, John; Davis, Claire; Peyton, Anthony

2017-01-01

This paper elaborates the sample preparation protocols required to obtain optimal domain patterns using the Bitter method, focusing on the extra steps compared to standard metallographic sample preparation procedures. The paper proposes a novel bespoke rig for dynamic domain imaging with in situ BH (magnetic hysteresis) measurements and elaborates the protocols for the sensor preparation and the use of the rig to ensure accurate BH measurement. The protocols for static and ordinary dynamic domain imaging (without in situ BH measurements) are also presented. The reported method takes advantage of the convenience and high sensitivity of the traditional Bitter method and enables in situ BH measurement without interrupting or interfering with the domain wall movement processes. This facilitates establishing a direct and quantitative link between the domain wall movement processes–microstructural feature interactions in ferritic steels with their BH loops. This method is anticipated to become a useful tool for the fundamental study of microstructure–magnetic property relationships in steels and to help interpret the electromagnetic sensor signals for non-destructive evaluation of steel microstructures. PMID:29155796

Diverse Protocols for Correlative Super-Resolution Fluorescence Imaging and Electron Microscopy of Cells and Tissue

DTIC Science & Technology

2016-05-25

tissue is critical to biology. Many factors determine optimal experimental design, including attainable localization precision, ultrastructural...both imaging modalities. Examples include: weak tissue preservation protocols resulting in poor ultrastructure, e.g. mitochondrial cristae membranes...tension effects during sample drying that may result in artifacts44. Samples dried in the presence of polyvinyl alcohol do not have the haziness

Impact of imaging approach on radiation dose and associated cancer risk in children undergoing cardiac catheterization.

PubMed

Hill, Kevin D; Wang, Chu; Einstein, Andrew J; Januzis, Natalie; Nguyen, Giao; Li, Jennifer S; Fleming, Gregory A; Yoshizumi, Terry K

2017-04-01

To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, antiscatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. We used anthropomorphic phantoms (ages: newborn and 5 years old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies' Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20 cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. For the newborn and 5-year-old phantoms, respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20 cm increase in source-to-image-distance; -42% and -48% with addition of 1-inch periphery collimation; -31% and -46% with removal of the antiscatter grid. Compared with an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and fourfold (5 years old). Estimated cancer LAR from 30-min of posteroanterior fluoroscopy using optimized versus suboptimal imaging, respectively was 0.42% versus 1.23% (newborn female), 0.20% versus 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% versus 0.69% (5-year-old male). Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

SU-F-I-46: Optimizing Dose Reduction in Adult Head CT Protocols While Maintaining Image Quality in Postmortem Head Scans

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

Lipnharski, I; Carranza, C; Quails, N

Purpose: To optimize adult head CT protocol by reducing dose to an appropriate level while providing CT images of diagnostic quality. Methods: Five cadavers were scanned from the skull base to the vertex using a routine adult head CT protocol (120 kVp, 270 mA, 0.75 s rotation, 0.5 mm × 32 detectors, 70.8 mGy CTDIvol) followed by seven reduced-dose protocols with varying combinations of reduced tube current, reduced rotation time, and increased detectors with CTDIvol ranging from 38.2 to 65.6 mGy. Organ doses were directly measured with 21 OSL dosimeters placed on the surface and implanted in the head bymore » a neurosurgeon. Two neuroradiologists assessed grey-white matter differentiation, fluid space, ventricular size, midline shift, brain mass, edema, ischemia, and skull fractures on a three point scale: (1) Unacceptable, (2) Borderline Acceptable, and (3) Acceptable. Results: For the standard scan, doses to the skin, lens of the eye, salivary glands, thyroid, and brain were 37.55 mGy, 49.65 mGy, 40.67 mGy, 4.63 mGy, and 27.33 mGy, respectively. Two cadavers had cerebral edema due to changing dynamics of postmortem effects, causing the grey-white matter differentiation to appear less distinct. Two cadavers with preserved grey-white matter received acceptable scores for all image quality features for the protocol with a CTDIvol of 57.3 mGy, allowing organ dose savings ranging from 34% to 45%. One cadaver allowed for greater dose reduction for the protocol with a CTDIvol of 42 mGy. Conclusion: Efforts to optimize scan protocol should consider both dose and clinical image quality. This is made possible with postmortem subjects, whose brains are similar to patients, allowing for an investigation of ideal scan parameters. Radiologists at our institution accepted scan protocols acquired with lower scan parameters, with CTDIvol values closer to the American College of Radiology’s (ACR) Achievable Dose level of 57 mGy.« less

Optimization of Whole-Body Zebrafish Sectioning Methods for Mass Spectrometry Imaging

EPA Science Inventory

Mass spectrometry imaging methods and protocols have become widely adapted to a variety of tissues and species. However, the mass spectrometry imaging literature contains minimal information on whole-body cryosection preparation for the zebrafish (Danio rerio), a model organism ...

Optimized magnetic resonance diffusion protocol for ex-vivo whole human brain imaging with a clinical scanner

NASA Astrophysics Data System (ADS)

Scherrer, Benoit; Afacan, Onur; Stamm, Aymeric; Singh, Jolene; Warfield, Simon K.

2015-03-01

Diffusion-weighted magnetic resonance imaging (DW-MRI) provides a novel insight into the brain to facilitate our understanding of the brain connectivity and microstructure. While in-vivo DW-MRI enables imaging of living patients and longitudinal studies of brain changes, post-mortem ex-vivo DW-MRI has numerous advantages. Ex-vivo imaging benefits from greater resolution and sensitivity due to the lack of imaging time constraints; the use of tighter fitting coils; and the lack of movement artifacts. This allows characterization of normal and abnormal tissues with unprecedented resolution and sensitivity, facilitating our ability to investigate anatomical structures that are inaccessible in-vivo. This also offers the opportunity to develop today novel imaging biomarkers that will, with tomorrow's MR technology, enable improved in-vivo assessment of the risk of disease in an individual. Post-mortem studies, however, generally rely on the fixation of specimen to inhibit tissue decay which starts as soon as tissue is deprived from its blood supply. Unfortunately, fixation of tissues substantially alters tissue diffusivity profiles. In addition, ex-vivo DW-MRI requires particular care when packaging the specimen because the presence of microscopic air bubbles gives rise to geometric and intensity image distortion. In this work, we considered the specific requirements of post-mortem imaging and designed an optimized protocol for ex-vivo whole brain DW-MRI using a human clinical 3T scanner. Human clinical 3T scanners are available to a large number of researchers and, unlike most animal scanners, have a bore diameter large enough to image a whole human brain. Our optimized protocol will facilitate widespread ex-vivo investigations of large specimen.

Multipinhole SPECT helical scan parameters and imaging volume

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

Yao, Rutao, E-mail: rutaoyao@buffalo.edu; Deng, Xiao; Wei, Qingyang

Purpose: The authors developed SPECT imaging capability on an animal PET scanner using a multiple-pinhole collimator and step-and-shoot helical data acquisition protocols. The objective of this work was to determine the preferred helical scan parameters, i.e., the angular and axial step sizes, and the imaging volume, that provide optimal imaging performance. Methods: The authors studied nine helical scan protocols formed by permuting three rotational and three axial step sizes. These step sizes were chosen around the reference values analytically calculated from the estimated spatial resolution of the SPECT system and the Nyquist sampling theorem. The nine helical protocols were evaluatedmore » by two figures-of-merit: the sampling completeness percentage (SCP) and the root-mean-square (RMS) resolution. SCP was an analytically calculated numerical index based on projection sampling. RMS resolution was derived from the reconstructed images of a sphere-grid phantom. Results: The RMS resolution results show that (1) the start and end pinhole planes of the helical scheme determine the axial extent of the effective field of view (EFOV), and (2) the diameter of the transverse EFOV is adequately calculated from the geometry of the pinhole opening, since the peripheral region beyond EFOV would introduce projection multiplexing and consequent effects. The RMS resolution results of the nine helical scan schemes show optimal resolution is achieved when the axial step size is the half, and the angular step size is about twice the corresponding values derived from the Nyquist theorem. The SCP results agree in general with that of RMS resolution but are less critical in assessing the effects of helical parameters and EFOV. Conclusions: The authors quantitatively validated the effective FOV of multiple pinhole helical scan protocols and proposed a simple method to calculate optimal helical scan parameters.« less

Preoperative magnetic resonance imaging protocol for endoscopic cranial base image-guided surgery.

PubMed

Grindle, Christopher R; Curry, Joseph M; Kang, Melissa D; Evans, James J; Rosen, Marc R

2011-01-01

Despite the increasing utilization of image-guided surgery, no radiology protocols for obtaining magnetic resonance (MR) imaging of adequate quality are available in the current literature. At our institution, more than 300 endonasal cranial base procedures including pituitary, extended pituitary, and other anterior skullbase procedures have been performed in the past 3 years. To facilitate and optimize preoperative evaluation and assessment, there was a need to develop a magnetic resonance protocol. Retrospective Technical Assessment was performed. Through a collaborative effort between the otolaryngology, neurosurgery, and neuroradiology departments at our institution, a skull base MR image-guided (IGS) protocol was developed with several ends in mind. First, it was necessary to generate diagnostic images useful for the more frequently seen pathologies to improve work flow and limit the expense and inefficiency of case specific MR studies. Second, it was necessary to generate sequences useful for IGS, preferably using sequences that best highlight that lesion. Currently, at our institution, all MR images used for IGS are obtained using this protocol as part of preoperative planning. The protocol that has been developed allows for thin cut precontrast and postcontrast axial cuts that can be used to plan intraoperative image guidance. It also obtains a thin cut T2 axial series that can be compiled separately for intraoperative imaging, or may be fused with computed tomographic images for combined modality. The outlined protocol obtains image sequences effective for diagnostic and operative purposes for image-guided surgery using both T1 and T2 sequences. Copyright © 2011 Elsevier Inc. All rights reserved.

Practical considerations for optimizing cardiac computed tomography protocols for comprehensive acquisition prior to transcatheter aortic valve replacement.

PubMed

Khalique, Omar K; Pulerwitz, Todd C; Halliburton, Sandra S; Kodali, Susheel K; Hahn, Rebecca T; Nazif, Tamim M; Vahl, Torsten P; George, Isaac; Leon, Martin B; D'Souza, Belinda; Einstein, Andrew J

2016-01-01

Transcatheter aortic valve replacement (TAVR) is performed frequently in patients with severe, symptomatic aortic stenosis who are at high risk or inoperable for open surgical aortic valve replacement. Computed tomography angiography (CTA) has become the gold standard imaging modality for pre-TAVR cardiac anatomic and vascular access assessment. Traditionally, cardiac CTA has been most frequently used for assessment of coronary artery stenosis, and scanning protocols have generally been tailored for this purpose. Pre-TAVR CTA has different goals than coronary CTA and the high prevalence of chronic kidney disease in the TAVR patient population creates a particular need to optimize protocols for a reduction in iodinated contrast volume. This document reviews details which allow the physician to tailor CTA examinations to maximize image quality and minimize harm, while factoring in multiple patient and scanner variables which must be considered in customizing a pre-TAVR protocol. Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Image quality and radiation reduction of 320-row area detector CT coronary angiography with optimal tube voltage selection and an automatic exposure control system: comparison with body mass index-adapted protocol.

PubMed

Lim, Jiyeon; Park, Eun-Ah; Lee, Whal; Shim, Hackjoon; Chung, Jin Wook

2015-06-01

To assess the image quality and radiation exposure of 320-row area detector computed tomography (320-ADCT) coronary angiography with optimal tube voltage selection with the guidance of an automatic exposure control system in comparison with a body mass index (BMI)-adapted protocol. Twenty-two patients (study group) underwent 320-ADCT coronary angiography using an automatic exposure control system with the target standard deviation value of 33 as the image quality index and the lowest possible tube voltage. For comparison, a sex- and BMI-matched group (control group, n = 22) using a BMI-adapted protocol was established. Images of both groups were reconstructed by an iterative reconstruction algorithm. For objective evaluation of the image quality, image noise, vessel density, signal to noise ratio (SNR), and contrast to noise ratio (CNR) were measured. Two blinded readers then subjectively graded the image quality using a four-point scale (1: nondiagnostic to 4: excellent). Radiation exposure was also measured. Although the study group tended to show higher image noise (14.1 ± 3.6 vs. 9.3 ± 2.2 HU, P = 0.111) and higher vessel density (665.5 ± 161 vs. 498 ± 143 HU, P = 0.430) than the control group, the differences were not significant. There was no significant difference between the two groups for SNR (52.5 ± 19.2 vs. 60.6 ± 21.8, P = 0.729), CNR (57.0 ± 19.8 vs. 67.8 ± 23.3, P = 0.531), or subjective image quality scores (3.47 ± 0.55 vs. 3.59 ± 0.56, P = 0.960). However, radiation exposure was significantly reduced by 42 % in the study group (1.9 ± 0.8 vs. 3.6 ± 0.4 mSv, P = 0.003). Optimal tube voltage selection with the guidance of an automatic exposure control system in 320-ADCT coronary angiography allows substantial radiation reduction without significant impairment of image quality, compared to the results obtained using a BMI-based protocol.

Quantitative mouse brain phenotyping based on single and multispectral MR protocols

PubMed Central

Badea, Alexandra; Gewalt, Sally; Avants, Brian B.; Cook, James J.; Johnson, G. Allan

2013-01-01

Sophisticated image analysis methods have been developed for the human brain, but such tools still need to be adapted and optimized for quantitative small animal imaging. We propose a framework for quantitative anatomical phenotyping in mouse models of neurological and psychiatric conditions. The framework encompasses an atlas space, image acquisition protocols, and software tools to register images into this space. We show that a suite of segmentation tools (Avants, Epstein et al., 2008) designed for human neuroimaging can be incorporated into a pipeline for segmenting mouse brain images acquired with multispectral magnetic resonance imaging (MR) protocols. We present a flexible approach for segmenting such hyperimages, optimizing registration, and identifying optimal combinations of image channels for particular structures. Brain imaging with T1, T2* and T2 contrasts yielded accuracy in the range of 83% for hippocampus and caudate putamen (Hc and CPu), but only 54% in white matter tracts, and 44% for the ventricles. The addition of diffusion tensor parameter images improved accuracy for large gray matter structures (by >5%), white matter (10%), and ventricles (15%). The use of Markov random field segmentation further improved overall accuracy in the C57BL/6 strain by 6%; so Dice coefficients for Hc and CPu reached 93%, for white matter 79%, for ventricles 68%, and for substantia nigra 80%. We demonstrate the segmentation pipeline for the widely used C57BL/6 strain, and two test strains (BXD29, APP/TTA). This approach appears promising for characterizing temporal changes in mouse models of human neurological and psychiatric conditions, and may provide anatomical constraints for other preclinical imaging, e.g. fMRI and molecular imaging. This is the first demonstration that multiple MR imaging modalities combined with multivariate segmentation methods lead to significant improvements in anatomical segmentation in the mouse brain. PMID:22836174

A simple protocol for attenuating the auto-fluorescence of cyanobacteria for optimized fluorescence in situ hybridization (FISH) imaging.

PubMed

Zeller, Perrine; Ploux, Olivier; Méjean, Annick

2016-03-01

Cyanobacteria contain pigments, which generate auto-fluorescence that interferes with fluorescence in situ hybridization (FISH) imaging of cyanobacteria. We describe simple chemical treatments using CuSO4 or H2O2 that significantly reduce the auto-fluorescence of Microcystis strains. These protocols were successfully applied in FISH experiments using 16S rRNA specific probes and filamentous cyanobacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Embedding and Chemical Reactivation of Green Fluorescent Protein in the Whole Mouse Brain for Optical Micro-Imaging

PubMed Central

Gang, Yadong; Zhou, Hongfu; Jia, Yao; Liu, Ling; Liu, Xiuli; Rao, Gong; Li, Longhui; Wang, Xiaojun; Lv, Xiaohua; Xiong, Hanqing; Yang, Zhongqin; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

2017-01-01

Resin embedding has been widely applied to fixing biological tissues for sectioning and imaging, but has long been regarded as incompatible with green fluorescent protein (GFP) labeled sample because it reduces fluorescence. Recently, it has been reported that resin-embedded GFP-labeled brain tissue can be imaged with high resolution. In this protocol, we describe an optimized protocol for resin embedding and chemical reactivation of fluorescent protein labeled mouse brain, we have used mice as experiment model, but the protocol should be applied to other species. This method involves whole brain embedding and chemical reactivation of the fluorescent signal in resin-embedded tissue. The whole brain embedding process takes a total of 7 days. The duration of chemical reactivation is ~2 min for penetrating 4 μm below the surface in the resin-embedded brain. This protocol provides an efficient way to prepare fluorescent protein labeled sample for high-resolution optical imaging. This kind of sample was demonstrated to be imaged by various optical micro-imaging methods. Fine structures labeled with GFP across a whole brain can be detected. PMID:28352214

Stent deployment protocol for optimized real-time visualization during endovascular neurosurgery.

PubMed

Silva, Michael A; See, Alfred P; Dasenbrock, Hormuzdiyar H; Ashour, Ramsey; Khandelwal, Priyank; Patel, Nirav J; Frerichs, Kai U; Aziz-Sultan, Mohammad A

2017-05-01

Successful application of endovascular neurosurgery depends on high-quality imaging to define the pathology and the devices as they are being deployed. This is especially challenging in the treatment of complex cases, particularly in proximity to the skull base or in patients who have undergone prior endovascular treatment. The authors sought to optimize real-time image guidance using a simple algorithm that can be applied to any existing fluoroscopy system. Exposure management (exposure level, pulse management) and image post-processing parameters (edge enhancement) were modified from traditional fluoroscopy to improve visualization of device position and material density during deployment. Examples include the deployment of coils in small aneurysms, coils in giant aneurysms, the Pipeline embolization device (PED), the Woven EndoBridge (WEB) device, and carotid artery stents. The authors report on the development of the protocol and their experience using representative cases. The stent deployment protocol is an image capture and post-processing algorithm that can be applied to existing fluoroscopy systems to improve real-time visualization of device deployment without hardware modifications. Improved image guidance facilitates aneurysm coil packing and proper positioning and deployment of carotid artery stents, flow diverters, and the WEB device, especially in the context of complex anatomy and an obscured field of view.

Reducing radiation dose to the female breast during conventional and dedicated breast computed tomography

NASA Astrophysics Data System (ADS)

Rupcich, Franco John

The purpose of this study was to quantify the effectiveness of techniques intended to reduce dose to the breast during CT coronary angiography (CTCA) scans with respect to task-based image quality, and to evaluate the effectiveness of optimal energy weighting in improving contrast-to-noise ratio (CNR), and thus the potential for reducing breast dose, during energy-resolved dedicated breast CT. A database quantifying organ dose for several radiosensitive organs irradiated during CTCA, including the breast, was generated using Monte Carlo simulations. This database facilitates estimation of organ-specific dose deposited during CTCA protocols using arbitrary x-ray spectra or tube-current modulation schemes without the need to run Monte Carlo simulations. The database was used to estimate breast dose for simulated CT images acquired for a reference protocol and five protocols intended to reduce breast dose. For each protocol, the performance of two tasks (detection of signals with unknown locations) was compared over a range of breast dose levels using a task-based, signal-detectability metric: the estimator of the area under the exponential free-response relative operating characteristic curve, AFE. For large-diameter/medium-contrast signals, when maintaining equivalent AFE, the 80 kV partial, 80 kV, 120 kV partial, and 120 kV tube-current modulated protocols reduced breast dose by 85%, 81%, 18%, and 6%, respectively, while the shielded protocol increased breast dose by 68%. Results for the small-diameter/high-contrast signal followed similar trends, but with smaller magnitude of the percent changes in dose. The 80 kV protocols demonstrated the greatest reduction to breast dose, however, the subsequent increase in noise may be clinically unacceptable. Tube output for these protocols can be adjusted to achieve more desirable noise levels with lesser dose reduction. The improvement in CNR of optimally projection-based and image-based weighted images relative to photon-counting was investigated for six different energy bin combinations using a bench-top energy-resolving CT system with a cadmium zinc telluride (CZT) detector. The non-ideal spectral response reduced the CNR for the projection-based weighted images, while image-based weighting improved CNR for five out of the six investigated bin combinations, despite this non-ideal response, indicating potential for image-based weighting to reduce breast dose during dedicated breast CT.

Novel SPECT Technologies and Approaches in Cardiac Imaging

PubMed Central

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

2017-01-01

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

Evaluation of similarity measures for use in the intensity-based rigid 2D-3D registration for patient positioning in radiotherapy

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

Wu Jian; Kim, Minho; Peters, Jorg

2009-12-15

Purpose: Rigid 2D-3D registration is an alternative to 3D-3D registration for cases where largely bony anatomy can be used for patient positioning in external beam radiation therapy. In this article, the authors evaluated seven similarity measures for use in the intensity-based rigid 2D-3D registration using a variation in Skerl's similarity measure evaluation protocol. Methods: The seven similarity measures are partitioned intensity uniformity, normalized mutual information (NMI), normalized cross correlation (NCC), entropy of the difference image, pattern intensity (PI), gradient correlation (GC), and gradient difference (GD). In contrast to traditional evaluation methods that rely on visual inspection or registration outcomes, themore » similarity measure evaluation protocol probes the transform parameter space and computes a number of similarity measure properties, which is objective and optimization method independent. The variation in protocol offers an improved property in the quantification of the capture range. The authors used this protocol to investigate the effects of the downsampling ratio, the region of interest, and the method of the digitally reconstructed radiograph (DRR) calculation [i.e., the incremental ray-tracing method implemented on a central processing unit (CPU) or the 3D texture rendering method implemented on a graphics processing unit (GPU)] on the performance of the similarity measures. The studies were carried out using both the kilovoltage (kV) and the megavoltage (MV) images of an anthropomorphic cranial phantom and the MV images of a head-and-neck cancer patient. Results: Both the phantom and the patient studies showed the 2D-3D registration using the GPU-based DRR calculation yielded better robustness, while providing similar accuracy compared to the CPU-based calculation. The phantom study using kV imaging suggested that NCC has the best accuracy and robustness, but its slow function value change near the global maximum requires a stricter termination condition for an optimization method. The phantom study using MV imaging indicated that PI, GD, and GC have the best accuracy, while NCC and NMI have the best robustness. The clinical study using MV imaging showed that NCC and NMI have the best robustness. Conclusions: The authors evaluated the performance of seven similarity measures for use in 2D-3D image registration using the variation in Skerl's similarity measure evaluation protocol. The generalized methodology can be used to select the best similarity measures, determine the optimal or near optimal choice of parameter, and choose the appropriate registration strategy for the end user in his specific registration applications in medical imaging.« less

SU-G-206-01: A Fully Automated CT Tool to Facilitate Phantom Image QA for Quantitative Imaging in Clinical Trials

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

Wahi-Anwar, M; Lo, P; Kim, H

Purpose: The use of Quantitative Imaging (QI) methods in Clinical Trials requires both verification of adherence to a specified protocol and an assessment of scanner performance under that protocol, which are currently accomplished manually. This work introduces automated phantom identification and image QA measure extraction towards a fully-automated CT phantom QA system to perform these functions and facilitate the use of Quantitative Imaging methods in clinical trials. Methods: This study used a retrospective cohort of CT phantom scans from existing clinical trial protocols - totaling 84 phantoms, across 3 phantom types using various scanners and protocols. The QA system identifiesmore » the input phantom scan through an ensemble of threshold-based classifiers. Each classifier - corresponding to a phantom type - contains a template slice, which is compared to the input scan on a slice-by-slice basis, resulting in slice-wise similarity metric values for each slice compared. Pre-trained thresholds (established from a training set of phantom images matching the template type) are used to filter the similarity distribution, and the slice with the most optimal local mean similarity, with local neighboring slices meeting the threshold requirement, is chosen as the classifier’s matched slice (if it existed). The classifier with the matched slice possessing the most optimal local mean similarity is then chosen as the ensemble’s best matching slice. If the best matching slice exists, image QA algorithm and ROIs corresponding to the matching classifier extracted the image QA measures. Results: Automated phantom identification performed with 84.5% accuracy and 88.8% sensitivity on 84 phantoms. Automated image quality measurements (following standard protocol) on identified water phantoms (n=35) matched user QA decisions with 100% accuracy. Conclusion: We provide a fullyautomated CT phantom QA system consistent with manual QA performance. Further work will include parallel component to automatically verify image acquisition parameters and automated adherence to specifications. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical Systems; Consultant, Samsung Electronics; NIH Grant support from: U01 CA181156.« less

Optimizing the Protocol for Pulmonary Cryoablation: A Comparison of a Dual- and Triple-Freeze Protocol

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

Hinshaw, J. Louis, E-mail: jhinshaw@uwhealth.or; Littrup, Peter J.; Durick, Nathan

2010-12-15

The purpose of this study was to compare a double freeze-thaw protocol to a triple freeze-thaw protocol for pulmonary cryoablation utilizing an in vivo porcine lung model. A total of 18 cryoablations were performed in normal porcine lung utilizing percutaneous technique with 9 each in a double- (10-5-10) and triple-freeze (3-3-7-7-5) protocol. Serial noncontrast CT images were obtained during the ablation. CT imaging findings and pathology were reviewed. No imaging changes were identified during the initial freeze cycle with either protocol. However, during the first thaw cycle, a region of ground glass opacity developed around the probe with both protocols.more » Because the initial freeze was shorter with the triple freeze-thaw protocol, the imaging findings were apparent sooner with this protocol (6 vs. 13 min). Also, despite a shorter total freeze time (15 vs. 20 min), the ablation zone identified with the triple freeze-thaw protocol was not significantly different from the double freeze-thaw protocol (mean diameter: 1.67 {+-} 0.41 cm vs. 1.66 {+-} 0.21 cm, P = 0.77; area: 2.1 {+-} 0.48 cm{sup 2} vs. 1.99 {+-} 0.62 cm{sup 2}, P = 0.7; and circularity: 0.95 {+-} 0.04 vs. 0.96 {+-} 0.03, P = 0.62, respectively). This study suggests that there may be several advantages of a triple freeze-thaw protocol for pulmonary cryoablation, including earlier identification of the imaging findings associated with the ablation, the promise of a shorter procedure time or larger zones of ablation, and theoretically, more effective cytotoxicity related to the additional freeze-thaw cycle.« less

Improved Compressive Sensing of Natural Scenes Using Localized Random Sampling

PubMed Central

Barranca, Victor J.; Kovačič, Gregor; Zhou, Douglas; Cai, David

2016-01-01

Compressive sensing (CS) theory demonstrates that by using uniformly-random sampling, rather than uniformly-spaced sampling, higher quality image reconstructions are often achievable. Considering that the structure of sampling protocols has such a profound impact on the quality of image reconstructions, we formulate a new sampling scheme motivated by physiological receptive field structure, localized random sampling, which yields significantly improved CS image reconstructions. For each set of localized image measurements, our sampling method first randomly selects an image pixel and then measures its nearby pixels with probability depending on their distance from the initially selected pixel. We compare the uniformly-random and localized random sampling methods over a large space of sampling parameters, and show that, for the optimal parameter choices, higher quality image reconstructions can be consistently obtained by using localized random sampling. In addition, we argue that the localized random CS optimal parameter choice is stable with respect to diverse natural images, and scales with the number of samples used for reconstruction. We expect that the localized random sampling protocol helps to explain the evolutionarily advantageous nature of receptive field structure in visual systems and suggests several future research areas in CS theory and its application to brain imaging. PMID:27555464

Improved identification of cranial nerves using paired-agent imaging: topical staining protocol optimization through experimentation and simulation

NASA Astrophysics Data System (ADS)

Torres, Veronica C.; Wilson, Todd; Staneviciute, Austeja; Byrne, Richard W.; Tichauer, Kenneth M.

2018-03-01

Skull base tumors are particularly difficult to visualize and access for surgeons because of the crowded environment and close proximity of vital structures, such as cranial nerves. As a result, accidental nerve damage is a significant concern and the likelihood of tumor recurrence is increased because of more conservative resections that attempt to avoid injuring these structures. In this study, a paired-agent imaging method with direct administration of fluorophores is applied to enhance cranial nerve identification. Here, a control imaging agent (ICG) accounts for non-specific uptake of the nerve-targeting agent (Oxazine 4), and ratiometric data analysis is employed to approximate binding potential (BP, a surrogate of targeted biomolecule concentration). For clinical relevance, animal experiments and simulations were conducted to identify parameters for an optimized stain and rinse protocol using the developed paired-agent method. Numerical methods were used to model the diffusive and kinetic behavior of the imaging agents in tissue, and simulation results revealed that there are various combinations of stain time and rinse number that provide improved contrast of cranial nerves, as suggested by optimal measures of BP and contrast-to-noise ratio.

Optimization of Whole-body Zebrafish Sectioning Methods for Mass Spectrometry Imaging

EPA Science Inventory

Mass spectrometry imaging (MSI) methods and protocols have become widely adapted to a variety of tissues and species. However, the MSI literature lacks information on whole-body cryosection preparation for the zebrafish (ZF; Danio rerio), a model organism routinely used in devel...

Optimized protocol for combined PALM-dSTORM imaging.

PubMed

Glushonkov, O; Réal, E; Boutant, E; Mély, Y; Didier, P

2018-06-08

Multi-colour super-resolution localization microscopy is an efficient technique to study a variety of intracellular processes, including protein-protein interactions. This technique requires specific labels that display transition between fluorescent and non-fluorescent states under given conditions. For the most commonly used label types, photoactivatable fluorescent proteins and organic fluorophores, these conditions are different, making experiments that combine both labels difficult. Here, we demonstrate that changing the standard imaging buffer of thiols/oxygen scavenging system, used for organic fluorophores, to the commercial mounting medium Vectashield increased the number of photons emitted by the fluorescent protein mEos2 and enhanced the photoconversion rate between its green and red forms. In addition, the photophysical properties of organic fluorophores remained unaltered with respect to the standard imaging buffer. The use of Vectashield together with our optimized protocol for correction of sample drift and chromatic aberrations enabled us to perform two-colour 3D super-resolution imaging of the nucleolus and resolve its three compartments.

Automated Breast Ultrasound for Ductal Pattern Reconstruction: Ground Truth File Generation and CADe Evaluation

NASA Astrophysics Data System (ADS)

Manousaki, D.; Panagiotopoulou, A.; Bizimi, V.; Haynes, M. S.; Love, S.; Kallergi, M.

2017-11-01

The purpose of this study was the generation of ground truth files (GTFs) of the breast ducts from 3D images of the Invenia™ Automated Breast Ultrasound System (ABUS) system (GE Healthcare, Little Chalfont, UK) and the application of these GTFs for the optimization of the imaging protocol and the evaluation of a computer aided detection (CADe) algorithm developed for automated duct detection. Six lactating, nursing volunteers were scanned with the ABUS before and right after breastfeeding their infants. An expert in breast ultrasound generated rough outlines of the milk-filled ducts in the transaxial slices of all image volumes and the final GTFs were created by using thresholding and smoothing tools in ImageJ. In addition, a CADe algorithm automatically segmented duct like areas and its results were compared to the expert’s GTFs by estimating true positive fraction (TPF) or % overlap. The CADe output differed significantly from the expert’s but both detected a smaller than expected volume of the ducts due to insufficient contrast (ducts were partially filled with milk), discontinuities, and artifacts. GTFs were used to modify the imaging protocol and improve the CADe method. In conclusion, electronic GTFs provide a valuable tool in the optimization of a tomographic imaging system, the imaging protocol, and the CADe algorithms. Their generation, however, is an extremely time consuming, strenuous process, particularly for multi-slice examinations, and alternatives based on phantoms or simulations are highly desirable.

Accounting for patient size in the optimization of dose and image quality of pelvis cone beam CT protocols on the Varian OBI system.

PubMed

Wood, Tim J; Moore, Craig S; Horsfield, Carl J; Saunderson, John R; Beavis, Andrew W

2015-01-01

The purpose of this study was to develop size-based radiotherapy kilovoltage cone beam CT (CBCT) protocols for the pelvis. Image noise was measured in an elliptical phantom of varying size for a range of exposure factors. Based on a previously defined "small pelvis" reference patient and CBCT protocol, appropriate exposure factors for small, medium, large and extra-large patients were derived which approximate the image noise behaviour observed on a Philips CT scanner (Philips Medical Systems, Best, Netherlands) with automatic exposure control (AEC). Selection criteria, based on maximum tube current-time product per rotation selected during the radiotherapy treatment planning scan, were derived based on an audit of patient size. It has been demonstrated that 110 kVp yields acceptable image noise for reduced patient dose in pelvic CBCT scans of small, medium and large patients, when compared with manufacturer's default settings (125 kVp). Conversely, extra-large patients require increased exposure factors to give acceptable images. 57% of patients in the local population now receive much lower radiation doses, whereas 13% require higher doses (but now yield acceptable images). The implementation of size-based exposure protocols has significantly reduced radiation dose to the majority of patients with no negative impact on image quality. Increased doses are required on the largest patients to give adequate image quality. The development of size-based CBCT protocols that use the planning CT scan (with AEC) to determine which protocol is appropriate ensures adequate image quality whilst minimizing patient radiation dose.

Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification - A multi-vendor study

PubMed Central

2011-01-01

Purpose Eddy current induced velocity offsets are of concern for accuracy in cardiovascular magnetic resonance (CMR) volume flow quantification. However, currently known theoretical aspects of eddy current behavior have not led to effective guidelines for the optimization of flow quantification sequences. This study is aimed at identifying correlations between protocol parameters and the resulting velocity error in clinical CMR flow measurements in a multi-vendor study. Methods Nine 1.5T scanners of three different types/vendors were studied. Measurements were performed on a large stationary phantom. Starting from a clinical breath-hold flow protocol, several protocol parameters were varied. Acquisitions were made in three clinically relevant orientations. Additionally, a time delay between the bipolar gradient and read-out, asymmetric versus symmetric velocity encoding, and gradient amplitude and slew rate were studied in adapted sequences as exploratory measurements beyond the protocol. Image analysis determined the worst-case offset for a typical great-vessel flow measurement. Results The results showed a great variation in offset behavior among scanners (standard deviation among samples of 0.3, 0.4, and 0.9 cm/s for the three different scanner types), even for small changes in the protocol. Considering the absolute values, none of the tested protocol settings consistently reduced the velocity offsets below the critical level of 0.6 cm/s neither for all three orientations nor for all three scanner types. Using multilevel linear model analysis, oblique aortic and pulmonary slices showed systematic higher offsets than the transverse aortic slices (oblique aortic 0.6 cm/s, and pulmonary 1.8 cm/s higher than transverse aortic). The exploratory measurements beyond the protocol yielded some new leads for further sequence development towards reduction of velocity offsets; however those protocols were not always compatible with the time-constraints of breath-hold imaging and flow-related artefacts. Conclusions This study showed that with current systems there was no generic protocol which resulted into acceptable flow offset values. Protocol optimization would have to be performed on a per scanner and per protocol basis. Proper optimization might make accurate (transverse) aortic flow quantification possible for most scanners. Pulmonary flow quantification would still need further (offline) correction. PMID:21388521

Imaging of iatrogenic oesophageal injuries using optimized CT oesophageal leak protocol: pearls and pitfalls.

PubMed

Madan, Rachna; Laur, Olga; Crudup, Breland; Peavy, Latia; Carter, Brett W

2018-02-01

Iatrogenic injury to the oesophagus is a serious complication which is increasingly seen in clinical practice secondary to expansion and greater acceptability of surgical and endoscopic oesophageal procedures. Morbidity and mortality following such injury is high. This is mostly due to an inflammatory response to gastric contents in the mediastinum, and the negative intrathoracic pressures that may further draw out oesophageal contents into the mediastinum leading to mediastinitis. Subsequently, pulmonary complications such as pneumonia or abscess may ensue leading to rapid clinical deterioration. Optimized and timely cross-sectional imaging evaluation is necessary for early and aggressive management of these complications. The goal of this review is to make the radiologist aware of the importance of early and accurate identification of postoperative oesophageal injury using optimized CT imaging protocols and use of oral contrast. Specifically, it is critical to differentiate benign post-operative findings, such as herniated viscus or redundant anastomosis, from clinically significant postoperative complications as this helps guide appropriate management. Advantages and drawbacks of other diagnostic methods, such as contrast oesophagogram, are also discussed.

Optimization of oncological {sup 18}F-FDG PET/CT imaging based on a multiparameter analysis

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

Menezes, Vinicius O., E-mail: vinicius@radtec.com.br; Machado, Marcos A. D.; Queiroz, Cleiton C.

2016-02-15

Purpose: This paper describes a method to achieve consistent clinical image quality in {sup 18}F-FDG scans accounting for patient habitus, dose regimen, image acquisition, and processing techniques. Methods: Oncological PET/CT scan data for 58 subjects were evaluated retrospectively to derive analytical curves that predict image quality. Patient noise equivalent count rate and coefficient of variation (CV) were used as metrics in their analysis. Optimized acquisition protocols were identified and prospectively applied to 179 subjects. Results: The adoption of different schemes for three body mass ranges (<60 kg, 60–90 kg, >90 kg) allows improved image quality with both point spread functionmore » and ordered-subsets expectation maximization-3D reconstruction methods. The application of this methodology showed that CV improved significantly (p < 0.0001) in clinical practice. Conclusions: Consistent oncological PET/CT image quality on a high-performance scanner was achieved from an analysis of the relations existing between dose regimen, patient habitus, acquisition, and processing techniques. The proposed methodology may be used by PET/CT centers to develop protocols to standardize PET/CT imaging procedures and achieve better patient management and cost-effective operations.« less

Advanced medical imaging protocol workflow-a flexible electronic solution to optimize process efficiency, care quality and patient safety in the National VA Enterprise.

PubMed

Medverd, Jonathan R; Cross, Nathan M; Font, Frank; Casertano, Andrew

2013-08-01

Radiologists routinely make decisions with only limited information when assigning protocol instructions for the performance of advanced medical imaging examinations. Opportunity exists to simultaneously improve the safety, quality and efficiency of this workflow through the application of an electronic solution leveraging health system resources to provide concise, tailored information and decision support in real-time. Such a system has been developed using an open source, open standards design for use within the Veterans Health Administration. The Radiology Protocol Tool Recorder (RAPTOR) project identified key process attributes as well as inherent weaknesses of paper processes and electronic emulators of paper processes to guide the development of its optimized electronic solution. The design provides a kernel that can be expanded to create an integrated radiology environment. RAPTOR has implications relevant to the greater health care community, and serves as a case model for modernization of legacy government health information systems.

Optimization of a secondary VOI protocol for lung imaging in a clinical CT scanner.

PubMed

Larsen, Thomas C; Gopalakrishnan, Vissagan; Yao, Jianhua; Nguyen, Catherine P; Chen, Marcus Y; Moss, Joel; Wen, Han

2018-05-21

We present a solution to meet an unmet clinical need of an in-situ "close look" at a pulmonary nodule or at the margins of a pulmonary cyst revealed by a primary (screening) chest CT while the patient is still in the scanner. We first evaluated options available on current whole-body CT scanners for high resolution screening scans, including ROI reconstruction of the primary scan data and HRCT, but found them to have insufficient SNR in lung tissue or discontinuous slice coverage. Within the capabilities of current clinical CT systems, we opted for the solution of a secondary, volume-of-interest (VOI) protocol where the radiation dose is focused into a short-beam axial scan at the z position of interest, combined with a small-FOV reconstruction at the xy position of interest. The objective of this work was to design a VOI protocol that is optimized for targeted lung imaging in a clinical whole-body CT system. Using a chest phantom containing a lung-mimicking foam insert with a simulated cyst, we identified the appropriate scan mode and optimized both the scan and recon parameters. The VOI protocol yielded 3.2 times the texture amplitude-to-noise ratio in the lung-mimicking foam when compared to the standard chest CT, and 8.4 times the texture difference between the lung mimicking and reference foams. It improved details of the wall of the simulated cyst and better resolution in a line-pair insert. The Effective Dose of the secondary VOI protocol was 42% on average and up to 100% in the worst-case scenario of VOI positioning relative to the standard chest CT. The optimized protocol will be used to obtain detailed CT textures of pulmonary lesions, which are biomarkers for the type and stage of lung diseases. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Experimental high-speed network

NASA Astrophysics Data System (ADS)

McNeill, Kevin M.; Klein, William P.; Vercillo, Richard; Alsafadi, Yasser H.; Parra, Miguel V.; Dallas, William J.

1993-09-01

Many existing local area networking protocols currently applied in medical imaging were originally designed for relatively low-speed, low-volume networking. These protocols utilize small packet sizes appropriate for text based communication. Local area networks of this type typically provide raw bandwidth under 125 MHz. These older network technologies are not optimized for the low delay, high data traffic environment of a totally digital radiology department. Some current implementations use point-to-point links when greater bandwidth is required. However, the use of point-to-point communications for a total digital radiology department network presents many disadvantages. This paper describes work on an experimental multi-access local area network called XFT. The work includes the protocol specification, and the design and implementation of network interface hardware and software. The protocol specifies the Physical and Data Link layers (OSI layers 1 & 2) for a fiber-optic based token ring providing a raw bandwidth of 500 MHz. The protocol design and implementation of the XFT interface hardware includes many features to optimize image transfer and provide flexibility for additional future enhancements which include: a modular hardware design supporting easy portability to a variety of host system buses, a versatile message buffer design providing 16 MB of memory, and the capability to extend the raw bandwidth of the network to 3.0 GHz.

Thin client performance for remote 3-D image display.

PubMed

Lai, Albert; Nieh, Jason; Laine, Andrew; Starren, Justin

2003-01-01

Several trends in biomedical computing are converging in a way that will require new approaches to telehealth image display. Image viewing is becoming an "anytime, anywhere" activity. In addition, organizations are beginning to recognize that healthcare providers are highly mobile and optimal care requires providing information wherever the provider and patient are. Thin-client computing is one way to support image viewing this complex environment. However little is known about the behavior of thin client systems in supporting image transfer in modern heterogeneous networks. Our results show that using thin-clients can deliver acceptable performance over conditions commonly seen in wireless networks if newer protocols optimized for these conditions are used.

Accounting for patient size in the optimization of dose and image quality of pelvis cone beam CT protocols on the Varian OBI system

PubMed Central

Moore, Craig S; Horsfield, Carl J; Saunderson, John R; Beavis, Andrew W

2015-01-01

Objective: The purpose of this study was to develop size-based radiotherapy kilovoltage cone beam CT (CBCT) protocols for the pelvis. Methods: Image noise was measured in an elliptical phantom of varying size for a range of exposure factors. Based on a previously defined “small pelvis” reference patient and CBCT protocol, appropriate exposure factors for small, medium, large and extra-large patients were derived which approximate the image noise behaviour observed on a Philips CT scanner (Philips Medical Systems, Best, Netherlands) with automatic exposure control (AEC). Selection criteria, based on maximum tube current–time product per rotation selected during the radiotherapy treatment planning scan, were derived based on an audit of patient size. Results: It has been demonstrated that 110 kVp yields acceptable image noise for reduced patient dose in pelvic CBCT scans of small, medium and large patients, when compared with manufacturer's default settings (125 kVp). Conversely, extra-large patients require increased exposure factors to give acceptable images. 57% of patients in the local population now receive much lower radiation doses, whereas 13% require higher doses (but now yield acceptable images). Conclusion: The implementation of size-based exposure protocols has significantly reduced radiation dose to the majority of patients with no negative impact on image quality. Increased doses are required on the largest patients to give adequate image quality. Advances in knowledge: The development of size-based CBCT protocols that use the planning CT scan (with AEC) to determine which protocol is appropriate ensures adequate image quality whilst minimizing patient radiation dose. PMID:26419892

Quality and Dose Optimized CT Trauma Protocol - Recommendation from a University Level-I Trauma Center.

PubMed

Kahn, Johannes; Kaul, David; Böning, Georg; Rotzinger, Roman; Freyhardt, Patrick; Schwabe, Philipp; Maurer, Martin H; Renz, Diane Miriam; Streitparth, Florian

2017-09-01

Purpose  As a supra-regional level-I trauma center, we evaluated computed tomography (CT) acquisitions of polytraumatized patients for quality and dose optimization purposes. Adapted statistical iterative reconstruction [(AS)IR] levels, tube voltage reduction as well as a split-bolus contrast agent (CA) protocol were applied. Materials and Methods  61 patients were split into 3 different groups that differed with respect to tube voltage (120 - 140 kVp) and level of applied ASIR reconstruction (ASIR 20 - 50 %). The CT protocol included a native acquisition of the head followed by a single contrast-enhanced acquisition of the whole body (64-MSCT). CA (350 mg/ml iodine) was administered as a split bolus injection of 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s) with a scan delay of 85 s to detect injuries of both the arterial system and parenchymal organs in a single acquisition. Both the quantitative (SNR/CNR) and qualitative (5-point Likert scale) image quality was evaluated in parenchymal organs that are often injured in trauma patients. Radiation exposure was assessed. Results  The use of IR combined with a reduction of tube voltage resulted in good qualitative and quantitative image quality and a significant reduction in radiation exposure of more than 40 % (DLP 1087 vs. 647 mGyxcm). Image quality could be improved due to a dedicated protocol that included different levels of IR adapted to different slice thicknesses, kernels and the examined area for the evaluation of head, lung, body and bone injury patterns. In synopsis of our results, we recommend the implementation of a polytrauma protocol with a tube voltage of 120 kVp and the following IR levels: cCT 5mm: ASIR 20; cCT 0.625 mm: ASIR 40; lung 2.5 mm: ASIR 30, body 5 mm: ASIR 40; body 1.25 mm: ASIR 50; body 0.625 mm: ASIR 0. Conclusion  A dedicated adaptation of the CT trauma protocol (level of reduction of tube voltage and of IR) according to the examined body region (head, lung, body, bone) combined with a split bolus CA injection protocol allows for a high-quality CT examination and a relevant reduction of radiation exposure in the examination of polytraumatized patients Key Points   · Dedicated adaption of the CT trauma protocol allows for an optimized examination.. · Different levels of iterative reconstruction, tube voltage and the CA injection protocol are crucial.. · A reduction of radiation exposure of more than 40 % with good image quality is possible.. Citation Format · Kahn J, Kaul D, Böning G et al. Quality and Dose Optimized CT Trauma Protocol - Recommendation from a University Level-I Trauma Center. Fortschr Röntgenstr 2017; 189: 844 - 854. © Georg Thieme Verlag KG Stuttgart · New York.

SU-F-207-16: CT Protocols Optimization Using Model Observer

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

Tseng, H; Fan, J; Kupinski, M

2015-06-15

Purpose: To quantitatively evaluate the performance of different CT protocols using task-based measures of image quality. This work studies the task of size and the contrast estimation of different iodine concentration rods inserted in head- and body-sized phantoms using different imaging protocols. These protocols are designed to have the same dose level (CTDIvol) but using different X-ray tube voltage settings (kVp). Methods: Different concentrations of iodine objects inserted in a head size phantom and a body size phantom are imaged on a 64-slice commercial CT scanner. Scanning protocols with various tube voltages (80, 100, and 120 kVp) and current settingsmore » are selected, which output the same absorbed dose level (CTDIvol). Because the phantom design (size of the iodine objects, the air gap between the inserted objects and the phantom) is not ideal for a model observer study, the acquired CT images are used to generate simulation images with four different sizes and five different contracts iodine objects. For each type of the objects, 500 images (100 x 100 pixels) are generated for the observer study. The observer selected in this study is the channelized scanning linear observer which could be applied to estimate the size and the contrast. The figure of merit used is the correct estimation ratio. The mean and the variance are estimated by the shuffle method. Results: The results indicate that the protocols with 100 kVp tube voltage setting provides the best performance for iodine insert size and contrast estimation for both head and body phantom cases. Conclusion: This work presents a practical and robust quantitative approach using channelized scanning linear observer to study contrast and size estimation performance from different CT protocols. Different protocols at same CTDIvol setting could Result in different image quality performance. The relationship between the absorbed dose and the diagnostic image quality is not linear.« less

The UNC/UMN Baby Connectome Project (BCP): An overview of the study design and protocol development.

PubMed

Howell, Brittany R; Styner, Martin A; Gao, Wei; Yap, Pew-Thian; Wang, Li; Baluyot, Kristine; Yacoub, Essa; Chen, Geng; Potts, Taylor; Salzwedel, Andrew; Li, Gang; Gilmore, John H; Piven, Joseph; Smith, J Keith; Shen, Dinggang; Ugurbil, Kamil; Zhu, Hongtu; Lin, Weili; Elison, Jed T

2018-03-22

The human brain undergoes extensive and dynamic growth during the first years of life. The UNC/UMN Baby Connectome Project (BCP), one of the Lifespan Connectome Projects funded by NIH, is an ongoing study jointly conducted by investigators at the University of North Carolina at Chapel Hill and the University of Minnesota. The primary objective of the BCP is to characterize brain and behavioral development in typically developing infants across the first 5 years of life. The ultimate goals are to chart emerging patterns of structural and functional connectivity during this period, map brain-behavior associations, and establish a foundation from which to further explore trajectories of health and disease. To accomplish these goals, we are combining state of the art MRI acquisition and analysis techniques, including high-resolution structural MRI (T1-and T2-weighted images), diffusion imaging (dMRI), and resting state functional connectivity MRI (rfMRI). While the overall design of the BCP largely is built on the protocol developed by the Lifespan Human Connectome Project (HCP), given the unique age range of the BCP cohort, additional optimization of imaging parameters and consideration of an age appropriate battery of behavioral assessments were needed. Here we provide the overall study protocol, including approaches for subject recruitment, strategies for imaging typically developing children 0-5 years of age without sedation, imaging protocol and optimization, a description of the battery of behavioral assessments, and QA/QC procedures. Combining HCP inspired neuroimaging data with well-established behavioral assessments during this time period will yield an invaluable resource for the scientific community. Copyright © 2018 Elsevier Inc. All rights reserved.

Contrast medium administration and image acquisition parameters in renal CT angiography: what radiologists need to know.

PubMed

Saade, Charbel; Deeb, Ibrahim Alsheikh; Mohamad, Maha; Al-Mohiy, Hussain; El-Merhi, Fadi

2016-01-01

Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged. Poor synchronization between scanner and contrast media administration have reduced the consistency in image quality with poor spatial and contrast resolution. Comprehensive understanding of contrast media dynamics is essential in the design and implementation of contrast administration and image acquisition protocols. This review includes an overview of the parameters affecting renal artery opacification and current protocol strategies to achieve optimal image quality during renal CT angiography with iodinated contrast media, with current safety issues highlighted.

Standardizing Quality Assessment of Fused Remotely Sensed Images

NASA Astrophysics Data System (ADS)

Pohl, C.; Moellmann, J.; Fries, K.

2017-09-01

The multitude of available operational remote sensing satellites led to the development of many image fusion techniques to provide high spatial, spectral and temporal resolution images. The comparison of different techniques is necessary to obtain an optimized image for the different applications of remote sensing. There are two approaches in assessing image quality: 1. Quantitatively by visual interpretation and 2. Quantitatively using image quality indices. However an objective comparison is difficult due to the fact that a visual assessment is always subject and a quantitative assessment is done by different criteria. Depending on the criteria and indices the result varies. Therefore it is necessary to standardize both processes (qualitative and quantitative assessment) in order to allow an objective image fusion quality evaluation. Various studies have been conducted at the University of Osnabrueck (UOS) to establish a standardized process to objectively compare fused image quality. First established image fusion quality assessment protocols, i.e. Quality with No Reference (QNR) and Khan's protocol, were compared on varies fusion experiments. Second the process of visual quality assessment was structured and standardized with the aim to provide an evaluation protocol. This manuscript reports on the results of the comparison and provides recommendations for future research.

Optimized Negative Staining: a High-throughput Protocol for Examining Small and Asymmetric Protein Structure by Electron Microscopy

DOE PAGES

Rames, Matthew; Yu, Yadong; Ren, Gang

2014-08-15

Structural determination of proteins is rather challenging for proteins with molecular masses between 40 - 200 kDa. Considering that more than half of natural proteins have a molecular mass between 40 - 200 kDa, a robust and high-throughput method with a nanometer resolution capability is needed. Negative staining (NS) electron microscopy (EM) is an easy, rapid, and qualitative approach which has frequently been used in research laboratories to examine protein structure and protein-protein interactions. Unfortunately, conventional NS protocols often generate structural artifacts on proteins, especially with lipoproteins that usually form presenting rouleaux artifacts. By using images of lipoproteins from cryo-electronmore » microscopy (cryo-EM) as a standard, the key parameters in NS specimen preparation conditions were recently screened and reported as the optimized NS protocol (OpNS), a modified conventional NS protocol. Artifacts like rouleaux can be greatly limited by OpNS, additionally providing high contrast along with reasonably high-resolution (near 1 nm) images of small and asymmetric proteins. These high-resolution and high contrast images are even favorable for an individual protein (a single object, no average) 3D reconstruction, such as a 160 kDa antibody, through the method of electron tomography. Moreover, OpNS can be a high-throughput tool to examine hundreds of samples of small proteins. For example, the previously published mechanism of 53 kDa cholesteryl ester transfer protein (CETP) involved the screening and imaging of hundreds of samples. Considering cryo-EM rarely successfully images proteins less than 200 kDa has yet to publish any study involving screening over one hundred sample conditions, it is fair to call OpNS a high-throughput method for studying small proteins. Hopefully the OpNS protocol presented here can be a useful tool to push the boundaries of EM and accelerate EM studies into small protein structure, dynamics and mechanisms.« less

Use of C-Arm Cone Beam CT During Hepatic Radioembolization: Protocol Optimization for Extrahepatic Shunting and Parenchymal Enhancement

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

Hoven, Andor F. van den, E-mail: a.f.vandenhoven@umcutrecht.nl; Prince, Jip F.; Keizer, Bart de

PurposeTo optimize a C-arm computed tomography (CT) protocol for radioembolization (RE), specifically for extrahepatic shunting and parenchymal enhancement.Materials and MethodsA prospective development study was performed per IDEAL recommendations. A literature-based protocol was applied in patients with unresectable and chemorefractory liver malignancies undergoing an angiography before radioembolization. Contrast and scan settings were adjusted stepwise and repeatedly reviewed in a consensus meeting. Afterwards, two independent raters analyzed all scans. A third rater evaluated the SPECT/CT scans as a reference standard for extrahepatic shunting and lack of target segment perfusion.ResultsFifty scans were obtained in 29 procedures. The first protocol, using a 6 s delaymore » and 10 s scan, showed insufficient parenchymal enhancement. In the second protocol, the delay was determined by timing parenchymal enhancement on DSA power injection (median 8 s, range 4–10 s): enhancement improved, but breathing artifacts increased (from 0 to 27 %). Since the third protocol with a 5 s scan decremented subjective image quality, the second protocol was deemed optimal. Median CNR (range) was 1.7 (0.6–3.2), 2.2 (−1.4–4.0), and 2.1 (−0.3–3.0) for protocol 1, 2, and 3 (p = 0.80). Delineation of perfused segments was possible in 57, 73, and 44 % of scans (p = 0.13). In all C-arm CTs combined, the negative predictive value was 95 % for extrahepatic shunting and 83 % for lack of target segment perfusion.ConclusionAn optimized C-arm CT protocol was developed that can be used to detect extrahepatic shunts and non-perfusion of target segments during RE.« less

Sensitivity regularization of the Cramér-Rao lower bound to minimize B1 nonuniformity effects in quantitative magnetization transfer imaging.

PubMed

Boudreau, Mathieu; Pike, G Bruce

2018-05-07

To develop and validate a regularization approach of optimizing B 1 insensitivity of the quantitative magnetization transfer (qMT) pool-size ratio (F). An expression describing the impact of B 1 inaccuracies on qMT fitting parameters was derived using a sensitivity analysis. To simultaneously optimize for robustness against noise and B 1 inaccuracies, the optimization condition was defined as the Cramér-Rao lower bound (CRLB) regularized by the B 1 -sensitivity expression for the parameter of interest (F). The qMT protocols were iteratively optimized from an initial search space, with and without B 1 regularization. Three 10-point qMT protocols (Uniform, CRLB, CRLB+B 1 regularization) were compared using Monte Carlo simulations for a wide range of conditions (e.g., SNR, B 1 inaccuracies, tissues). The B 1 -regularized CRLB optimization protocol resulted in the best robustness of F against B 1 errors, for a wide range of SNR and for both white matter and gray matter tissues. For SNR = 100, this protocol resulted in errors of less than 1% in mean F values for B 1 errors ranging between -10 and 20%, the range of B 1 values typically observed in vivo in the human head at field strengths of 3 T and less. Both CRLB-optimized protocols resulted in the lowest σ F values for all SNRs and did not increase in the presence of B 1 inaccuracies. This work demonstrates a regularized optimization approach for improving the robustness of auxiliary measurements (e.g., B 1 ) sensitivity of qMT parameters, particularly the pool-size ratio (F). Predicting substantially less B 1 sensitivity using protocols optimized with this method, B 1 mapping could even be omitted for qMT studies primarily interested in F. © 2018 International Society for Magnetic Resonance in Medicine.

A time-efficient acquisition protocol for multipurpose diffusion-weighted microstructural imaging at 7 Tesla.

PubMed

Sepehrband, Farshid; O'Brien, Kieran; Barth, Markus

2017-12-01

Several diffusion-weighted MRI techniques have been developed and validated during the past 2 decades. While offering various neuroanatomical inferences, these techniques differ in their proposed optimal acquisition design, preventing clinicians and researchers benefiting from all potential inference methods, particularly when limited time is available. This study reports an optimal design that enables for a time-efficient diffusion-weighted MRI acquisition scheme at 7 Tesla. The primary audience of this article is the typical end user, interested in diffusion-weighted microstructural imaging at 7 Tesla. We tested b-values in the range of 700 to 3000 s/mm 2 with different number of angular diffusion-encoding samples, against a data-driven "gold standard." The suggested design is a protocol with b-values of 1000 and 2500 s/mm 2 , with 25 and 50 samples, uniformly distributed over two shells. We also report a range of protocols in which the results of fitting microstructural models to the diffusion-weighted data had high correlation with the gold standard. We estimated minimum acquisition requirements that enable diffusion tensor imaging, higher angular resolution diffusion-weighted imaging, neurite orientation dispersion, and density imaging and white matter tract integrity across whole brain with isotropic resolution of 1.8 mm in less than 11 min. Magn Reson Med 78:2170-2184, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

System for verifiable CT radiation dose optimization based on image quality. part II. process control system.

PubMed

Larson, David B; Malarik, Remo J; Hall, Seth M; Podberesky, Daniel J

2013-10-01

To evaluate the effect of an automated computed tomography (CT) radiation dose optimization and process control system on the consistency of estimated image noise and size-specific dose estimates (SSDEs) of radiation in CT examinations of the chest, abdomen, and pelvis. This quality improvement project was determined not to constitute human subject research. An automated system was developed to analyze each examination immediately after completion, and to report individual axial-image-level and study-level summary data for patient size, image noise, and SSDE. The system acquired data for 4 months beginning October 1, 2011. Protocol changes were made by using parameters recommended by the prediction application, and 3 months of additional data were acquired. Preimplementation and postimplementation mean image noise and SSDE were compared by using unpaired t tests and F tests. Common-cause variation was differentiated from special-cause variation by using a statistical process control individual chart. A total of 817 CT examinations, 490 acquired before and 327 acquired after the initial protocol changes, were included in the study. Mean patient age and water-equivalent diameter were 12.0 years and 23.0 cm, respectively. The difference between actual and target noise increased from -1.4 to 0.3 HU (P < .01) and the standard deviation decreased from 3.9 to 1.6 HU (P < .01). Mean SSDE decreased from 11.9 to 7.5 mGy, a 37% reduction (P < .01). The process control chart identified several special causes of variation. Implementation of an automated CT radiation dose optimization system led to verifiable simultaneous decrease in image noise variation and SSDE. The automated nature of the system provides the opportunity for consistent CT radiation dose optimization on a broad scale. © RSNA, 2013.

Surface radiation dose comparison of a dedicated extremity cone beam computed tomography (CBCT) device and a multidetector computed tomography (MDCT) machine in pediatric ankle and wrist phantoms

PubMed Central

Nagy, Eszter; Apfaltrer, Georg; Riccabona, Michael; Singer, Georg; Stücklschweiger, Georg; Guss, Helmuth; Sorantin, Erich

2017-01-01

Objectives To evaluate and compare surface doses of a cone beam computed tomography (CBCT) and a multidetector computed tomography (MDCT) device in pediatric ankle and wrist phantoms. Methods Thermoluminescent dosimeters (TLD) were used to measure and compare surface doses between CBCT and MDCT in a left ankle and a right wrist pediatric phantom. In both modalities adapted pediatric dose protocols were utilized to achieve realistic imaging conditions. All measurements were repeated three times to prove test-retest reliability. Additionally, objective and subjective image quality parameters were assessed. Results Average surface doses were 3.8 ±2.1 mGy for the ankle, and 2.2 ±1.3 mGy for the wrist in CBCT. The corresponding surface doses in optimized MDCT were 4.5 ±1.3 mGy for the ankle, and 3.4 ±0.7 mGy for the wrist. Overall, mean surface dose was significantly lower in CBCT (3.0 ±1.9 mGy vs. 3.9 ±1.2 mGy, p<0.001). Subjectively rated general image quality was not significantly different between the study protocols (p = 0.421), whereas objectively measured image quality parameters were in favor of CBCT (p<0.001). Conclusions Adapted extremity CBCT imaging protocols have the potential to fall below optimized pediatric ankle and wrist MDCT doses at comparable image qualities. These possible dose savings warrant further development and research in pediatric extremity CBCT applications. PMID:28570626

An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo

PubMed Central

Grussu, Francesco; Ianus, Andrada; Schneider, Torben; Prados, Ferran; Fairney, James; Ourselin, Sebastien; Alexander, Daniel C.; Cercignani, Mara; Gandini Wheeler‐Kingshott, Claudia A.M.; Samson, Rebecca S.

2017-01-01

Purpose To develop a framework to fully characterize quantitative magnetization transfer indices in the human cervical cord in vivo within a clinically feasible time. Methods A dedicated spinal cord imaging protocol for quantitative magnetization transfer was developed using a reduced field‐of‐view approach with echo planar imaging (EPI) readout. Sequence parameters were optimized based in the Cramer‐Rao‐lower bound. Quantitative model parameters (i.e., bound pool fraction, free and bound pool transverse relaxation times [ T2F, T2B], and forward exchange rate [k FB]) were estimated implementing a numerical model capable of dealing with the novelties of the sequence adopted. The framework was tested on five healthy subjects. Results Cramer‐Rao‐lower bound minimization produces optimal sampling schemes without requiring the establishment of a steady‐state MT effect. The proposed framework allows quantitative voxel‐wise estimation of model parameters at the resolution typically used for spinal cord imaging (i.e. 0.75 × 0.75 × 5 mm3), with a protocol duration of ∼35 min. Quantitative magnetization transfer parametric maps agree with literature values. Whole‐cord mean values are: bound pool fraction = 0.11(±0.01), T2F = 46.5(±1.6) ms, T2B = 11.0(±0.2) µs, and k FB = 1.95(±0.06) Hz. Protocol optimization has a beneficial effect on reproducibility, especially for T2B and k FB. Conclusion The framework developed enables robust characterization of spinal cord microstructure in vivo using qMT. Magn Reson Med 79:2576–2588, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:28921614

Towards an improved LAI collection protocol via simulated field-based PAR sensing

DOE PAGES

Yao, Wei; Van Leeuwen, Martin; Romanczyk, Paul; ...

2016-07-14

In support of NASA’s next-generation spectrometer—the Hyperspectral Infrared Imager (HyspIRI)—we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopymore » gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. Furthermore, these collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the “classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data (R 2 was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI < 3–5 ( m 2/m 2)).« less

Optimal and secure measurement protocols for quantum sensor networks

NASA Astrophysics Data System (ADS)

Eldredge, Zachary; Foss-Feig, Michael; Gross, Jonathan A.; Rolston, S. L.; Gorshkov, Alexey V.

2018-04-01

Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared with unentangled states. In this paper, we quantify the metrological advantage of entanglement in a setting where the measured quantity is a linear function of parameters individually coupled to each qubit. We first generalize the Heisenberg limit to the measurement of nonlocal observables in a quantum network, deriving a bound based on the multiparameter quantum Fisher information. We then propose measurement protocols that can make use of Greenberger-Horne-Zeilinger (GHZ) states or spin-squeezed states and show that in the case of GHZ states the protocol is optimal, i.e., it saturates our bound. We also identify nanoscale magnetic resonance imaging as a promising setting for this technology.

Contrast medium administration and image acquisition parameters in renal CT angiography: what radiologists need to know

PubMed Central

Saade, Charbel; Deeb, Ibrahim Alsheikh; Mohamad, Maha; Al-Mohiy, Hussain; El-Merhi, Fadi

2016-01-01

Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged. Poor synchronization between scanner and contrast media administration have reduced the consistency in image quality with poor spatial and contrast resolution. Comprehensive understanding of contrast media dynamics is essential in the design and implementation of contrast administration and image acquisition protocols. This review includes an overview of the parameters affecting renal artery opacification and current protocol strategies to achieve optimal image quality during renal CT angiography with iodinated contrast media, with current safety issues highlighted. PMID:26728701

A Methodology for Anatomic Ultrasound Image Diagnostic Quality Assessment.

PubMed

Hemmsen, Martin Christian; Lange, Theis; Brandt, Andreas Hjelm; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

2017-01-01

This paper discusses the methods for the assessment of ultrasound image quality based on our experiences with evaluating new methods for anatomic imaging. It presents a methodology to ensure a fair assessment between competing imaging methods using clinically relevant evaluations. The methodology is valuable in the continuing process of method optimization and guided development of new imaging methods. It includes a three phased study plan covering from initial prototype development to clinical assessment. Recommendations to the clinical assessment protocol, software, and statistical analysis are presented. Earlier uses of the methodology has shown that it ensures validity of the assessment, as it separates the influences between developer, investigator, and assessor once a research protocol has been established. This separation reduces confounding influences on the result from the developer to properly reveal the clinical value. This paper exemplifies the methodology using recent studies of synthetic aperture sequential beamforming tissue harmonic imaging.

Matrix Sublimation/Recrystallization for Imaging Proteins by Mass Spectrometry at High Spatial Resolution

PubMed Central

Yang, Junhai; Caprioli, Richard M.

2011-01-01

We have employed matrix deposition by sublimation for protein image analysis on tissue sections using a hydration/recrystallization process that produces high quality MALDI mass spectra and high spatial resolution ion images. We systematically investigated different washing protocols, the effect of tissue section thickness, the amount of sublimated matrix per unit area and different recrystallization conditions. The results show that an organic solvent rinse followed by ethanol/water rinses substantially increased sensitivity for the detection of proteins. Both the thickness of tissue section and amount of sinapinic acid sublimated per unit area have optimal ranges for maximal protein signal intensity. Ion images of mouse and rat brain sections at 50, 20 and 10 µm spatial resolution are presented and are correlated with H&E stained optical images. For targeted analysis, histology directed imaging can be performed using this protocol where MS analysis and H&E staining are performed on the same section. PMID:21639088

Live-Cell Imaging of Mitochondria and the Actin Cytoskeleton in Budding Yeast.

PubMed

Higuchi-Sanabria, Ryo; Swayne, Theresa C; Boldogh, Istvan R; Pon, Liza A

2016-01-01

Maintenance and regulation of proper mitochondrial dynamics and functions are necessary for cellular homeostasis. Numerous diseases, including neurodegeneration and muscle myopathies, and overall cellular aging are marked by declining mitochondrial function and subsequent loss of multiple other cellular functions. For these reasons, optimized protocols are needed for visualization and quantification of mitochondria and their function and fitness. In budding yeast, mitochondria are intimately associated with the actin cytoskeleton and utilize actin for their movement and inheritance. This chapter describes optimal approaches for labeling mitochondria and the actin cytoskeleton in living budding yeast cells, for imaging the labeled cells, and for analyzing the resulting images.

Whole brain inhomogeneous magnetization transfer (ihMT) imaging: Sensitivity enhancement within a steady-state gradient echo sequence.

PubMed

Mchinda, Samira; Varma, Gopal; Prevost, Valentin H; Le Troter, Arnaud; Rapacchi, Stanislas; Guye, Maxime; Pelletier, Jean; Ranjeva, Jean-Philippe; Alsop, David C; Duhamel, Guillaume; Girard, Olivier M

2018-05-01

To implement, characterize, and optimize an interleaved inhomogeneous magnetization transfer (ihMT) gradient echo sequence allowing for whole-brain imaging within a clinically compatible scan time. A general framework for ihMT modelling was developed based on the Provotorov theory of radiofrequency saturation, which accounts for the dipolar order underpinning the ihMT effect. Experimental studies and numerical simulations were performed to characterize and optimize the ihMT-gradient echo dependency with sequence timings, saturation power, and offset frequency. The protocol was optimized in terms of maximum signal intensity and the reproducibility assessed for a nominal resolution of 1.5 mm isotropic. All experiments were performed on healthy volunteers at 1.5T. An important mechanism driving signal optimization and leading to strong ihMT signal enhancement that relies on the dynamics of radiofrequency energy deposition has been identified. By taking advantage of the delay allowed for readout between ihMT pulse bursts, it was possible to boost the ihMT signal by almost 2-fold compared to previous implementation. Reproducibility of the optimal protocol was very good, with an intra-individual error < 2%. The proposed sensitivity-boosted and time-efficient steady-state ihMT-gradient echo sequence, implemented and optimized at 1.5T, allowed robust high-resolution 3D ihMT imaging of the whole brain within a clinically compatible scan time. Magn Reson Med 79:2607-2619, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Consensus Recommendations of the Multiple Sclerosis Study Group and Portuguese Neuroradiological Society for the Use of the Magnetic Resonance Imaging in Multiple Sclerosis in Clinical Practice: Part 1.

PubMed

Abreu, Pedro; Pedrosa, Rui; Sá, Maria José; Cerqueira, João; Sousa, Lívia; Da Silva, Ana Martins; Pinheiro, Joaquim; De Sá, João; Batista, Sónia; Simões, Rita Moiron; Pereira, Daniela Jardim; Vilela, Pedro; Vale, José

2018-05-30

Magnetic resonance imaging is established as a recognizable tool in the diagnosis and monitoring of multiple sclerosis patients. In the present, among multiple sclerosis centers, there are different magnetic resonance imaging sequences and protocols used to study multiple sclerosis that may hamper the optimal use of magnetic resonance imaging in multiple sclerosis. In this context, the Group of Studies of Multiple Sclerosis and the Portuguese Society of Neuroradiology, after a joint discussion, appointed a committee of experts to create recommendations adapted to the national reality on the use of magnetic resonance imaging in multiple sclerosis. The purpose of this document is to publish the first Portuguese consensus recommendations on the use of magnetic resonance imaging in multiple sclerosis in clinical practice. The Group of Studies of Multiple Sclerosis and the Portuguese Society of Neuroradiology, after discussion of the topic in national meetings and after a working group meeting held in Figueira da Foz on May 2017, have appointed a committee of experts that have developed by consensus several standard protocols on the use of magnetic resonance imaging in the diagnosis and follow-up of multiple sclerosis. The document obtained was based on the best scientific evidence and expert opinion. Subsequently, the majority of Portuguese multiple sclerosis consultants and departments of neuroradiology scrutinized and reviewed the consensus paper; comments and suggestions were considered. Technical magnetic resonance imaging protocols regarding diagnostic, monitoring and the recommended information to be included in the magnetic resonance imaging report will be published in a separate paper. We provide some practical guidelines to promote standardized strategies to be applied in the clinical practice setting of Portuguese healthcare professionals regarding the use of magnetic resonance imaging in multiple sclerosis. We hope that these first Portuguese magnetic resonance imaging guidelines, based in the best available clinical evidence and practices, will serve to optimize multiple sclerosis management and improve multiple sclerosis patient care across Portugal.

Multiple enface image averaging for enhanced optical coherence tomography angiography imaging.

PubMed

Uji, Akihito; Balasubramanian, Siva; Lei, Jianqin; Baghdasaryan, Elmira; Al-Sheikh, Mayss; Borrelli, Enrico; Sadda, SriniVas R

2018-05-31

To investigate the effect of multiple enface image averaging on image quality of the optical coherence tomography angiography (OCTA). Twenty-one normal volunteers were enrolled in this study. For each subject, one eye was imaged with 3 × 3 mm scan protocol, and another eye was imaged with the 6 × 6 mm scan protocol centred on the fovea using the ZEISS Angioplex™ spectral-domain OCTA device. Eyes were repeatedly imaged to obtain nine OCTA cube scan sets, and nine superficial capillary plexus (SCP) and deep capillary plexus (DCP) were individually averaged after registration. Eighteen eyes with a 3 × 3 mm scan field and 14 eyes with a 6 × 6 mm scan field were studied. Averaged images showed more continuous vessels and less background noise in both the SCP and the DCP as the number of frames used for averaging increased, with both 3 × 3 and 6 × 6 mm scan protocols. The intensity histogram of the vessels dramatically changed after averaging. Contrast-to-noise ratio (CNR) and subjectively assessed image quality scores also increased as the number of frames used for averaging increased in all image types. However, the additional benefit in quality diminished when averaging more than five frames. Averaging only three frames achieved significant improvement in CNR and the score assigned by certified grades. Use of multiple image averaging in OCTA enface images was found to be both objectively and subjectively effective for enhancing image quality. These findings may of value for developing optimal OCTA imaging protocols for future studies. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Optimizing 4-Dimensional Magnetic Resonance Imaging Data Sampling for Respiratory Motion Analysis of Pancreatic Tumors

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

Stemkens, Bjorn, E-mail: b.stemkens@umcutrecht.nl; Tijssen, Rob H.N.; Senneville, Baudouin D. de

2015-03-01

Purpose: To determine the optimum sampling strategy for retrospective reconstruction of 4-dimensional (4D) MR data for nonrigid motion characterization of tumor and organs at risk for radiation therapy purposes. Methods and Materials: For optimization, we compared 2 surrogate signals (external respiratory bellows and internal MRI navigators) and 2 MR sampling strategies (Cartesian and radial) in terms of image quality and robustness. Using the optimized protocol, 6 pancreatic cancer patients were scanned to calculate the 4D motion. Region of interest analysis was performed to characterize the respiratory-induced motion of the tumor and organs at risk simultaneously. Results: The MRI navigator was foundmore » to be a more reliable surrogate for pancreatic motion than the respiratory bellows signal. Radial sampling is most benign for undersampling artifacts and intraview motion. Motion characterization revealed interorgan and interpatient variation, as well as heterogeneity within the tumor. Conclusions: A robust 4D-MRI method, based on clinically available protocols, is presented and successfully applied to characterize the abdominal motion in a small number of pancreatic cancer patients.« less

Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images.

PubMed

Umeda, Takuro; Miwa, Kenta; Murata, Taisuke; Miyaji, Noriaki; Wagatsuma, Kei; Motegi, Kazuki; Terauchi, Takashi; Koizumi, Mitsuru

2017-12-01

The present study aimed to qualitatively and quantitatively evaluate PET images as a function of acquisition time for various leg sizes, and to optimize a shorter variable-acquisition time protocol for legs to achieve better qualitative and quantitative accuracy of true whole-body PET/CT images. The diameters of legs to be modeled as phantoms were defined based on data derived from 53 patients. This study analyzed PET images of a NEMA phantom and three plastic bottle phantoms (diameter, 5.68, 8.54 and 10.7 cm) that simulated the human body and legs, respectively. The phantoms comprised two spheres (diameters, 10 and 17 mm) containing fluorine-18 fluorodeoxyglucose solution with sphere-to-background ratios of 4 at a background radioactivity level of 2.65 kBq/mL. All PET data were reconstructed with acquisition times ranging from 10 to 180, and 1200 s. We visually evaluated image quality and determined the coefficient of variance (CV) of the background, contrast and the quantitative %error of the hot spheres, and then determined two shorter variable-acquisition protocols for legs. Lesion detectability and quantitative accuracy determined based on maximum standardized uptake values (SUV max ) in PET images of a patient using the proposed protocols were also evaluated. A larger phantom and a shorter acquisition time resulted in increased background noise on images and decreased the contrast in hot spheres. A visual score of ≥ 1.5 was obtained when the acquisition time was ≥ 30 s for three leg phantoms, and ≥ 120 s for the NEMA phantom. The quantitative %errors of the 10- and 17-mm spheres in the leg phantoms were ± 15 and ± 10%, respectively, in PET images with a high CV (scan < 30 s). The mean SUV max of three lesions using the current fixed-acquisition and two proposed variable-acquisition time protocols in the clinical study were 3.1, 3.1 and 3.2, respectively, which did not significantly differ. Leg acquisition time per bed position of even 30-90 s allows axial equalization, uniform image noise and a maximum ± 15% quantitative accuracy for the smallest lesion. The overall acquisition time was reduced by 23-42% using the proposed shorter variable than the current fixed-acquisition time for imaging legs, indicating that this is a useful and practical protocol for routine qualitative and quantitative PET/CT assessment in the clinical setting.

Cancer imaging using Surface-Enhanced Resonance Raman Scattering (SERRS) nanoparticles

PubMed Central

Harmsen, Stefan; Wall, Matthew A.; Huang, Ruimin

2017-01-01

The unique spectral signatures and biologically inert compositions of surface-enhanced (resonance) Raman scattering (SE(R)RS) nanoparticles make them promising contrast agents for in vivo cancer imaging. Subtle aspects of their preparation can shift their limit of detection by orders of magnitude. In this protocol, we present the optimized, step-by-step procedure for generating reproducible SERRS nanoparticles with femtomolar (10−15 M) limits of detection. We introduce several applications of these nanoprobes for biomedical research, with a focus on intraoperative cancer imaging via Raman imaging. A detailed account is provided for successful intravenous administration of SERRS nanoparticles such that delineation of cancerous lesions may be achieved without the need for specific biomarker targeting. The time estimate for this straightforward, yet comprehensive protocol from initial de novo gold nanoparticle synthesis to SE(R)RS nanoparticle contrast-enhanced preclinical Raman imaging in animal models is ~96 h. PMID:28686581

A Natural Language Processing-based Model to Automate MRI Brain Protocol Selection and Prioritization.

PubMed

Brown, Andrew D; Marotta, Thomas R

2017-02-01

Incorrect imaging protocol selection can contribute to increased healthcare cost and waste. To help healthcare providers improve the quality and safety of medical imaging services, we developed and evaluated three natural language processing (NLP) models to determine whether NLP techniques could be employed to aid in clinical decision support for protocoling and prioritization of magnetic resonance imaging (MRI) brain examinations. To test the feasibility of using an NLP model to support clinical decision making for MRI brain examinations, we designed three different medical imaging prediction tasks, each with a unique outcome: selecting an examination protocol, evaluating the need for contrast administration, and determining priority. We created three models for each prediction task, each using a different classification algorithm-random forest, support vector machine, or k-nearest neighbor-to predict outcomes based on the narrative clinical indications and demographic data associated with 13,982 MRI brain examinations performed from January 1, 2013 to June 30, 2015. Test datasets were used to calculate the accuracy, sensitivity and specificity, predictive values, and the area under the curve. Our optimal results show an accuracy of 82.9%, 83.0%, and 88.2% for the protocol selection, contrast administration, and prioritization tasks, respectively, demonstrating that predictive algorithms can be used to aid in clinical decision support for examination protocoling. NLP models developed from the narrative clinical information provided by referring clinicians and demographic data are feasible methods to predict the protocol and priority of MRI brain examinations. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Dependency of image quality on acquisition protocol and image processing in chest tomosynthesis-a visual grading study based on clinical data.

PubMed

Jadidi, Masoud; Båth, Magnus; Nyrén, Sven

2018-04-09

To compare the quality of images obtained with two different protocols with different acquisition time and the influence from image post processing in a chest digital tomosynthesis (DTS) system. 20 patients with suspected lung cancer were imaged with a chest X-ray equipment with tomosynthesis option. Two examination protocols with different acquisition times (6.3 and 12 s) were performed on each patient. Both protocols were presented with two different image post-processing (standard DTS processing and more advanced processing optimised for chest radiography). Thus, 4 series from each patient, altogether 80 series, were presented anonymously and in a random order. Five observers rated the quality of the reconstructed section images according to predefined quality criteria in three different classes. Visual grading characteristics (VGC) was used to analyse the data and the area under the VGC curve (AUC VGC ) was used as figure-of-merit. The 12 s protocol and the standard DTS processing were used as references in the analyses. The protocol with 6.3 s acquisition time had a statistically significant advantage over the vendor-recommended protocol with 12 s acquisition time for the classes of criteria, Demarcation (AUC VGC = 0.56, p = 0.009) and Disturbance (AUC VGC = 0.58, p < 0.001). A similar value of AUC VGC was found also for the class Structure (definition of bone structures in the spine) (0.56) but it could not be statistically separated from 0.5 (p = 0.21). For the image processing, the VGC analysis showed a small but statistically significant advantage for the standard DTS processing over the more advanced processing for the classes of criteria Demarcation (AUC VGC = 0.45, p = 0.017) and Disturbance (AUC VGC = 0.43, p = 0.005). A similar value of AUC VGC was found also for the class Structure (0.46), but it could not be statistically separated from 0.5 (p = 0.31). The study indicates that the protocol with 6.3 s acquisition time yields slightly better image quality than the vender-recommended protocol with acquisition time 12 s for several anatomical structures. Furthermore, the standard gradation processing  (the vendor-recommended post-processing for DTS), yields to some extent advantage over the gradation processing/multiobjective frequency processing/flexible noise control processing in terms of image quality for all classes of criteria. Advances in knowledge: The study proves that the image quality may be strongly affected by the selection of DTS protocol and that the vendor-recommended protocol may not always be the optimal choice.

Application of EARL (ResEARch 4 Life®) protocols for [18F]FDG-PET/CT clinical and research studies. A roadmap towards exact recovery coefficient

NASA Astrophysics Data System (ADS)

Balcerzyk, Marcin; Fernández-López, Rosa; Parrado-Gallego, Ángel; Pachón-Garrudo, Víctor Manuel; Chavero-Royan, José; Hevilla, Juan; Jiménez-Ortega, Elisa; Leal, Antonio

2017-11-01

Tumour uptake value is a critical result in [18F]FDG-PET/CT ([18F]fluorodeoxyglucose) quantitative scans such as the dose prescription for radiotherapy and oncology. The quantification is highly dependent on the protocol of acquisition and reconstruction of the image, especially in low activity tumours. During adjusting acquisition and reconstruction protocols available in our Siemens Biograph mCT scanner for EARL (ResEARch 4 Life®) [18F]FDG-PET/CT accreditation requirements, we developed reconstruction protocols which will be used in PET based radiotherapy planning able to reduce inter-/intra-institute variability in Standard Uptake Value (SUV) results, and to bring Recovery Coefficient to 1 as close as possible for Image Quality NEMA 2007 phantom. Primary and secondary tumours from two patients were assessed by four independent evaluators. The influence of reconstruction protocols on tumour clinical assessment was presented. We proposed the improvement route for EARL accredited protocols so that they may be developed in classes to take advantage of scanner possibilities. The application of optimized reconstruction protocol eliminates the need of partial volume corrections.

Electronic Photography at the NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Holm, Jack; Judge, Nancianne

1995-01-01

An electronic photography facility has been established in the Imaging & Photographic Technology Section, Visual Imaging Branch, at the NASA Langley Research Center (LaRC). The purpose of this facility is to provide the LaRC community with access to digital imaging technology. In particular, capabilities have been established for image scanning, direct image capture, optimized image processing for storage, image enhancement, and optimized device dependent image processing for output. Unique approaches include: evaluation and extraction of the entire film information content through scanning; standardization of image file tone reproduction characteristics for optimal bit utilization and viewing; education of digital imaging personnel on the effects of sampling and quantization to minimize image processing related information loss; investigation of the use of small kernel optimal filters for image restoration; characterization of a large array of output devices and development of image processing protocols for standardized output. Currently, the laboratory has a large collection of digital image files which contain essentially all the information present on the original films. These files are stored at 8-bits per color, but the initial image processing was done at higher bit depths and/or resolutions so that the full 8-bits are used in the stored files. The tone reproduction of these files has also been optimized so the available levels are distributed according to visual perceptibility. Look up tables are available which modify these files for standardized output on various devices, although color reproduction has been allowed to float to some extent to allow for full utilization of output device gamut.

Optimization of 64-MDCT urography: effect of dual-phase imaging with furosemide on collecting system opacification and radiation dose.

PubMed

Portnoy, Orith; Guranda, Larisa; Apter, Sara; Eiss, David; Amitai, Marianne Michal; Konen, Eli

2011-11-01

The purpose of this study was to compare opacification of the urinary collecting system and radiation dose associated with three-phase 64-MDCT urographic protocols and those associated with a split-bolus dual-phase protocol including furosemide. Images from 150 CT urographic examinations performed with three scanning protocols were retrospectively evaluated. Group A consisted of 50 sequentially registered patients who underwent a three-phase protocol with saline infusion. Group B consisted of 50 sequentially registered patients who underwent a reduced-radiation three-phase protocol with saline. Group C consisted of 50 sequentially registered patients who underwent a dual-phase split-bolus protocol that included a low-dose furosemide injection. Opacification of the urinary collecting system was evaluated with segmental binary scoring. Contrast artifacts were evaluated, and radiation doses were recorded. Results were compared by analysis of variance. A significant reduction in mean effective radiation dose was found between groups A and B (p < 0.001) and between groups B and C (p < 0.001), resulting in 65% reduction between groups A and C (p < 0.001). This reduction did not significantly affect opacification score in any of the 12 urinary segments (p = 0.079). In addition, dense contrast artifacts overlying the renal parenchyma observed with the three-phase protocols (groups A and B) were avoided with the dual-phase protocol (group C) (p < 0.001). A dual-phase protocol with furosemide injection is the preferable technique for CT urography. In comparison with commonly used three-phase protocols, the dual-phase protocol significantly reduces radiation exposure dose without reduction in image quality.

Emerging Techniques for Dose Optimization in Abdominal CT

PubMed Central

Platt, Joel F.; Goodsitt, Mitchell M.; Al-Hawary, Mahmoud M.; Maturen, Katherine E.; Wasnik, Ashish P.; Pandya, Amit

2014-01-01

Recent advances in computed tomographic (CT) scanning technique such as automated tube current modulation (ATCM), optimized x-ray tube voltage, and better use of iterative image reconstruction have allowed maintenance of good CT image quality with reduced radiation dose. ATCM varies the tube current during scanning to account for differences in patient attenuation, ensuring a more homogeneous image quality, although selection of the appropriate image quality parameter is essential for achieving optimal dose reduction. Reducing the x-ray tube voltage is best suited for evaluating iodinated structures, since the effective energy of the x-ray beam will be closer to the k-edge of iodine, resulting in a higher attenuation for the iodine. The optimal kilovoltage for a CT study should be chosen on the basis of imaging task and patient habitus. The aim of iterative image reconstruction is to identify factors that contribute to noise on CT images with use of statistical models of noise (statistical iterative reconstruction) and selective removal of noise to improve image quality. The degree of noise suppression achieved with statistical iterative reconstruction can be customized to minimize the effect of altered image quality on CT images. Unlike with statistical iterative reconstruction, model-based iterative reconstruction algorithms model both the statistical noise and the physical acquisition process, allowing CT to be performed with further reduction in radiation dose without an increase in image noise or loss of spatial resolution. Understanding these recently developed scanning techniques is essential for optimization of imaging protocols designed to achieve the desired image quality with a reduced dose. © RSNA, 2014 PMID:24428277

Data-driven optimal binning for respiratory motion management in PET.

PubMed

Kesner, Adam L; Meier, Joseph G; Burckhardt, Darrell D; Schwartz, Jazmin; Lynch, David A

2018-01-01

Respiratory gating has been used in PET imaging to reduce the amount of image blurring caused by patient motion. Optimal binning is an approach for using the motion-characterized data by binning it into a single, easy to understand/use, optimal bin. To date, optimal binning protocols have utilized externally driven motion characterization strategies that have been tuned with population-derived assumptions and parameters. In this work, we are proposing a new strategy with which to characterize motion directly from a patient's gated scan, and use that signal to create a patient/instance-specific optimal bin image. Two hundred and nineteen phase-gated FDG PET scans, acquired using data-driven gating as described previously, were used as the input for this study. For each scan, a phase-amplitude motion characterization was generated and normalized using principle component analysis. A patient-specific "optimal bin" window was derived using this characterization, via methods that mirror traditional optimal window binning strategies. The resulting optimal bin images were validated by correlating quantitative and qualitative measurements in the population of PET scans. In 53% (n = 115) of the image population, the optimal bin was determined to include 100% of the image statistics. In the remaining images, the optimal binning windows averaged 60% of the statistics and ranged between 20% and 90%. Tuning the algorithm, through a single acceptance window parameter, allowed for adjustments of the algorithm's performance in the population toward conservation of motion or reduced noise-enabling users to incorporate their definition of optimal. In the population of images that were deemed appropriate for segregation, average lesion SUV max were 7.9, 8.5, and 9.0 for nongated images, optimal bin, and gated images, respectively. The Pearson correlation of FWHM measurements between optimal bin images and gated images were better than with nongated images, 0.89 and 0.85, respectively. Generally, optimal bin images had better resolution than the nongated images and better noise characteristics than the gated images. We extended the concept of optimal binning to a data-driven form, updating a traditionally one-size-fits-all approach to a conformal one that supports adaptive imaging. This automated strategy was implemented easily within a large population and encapsulated motion information in an easy to use 3D image. Its simplicity and practicality may make this, or similar approaches ideal for use in clinical settings. © 2017 American Association of Physicists in Medicine.

TH-C-18A-06: Combined CT Image Quality and Radiation Dose Monitoring Program Based On Patient Data to Assess Consistency of Clinical Imaging Across Scanner Models

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

Christianson, O; Winslow, J; Samei, E

2014-06-15

Purpose: One of the principal challenges of clinical imaging is to achieve an ideal balance between image quality and radiation dose across multiple CT models. The number of scanners and protocols at large medical centers necessitates an automated quality assurance program to facilitate this objective. Therefore, the goal of this work was to implement an automated CT image quality and radiation dose monitoring program based on actual patient data and to use this program to assess consistency of protocols across CT scanner models. Methods: Patient CT scans are routed to a HIPPA compliant quality assurance server. CTDI, extracted using opticalmore » character recognition, and patient size, measured from the localizers, are used to calculate SSDE. A previously validated noise measurement algorithm determines the noise in uniform areas of the image across the scanned anatomy to generate a global noise level (GNL). Using this program, 2358 abdominopelvic scans acquired on three commercial CT scanners were analyzed. Median SSDE and GNL were compared across scanner models and trends in SSDE and GNL with patient size were used to determine the impact of differing automatic exposure control (AEC) algorithms. Results: There was a significant difference in both SSDE and GNL across scanner models (9–33% and 15–35% for SSDE and GNL, respectively). Adjusting all protocols to achieve the same image noise would reduce patient dose by 27–45% depending on scanner model. Additionally, differences in AEC methodologies across vendors resulted in disparate relationships of SSDE and GNL with patient size. Conclusion: The difference in noise across scanner models indicates that protocols are not optimally matched to achieve consistent image quality. Our results indicated substantial possibility for dose reduction while achieving more consistent image appearance. Finally, the difference in AEC methodologies suggests the need for size-specific CT protocols to minimize variability in image quality across CT vendors.« less

Comparative study of two protocols for quantitative image-analysis of serotonin transporter clustering in lymphocytes, a putative biomarker of therapeutic efficacy in major depression.

PubMed

Romay-Tallon, Raquel; Rivera-Baltanas, Tania; Allen, Josh; Olivares, Jose M; Kalynchuk, Lisa E; Caruncho, Hector J

2017-01-01

The pattern of serotonin transporter clustering on the plasma membrane of lymphocytes extracted from human whole blood samples has been identified as a putative biomarker of therapeutic efficacy in major depression. Here we evaluated the possibility of performing a similar analysis using blood smears obtained from rats, and from control human subjects and depression patients. We hypothesized that we could optimize a protocol to make the analysis of serotonin protein clustering in blood smears comparable to the analysis of serotonin protein clustering using isolated lymphocytes. Our data indicate that blood smears require a longer fixation time and longer times of incubation with primary and secondary antibodies. In addition, one needs to optimize the image analysis settings for the analysis of smears. When these steps are followed, the quantitative analysis of both the number and size of serotonin transporter clusters on the plasma membrane of lymphocytes is similar using both blood smears and isolated lymphocytes. The development of this novel protocol will greatly facilitate the collection of appropriate samples by eliminating the necessity and cost of specialized personnel for drawing blood samples, and by being a less invasive procedure. Therefore, this protocol will help us advance the validation of membrane protein clustering in lymphocytes as a biomarker of therapeutic efficacy in major depression, and bring it closer to its clinical application.

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

PubMed

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

2013-10-21

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 acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole body. In addition, the total acquisition length can be reduced from 45 to ~35 min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error and the CNR metrics, resulting in enhanced task-based imaging.

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

PubMed Central

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

2013-01-01

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 ~45min 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 (6 passes x 7 bed positions, each scanned for 45sec). Standard Patlak linear graphical analysis modeling was employed, coupled with image-derived plasma input function measurements. Ordinary least squares (OLS) 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 10 different clinically acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole-body. In addition, the total acquisition length can be reduced from 45min to ~35min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error (MSE) and the CNR metrics, resulting in enhanced task-based imaging. PMID:24080962

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 acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole body. In addition, the total acquisition length can be reduced from 45 to ˜35 min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error and the CNR metrics, resulting in enhanced task-based imaging.

MO-G-18A-01: Radiation Dose Reducing Strategies in CT, Fluoroscopy and Radiography

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

Mahesh, M; Gingold, E; Jones, A

2014-06-15

Advances in medical x-ray imaging have provided significant benefits to patient care. According to NCRP 160, there are more than 400 million x-ray procedures performed annually in the United States alone that contributes to nearly half of all the radiation exposure to the US population. Similar growth trends in medical x-ray imaging are observed worldwide. Apparent increase in number of medical x-ray imaging procedures, new protocols and the associated radiation dose and risk has drawn considerable attention. This has led to a number of technological innovations such as tube current modulation, iterative reconstruction algorithms, dose alerts, dose displays, flat panelmore » digital detectors, high efficient digital detectors, storage phosphor radiography, variable filters, etc. that are enabling users to acquire medical x-ray images at a much lower radiation dose. Along with these, there are number of radiation dose optimization strategies that users can adapt to effectively lower radiation dose in medical x-ray procedures. The main objectives of this SAM course are to provide information and how to implement the various radiation dose optimization strategies in CT, Fluoroscopy and Radiography. Learning Objectives: To update impact of technological advances on dose optimization in medical imaging. To identify radiation optimization strategies in computed tomography. To describe strategies for configuring fluoroscopic equipment that yields optimal images at reasonable radiation dose. To assess ways to configure digital radiography systems and recommend ways to improve image quality at optimal dose.« less

Achieving High Throughput for Data Transfer over ATM Networks

NASA Technical Reports Server (NTRS)

Johnson, Marjory J.; Townsend, Jeffrey N.

1996-01-01

File-transfer rates for ftp are often reported to be relatively slow, compared to the raw bandwidth available in emerging gigabit networks. While a major bottleneck is disk I/O, protocol issues impact performance as well. Ftp was developed and optimized for use over the TCP/IP protocol stack of the Internet. However, TCP has been shown to run inefficiently over ATM. In an effort to maximize network throughput, data-transfer protocols can be developed to run over UDP or directly over IP, rather than over TCP. If error-free transmission is required, techniques for achieving reliable transmission can be included as part of the transfer protocol. However, selected image-processing applications can tolerate a low level of errors in images that are transmitted over a network. In this paper we report on experimental work to develop a high-throughput protocol for unreliable data transfer over ATM networks. We attempt to maximize throughput by keeping the communications pipe full, but still keep packet loss under five percent. We use the Bay Area Gigabit Network Testbed as our experimental platform.

Optimization of Rb-82 PET acquisition and reconstruction protocols for myocardial perfusion defect detection

NASA Astrophysics Data System (ADS)

Tang, Jing; Rahmim, Arman; Lautamäki, Riikka; Lodge, Martin A.; Bengel, Frank M.; Tsui, Benjamin M. W.

2009-05-01

The purpose of this study is to optimize the dynamic Rb-82 cardiac PET acquisition and reconstruction protocols for maximum myocardial perfusion defect detection using realistic simulation data and task-based evaluation. Time activity curves (TACs) of different organs under both rest and stress conditions were extracted from dynamic Rb-82 PET images of five normal patients. Combined SimSET-GATE Monte Carlo simulation was used to generate nearly noise-free cardiac PET data from a time series of 3D NCAT phantoms with organ activities modeling different pre-scan delay times (PDTs) and total acquisition times (TATs). Poisson noise was added to the nearly noise-free projections and the OS-EM algorithm was applied to generate noisy reconstructed images. The channelized Hotelling observer (CHO) with 32× 32 spatial templates corresponding to four octave-wide frequency channels was used to evaluate the images. The area under the ROC curve (AUC) was calculated from the CHO rating data as an index for image quality in terms of myocardial perfusion defect detection. The 0.5 cycle cm-1 Butterworth post-filtering on OS-EM (with 21 subsets) reconstructed images generates the highest AUC values while those from iteration numbers 1 to 4 do not show different AUC values. The optimized PDTs for both rest and stress conditions are found to be close to the cross points of the left ventricular chamber and myocardium TACs, which may promote an individualized PDT for patient data processing and image reconstruction. Shortening the TATs for <~3 min from the clinically employed acquisition time does not affect the myocardial perfusion defect detection significantly for both rest and stress studies.

An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo.

PubMed

Battiston, Marco; Grussu, Francesco; Ianus, Andrada; Schneider, Torben; Prados, Ferran; Fairney, James; Ourselin, Sebastien; Alexander, Daniel C; Cercignani, Mara; Gandini Wheeler-Kingshott, Claudia A M; Samson, Rebecca S

2018-05-01

To develop a framework to fully characterize quantitative magnetization transfer indices in the human cervical cord in vivo within a clinically feasible time. A dedicated spinal cord imaging protocol for quantitative magnetization transfer was developed using a reduced field-of-view approach with echo planar imaging (EPI) readout. Sequence parameters were optimized based in the Cramer-Rao-lower bound. Quantitative model parameters (i.e., bound pool fraction, free and bound pool transverse relaxation times [ T2F, T2B], and forward exchange rate [k FB ]) were estimated implementing a numerical model capable of dealing with the novelties of the sequence adopted. The framework was tested on five healthy subjects. Cramer-Rao-lower bound minimization produces optimal sampling schemes without requiring the establishment of a steady-state MT effect. The proposed framework allows quantitative voxel-wise estimation of model parameters at the resolution typically used for spinal cord imaging (i.e. 0.75 × 0.75 × 5 mm 3 ), with a protocol duration of ∼35 min. Quantitative magnetization transfer parametric maps agree with literature values. Whole-cord mean values are: bound pool fraction = 0.11(±0.01), T2F = 46.5(±1.6) ms, T2B = 11.0(±0.2) µs, and k FB  = 1.95(±0.06) Hz. Protocol optimization has a beneficial effect on reproducibility, especially for T2B and k FB . The framework developed enables robust characterization of spinal cord microstructure in vivo using qMT. Magn Reson Med 79:2576-2588, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Measuring Cerebral Hypoperfusion Induced by Hyperventilation Challenge With Intravoxel Incoherent Motion Magnetic Resonance Imaging in Healthy Volunteers.

PubMed

Pavilla, Aude; Arrigo, Alessandro; Mejdoubi, Mehdi; Duvauferrier, Régis; Gambarota, Giulio; Saint-Jalmes, Hervé

The aim of this study was to demonstrate the feasibility to assess cerebral hypoperfusion with a hyperventilation (HV) challenge protocol using intravoxel incoherent motion (IVIM) magnetic resonance imaging. Magnetic resonance imaging experiments were performed on 10 healthy volunteers at 1.5 T, with a diffusion IVIM magnetic resonance imaging protocol using a set of b-values optimized by Cramer-Rao Lower Bound analysis. Hypoperfusion was induced by an HV maneuver. Measurements were performed in normoventilation and HV conditions. Biexponential curve fitting was used to obtain the perfusion fraction (f), pseudodiffusion coefficient (D*), and the product fD* in gray matter (GM) regions of interest (ROIs). Regional cerebral blood flow in the same ROIs was also assessed with arterial spin labeling. The HV challenge led to a diminution of IVIM perfusion-related parameters, with a decrease of f and fD* in the cerebellum (P = 0.03 for f; P = 0.01 for fD*), thalamus GM (P = 0.09 for f; P = 0.01 for fD*), and lenticular nuclei (P = 0.03 for f; P = 0.02 for fD*). Mean GM cerebral blood flow (in mL/100 g tissue/min) measured with arterial spin labeling averaged over all ROIs also decreased (normoventilation: 42.7 ± 4.1 vs HV: 33.2 ± 2.2, P = 0.004) during the HV challenge. The optimized IVIM protocol proposed in the current study allows for measurements of cerebral hypoperfusion that might be of great interest for pathologies diagnosis such as ischemic stroke.

Dual-layer DECT for multiphasic hepatic CT with 50 percent iodine load: a matched-pair comparison with a 120 kVp protocol.

PubMed

Nagayama, Yasunori; Nakaura, Takeshi; Oda, Seitaro; Utsunomiya, Daisuke; Funama, Yoshinori; Iyama, Yuji; Taguchi, Narumi; Namimoto, Tomohiro; Yuki, Hideaki; Kidoh, Masafumi; Hirata, Kenichiro; Nakagawa, Masataka; Yamashita, Yasuyuki

2018-04-01

To evaluate the image quality and lesion conspicuity of virtual-monochromatic-imaging (VMI) with dual-layer DECT (DL-DECT) for reduced-iodine-load multiphasic-hepatic CT. Forty-five adults with renal dysfunction who had undergone hepatic DL-DECT with 300-mgI/kg were included. VMI (40-70-keV, DL-DECT-VMI) was generated at each enhancement phase. As controls, 45 matched patients undergoing standard 120-kVp protocol (120-kVp, 600-mgI/kg, and iterative reconstruction) were included. We compared the size-specific dose estimate (SSDE), image noise, CT attenuation, and contrast-to-noise ratio (CNR) between protocols. Two radiologists scored the image quality and lesion conspicuity. SSDE was significantly lower in DL-DECT group (p < 0.01). Image noise of DL-DECT-VMI was almost constant at each keV (differences of ≤15%) and equivalent to or lower than of 120-kVp. As the energy decreased, CT attenuation and CNR gradually increased; the values of 55-60 keV images were almost equivalent to those of standard 120-kVp. The highest scores for overall quality and lesion conspicuity were assigned at 40-keV followed by 45 to 55-keV, all of which were similar to or better than of 120-kVp. For multiphasic-hepatic CT with 50% iodine-load, DL-DECT-VMI at 40- to 55-keV provides equivalent or better image quality and lesion conspicuity without increasing radiation dose compared with standard 120-kVp protocol. • 40-55-keV yields optimal image quality for half-iodine-load multiphasic-hepatic CT with DL-DECT. • DL-DECT protocol decreases radiation exposure compared with 120-kVp scans with iterative reconstruction. • 40-keV images maximise conspicuity of hepatocellular carcinoma especially at hepatic-arterial phase.

Validity of linear measurements of the jaws using ultralow-dose MDCT and the iterative techniques of ASIR and MBIR.

PubMed

Al-Ekrish, Asma'a A; Al-Shawaf, Reema; Schullian, Peter; Al-Sadhan, Ra'ed; Hörmann, Romed; Widmann, Gerlig

2016-10-01

To assess the comparability of linear measurements of dental implant sites recorded from multidetector computed tomography (MDCT) images obtained using standard-dose filtered backprojection (FBP) technique with those from various ultralow doses combined with FBP, adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) techniques. The results of the study may contribute to MDCT dose optimization for dental implant site imaging. MDCT scans of two cadavers were acquired using a standard reference protocol and four ultralow-dose test protocols (TP). The volume CT dose index of the different dose protocols ranged from a maximum of 30.48-36.71 mGy to a minimum of 0.44-0.53 mGy. All scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Linear measurements were recorded from standardized images of the jaws by two examiners. Intra- and inter-examiner reliability of the measurements were analyzed using Cronbach's alpha and inter-item correlation. Agreement between the measurements obtained with the reference-dose/FBP protocol and each of the test protocols was determined with Bland-Altman plots and linear regression. Statistical significance was set at a P-value of 0.05. No systematic variation was found between the linear measurements obtained with the reference protocol and the other imaging protocols. The only exceptions were TP3/ASIR-50 (bone kernel) and TP4/ASIR-100 (bone and standard kernels). The mean measurement differences between these three protocols and the reference protocol were within ±0.1 mm, with the 95 % confidence interval limits being within the range of ±1.15 mm. A nearly 97.5 % reduction in dose did not significantly affect the height and width measurements of edentulous jaws regardless of the reconstruction algorithm used.

TH-E-209-02: Dose Monitoring and Protocol Optimization: The Pediatric Perspective

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

MacDougall, R.

Radiation dose monitoring solutions have opened up new opportunities for medical physicists to be more involved in modern clinical radiology practices. In particular, with the help of comprehensive radiation dose data, data-driven protocol management and informed case follow up are now feasible. Significant challenges remain however and the problems faced by medical physicists are highly heterogeneous. Imaging systems from multiple vendors and a wide range of vintages co-exist in the same department and employ data communication protocols that are not fully standardized or implemented making harmonization complex. Many different solutions for radiation dose monitoring have been implemented by imaging facilitiesmore » over the past few years. Such systems are based on commercial software, home-grown IT solutions, manual PACS data dumping, etc., and diverse pathways can be used to bring the data to impact clinical practice. The speakers will share their experiences with creating or tailoring radiation dose monitoring/management systems and procedures over the past few years, which vary significantly in design and scope. Topics to cover: (1) fluoroscopic dose monitoring and high radiation event handling from a large academic hospital; (2) dose monitoring and protocol optimization in pediatric radiology; and (3) development of a home-grown IT solution and dose data analysis framework. Learning Objectives: Describe the scope and range of radiation dose monitoring and protocol management in a modern radiology practice Review examples of data available from a variety of systems and how it managed and conveyed. Reflect on the role of the physicist in radiation dose awareness.« less

Analytical approach to cross-layer protocol optimization in wireless sensor networks

NASA Astrophysics Data System (ADS)

Hortos, William S.

2008-04-01

In the distributed operations of route discovery and maintenance, strong interaction occurs across mobile ad hoc network (MANET) protocol layers. Quality of service (QoS) requirements of multimedia service classes must be satisfied by the cross-layer protocol, along with minimization of the distributed power consumption at nodes and along routes to battery-limited energy constraints. In previous work by the author, cross-layer interactions in the MANET protocol are modeled in terms of a set of concatenated design parameters and associated resource levels by multivariate point processes (MVPPs). Determination of the "best" cross-layer design is carried out using the optimal control of martingale representations of the MVPPs. In contrast to the competitive interaction among nodes in a MANET for multimedia services using limited resources, the interaction among the nodes of a wireless sensor network (WSN) is distributed and collaborative, based on the processing of data from a variety of sensors at nodes to satisfy common mission objectives. Sensor data originates at the nodes at the periphery of the WSN, is successively transported to other nodes for aggregation based on information-theoretic measures of correlation and ultimately sent as information to one or more destination (decision) nodes. The "multimedia services" in the MANET model are replaced by multiple types of sensors, e.g., audio, seismic, imaging, thermal, etc., at the nodes; the QoS metrics associated with MANETs become those associated with the quality of fused information flow, i.e., throughput, delay, packet error rate, data correlation, etc. Significantly, the essential analytical approach to MANET cross-layer optimization, now based on the MVPPs for discrete random events occurring in the WSN, can be applied to develop the stochastic characteristics and optimality conditions for cross-layer designs of sensor network protocols. Functional dependencies of WSN performance metrics are described in terms of the concatenated protocol parameters. New source-to-destination routes are sought that optimize cross-layer interdependencies to achieve the "best available" performance in the WSN. The protocol design, modified from a known reactive protocol, adapts the achievable performance to the transient network conditions and resource levels. Control of network behavior is realized through the conditional rates of the MVPPs. Optimal cross-layer protocol parameters are determined by stochastic dynamic programming conditions derived from models of transient packetized sensor data flows. Moreover, the defining conditions for WSN configurations, grouping sensor nodes into clusters and establishing data aggregation at processing nodes within those clusters, lead to computationally tractable solutions to the stochastic differential equations that describe network dynamics. Closed-form solution characteristics provide an alternative to the "directed diffusion" methods for resource-efficient WSN protocols published previously by other researchers. Performance verification of the resulting cross-layer designs is found by embedding the optimality conditions for the protocols in actual WSN scenarios replicated in a wireless network simulation environment. Performance tradeoffs among protocol parameters remain for a sequel to the paper.

Optimizing Filter-Probe Diffusion Weighting in the Rat Spinal Cord for Human Translation

PubMed Central

Budde, Matthew D.; Skinner, Nathan P.; Muftuler, L. Tugan; Schmit, Brian D.; Kurpad, Shekar N.

2017-01-01

Diffusion tensor imaging (DTI) is a promising biomarker of spinal cord injury (SCI). In the acute aftermath, DTI in SCI animal models consistently demonstrates high sensitivity and prognostic performance, yet translation of DTI to acute human SCI has been limited. In addition to technical challenges, interpretation of the resulting metrics is ambiguous, with contributions in the acute setting from both axonal injury and edema. Novel diffusion MRI acquisition strategies such as double diffusion encoding (DDE) have recently enabled detection of features not available with DTI or similar methods. In this work, we perform a systematic optimization of DDE using simulations and an in vivo rat model of SCI and subsequently implement the protocol to the healthy human spinal cord. First, two complementary DDE approaches were evaluated using an orientationally invariant or a filter-probe diffusion encoding approach. While the two methods were similar in their ability to detect acute SCI, the filter-probe DDE approach had greater predictive power for functional outcomes. Next, the filter-probe DDE was compared to an analogous single diffusion encoding (SDE) approach, with the results indicating that in the spinal cord, SDE provides similar contrast with improved signal to noise. In the SCI rat model, the filter-probe SDE scheme was coupled with a reduced field of view (rFOV) excitation, and the results demonstrate high quality maps of the spinal cord without contamination from edema and cerebrospinal fluid, thereby providing high sensitivity to injury severity. The optimized protocol was demonstrated in the healthy human spinal cord using the commercially-available diffusion MRI sequence with modifications only to the diffusion encoding directions. Maps of axial diffusivity devoid of CSF partial volume effects were obtained in a clinically feasible imaging time with a straightforward analysis and variability comparable to axial diffusivity derived from DTI. Overall, the results and optimizations describe a protocol that mitigates several difficulties with DTI of the spinal cord. Detection of acute axonal damage in the injured or diseased spinal cord will benefit the optimized filter-probe diffusion MRI protocol outlined here. PMID:29311786

Optimizing MRI for imaging peripheral arthritis.

PubMed

Hodgson, Richard J; O'Connor, Philip J; Ridgway, John P

2012-11-01

MRI is increasingly used for the assessment of both inflammatory arthritis and osteoarthritis. The wide variety of MRI systems in use ranges from low-field, low-cost extremity units to whole-body high-field 7-T systems, each with different strengths for specific applications. The availability of dedicated radiofrequency phased-array coils allows the rapid acquisition of high-resolution images of one or more peripheral joints. MRI is uniquely flexible in its ability to manipulate image contrast, and individual MR sequences may be combined into protocols to sensitively visualize multiple features of arthritis including synovitis, bone marrow lesions, erosions, cartilage changes, and tendinopathy. Careful choice of the imaging parameters allows images to be generated with optimal quality while minimizing unwanted artifacts. Finally, there are many novel MRI techniques that can quantify disease levels in arthritis in tissues including synovitis and cartilage. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

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

PubMed Central

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

2013-01-01

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 (~15–20cm) 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, was employed along with extensive Monte Carlo simulations and an initial clinical FDG patient dataset to validate and demonstrate the potential of the proposed statistical estimation methods. Both simulated and clinical results suggest that hybrid regression in the context of whole-body Patlak Ki imaging considerably reduces MSE without compromising high CNR. Alternatively, for a given CNR, hybrid regression enables larger reductions than OLS in the number of dynamic frames per bed, allowing for even shorter acquisitions of ~30min, thus further contributing to the clinical adoption of the proposed framework. Compared to the SUV approach, whole body parametric imaging can provide better tumor quantification, and can act as a complement to SUV, for the task of tumor detection. PMID:24080994

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, was employed along with extensive Monte Carlo simulations and an initial clinical (18)F-deoxyglucose patient dataset to validate and demonstrate the potential of the proposed statistical estimation methods. Both simulated and clinical results suggest that hybrid regression in the context of whole-body Patlak Ki imaging considerably reduces MSE without compromising high CNR. Alternatively, for a given CNR, hybrid regression enables larger reductions than OLS in the number of dynamic frames per bed, allowing for even shorter acquisitions of ~30 min, thus further contributing to the clinical adoption of the proposed framework. Compared to the SUV approach, whole-body parametric imaging can provide better tumor quantification, and can act as a complement to SUV, for the task of tumor detection.

Optimization of propagation-based x-ray phase-contrast tomography for breast cancer imaging

NASA Astrophysics Data System (ADS)

Baran, P.; Pacile, S.; Nesterets, Y. I.; Mayo, S. C.; Dullin, C.; Dreossi, D.; Arfelli, F.; Thompson, D.; Lockie, D.; McCormack, M.; Taba, S. T.; Brun, F.; Pinamonti, M.; Nickson, C.; Hall, C.; Dimmock, M.; Zanconati, F.; Cholewa, M.; Quiney, H.; Brennan, P. C.; Tromba, G.; Gureyev, T. E.

2017-03-01

The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue samples, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, sample-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy sample with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the sample-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.

Rapid analysis and exploration of fluorescence microscopy images.

PubMed

Pavie, Benjamin; Rajaram, Satwik; Ouyang, Austin; Altschuler, Jason M; Steininger, Robert J; Wu, Lani F; Altschuler, Steven J

2014-03-19

Despite rapid advances in high-throughput microscopy, quantitative image-based assays still pose significant challenges. While a variety of specialized image analysis tools are available, most traditional image-analysis-based workflows have steep learning curves (for fine tuning of analysis parameters) and result in long turnaround times between imaging and analysis. In particular, cell segmentation, the process of identifying individual cells in an image, is a major bottleneck in this regard. Here we present an alternate, cell-segmentation-free workflow based on PhenoRipper, an open-source software platform designed for the rapid analysis and exploration of microscopy images. The pipeline presented here is optimized for immunofluorescence microscopy images of cell cultures and requires minimal user intervention. Within half an hour, PhenoRipper can analyze data from a typical 96-well experiment and generate image profiles. Users can then visually explore their data, perform quality control on their experiment, ensure response to perturbations and check reproducibility of replicates. This facilitates a rapid feedback cycle between analysis and experiment, which is crucial during assay optimization. This protocol is useful not just as a first pass analysis for quality control, but also may be used as an end-to-end solution, especially for screening. The workflow described here scales to large data sets such as those generated by high-throughput screens, and has been shown to group experimental conditions by phenotype accurately over a wide range of biological systems. The PhenoBrowser interface provides an intuitive framework to explore the phenotypic space and relate image properties to biological annotations. Taken together, the protocol described here will lower the barriers to adopting quantitative analysis of image based screens.

High-pressure freezing for scanning transmission electron tomography analysis of cellular organelles.

PubMed

Walther, Paul; Schmid, Eberhard; Höhn, Katharina

2013-01-01

Using an electron microscope's scanning transmission mode (STEM) for collection of tomographic datasets is advantageous compared to bright field transmission electron microscopic (TEM). For image formation, inelastic scattering does not cause chromatic aberration, since in STEM mode no image forming lenses are used after the beam has passed the sample, in contrast to regular TEM. Therefore, thicker samples can be imaged. It has been experimentally demonstrated that STEM is superior to TEM and energy filtered TEM for tomography of samples as thick as 1 μm. Even when using the best electron microscope, adequate sample preparation is the key for interpretable results. We adapted protocols for high-pressure freezing of cultivated cells from a physiological state. In this chapter, we describe optimized high-pressure freezing and freeze substitution protocols for STEM tomography in order to obtain high membrane contrast.

Patient-specific 3D FLAIR for enhanced visualization of brain white matter lesions in multiple sclerosis.

PubMed

Gabr, Refaat E; Pednekar, Amol S; Govindarajan, Koushik A; Sun, Xiaojun; Riascos, Roy F; Ramírez, María G; Hasan, Khader M; Lincoln, John A; Nelson, Flavia; Wolinsky, Jerry S; Narayana, Ponnada A

2017-08-01

To improve the conspicuity of white matter lesions (WMLs) in multiple sclerosis (MS) using patient-specific optimization of single-slab 3D fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Sixteen MS patients were enrolled in a prospective 3.0T MRI study. FLAIR inversion time and echo time were automatically optimized for each patient during the same scan session based on measurements of the relative proton density and relaxation times of the brain tissues. The optimization criterion was to maximize the contrast between gray matter (GM) and white matter (WM), while suppressing cerebrospinal fluid. This criterion also helps increase the contrast between WMLs and WM. The performance of the patient-specific 3D FLAIR protocol relative to the fixed-parameter protocol was assessed both qualitatively and quantitatively. Patient-specific optimization achieved a statistically significant 41% increase in the GM-WM contrast ratio (P < 0.05) and 32% increase in the WML-WM contrast ratio (P < 0.01) compared with fixed-parameter FLAIR. The increase in WML-WM contrast ratio correlated strongly with echo time (P < 10 -11 ). Two experienced neuroradiologists indicated substantially higher lesion conspicuity on the patient-specific FLAIR images over conventional FLAIR in 3-4 cases (intrarater correlation coefficient ICC = 0.72). In no case was the image quality of patient-specific FLAIR considered inferior to conventional FLAIR by any of the raters (ICC = 0.32). Changes in proton density and relaxation times render fixed-parameter FLAIR suboptimal in terms of lesion contrast. Patient-specific optimization of 3D FLAIR increases lesion conspicuity without scan time penalty, and has potential to enhance the detection of subtle and small lesions in MS. 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:557-564. © 2016 International Society for Magnetic Resonance in Medicine.

Measurement of drug-target engagement in live cells by two-photon fluorescence anisotropy imaging.

PubMed

Vinegoni, Claudio; Fumene Feruglio, Paolo; Brand, Christian; Lee, Sungon; Nibbs, Antoinette E; Stapleton, Shawn; Shah, Sunil; Gryczynski, Ignacy; Reiner, Thomas; Mazitschek, Ralph; Weissleder, Ralph

2017-07-01

The ability to directly image and quantify drug-target engagement and drug distribution with subcellular resolution in live cells and whole organisms is a prerequisite to establishing accurate models of the kinetics and dynamics of drug action. Such methods would thus have far-reaching applications in drug development and molecular pharmacology. We recently presented one such technique based on fluorescence anisotropy, a spectroscopic method based on polarization light analysis and capable of measuring the binding interaction between molecules. Our technique allows the direct characterization of target engagement of fluorescently labeled drugs, using fluorophores with a fluorescence lifetime larger than the rotational correlation of the bound complex. Here we describe an optimized protocol for simultaneous dual-channel two-photon fluorescence anisotropy microscopy acquisition to perform drug-target measurements. We also provide the necessary software to implement stream processing to visualize images and to calculate quantitative parameters. The assembly and characterization part of the protocol can be implemented in 1 d. Sample preparation, characterization and imaging of drug binding can be completed in 2 d. Although currently adapted to an Olympus FV1000MPE microscope, the protocol can be extended to other commercial or custom-built microscopes.

Relationships of pediatric anthropometrics for CT protocol selection.

PubMed

Phillips, Grace S; Stanescu, Arta-Luana; Alessio, Adam M

2014-07-01

Determining the optimal CT technique to minimize patient radiation exposure while maintaining diagnostic utility requires patient-specific protocols that are based on patient characteristics. This work develops relationships between different anthropometrics and CT image noise to determine appropriate protocol classification schemes. We measured the image noise in 387 CT examinations of pediatric patients (222 boys, 165 girls) of the chest, abdomen, and pelvis and generated mathematic relationships between image noise and patient lateral and anteroposterior dimensions, age, and weight. At the chest level, lateral distance (ld) across the body is strongly correlated with weight (ld = 0.23 × weight + 16.77; R(2) = 0.93) and is less well correlated with age (ld = 1.10 × age + 17.13; R(2) = 0.84). Similar trends were found for anteroposterior dimensions and at the abdomen level. Across all studies, when acquisition-specific parameters are factored out of the noise, the log of image noise was highly correlated with lateral distance (R(2) = 0.72) and weight (R(2) = 0.72) and was less correlated with age (R(2) = 0.62). Following first-order relationships of image noise and scanner technique, plots were formed to show techniques that could achieve matched noise across the pediatric population. Patient lateral distance and weight are essentially equally effective metrics to base maximum technique settings for pediatric patient-specific protocols. These metrics can also be used to help categorize appropriate reference levels for CT technique and size-specific dose estimates across the pediatric population.

Defining PET / CT Protocols With Optimized F18-FDG (Fluorodeoxyglucose) Dose, Focusing on Reduced Radiation Dose and Improved Image Quality

ClinicalTrials.gov

2017-11-27

Malignant Neoplasm of Breast; Hodgkin Disease; Non-Hodgkin Lymphoma, Follicular (Nodular); Malignant Neoplasm of Bronchus and Lung; Malignant Neoplasm of Colon; Secondary Neoplasm Malignant and Unspecified Lymph Nodes; Malignant Melanoma of the Skin; Malignant Neoplasm of Small Intestine

Optimisation d'analyses de grenat almandin realisees au microscope electronique a balayage

NASA Astrophysics Data System (ADS)

Larose, Miguel

The electron microprobe (EMP) is considered as the golden standard for the collection of precise and representative chemical composition of minerals in rocks, but data of similar quality should be obtainable with a scanning electron microscope (SEM). This thesis presents an analytical protocol aimed at optimizing operational parameters of an SEM paired with an EDS Si(Li) X-ray detector (JEOL JSM-840A) for the imaging, quantitative chemical analysis and compositional X-ray maps of almandine garnet found in pelitic schists from the Canadian Cordillera. Results are then compared to those obtained for the same samples on a JEOL JXA 8900 EMP. For imaging purposes, the secondary electrons and backscattered electrons signals have been used to obtain topographic and chemical contrast of the samples, respectively. The SEM allows the acquisition of images with higher resolution than the EMP when working at high magnifications. However, for millimetric size minerals requiring very low magnifications, the EMP can usually match the imaging capabilities of an SEM. When optimizing images for both signals, the optimal operational parameters to show similar contrasts are not restricted to a unique combination of values. Optimization of operational parameters for quantitative chemical analysis resulted in analytical data with a similar precision and showing good correlation to that obtained with an EMP. Optimization of operational parameters for compositional X-ray maps aimed at maximizing the collected intensity within a pixel as well as complying with the spatial resolution criterion in order to obtain a qualitative compositional map representative of the chemical variation within the grain. Even though various corrections were needed, such as the shadow effect and the background noise removal, as well as the impossibility to meet the spatial resolution criterion because of the limited pixel density available on the SEM, the compositional X-ray maps show a good correlation with those obtained with the EMP, even for concentrations as low as 0,5%. When paired with a rigorous analytical protocol, the use of an SEM equipped with an EDS Si (Li) X-ray detector allows the collection of qualitative and quantitative results similar to those obtained with an EMP for all three of the applications considered.

Correlative Stochastic Optical Reconstruction Microscopy and Electron Microscopy

PubMed Central

Kim, Doory; Deerinck, Thomas J.; Sigal, Yaron M.; Babcock, Hazen P.; Ellisman, Mark H.; Zhuang, Xiaowei

2015-01-01

Correlative fluorescence light microscopy and electron microscopy allows the imaging of spatial distributions of specific biomolecules in the context of cellular ultrastructure. Recent development of super-resolution fluorescence microscopy allows the location of molecules to be determined with nanometer-scale spatial resolution. However, correlative super-resolution fluorescence microscopy and electron microscopy (EM) still remains challenging because the optimal specimen preparation and imaging conditions for super-resolution fluorescence microscopy and EM are often not compatible. Here, we have developed several experiment protocols for correlative stochastic optical reconstruction microscopy (STORM) and EM methods, both for un-embedded samples by applying EM-specific sample preparations after STORM imaging and for embedded and sectioned samples by optimizing the fluorescence under EM fixation, staining and embedding conditions. We demonstrated these methods using a variety of cellular targets. PMID:25874453

Rainbow correlation imaging with macroscopic twin beam

NASA Astrophysics Data System (ADS)

Allevi, Alessia; Bondani, Maria

2017-06-01

We present the implementation of a correlation-imaging protocol that exploits both the spatial and spectral correlations of macroscopic twin-beam states generated by parametric downconversion. In particular, the spectral resolution of an imaging spectrometer coupled to an EMCCD camera is used in a proof-of-principle experiment to encrypt and decrypt a simple code to be transmitted between two parties. In order to optimize the trade-off between visibility and resolution, we provide the characterization of the correlation images as a function of the spatio-spectral properties of twin beams generated at different pump power values.

Acoustic-noise-optimized diffusion-weighted imaging.

PubMed

Ott, Martin; Blaimer, Martin; Grodzki, David M; Breuer, Felix A; Roesch, Julie; Dörfler, Arnd; Heismann, Björn; Jakob, Peter M

2015-12-01

This work was aimed at reducing acoustic noise in diffusion-weighted MR imaging (DWI) that might reach acoustic noise levels of over 100 dB(A) in clinical practice. A diffusion-weighted readout-segmented echo-planar imaging (EPI) sequence was optimized for acoustic noise by utilizing small readout segment widths to obtain low gradient slew rates and amplitudes instead of faster k-space coverage. In addition, all other gradients were optimized for low slew rates. Volunteer and patient imaging experiments were conducted to demonstrate the feasibility of the method. Acoustic noise measurements were performed and analyzed for four different DWI measurement protocols at 1.5T and 3T. An acoustic noise reduction of up to 20 dB(A) was achieved, which corresponds to a fourfold reduction in acoustic perception. The image quality was preserved at the level of a standard single-shot (ss)-EPI sequence, with a 27-54% increase in scan time. The diffusion-weighted imaging technique proposed in this study allowed a substantial reduction in the level of acoustic noise compared to standard single-shot diffusion-weighted EPI. This is expected to afford considerably more patient comfort, but a larger study would be necessary to fully characterize the subjective changes in patient experience.

Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to an Amyotrophic Lateral Sclerosis Model

PubMed Central

Marcuzzo, Stefania; Bonanno, Silvia; Padelli, Francesco; Moreno-Manzano, Victoria; García-Verdugo, José Manuel; Bernasconi, Pia; Mantegazza, Renato; Bruzzone, Maria Grazia; Zucca, Ileana

2016-01-01

Diffusion-weighted Magnetic Resonance Imaging (dMRI) has relevant applications in the microstructural characterization of the spinal cord, especially in neurodegenerative diseases. Animal models have a pivotal role in the study of such diseases; however, in vivo spinal dMRI of small animals entails additional challenges that require a systematical investigation of acquisition parameters. The purpose of this study is to compare three acquisition protocols and identify the scanning parameters allowing a robust estimation of the main diffusion quantities and a good sensitivity to neurodegeneration in the mouse spinal cord. For all the protocols, the signal-to-noise and contrast-to noise ratios and the mean value and variability of Diffusion Tensor metrics were evaluated in healthy controls. For the estimation of fractional anisotropy less variability was provided by protocols with more diffusion directions, for the estimation of mean, axial and radial diffusivity by protocols with fewer diffusion directions and higher diffusion weighting. Intermediate features (12 directions, b = 1200 s/mm2) provided the overall minimum inter- and intra-subject variability in most cases. In order to test the diagnostic sensitivity of the protocols, 7 G93A-SOD1 mice (model of amyotrophic lateral sclerosis) at 10 and 17 weeks of age were scanned and the derived diffusion parameters compared with those estimated in age-matched healthy animals. The protocols with an intermediate or high number of diffusion directions provided the best differentiation between the two groups at week 17, whereas only few local significant differences were highlighted at week 10. According to our results, a dMRI protocol with an intermediate number of diffusion gradient directions and a relatively high diffusion weighting is optimal for spinal cord imaging. Further work is needed to confirm these results and for a finer tuning of acquisition parameters. Nevertheless, our findings could be important for the optimization of acquisition protocols for preclinical and clinical dMRI studies on the spinal cord. PMID:27560686

Low-Dose CT of the Paranasal Sinuses: Minimizing X-Ray Exposure with Spectral Shaping.

PubMed

Wuest, Wolfgang; May, Matthias; Saake, Marc; Brand, Michael; Uder, Michael; Lell, Michael

2016-11-01

Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study's aim was to investigate dose and image quality of tin filtration at 100 kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100 kV with additional tin filtration, 150mAs, 192x0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100 kV, 50mAs, 128 × 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDI vol 1.2 mGy vs. 4.4 mGy, p < 0.001). Spectral optimization (tin filtration at 100 kV) allows for visualization of the paranasal sinus with sufficient image quality at a very low radiation exposure. • Spectral optimization (tin filtration) is beneficial to low-dose parasinus CT • Tin filtration at 100 kV yields sufficient image quality for pre-operative planning • Diagnostic parasinus CT can be performed with an effective dose <0.05 mSv.

Dual-Energy Computed Tomography for the Characterization of Intracranial Hemorrhage and Calcification: A Systematic Approach in a Phantom System.

PubMed

Nute, Jessica L; Jacobsen, Megan C; Chandler, Adam; Cody, Dianna D; Schellingerhout, Dawid

2017-01-01

The aim of this study was to develop a diagnostic framework for distinguishing calcific from hemorrhagic cerebral lesions using dual-energy computed tomography (DECT) in an anthropomorphic phantom system. An anthropomorphic phantom was designed to mimic the CT imaging characteristics of the human head. Cylindrical lesion models containing either calcium or iron, mimicking calcification or hemorrhage, respectively, were developed to exhibit matching, and therefore indistinguishable, single-energy CT (SECT) attenuation values from 40 to 100 HU. These lesion models were fabricated at 0.5, 1, and 1.5 cm in diameter and positioned in simulated cerebrum and skull base locations within the anthropomorphic phantom. All lesion sizes were modeled in the cerebrum, while only 1.5-cm lesions were modeled in the skull base. Images were acquired using a GE 750HD CT scanner and an expansive dual-energy protocol that covered variations in dose (36.7-132.6 mGy CTDIvol, n = 12), image thickness (0.625-5 mm, n = 4), and reconstruction filter (soft, standard, detail, n = 3) for a total of 144 unique technique combinations. Images representing each technique combination were reconstructed into water and calcium material density images, as well as a monoenergetic image chosen to mimic the attenuation of a 120-kVp SECT scan. A true single-energy routine brain protocol was also included for verification of lesion SECT attenuation. Points representing the 3 dual-energy reconstructions were plotted into a 3-dimensional space (water [milligram/milliliter], calcium [milligram/milliliter], monoenergetic Hounsfield unit as x, y, and z axes, respectively), and the distribution of points analyzed using 2 approaches: support vector machines and a simple geometric bisector (GB). Each analysis yielded a plane of optimal differentiation between the calcification and hemorrhage lesion model distributions. By comparing the predicted lesion composition to the known lesion composition, we identified the optimal combination of CTDIvol, image thickness, and reconstruction filter to maximize differentiation between the lesion model types. To validate these results, a new set of hemorrhage and calcification lesion models were created, scanned in a blinded fashion, and prospectively classified using the planes of differentiation derived from support vector machine and GB methods. Accuracy of differentiation improved with increasing dose (CTDIvol) and image thickness. Reconstruction filter had no effect on the accuracy of differentiation. Using an optimized protocol consisting of the maximum CTDIvol of 132.6 mGy, 5-mm-thick images, and a standard filter, hemorrhagic and calcific lesion models with equal SECT attenuation (Hounsfield unit) were differentiated with over 90% accuracy down to 70 HU for skull base lesions of 1.5 cm, and down to 100 HU, 60 HU, and 60 HU for cerebrum lesions of 0.5, 1.0, and 1.5 cm, respectively. The analytic method that yielded the best results was a simple GB plane through the 3-dimensional DECT space. In the validation study, 96% of unknown lesions were correctly classified across all lesion sizes and locations investigated. We define the optimal scan parameters and expected limitations for the accurate classification of hemorrhagic versus calcific cerebral lesions in an anthropomorphic phantom with DECT. Although our proposed DECT protocol represents an increase in dose compared with routine brain CT, this method is intended as a specialized evaluation of potential brain hemorrhage and is thus counterbalanced by increased diagnostic benefit. This work provides justification for the application of this technique in human clinical trials.

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions.

PubMed

Saha, Tanumoy; Rathmann, Isabel; Galic, Milos

2017-07-11

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

Improved spatial coverage for brain 3D PRESS MRSI by automatic placement of outer-volume suppression saturation bands.

PubMed

Ozhinsky, Eugene; Vigneron, Daniel B; Nelson, Sarah J

2011-04-01

To develop a technique for optimizing coverage of brain 3D (1) H magnetic resonance spectroscopic imaging (MRSI) by automatic placement of outer-volume suppression (OVS) saturation bands (sat bands) and to compare the performance for point-resolved spectroscopic sequence (PRESS) MRSI protocols with manual and automatic placement of sat bands. The automated OVS procedure includes the acquisition of anatomic images from the head, obtaining brain and lipid tissue maps, calculating optimal sat band placement, and then using those optimized parameters during the MRSI acquisition. The data were analyzed to quantify brain coverage volume and data quality. 3D PRESS MRSI data were acquired from three healthy volunteers and 29 patients using protocols that included either manual or automatic sat band placement. On average, the automatic sat band placement allowed the acquisition of PRESS MRSI data from 2.7 times larger brain volumes than the conventional method while maintaining data quality. The technique developed helps solve two of the most significant problems with brain PRESS MRSI acquisitions: limited brain coverage and difficulty in prescription. This new method will facilitate routine clinical brain 3D MRSI exams and will be important for performing serial evaluation of response to therapy in patients with brain tumors and other neurological diseases. Copyright © 2011 Wiley-Liss, Inc.

Nanoscale imaging of clinical specimens using pathology-optimized expansion microscopy

PubMed Central

Zhao, Yongxin; Bucur, Octavian; Irshad, Humayun; Chen, Fei; Weins, Astrid; Stancu, Andreea L.; Oh, Eun-Young; DiStasio, Marcello; Torous, Vanda; Glass, Benjamin; Stillman, Isaac E.; Schnitt, Stuart J.; Beck, Andrew H.; Boyden, Edward S.

2017-01-01

Expansion microscopy (ExM), a method for improving the resolution of light microscopy by physically expanding the specimen, has not been applied to clinical tissue samples. Here we report a clinically optimized form of ExM that supports nanoscale imaging of human tissue specimens that have been fixed with formalin, embedded in paraffin, stained with hematoxylin and eosin (H&E), and/or fresh frozen. The method, which we call expansion pathology (ExPath), converts clinical samples into an ExM-compatible state, then applies an ExM protocol with protein anchoring and mechanical homogenization steps optimized for clinical samples. ExPath enables ~70 nm resolution imaging of diverse biomolecules in intact tissues using conventional diffraction-limited microscopes, and standard antibody and fluorescent DNA in situ hybridization reagents. We use ExPath for optical diagnosis of kidney minimal-change disease, which previously required electron microscopy (EM), and demonstrate high-fidelity computational discrimination between early breast neoplastic lesions that to date have challenged human judgment. ExPath may enable the routine use of nanoscale imaging in pathology and clinical research. PMID:28714966

Nanoscale imaging of clinical specimens using pathology-optimized expansion microscopy.

PubMed

Zhao, Yongxin; Bucur, Octavian; Irshad, Humayun; Chen, Fei; Weins, Astrid; Stancu, Andreea L; Oh, Eun-Young; DiStasio, Marcello; Torous, Vanda; Glass, Benjamin; Stillman, Isaac E; Schnitt, Stuart J; Beck, Andrew H; Boyden, Edward S

2017-08-01

Expansion microscopy (ExM), a method for improving the resolution of light microscopy by physically expanding a specimen, has not been applied to clinical tissue samples. Here we report a clinically optimized form of ExM that supports nanoscale imaging of human tissue specimens that have been fixed with formalin, embedded in paraffin, stained with hematoxylin and eosin, and/or fresh frozen. The method, which we call expansion pathology (ExPath), converts clinical samples into an ExM-compatible state, then applies an ExM protocol with protein anchoring and mechanical homogenization steps optimized for clinical samples. ExPath enables ∼70-nm-resolution imaging of diverse biomolecules in intact tissues using conventional diffraction-limited microscopes and standard antibody and fluorescent DNA in situ hybridization reagents. We use ExPath for optical diagnosis of kidney minimal-change disease, a process that previously required electron microscopy, and we demonstrate high-fidelity computational discrimination between early breast neoplastic lesions for which pathologists often disagree in classification. ExPath may enable the routine use of nanoscale imaging in pathology and clinical research.

Technical aspects of dental CBCT: state of the art

PubMed Central

Araki, K; Siewerdsen, J H; Thongvigitmanee, S S

2015-01-01

As CBCT is widely used in dental and maxillofacial imaging, it is important for users as well as referring practitioners to understand the basic concepts of this imaging modality. This review covers the technical aspects of each part of the CBCT imaging chain. First, an overview is given of the hardware of a CBCT device. The principles of cone beam image acquisition and image reconstruction are described. Optimization of imaging protocols in CBCT is briefly discussed. Finally, basic and advanced visualization methods are illustrated. Certain topics in these review are applicable to all types of radiographic imaging (e.g. the principle and properties of an X-ray tube), others are specific for dental CBCT imaging (e.g. advanced visualization techniques). PMID:25263643

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

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

Cui, Y; Bowsher, J; Yan, S

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 Medicalmore » 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.« less

Efficiency Improvement in a Busy Radiology Practice: Determination of Musculoskeletal Magnetic Resonance Imaging Protocol Using Deep-Learning Convolutional Neural Networks.

PubMed

Lee, Young Han

2018-04-04

The purposes of this study are to evaluate the feasibility of protocol determination with a convolutional neural networks (CNN) classifier based on short-text classification and to evaluate the agreements by comparing protocols determined by CNN with those determined by musculoskeletal radiologists. Following institutional review board approval, the database of a hospital information system (HIS) was queried for lists of MRI examinations, referring department, patient age, and patient gender. These were exported to a local workstation for analyses: 5258 and 1018 consecutive musculoskeletal MRI examinations were used for the training and test datasets, respectively. The subjects for pre-processing were routine or tumor protocols and the contents were word combinations of the referring department, region, contrast media (or not), gender, and age. The CNN Embedded vector classifier was used with Word2Vec Google news vectors. The test set was tested with each classification model and results were output as routine or tumor protocols. The CNN determinations were evaluated using the receiver operating characteristic (ROC) curves. The accuracies were evaluated by a radiologist-confirmed protocol as the reference protocols. The optimal cut-off values for protocol determination between routine protocols and tumor protocols was 0.5067 with a sensitivity of 92.10%, a specificity of 95.76%, and an area under curve (AUC) of 0.977. The overall accuracy was 94.2% for the ConvNet model. All MRI protocols were correct in the pelvic bone, upper arm, wrist, and lower leg MRIs. Deep-learning-based convolutional neural networks were clinically utilized to determine musculoskeletal MRI protocols. CNN-based text learning and applications could be extended to other radiologic tasks besides image interpretations, improving the work performance of the radiologist.

TU-H-CAMPUS-JeP1-04: Deformable Image Registration Performances in Pelvis Patients: Impact of CBCT Image Quality

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

Fusella, M; Loi, G; Fiandra, C

Purpose: To investigate the accuracy and robustness, against image noise and artifacts (typical of CBCT images), of a commercial algorithm for deformable image registration (DIR), to propagate regions of interest (ROIs) in computational phantoms based on real prostate patient images. Methods: The Anaconda DIR algorithm, implemented in RayStation was tested. Two specific Deformation Vector Fields (DVFs) were applied to the reference data set (CTref) using the ImSimQA software, obtaining two deformed CTs. For each dataset twenty-four different level of noise and/or capping artifacts were applied to simulate CBCT images. DIR was performed between CTref and each deformed CTs and CBCTs.more » In order to investigate the relationship between image quality parameters and the DIR results (expressed by a logit transform of the Dice Index) a bilinear regression was defined. Results: More than 550 DIR-mapped ROIs were analyzed. The Statistical analysis states that deformation strenght and artifacts were significant prognostic factors of DIR performances, while noise appeared to have a minor role in DIR process as implemented in RayStation as expected by the image similarity metric built in the registration algorithm. Capping artifacts reveals a determinant role for the accuracy of DIR results. Two optimal values for capping artifacts were found to obtain acceptable DIR results (DICE> 075/ 0.85). Various clinical CBCT acquisition protocol were reported to evaluate the significance of the study. Conclusion: This work illustrates the impact of image quality on DIR performance. Clinical issues like Adaptive Radiation Therapy (ART) and Dose Accumulation need accurate and robust DIR software. The RayStation DIR algorithm resulted robust against noise, but sensitive to image artifacts. This result highlights the need of robustness quality assurance against image noise and artifacts in the commissioning of a DIR commercial system and underlines the importance to adopt optimized protocols for CBCT image acquisitions in ART clinical implementation.« less

Chest CT in children: anesthesia and atelectasis.

PubMed

Newman, Beverley; Krane, Elliot J; Gawande, Rakhee; Holmes, Tyson H; Robinson, Terry E

2014-02-01

There has been an increasing tendency for anesthesiologists to be responsible for providing sedation or anesthesia during chest CT imaging in young children. Anesthesia-related atelectasis noted on chest CT imaging has proven to be a common and troublesome problem, affecting image quality and diagnostic sensitivity. To evaluate the safety and effectiveness of a standardized anesthesia, lung recruitment, controlled-ventilation technique developed at our institution to prevent atelectasis for chest CT imaging in young children. Fifty-six chest CT scans were obtained in 42 children using a research-based intubation, lung recruitment and controlled-ventilation CT scanning protocol. These studies were compared with 70 non-protocolized chest CT scans under anesthesia taken from 18 of the same children, who were tested at different times, without the specific lung recruitment and controlled-ventilation technique. Two radiology readers scored all inspiratory chest CT scans for overall CT quality and atelectasis. Detailed cardiorespiratory parameters were evaluated at baseline, and during recruitment and inspiratory imaging on 21 controlled-ventilation cases and 8 control cases. Significant differences were noted between groups for both quality and atelectasis scores with optimal scoring demonstrated in the controlled-ventilation cases where 70% were rated very good to excellent quality scans compared with only 24% of non-protocol cases. There was no or minimal atelectasis in 48% of the controlled ventilation cases compared to 51% of non-protocol cases with segmental, multisegmental or lobar atelectasis present. No significant difference in cardiorespiratory parameters was found between controlled ventilation and other chest CT cases and no procedure-related adverse events occurred. Controlled-ventilation infant CT scanning under general anesthesia, utilizing intubation and recruitment maneuvers followed by chest CT scans, appears to be a safe and effective method to obtain reliable and reproducible high-quality, motion-free chest CT images in children.

SU-E-I-89: Assessment of CT Radiation Dose and Image Quality for An Automated Tube Potential Selection Algorithm Using Pediatric Anthropomorphic and ACR Phantoms

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

Mahmood, U; Erdi, Y; Wang, W

Purpose: To assess the impact of General Electrics automated tube potential algorithm, kV assist (kVa) on radiation dose and image quality, with an emphasis on optimizing protocols based on noise texture. Methods: Radiation dose was assessed by inserting optically stimulated luminescence dosimeters (OSLs) throughout the body of a pediatric anthropomorphic phantom (CIRS). The baseline protocol was: 120 kVp, 80 mA, 0.7s rotation time. Image quality was assessed by calculating the contrast to noise ratio (CNR) and noise power spectrum (NPS) from the ACR CT accreditation phantom. CNRs were calculated according to the steps described in ACR CT phantom testing document.more » NPS was determined by taking the 3D FFT of the uniformity section of the ACR phantom. NPS and CNR were evaluated with and without kVa and for all available adaptive iterative statistical reconstruction (ASiR) settings, ranging from 0 to 100%. Each NPS was also evaluated for its peak frequency difference (PFD) with respect to the baseline protocol. Results: For the baseline protocol, CNR was found to decrease from 0.460 ± 0.182 to 0.420 ± 0.057 when kVa was activated. When compared against the baseline protocol, the PFD at ASiR of 40% yielded a decrease in noise magnitude as realized by the increase in CNR = 0.620 ± 0.040. The liver dose decreased by 30% with kVa activation. Conclusion: Application of kVa reduces the liver dose up to 30%. However, reduction in image quality for abdominal scans occurs when using the automated tube voltage selection feature at the baseline protocol. As demonstrated by the CNR and NPS analysis, the texture and magnitude of the noise in reconstructed images at ASiR 40% was found to be the same as our baseline images. We have demonstrated that 30% dose reduction is possible when using 40% ASiR with kVa in pediatric patients.« less

SU-E-J-207: Effect of Pulse Sequence Parameters On Geometric Distortions Induced by a Titanium Brachytherapy Applicator

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

Shea, S; Diak, A; Surucu, M

2015-06-15

Purpose: To investigate the effect of readout bandwidth and voxel size on the appearance of distortion artifacts caused by a titanium brachytherapy applicator. Methods: An acrylic phantom was constructed to rigidly hold a MR conditional, titanium Fletcher-Suit-Delclos-style applicator set (Varian Medical Systems) for imaging on CT (Philips Brilliance) and 1.5T MRI (Siemens Magnetom Aera). Several variants of MRI parameters were tried for 2D T2-weighted turbo spin echo imaging in comparison against the standard clinical protocol with the criteria to keep relative SNR loss less than 20% and imaging time as short as possible. Two 3D sequences were also used formore » comparison with similar parameters. The applicator tandem was segmented on axial CT images (0.4×0.4×1.5mm {sup 3} resolution) and the CT images were registered to the 3D MR images in Eclipse (Varian). The applicator volume was then overlaid on all MRI sets in 3D-Slicer and distances were measured from the tandem tip to the MRI artifact edge in right/left/superior and anterior/posterior/superior directions from coronal and sagittal 2D acquisitions, respectively, or 3D data reformats. Artifact regions were also manually contoured in coronal/sagittal orientations for area measurements. Results: As would be expected, reductions in voxel size and increases in readout bandwidth reduced artifact size (average max artifact length decreased by 0.95 mm and average max area decrease by 0.27 cm{sup 2}). Interestingly, bandwidth increases yielded reductions in area (0.19 cm{sup 2}) and in distance measurements (1 mm) even with voxel increases, as compared to a standard protocol. This could be useful when high performance protocols are not feasible due to long imaging times. Conclusion: We have characterized artifacts caused by cervical brachytherapy applicator across multiple sequence parameters at 1.5T. Future work will focus on finalizing an optimal protocol that balances artifact reduction with imaging time and then testing this new protocol in patients.« less

Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

PubMed

Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

2015-07-01

CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

3.0 Tesla magnetic resonance imaging: A new standard in liver imaging?

PubMed Central

Girometti, Rossano

2015-01-01

An ever-increasing number of 3.0 Tesla (T) magnets are installed worldwide. Moving from the standard of 1.5 T to higher field strength implies a number of potential advantage and drawbacks, requiring careful optimization of imaging protocols or implementation of novel hardware components. Clinical practice and literature review suggest that state-of-the-art 3.0 T is equivalent to 1.5 T in the assessment of focal liver lesions and diffuse liver disease. Therefore, further technical improvements are needed in order to fully exploit the potential of higher field strength. PMID:26244063

3.0 Tesla magnetic resonance imaging: A new standard in liver imaging?

PubMed

Girometti, Rossano

2015-07-28

An ever-increasing number of 3.0 Tesla (T) magnets are installed worldwide. Moving from the standard of 1.5 T to higher field strength implies a number of potential advantage and drawbacks, requiring careful optimization of imaging protocols or implementation of novel hardware components. Clinical practice and literature review suggest that state-of-the-art 3.0 T is equivalent to 1.5 T in the assessment of focal liver lesions and diffuse liver disease. Therefore, further technical improvements are needed in order to fully exploit the potential of higher field strength.

Maximizing the Biochemical Resolving Power of Fluorescence Microscopy

PubMed Central

Esposito, Alessandro; Popleteeva, Marina; Venkitaraman, Ashok R.

2013-01-01

Most recent advances in fluorescence microscopy have focused on achieving spatial resolutions below the diffraction limit. However, the inherent capability of fluorescence microscopy to non-invasively resolve different biochemical or physical environments in biological samples has not yet been formally described, because an adequate and general theoretical framework is lacking. Here, we develop a mathematical characterization of the biochemical resolution in fluorescence detection with Fisher information analysis. To improve the precision and the resolution of quantitative imaging methods, we demonstrate strategies for the optimization of fluorescence lifetime, fluorescence anisotropy and hyperspectral detection, as well as different multi-dimensional techniques. We describe optimized imaging protocols, provide optimization algorithms and describe precision and resolving power in biochemical imaging thanks to the analysis of the general properties of Fisher information in fluorescence detection. These strategies enable the optimal use of the information content available within the limited photon-budget typically available in fluorescence microscopy. This theoretical foundation leads to a generalized strategy for the optimization of multi-dimensional optical detection, and demonstrates how the parallel detection of all properties of fluorescence can maximize the biochemical resolving power of fluorescence microscopy, an approach we term Hyper Dimensional Imaging Microscopy (HDIM). Our work provides a theoretical framework for the description of the biochemical resolution in fluorescence microscopy, irrespective of spatial resolution, and for the development of a new class of microscopes that exploit multi-parametric detection systems. PMID:24204821

Visualization of the internal globus pallidus: sequence and orientation for deep brain stimulation using a standard installation protocol at 3.0 Tesla.

PubMed

Nölte, Ingo S; Gerigk, Lars; Al-Zghloul, Mansour; Groden, Christoph; Kerl, Hans U

2012-03-01

Deep-brain stimulation (DBS) of the internal globus pallidus (GPi) has shown remarkable therapeutic benefits for treatment-resistant neurological disorders including dystonia and Parkinson's disease (PD). The success of the DBS is critically dependent on the reliable visualization of the GPi. The aim of the study was to evaluate promising 3.0 Tesla magnetic resonance imaging (MRI) methods for pre-stereotactic visualization of the GPi using a standard installation protocol. MRI at 3.0 T of nine healthy individuals and of one patient with PD was acquired (FLAIR, T1-MPRAGE, T2-SPACE, T2*-FLASH2D, susceptibility-weighted imaging mapping (SWI)). Image quality and visualization of the GPi for each sequence were assessed by two neuroradiologists independently using a 6-point scale. Axial, coronal, and sagittal planes of the T2*-FLASH2D images were compared. Inter-rater reliability, contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) for the GPi were determined. For illustration, axial T2*-FLASH2D images were fused with a section schema of the Schaltenbrand-Wahren stereotactic atlas. The GPi was best and reliably visualized in axial and to a lesser degree on coronal T2*-FLASH2D images. No major artifacts in the GPi were observed in any of the sequences. SWI offered a significantly higher CNR for the GPi compared to standard T2-weighted imaging using the standard parameters. The fusion of the axial T2*-FLASH2D images and the atlas projected the GPi clearly in the boundaries of the section schema. Using a standard installation protocol at 3.0 T T2*-FLASH2D imaging (particularly axial view) provides optimal and reliable delineation of the GPi.

Optimizing radiotherapy protocols using computer automata to model tumour cell death as a function of oxygen diffusion processes.

PubMed

Paul-Gilloteaux, Perrine; Potiron, Vincent; Delpon, Grégory; Supiot, Stéphane; Chiavassa, Sophie; Paris, François; Costes, Sylvain V

2017-05-23

The concept of hypofractionation is gaining momentum in radiation oncology centres, enabled by recent advances in radiotherapy apparatus. The gain of efficacy of this innovative treatment must be defined. We present a computer model based on translational murine data for in silico testing and optimization of various radiotherapy protocols with respect to tumour resistance and the microenvironment heterogeneity. This model combines automata approaches with image processing algorithms to simulate the cellular response of tumours exposed to ionizing radiation, modelling the alteration of oxygen permeabilization in blood vessels against repeated doses, and introducing mitotic catastrophe (as opposed to arbitrary delayed cell-death) as a means of modelling radiation-induced cell death. Published data describing cell death in vitro as well as tumour oxygenation in vivo are used to inform parameters. Our model is validated by comparing simulations to in vivo data obtained from the radiation treatment of mice transplanted with human prostate tumours. We then predict the efficacy of untested hypofractionation protocols, hypothesizing that tumour control can be optimized by adjusting daily radiation dosage as a function of the degree of hypoxia in the tumour environment. Further biological refinement of this tool will permit the rapid development of more sophisticated strategies for radiotherapy.

Multicontrast multiecho FLASH MRI for targeting the subthalamic nucleus.

PubMed

Xiao, Yiming; Beriault, Silvain; Pike, G Bruce; Collins, D Louis

2012-06-01

The subthalamic nucleus (STN) is one of the most common stimulation targets for treating Parkinson's disease using deep brain stimulation (DBS). This procedure requires precise placement of the stimulating electrode. Common practice of DBS implantation utilizes microelectrode recording to locate the sites with the correct electrical response after an initial location estimate based on a universal human brain atlas that is linearly scaled to the patient's anatomy as seen on the preoperative images. However, this often results in prolonged surgical time and possible surgical complications since the small-sized STN is difficult to visualize on conventional magnetic resonance (MR) images and its intersubject variability is not sufficiently considered in the atlas customization. This paper proposes a multicontrast, multiecho MR imaging (MRI) method that directly delineates the STN and other basal ganglia structures through five co-registered image contrasts (T1-weighted navigation image, R2 map, susceptibility-weighted imaging (phase, magnitude and fusion image)) obtained within a clinically acceptable time. The image protocol was optimized through both simulation and in vivo experiments to obtain the best image quality. Taking advantage of the multiple echoes and high readout bandwidths, no interimage registration is required since all images are produced in one acquisition, and image distortion and chemical shift are reduced. This MRI protocol is expected to mitigate some of the shortcomings of the state-of-the-art DBS implantation methods. Copyright © 2012 Elsevier Inc. All rights reserved.

Liver metastases: imaging considerations for protocol development with Multislice CT (MSCT)

PubMed Central

Silverman, Paul M

2006-01-01

Conventional, single-slice helical computed tomography (SSCT) allowed for scanning the majority of the liver during the critical portal venous phase. This was often referred to as the ‘optimal temporal window’. The introduction of current day multislice CT (MSCT) now allows us to acquire images in a much shorter time and more precisely than ever before. This yields increased conspicuity between low attenuation lesions and the enhanced normal liver parenchyma and optimal imaging for the vast majority of hepatic hypovascular metastases. Most importantly, these scanners, when compared to conventional non-helical scanners, avoid impinging upon the ‘equilibrium’ phase when tumors can become isodense/invisible. MSCT also allows for true multiphase scanning during the arterial and late arterial phases for detection of hypervascular metastases. The MSCT imaging speed has increased significantly over the past years with the introduction of 32- and 64-detector systems and will continue to increase in the future volumetric CT. This provides a number of important gains that are discussed in detail. PMID:17098650

Active SAmpling Protocol (ASAP) to Optimize Individual Neurocognitive Hypothesis Testing: A BCI-Inspired Dynamic Experimental Design.

PubMed

Sanchez, Gaëtan; Lecaignard, Françoise; Otman, Anatole; Maby, Emmanuel; Mattout, Jérémie

2016-01-01

The relatively young field of Brain-Computer Interfaces has promoted the use of electrophysiology and neuroimaging in real-time. In the meantime, cognitive neuroscience studies, which make extensive use of functional exploration techniques, have evolved toward model-based experiments and fine hypothesis testing protocols. Although these two developments are mostly unrelated, we argue that, brought together, they may trigger an important shift in the way experimental paradigms are being designed, which should prove fruitful to both endeavors. This change simply consists in using real-time neuroimaging in order to optimize advanced neurocognitive hypothesis testing. We refer to this new approach as the instantiation of an Active SAmpling Protocol (ASAP). As opposed to classical (static) experimental protocols, ASAP implements online model comparison, enabling the optimization of design parameters (e.g., stimuli) during the course of data acquisition. This follows the well-known principle of sequential hypothesis testing. What is radically new, however, is our ability to perform online processing of the huge amount of complex data that brain imaging techniques provide. This is all the more relevant at a time when physiological and psychological processes are beginning to be approached using more realistic, generative models which may be difficult to tease apart empirically. Based upon Bayesian inference, ASAP proposes a generic and principled way to optimize experimental design adaptively. In this perspective paper, we summarize the main steps in ASAP. Using synthetic data we illustrate its superiority in selecting the right perceptual model compared to a classical design. Finally, we briefly discuss its future potential for basic and clinical neuroscience as well as some remaining challenges.

An anthropomorphic phantom for quantitative evaluation of breast MRI.

PubMed

Freed, Melanie; de Zwart, Jacco A; Loud, Jennifer T; El Khouli, Riham H; Myers, Kyle J; Greene, Mark H; Duyn, Jeff H; Badano, Aldo

2011-02-01

In this study, the authors aim to develop a physical, tissue-mimicking phantom for quantitative evaluation of breast MRI protocols. The objective of this phantom is to address the need for improved standardization in breast MRI and provide a platform for evaluating the influence of image protocol parameters on lesion detection and discrimination. Quantitative comparisons between patient and phantom image properties are presented. The phantom is constructed using a mixture of lard and egg whites, resulting in a random structure with separate adipose- and glandular-mimicking components. T1 and T2 relaxation times of the lard and egg components of the phantom were estimated at 1.5 T from inversion recovery and spin-echo scans, respectively, using maximum-likelihood methods. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of phantom and patient images. A static, enhancing lesion was introduced by creating a hollow mold with stereolithography and filling it with a gadolinium-doped water solution. Measured phantom relaxation values fall within 2 standard errors of human values from the literature and are reasonably stable over 9 months of testing. Comparison of the covariance matrices of phantom and patient data demonstrates that the phantom and patient data have similar image structure. Their covariance matrices are the same to within error bars in the anterior-posterior direction and to within about two error bars in the right-left direction. The signal from the phantom's adipose-mimicking material can be suppressed using active fat-suppression protocols. A static, enhancing lesion can also be included with the ability to change morphology and contrast agent concentration. The authors have constructed a phantom and demonstrated its ability to mimic human breast images in terms of key physical properties that are relevant to breast MRI. This phantom provides a platform for the optimization and standardization of breast MRI imaging protocols for lesion detection and characterization.

Light Sheet Fluorescence Microscopy Quantifies Calcium Oscillations in Root Hairs of Arabidopsis thaliana.

PubMed

Candeo, Alessia; Doccula, Fabrizio G; Valentini, Gianluca; Bassi, Andrea; Costa, Alex

2017-07-01

Calcium oscillations play a role in the regulation of the development of tip-growing plant cells. Using optical microscopy, calcium oscillations have been observed in a few systems (e.g. pollen tubes, fungal hyphae and algal rhizoids). High-resolution, non-phototoxic and rapid imaging methods are required to study the calcium oscillation in root hairs. We show that light sheet fluorescence microscopy is optimal to image growing root hairs of Arabidopsis thaliana and to follow their oscillatory tip-focused calcium gradient. We describe a protocol for performing live imaging of root hairs in seedlings expressing the cytosol-localized ratiometric calcium indicator Yellow Cameleon 3.6. Using this protocol, we measured the calcium gradient in a large number of root hairs. We characterized their calcium oscillations and correlated them with the rate of hair growth. The method was then used to screen the effect of auxin on the properties of the growing root hairs. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

Heterogeneous Optimization Framework: Reproducible Preprocessing of Multi-Spectral Clinical MRI for Neuro-Oncology Imaging Research.

PubMed

Milchenko, Mikhail; Snyder, Abraham Z; LaMontagne, Pamela; Shimony, Joshua S; Benzinger, Tammie L; Fouke, Sarah Jost; Marcus, Daniel S

2016-07-01

Neuroimaging research often relies on clinically acquired magnetic resonance imaging (MRI) datasets that can originate from multiple institutions. Such datasets are characterized by high heterogeneity of modalities and variability of sequence parameters. This heterogeneity complicates the automation of image processing tasks such as spatial co-registration and physiological or functional image analysis. Given this heterogeneity, conventional processing workflows developed for research purposes are not optimal for clinical data. In this work, we describe an approach called Heterogeneous Optimization Framework (HOF) for developing image analysis pipelines that can handle the high degree of clinical data non-uniformity. HOF provides a set of guidelines for configuration, algorithm development, deployment, interpretation of results and quality control for such pipelines. At each step, we illustrate the HOF approach using the implementation of an automated pipeline for Multimodal Glioma Analysis (MGA) as an example. The MGA pipeline computes tissue diffusion characteristics of diffusion tensor imaging (DTI) acquisitions, hemodynamic characteristics using a perfusion model of susceptibility contrast (DSC) MRI, and spatial cross-modal co-registration of available anatomical, physiological and derived patient images. Developing MGA within HOF enabled the processing of neuro-oncology MR imaging studies to be fully automated. MGA has been successfully used to analyze over 160 clinical tumor studies to date within several research projects. Introduction of the MGA pipeline improved image processing throughput and, most importantly, effectively produced co-registered datasets that were suitable for advanced analysis despite high heterogeneity in acquisition protocols.

Using connectome-based predictive modeling to predict individual behavior from brain connectivity

PubMed Central

Shen, Xilin; Finn, Emily S.; Scheinost, Dustin; Rosenberg, Monica D.; Chun, Marvin M.; Papademetris, Xenophon; Constable, R Todd

2017-01-01

Neuroimaging is a fast developing research area where anatomical and functional images of human brains are collected using techniques such as functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), and electroencephalography (EEG). Technical advances and large-scale datasets have allowed for the development of models capable of predicting individual differences in traits and behavior using brain connectivity measures derived from neuroimaging data. Here, we present connectome-based predictive modeling (CPM), a data-driven protocol for developing predictive models of brain-behavior relationships from connectivity data using cross-validation. This protocol includes the following steps: 1) feature selection, 2) feature summarization, 3) model building, and 4) assessment of prediction significance. We also include suggestions for visualizing the most predictive features (i.e., brain connections). The final result should be a generalizable model that takes brain connectivity data as input and generates predictions of behavioral measures in novel subjects, accounting for a significant amount of the variance in these measures. It has been demonstrated that the CPM protocol performs equivalently or better than most of the existing approaches in brain-behavior prediction. However, because CPM focuses on linear modeling and a purely data-driven driven approach, neuroscientists with limited or no experience in machine learning or optimization would find it easy to implement the protocols. Depending on the volume of data to be processed, the protocol can take 10–100 minutes for model building, 1–48 hours for permutation testing, and 10–20 minutes for visualization of results. PMID:28182017

Prediction of canned black bean texture (Phaseolus vulgaris L.) from intact dry seeds using visible/near-infrared spectroscopy and hyperspectral imaging data

USDA-ARS?s Scientific Manuscript database

BACKGROUND: Texture is a major quality parameter for the acceptability of canned whole beans. Prior knowledge of this quality trait before processing would be useful to guide variety development by bean breeders and optimize handling protocols by processors. The objective of this study was to evalua...

Capillary electrophoretic separation-based approach to determine the labeling kinetics of oligodeoxynucleotides

PubMed Central

Kanavarioti, Anastassia; Greenman, Kevin L.; Hamalainen, Mark; Jain, Aakriti; Johns, Adam M.; Melville, Chris R.; Kemmish, Kent; Andregg, William

2014-01-01

With the recent advances in electron microscopy (EM), computation, and nanofabrication, the original idea of reading DNA sequence directly from an image can now be tested. One approach is to develop heavy atom labels that can provide the contrast required for EM imaging. While evaluating tentative labels for the respective nucleobases in synthetic oligodeoxynucleotides (oligos), we developed a streamlined capillary electrophoresis (CE) protocol to assess the label stability, reactivity, and selectivity. We report our protocol using osmium tetroxide 2,2′-bipyridine (Osbipy) as a thymidine (T) specific label. The observed rates show that the labeling process is kinetically independent of both the oligo length, and the base composition. The conditions, i.e. temperature, optimal Osbipy concentration, and molar ratio of reagents, to promote 100% conversion of the starting oligo to labeled product were established. Hence the optimized conditions developed with the oligos could be leveraged to allow osmylation of effectively all Ts in single-stranded (ss) DNA, while achieving minimal mislabeling. In addition, the approach and methods employed here may be adapted to the evaluation of other prospective contrasting agents/labels to facilitate next-generation DNA sequencing by EM. PMID:23147698

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

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Assessment of hemodynamics in a rat model of liver cirrhosis with precancerous lesions using multislice spiral CT perfusion imaging.

PubMed

Ma, Guolin; Bai, Rongjie; Jiang, Huijie; Hao, Xuejia; Ling, Zaisheng; Li, Kefeng

2013-01-01

To develop an optimal scanning protocol for multislice spiral CT perfusion (CTP) imaging to evaluate hemodynamic changes in liver cirrhosis with diethylnitrosamine- (DEN-) induced precancerous lesions. Male Wistar rats were randomly divided into the control group (n = 80) and the precancerous liver cirrhosis group (n = 40). The control group received saline injection and the liver cirrhosis group received 50 mg/kg DEN i.p. twice a week for 12 weeks. All animals underwent plain CT scanning, CTP, and contrast-enhanced CT scanning. Scanning parameters were optimized by adjusting the diatrizoate concentration, the flow rate, and the delivery time. The hemodynamics of both groups was further compared using optimized multislice spiral CTP imaging. High-quality CTP images were obtained with following parameters: 150 kV; 150 mAs; 5 mm thickness, 5 mm interval; pitch, 1; matrix, 512 × 512; and FOV, 9.6 cm. Compared to the control group, the liver cirrhosis group had a significantly increased value of the hepatic arterial fraction and the hepatic artery perfusion (P < 0.05) but significantly decreased hepatic portal perfusion and mean transit time (P < 0.05). Multislice spiral CTP imaging can be used to evaluate the hemodynamic changes in the rat model of liver cirrhosis with precancerous lesions.

Abdominal MR imaging in children: motion compensation, sequence optimization, and protocol organization.

PubMed

Chavhan, Govind B; Babyn, Paul S; Vasanawala, Shreyas S

2013-05-01

Familiarity with basic sequence properties and their trade-offs is necessary for radiologists performing abdominal magnetic resonance (MR) imaging. Acquiring diagnostic-quality MR images in the pediatric abdomen is challenging due to motion, inability to breath hold, varying patient size, and artifacts. Motion-compensation techniques (eg, respiratory gating, signal averaging, suppression of signal from moving tissue, swapping phase- and frequency-encoding directions, use of faster sequences with breath holding, parallel imaging, and radial k-space filling) can improve image quality. Each of these techniques is more suitable for use with certain sequences and acquisition planes and in specific situations and age groups. Different T1- and T2-weighted sequences work better in different age groups and with differing acquisition planes and have specific advantages and disadvantages. Dynamic imaging should be performed differently in younger children than in older children. In younger children, the sequence and the timing of dynamic phases need to be adjusted. Different sequences work better in smaller children and in older children because of differing breath-holding ability, breathing patterns, field of view, and use of sedation. Hence, specific protocols should be maintained for younger children and older children. Combining longer-higher-resolution sequences and faster-lower-resolution sequences helps acquire diagnostic-quality images in a reasonable time. © RSNA, 2013.

Use of a web-based image reporting and tracking system for assessing abdominal imaging examination quality issues in a single practice.

PubMed

Rosenkrantz, Andrew B; Johnson, Evan; Sanger, Joseph J

2015-10-01

This article presents our local experience in the implementation of a real-time web-based system for reporting and tracking quality issues relating to abdominal imaging examinations. This system allows radiologists to electronically submit examination quality issues during clinical readouts. The submitted information is e-mailed to a designate for the given modality for further follow-up; the designate may subsequently enter text describing their response or action taken, which is e-mailed back to the radiologist. Review of 558 entries over a 6-year period demonstrated documentation of a broad range of examination quality issues, including specific issues relating to protocol deviation, post-processing errors, positioning errors, artifacts, and IT concerns. The most common issues varied among US, CT, MRI, radiography, and fluoroscopy. In addition, the most common issues resulting in a patient recall for repeat imaging (generally related to protocol deviation in MRI and US) were identified. In addition to submitting quality problems, radiologists also commonly used the tool to provide recognition of a well-performed examination. An electronic log of actions taken in response to radiologists' submissions indicated that both positive and negative feedback were commonly communicated to the performing technologist. Information generated using the tool can be used to guide subsequent quality improvement initiatives within a practice, including continued protocol standardization as well as education of technologists in the optimization of abdominal imaging examinations.

Study of the development of fetal baboon brain using magnetic resonance imaging at 3 Tesla

PubMed Central

Liu, Feng; Garland, Marianne; Duan, Yunsuo; Stark, Raymond I.; Xu, Dongrong; Dong, Zhengchao; Bansal, Ravi; Peterson, Bradley S.; Kangarlu, Alayar

2008-01-01

Direct observational data on the development of the brains of human and nonhuman primates is on remarkably scant, and most of our understanding of primate brain development is extrapolated from findings in rodent models. Magnetic resonance imaging (MRI) is a promising tool for the noninvasive, longitudinal study of the developing primate brain. We devised a protocol to scan pregnant baboons serially at 3 T for up to 3 h per session. Seven baboons were scanned 1–6 times, beginning as early as 56 days post-conceptional age, and as late as 185 days (term ~185 days). Successful scanning of the fetal baboon required careful animal preparation and anesthesia, in addition to optimization of the scanning protocol. We successfully acquired maps of relaxation times (T1 and T2) and high-resolution anatomical images of the brains of fetal baboons at multiple time points during the course of gestation. These images demonstrated the convergence of gray and white matter contrast near term, and furthermore demonstrated that the loss of contrast at that age is a consequence of the continuous change in relaxation times during fetal brain development. These data furthermore demonstrate that maps of relaxation times have clear advantages over the relaxation time weighted images for the tracking of the changes in brain structure during fetal development. This protocol for in utero MRI of fetal baboon brains will help to advance the use of nonhuman primate models to study fetal brain development longitudinally. PMID:18155925

Dedicated mobile volumetric cone-beam computed tomography for human brain imaging: A phantom study.

PubMed

Ryu, Jong-Hyun; Kim, Tae-Hoon; Jeong, Chang-Won; Jun, Hong-Young; Heo, Dong-Woon; Lee, Jinseok; Kim, Kyong-Woo; Yoon, Kwon-Ha

2015-01-01

Mobile computed tomography (CT) with a cone-beam source is increasingly used in the clinical field. Mobile cone-beam CT (CBCT) has great merits; however, its clinical utility for brain imaging has been limited due to problems including scan time and image quality. The aim of this study was to develop a dedicated mobile volumetric CBCT for obtaining brain images, and to optimize the imaging protocol using a brain phantom. The mobile volumetric CBCT system was evaluated with regards to scan time and image quality, measured as signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), spatial resolution (10% MTF), and effective dose. Brain images were obtained using a CT phantom. The CT scan took 5.14 s at 360 projection views. SNR and CNR were 5.67 and 14.5 at 120 kV/10 mA. SNR and CNR values showed slight improvement as the x-ray voltage and current increased (p < 0.001). Effective dose and 10% MTF were 0.92 mSv and 360 μ m at 120 kV/10 mA. Various intracranial structures were clearly visible in the brain phantom images. Using this CBCT under optimal imaging acquisition conditions, it is possible to obtain human brain images with low radiation dose, reproducible image quality, and fast scan time.

Multiphase contrast medium injection for optimization of computed tomographic coronary angiography.

PubMed

Budoff, Matthew Jay; Shinbane, Jerold S; Child, Janis; Carson, Sivi; Chau, Alex; Liu, Stephen H; Mao, SongShou

2006-02-01

Electron beam angiography is a minimally invasive imaging technique. Adequate vascular opacification throughout the study remains a critical issue for image quality. We hypothesized that vascular image opacification and uniformity of vascular enhancement between slices can be improved using multiphase contrast medium injection protocols. We enrolled 244 consecutive patients who were randomized to three different injection protocols: single-phase contrast medium injection (Group 1), dual-phase contrast medium injection with each phase at a different injection rate (Group 2), and a three-phase injection with two phases of contrast medium injection followed by a saline injection phase (Group 3). Parameters measured were aortic opacification based on Hounsfield units and uniformity of aortic enhancement at predetermined slices (locations from top [level 1] to base [level 60]). In Group 1, contrast opacification differed across seven predetermined locations (scan levels: 1st versus 60th, P < .05), demonstrating significant nonuniformity. In Group 2, there was more uniform vascular enhancement, with no significant differences between the first 50 slices (P > .05). In Group 3, there was greater uniformity of vascular enhancement and higher mean Hounsfield units value across all 60 images, from the aortic root to the base of the heart (P < .05). The three-phase injection protocol improved vascular opacification at the base of the heart, as well as uniformity of arterial enhancement throughout the study.

Improving cerebellar segmentation with statistical fusion

NASA Astrophysics Data System (ADS)

Plassard, Andrew J.; Yang, Zhen; Prince, Jerry L.; Claassen, Daniel O.; Landman, Bennett A.

2016-03-01

The cerebellum is a somatotopically organized central component of the central nervous system well known to be involved with motor coordination and increasingly recognized roles in cognition and planning. Recent work in multiatlas labeling has created methods that offer the potential for fully automated 3-D parcellation of the cerebellar lobules and vermis (which are organizationally equivalent to cortical gray matter areas). This work explores the trade offs of using different statistical fusion techniques and post hoc optimizations in two datasets with distinct imaging protocols. We offer a novel fusion technique by extending the ideas of the Selective and Iterative Method for Performance Level Estimation (SIMPLE) to a patch-based performance model. We demonstrate the effectiveness of our algorithm, Non- Local SIMPLE, for segmentation of a mixed population of healthy subjects and patients with severe cerebellar anatomy. Under the first imaging protocol, we show that Non-Local SIMPLE outperforms previous gold-standard segmentation techniques. In the second imaging protocol, we show that Non-Local SIMPLE outperforms previous gold standard techniques but is outperformed by a non-locally weighted vote with the deeper population of atlases available. This work advances the state of the art in open source cerebellar segmentation algorithms and offers the opportunity for routinely including cerebellar segmentation in magnetic resonance imaging studies that acquire whole brain T1-weighted volumes with approximately 1 mm isotropic resolution.

Optimizing radiation exposure in screening of body packing: image quality and diagnostic acceptability of an 80 kVp protocol with automated tube current modulation.

PubMed

Aissa, Joel; Boos, Johannes; Rubbert, Christian; Caspers, Julian; Schleich, Christoph; Thomas, Christoph; Kröpil, Patric; Antoch, Gerald; Miese, Falk

2017-06-01

The aim of this study was to evaluate the objective and subjective image quality of a novel computed tomography (CT) protocol with reduced radiation dose for body packing with 80 kVp and automated tube current modulation (ATCM) compared to a standard body packing CT protocol. 80 individuals who were examined between March 2012 and July 2015 in suspicion of ingested drug packets were retrospectively included in this study. Thirty-one CT examinations were performed using ATCM and a fixed tube voltage of 80 kVp (group A). Forty-nine CT examinations were performed using a standard protocol with a tube voltage of 120 kVp and a fixed tube current time product of 40 mAs (group B). Subjective and objective image quality and visibility of drug packets were assessed. Radiation exposure of both protocols was compared. Contrast-to-noise ratio (group A: 0.56 ± 0.36; group B: 1.13 ± 0.91) and Signal-to-noise ratio (group A: 3.69 ± 0.98; group B: 7.08 ± 2.67) were significantly lower for group A compared to group B (p < 0.001). Subjectively, image quality was decreased for group A compared to group B (2.5 ± 0.8 vs. 1.2 ± 0.4; p < 0.001). Attenuation of body packets was higher with the new protocol (group A: 362.2 ± 70.3 Hounsfield Units (HU); group B: 210.6 ± 60.2 HU; p = 0.005). Volumetric Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) were significantly lower in group A (CTDIvol 2.2 ± 0.9 mGy, DLP 105.7 ± 52.3 mGycm) as compared to group B (CTDIvol 2.7 ± 0.1 mGy, DLP 126.0 ± 9.7 mGycm, p = 0.002 and p = 0.01). The novel 80 kVp CT protocol with ATCM leads to a significant dose reduction compared to a standard CT body packing protocol. The novel protocol led to a diagnostic image quality and cocaine body packets were reliably detected due to the high attenuation.

Numerical simulation of the optimal two-mode attacks for two-way continuous-variable quantum cryptography in reverse reconciliation

NASA Astrophysics Data System (ADS)

Zhang, Yichen; Li, Zhengyu; Zhao, Yijia; Yu, Song; Guo, Hong

2017-02-01

We analyze the security of the two-way continuous-variable quantum key distribution protocol in reverse reconciliation against general two-mode attacks, which represent all accessible attacks at fixed channel parameters. Rather than against one specific attack model, the expression of secret key rates of the two-way protocol are derived against all accessible attack models. It is found that there is an optimal two-mode attack to minimize the performance of the protocol in terms of both secret key rates and maximal transmission distances. We identify the optimal two-mode attack, give the specific attack model of the optimal two-mode attack and show the performance of the two-way protocol against the optimal two-mode attack. Even under the optimal two-mode attack, the performances of two-way protocol are still better than the corresponding one-way protocol, which shows the advantage of making double use of the quantum channel and the potential of long-distance secure communication using a two-way protocol.

A technique for multi-dimensional optimization of radiation dose, contrast dose, and image quality in CT imaging

NASA Astrophysics Data System (ADS)

Sahbaee, Pooyan; Abadi, Ehsan; Sanders, Jeremiah; Becchetti, Marc; Zhang, Yakun; Agasthya, Greeshma; Segars, Paul; Samei, Ehsan

2016-03-01

The purpose of this study was to substantiate the interdependency of image quality, radiation dose, and contrast material dose in CT towards the patient-specific optimization of the imaging protocols. The study deployed two phantom platforms. First, a variable sized phantom containing an iodinated insert was imaged on a representative CT scanner at multiple CTDI values. The contrast and noise were measured from the reconstructed images for each phantom diameter. Linearly related to iodine-concentration, contrast to noise ratio (CNR), was calculated for different iodine-concentration levels. Second, the analysis was extended to a recently developed suit of 58 virtual human models (5D-XCAT) with added contrast dynamics. Emulating a contrast-enhanced abdominal image procedure and targeting a peak-enhancement in aorta, each XCAT phantom was "imaged" using a CT simulation platform. 3D surfaces for each patient/size established the relationship between iodine-concentration, dose, and CNR. The Sensitivity of Ratio (SR), defined as ratio of change in iodine-concentration versus dose to yield a constant change in CNR was calculated and compared at high and low radiation dose for both phantom platforms. The results show that sensitivity of CNR to iodine concentration is larger at high radiation dose (up to 73%). The SR results were highly affected by radiation dose metric; CTDI or organ dose. Furthermore, results showed that the presence of contrast material could have a profound impact on optimization results (up to 45%).

Optimization of White-Matter-Nulled Magnetization Prepared Rapid Gradient Echo (MP-RAGE) Imaging

PubMed Central

Saranathan, Manojkumar; Tourdias, Thomas; Bayram, Ersin; Ghanouni, Pejman; Rutt, Brian K.

2014-01-01

Purpose To optimize the white-matter-nulled (WMn) Magnetization Prepared Rapid Gradient Echo (MP-RAGE) sequence at 7T, with comparisons to 3T. Methods Optimal parameters for maximising SNR efficiency were derived. The effect of flip angle and TR on image blurring was modeled using simulations and validated in vivo. A novel 2D-centric radial fan beam (RFB) k-space segmentation scheme was used to shorten scan times and improve parallel imaging. Healthy subjects as well as patients with multiple sclerosis and tremor were scanned using the optimized protocols. Results Inversion repetition times (TS) of 4.5s and 6s were found to yield the highest SNR efficiency for WMn MP-RAGE at 3T and 7T, respectively. Blurring was more sensitive to flip in WMn than in CSFn MP-RAGE and relatively insensitive to TR for both regimes. The 2D RFB scheme had 19% and 47% higher thalamic SNR and SNR efficiency than the 1D centric scheme for WMn MP-RAGE. Compared to 3T, SNR and SNR efficiency were higher for the 7T WMn regime by 56% and 41% respectively. MS lesions in the cortex and thalamus as well as thalamic subnuclei in tremor patients were clearly delineated using WMn MP-RAGE. Conclusion Optimization and new view ordering enabled MP-RAGE imaging with 0.8–1 mm3 isotropic spatial resolution in scan times of 5 minutes with whole brain coverage. PMID:24889754

MO-C-18A-01: Advances in Model-Based 3D Image Reconstruction

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

Chen, G; Pan, X; Stayman, J

2014-06-15

Recent years have seen the emergence of CT image reconstruction techniques that exploit physical models of the imaging system, photon statistics, and even the patient to achieve improved 3D image quality and/or reduction of radiation dose. With numerous advantages in comparison to conventional 3D filtered backprojection, such techniques bring a variety of challenges as well, including: a demanding computational load associated with sophisticated forward models and iterative optimization methods; nonlinearity and nonstationarity in image quality characteristics; a complex dependency on multiple free parameters; and the need to understand how best to incorporate prior information (including patient-specific prior images) within themore » reconstruction process. The advantages, however, are even greater – for example: improved image quality; reduced dose; robustness to noise and artifacts; task-specific reconstruction protocols; suitability to novel CT imaging platforms and noncircular orbits; and incorporation of known characteristics of the imager and patient that are conventionally discarded. This symposium features experts in 3D image reconstruction, image quality assessment, and the translation of such methods to emerging clinical applications. Dr. Chen will address novel methods for the incorporation of prior information in 3D and 4D CT reconstruction techniques. Dr. Pan will show recent advances in optimization-based reconstruction that enable potential reduction of dose and sampling requirements. Dr. Stayman will describe a “task-based imaging” approach that leverages models of the imaging system and patient in combination with a specification of the imaging task to optimize both the acquisition and reconstruction process. Dr. Samei will describe the development of methods for image quality assessment in such nonlinear reconstruction techniques and the use of these methods to characterize and optimize image quality and dose in a spectrum of clinical applications. Learning Objectives: Learn the general methodologies associated with model-based 3D image reconstruction. Learn the potential advantages in image quality and dose associated with model-based image reconstruction. Learn the challenges associated with computational load and image quality assessment for such reconstruction methods. Learn how imaging task can be incorporated as a means to drive optimal image acquisition and reconstruction techniques. Learn how model-based reconstruction methods can incorporate prior information to improve image quality, ease sampling requirements, and reduce dose.« less

Effectiveness of a Rapid Lumbar Spine MRI Protocol Using 3D T2-Weighted SPACE Imaging Versus a Standard Protocol for Evaluation of Degenerative Changes of the Lumbar Spine.

PubMed

Sayah, Anousheh; Jay, Ann K; Toaff, Jacob S; Makariou, Erini V; Berkowitz, Frank

2016-09-01

Reducing lumbar spine MRI scanning time while retaining diagnostic accuracy can benefit patients and reduce health care costs. This study compares the effectiveness of a rapid lumbar MRI protocol using 3D T2-weighted sampling perfection with application-optimized contrast with different flip-angle evolutions (SPACE) sequences with a standard MRI protocol for evaluation of lumbar spondylosis. Two hundred fifty consecutive unenhanced lumbar MRI examinations performed at 1.5 T were retrospectively reviewed. Full, rapid, and complete versions of each examination were interpreted for spondylotic changes at each lumbar level, including herniations and neural compromise. The full examination consisted of sagittal T1-weighted, T2-weighted turbo spin-echo (TSE), and STIR sequences; and axial T1- and T2-weighted TSE sequences (time, 18 minutes 40 seconds). The rapid examination consisted of sagittal T1- and T2-weighted SPACE sequences, with axial SPACE reformations (time, 8 minutes 46 seconds). The complete examination consisted of the full examination plus the T2-weighted SPACE sequence. Sensitivities and specificities of the full and rapid examinations were calculated using the complete study as the reference standard. The rapid and full studies had sensitivities of 76.0% and 69.3%, with specificities of 97.2% and 97.9%, respectively, for all degenerative processes. Rapid and full sensitivities were 68.7% and 66.3% for disk herniation, 85.2% and 81.5% for canal compromise, 82.9% and 69.1% for lateral recess compromise, and 76.9% and 69.7% for foraminal compromise, respectively. Isotropic SPACE T2-weighted imaging provides high-quality imaging of lumbar spondylosis, with multiplanar reformatting capability. Our SPACE-based rapid protocol had sensitivities and specificities for herniations and neural compromise comparable to those of the protocol without SPACE. This protocol fits within a 15-minute slot, potentially reducing costs and discomfort for a large subgroup of patients.

Phase Transition in Protocols Minimizing Work Fluctuations

NASA Astrophysics Data System (ADS)

Solon, Alexandre P.; Horowitz, Jordan M.

2018-05-01

For two canonical examples of driven mesoscopic systems—a harmonically trapped Brownian particle and a quantum dot—we numerically determine the finite-time protocols that optimize the compromise between the standard deviation and the mean of the dissipated work. In the case of the oscillator, we observe a collection of protocols that smoothly trade off between average work and its fluctuations. However, for the quantum dot, we find that as we shift the weight of our optimization objective from average work to work standard deviation, there is an analog of a first-order phase transition in protocol space: two distinct protocols exchange global optimality with mixed protocols akin to phase coexistence. As a result, the two types of protocols possess qualitatively different properties and remain distinct even in the infinite duration limit: optimal-work-fluctuation protocols never coalesce with the minimal-work protocols, which therefore never become quasistatic.

Preservation of three-dimensional spatial structure in the gut microbiome.

PubMed

Hasegawa, Yuko; Mark Welch, Jessica L; Rossetti, Blair J; Borisy, Gary G

2017-01-01

Preservation of three-dimensional structure in the gut is necessary in order to analyze the spatial organization of the gut microbiota and gut luminal contents. In this study, we evaluated preparation methods for mouse gut with the goal of preserving micron-scale spatial structure while performing fluorescence imaging assays. Our evaluation of embedding methods showed that commonly used media such as Tissue-Tek Optimal Cutting Temperature (OCT) compound, paraffin, and polyester waxes resulted in redistribution of luminal contents. By contrast, a hydrophilic methacrylate resin, Technovit H8100, preserved three-dimensional organization. Our mouse intestinal preparation protocol optimized using the Technovit H8100 embedding method was compatible with microbial fluorescence in situ hybridization (FISH) and other labeling techniques, including immunostaining and staining with both wheat germ agglutinin (WGA) and 4', 6-diamidino-2-phenylindole (DAPI). Mucus could be visualized whether the sample was fixed with paraformaldehyde (PFA) or with Carnoy's fixative. The protocol optimized in this study enabled simultaneous visualization of micron-scale spatial patterns formed by microbial cells in the mouse intestines along with biogeographical landmarks such as host-derived mucus and food particles.

Low-Contrast and Low-Radiation Dose Protocol in Cardiac Computed Tomography: Usefulness of Low Tube Voltage and Knowledge-Based Iterative Model Reconstruction Algorithm.

PubMed

Iyama, Yuji; Nakaura, Takeshi; Yokoyama, Koichi; Kidoh, Masafumi; Harada, Kazunori; Oda, Seitaro; Tokuyasu, Shinichi; Yamashita, Yasuyuki

This study aimed to evaluate the feasibility of a low contrast, low-radiation dose protocol of 80-peak kilovoltage (kVp) with prospective electrocardiography-gated cardiac computed tomography (CT) using knowledge-based iterative model reconstruction (IMR). Thirty patients underwent an 80-kVp prospective electrocardiography-gated cardiac CT with low-contrast agent (222-mg iodine per kilogram of body weight) dose. We also enrolled 30 consecutive patients who were scanned with a 120-kVp cardiac CT with filtered back projection using the standard contrast agent dose (370-mg iodine per kilogram of body weight) as a historical control group. We evaluated the radiation dose for the 2 groups. The 80-kVp images were reconstructed with filtered back projection (protocol A), hybrid iterative reconstruction (HIR, protocol B), and IMR (protocol C). We compared CT numbers, image noise, and contrast-to-noise ratio among 120-kVp protocol, protocol A, protocol B, and protocol C. In addition, we compared the noise reduction rate between HIR and IMR. Two independent readers compared image contrast, image noise, image sharpness, unfamiliar image texture, and overall image quality among the 4 protocols. The estimated effective dose (ED) of the 80-kVp protocol was 74% lower than that of the 120-kVp protocol (1.4 vs 5.4 mSv). The contrast-to-noise ratio of protocol C was significantly higher than that of protocol A. The noise reduction rate of IMR was significantly higher than that of HIR (P < 0.01). There was no significant difference in almost all qualitative image quality between 120-kVp protocol and protocol C except for image contrast. A 80-kVp protocol with IMR yields higher image quality with 74% decreased radiation dose and 40% decreased contrast agent dose as compared with a 120-kVp protocol, while decreasing more image noise compared with the 80-kVp protocol with HIR.

A simple procedure to analyze positions of interest in infectious cell cultures by correlative light and electron microscopy.

PubMed

Madela, Kazimierz; Banhart, Sebastian; Zimmermann, Anja; Piesker, Janett; Bannert, Norbert; Laue, Michael

2014-01-01

Plastic cell culture dishes that contain a thin bottom of highest optical quality including an imprinted finder grid (μ-Dish Grid-500) are optimally suited for routine correlative light and electron microscopy using chemical fixation. Such dishes allow high-resolution fluorescence and bright-field imaging using fixed and living cells and are compatible with standard protocols for scanning and transmission electron microscopy. Ease of use during cell culture and imaging, as well as a tight cover render the dishes particularly suitable for working with infectious organisms up to the highest biosafety level. Detailed protocols are provided and demonstrated by showing two examples: monitoring the production of virus-like particles of the Human Endogenous Retrovirus HERV-K(HML-2) by HeLa cells and investigation of Rab11-positive membrane-compartments of HeLa cells after infection with Chlamydia trachomatis. © 2014 Elsevier Inc. All rights reserved.

Short Term Reproducibility of a High Contrast 3-D Isotropic Optic Nerve Imaging Sequence in Healthy Controls.

PubMed

Harrigan, Robert L; Smith, Alex K; Mawn, Louise A; Smith, Seth A; Landman, Bennett A

2016-02-27

The optic nerve (ON) plays a crucial role in human vision transporting all visual information from the retina to the brain for higher order processing. There are many diseases that affect the ON structure such as optic neuritis, anterior ischemic optic neuropathy and multiple sclerosis. Because the ON is the sole pathway for visual information from the retina to areas of higher level processing, measures of ON damage have been shown to correlate well with visual deficits. Increased intracranial pressure has been shown to correlate with the size of the cerebrospinal fluid (CSF) surrounding the ON. These measures are generally taken at an arbitrary point along the nerve and do not account for changes along the length of the ON. We propose a high contrast and high-resolution 3-D acquired isotropic imaging sequence optimized for ON imaging. We have acquired scan-rescan data using the optimized sequence and a current standard of care protocol for 10 subjects. We show that this sequence has superior contrast-to-noise ratio to the current standard of care while achieving a factor of 11 higher resolution. We apply a previously published automatic pipeline to segment the ON and CSF sheath and measure the size of each individually. We show that these measures of ON size have lower short-term reproducibility than the population variance and the variability along the length of the nerve. We find that the proposed imaging protocol is (1) useful in detecting population differences and local changes and (2) a promising tool for investigating biomarkers related to structural changes of the ON.

Short term reproducibility of a high contrast 3-D isotropic optic nerve imaging sequence in healthy controls

NASA Astrophysics Data System (ADS)

Harrigan, Robert L.; Smith, Alex K.; Mawn, Louise A.; Smith, Seth A.; Landman, Bennett A.

2016-03-01

The optic nerve (ON) plays a crucial role in human vision transporting all visual information from the retina to the brain for higher order processing. There are many diseases that affect the ON structure such as optic neuritis, anterior ischemic optic neuropathy and multiple sclerosis. Because the ON is the sole pathway for visual information from the retina to areas of higher level processing, measures of ON damage have been shown to correlate well with visual deficits. Increased intracranial pressure has been shown to correlate with the size of the cerebrospinal fluid (CSF) surrounding the ON. These measures are generally taken at an arbitrary point along the nerve and do not account for changes along the length of the ON. We propose a high contrast and high-resolution 3-D acquired isotropic imaging sequence optimized for ON imaging. We have acquired scan-rescan data using the optimized sequence and a current standard of care protocol for 10 subjects. We show that this sequence has superior contrast-to-noise ratio to the current standard of care while achieving a factor of 11 higher resolution. We apply a previously published automatic pipeline to segment the ON and CSF sheath and measure the size of each individually. We show that these measures of ON size have lower short- term reproducibility than the population variance and the variability along the length of the nerve. We find that the proposed imaging protocol is (1) useful in detecting population differences and local changes and (2) a promising tool for investigating biomarkers related to structural changes of the ON.

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

Lakshminarayan, Raghuram, E-mail: raghuram.lakshminarayan@hey.nhs.u; Simpson, James O.; Ettles, Duncan F., E-mail: Duncan.Ettles@hey.nhs.u

Magnetic resonance angiography (MRA) has become an established imaging modality in the management of lower-limb arterial disease, with emerging roles in treatment planning and follow-up. Contrast-enhanced MRA is now the most widely used technique with clinically acceptable results in the majority of patients. Difficulties in imaging and image interpretation are recognised in certain subgroups, including patients with critical limb ischaemia as well as patients with stents. Although newer contrast agents and refined imaging protocols may offer some solutions to these problems, this optimism is balanced by concerns about the toxicity of certain gadolinium chelates. Further development of interventional MRA remainsmore » one of the most significant challenges in the development of magnetic resonance imaging-guided peripheral vascular intervention. The status of MRA in managing patients with lower-limb arterial disease in current clinical practice is reviewed.« less

Live-cell imaging of budding yeast telomerase RNA and TERRA.

PubMed

Laprade, Hadrien; Lalonde, Maxime; Guérit, David; Chartrand, Pascal

2017-02-01

In most eukaryotes, the ribonucleoprotein complex telomerase is responsible for maintaining telomere length. In recent years, single-cell microscopy techniques such as fluorescent in situ hybridization and live-cell imaging have been developed to image the RNA subunit of the telomerase holoenzyme. These techniques are now becoming important tools for the study of telomerase biogenesis, its association with telomeres and its regulation. Here, we present detailed protocols for live-cell imaging of the Saccharomyces cerevisiae telomerase RNA subunit, called TLC1, and also of the non-coding telomeric repeat-containing RNA TERRA. We describe the approach used for genomic integration of MS2 stem-loops in these transcripts, and provide information for optimal live-cell imaging of these non-coding RNAs. Copyright © 2016 Elsevier Inc. All rights reserved.

Multi-pass transmission electron microscopy

DOE PAGES

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.; ...

2017-05-10

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Spectral optimization for micro-CT.

PubMed

Hupfer, Martin; Nowak, Tristan; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A

2012-06-01

To optimize micro-CT protocols with respect to x-ray spectra and thereby reduce radiation dose at unimpaired image quality. Simulations were performed to assess image contrast, noise, and radiation dose for different imaging tasks. The figure of merit used to determine the optimal spectrum was the dose-weighted contrast-to-noise ratio (CNRD). Both optimal photon energy and tube voltage were considered. Three different types of filtration were investigated for polychromatic x-ray spectra: 0.5 mm Al, 3.0 mm Al, and 0.2 mm Cu. Phantoms consisted of water cylinders of 20, 32, and 50 mm in diameter with a central insert of 9 mm which was filled with different contrast materials: an iodine-based contrast medium (CM) to mimic contrast-enhanced (CE) imaging, hydroxyapatite to mimic bone structures, and water with reduced density to mimic soft tissue contrast. Validation measurements were conducted on a commercially available micro-CT scanner using phantoms consisting of water-equivalent plastics. Measurements on a mouse cadaver were performed to assess potential artifacts like beam hardening and to further validate simulation results. The optimal photon energy for CE imaging was found at 34 keV. For bone imaging, optimal energies were 17, 20, and 23 keV for the 20, 32, and 50 mm phantom, respectively. For density differences, optimal energies varied between 18 and 50 keV for the 20 and 50 mm phantom, respectively. For the 32 mm phantom and density differences, CNRD was found to be constant within 2.5% for the energy range of 21-60 keV. For polychromatic spectra and CMs, optimal settings were 50 kV with 0.2 mm Cu filtration, allowing for a dose reduction of 58% compared to the optimal setting for 0.5 mm Al filtration. For bone imaging, optimal tube voltages were below 35 kV. For soft tissue imaging, optimal tube settings strongly depended on phantom size. For 20 mm, low voltages were preferred. For 32 mm, CNRD was found to be almost independent of tube voltage. For 50 mm, voltages larger than 50 kV were preferred. For all three phantom sizes stronger filtration led to notable dose reduction for soft tissue imaging. Validation measurements were found to match simulations well, with deviations being less than 10%. Mouse measurements confirmed simulation results. Optimal photon energies and tube settings strongly depend on both phantom size and imaging task at hand. For in vivo CE imaging and density differences, strong filtration and voltages of 50-65 kV showed good overall results. For soft tissue imaging of animals the size of a rat or larger, voltages higher than 65 kV allow to greatly reduce scan times while maintaining dose efficiency. For imaging of bone structures, usage of only minimum filtration and low tube voltages of 40 kV and below allow exploiting the high contrast of bone at very low energies. Therefore, a combination of two filtrations could prove beneficial for micro-CT: a soft filtration allowing for bone imaging at low voltages, and a variable stronger filtration (e.g., 0.2 mm Cu) for soft tissue and contrast-enhanced imaging. © 2012 American Association of Physicists in Medicine.

An Adaptive Cultural Algorithm with Improved Quantum-behaved Particle Swarm Optimization for Sonar Image Detection.

PubMed

Wang, Xingmei; Hao, Wenqian; Li, Qiming

2017-12-18

This paper proposes an adaptive cultural algorithm with improved quantum-behaved particle swarm optimization (ACA-IQPSO) to detect the underwater sonar image. In the population space, to improve searching ability of particles, iterative times and the fitness value of particles are regarded as factors to adaptively adjust the contraction-expansion coefficient of the quantum-behaved particle swarm optimization algorithm (QPSO). The improved quantum-behaved particle swarm optimization algorithm (IQPSO) can make particles adjust their behaviours according to their quality. In the belief space, a new update strategy is adopted to update cultural individuals according to the idea of the update strategy in shuffled frog leaping algorithm (SFLA). Moreover, to enhance the utilization of information in the population space and belief space, accept function and influence function are redesigned in the new communication protocol. The experimental results show that ACA-IQPSO can obtain good clustering centres according to the grey distribution information of underwater sonar images, and accurately complete underwater objects detection. Compared with other algorithms, the proposed ACA-IQPSO has good effectiveness, excellent adaptability, a powerful searching ability and high convergence efficiency. Meanwhile, the experimental results of the benchmark functions can further demonstrate that the proposed ACA-IQPSO has better searching ability, convergence efficiency and stability.

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

PubMed

Yan, Hao; Zhen, Xin; Folkerts, Michael; Li, Yongbao; Pan, Tinsu; Cervino, Laura; Jiang, Steve B; Jia, Xun

2014-07-01

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. 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. 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. High-quality 4D-CBCT imaging based on the clinically standard 1-min 3D CBCT scanning protocol is feasible via the proposed hybrid reconstruction algorithm.

Rapid whole-brain resting-state fMRI at 3 T: Efficiency-optimized three-dimensional EPI versus repetition time-matched simultaneous-multi-slice EPI.

PubMed

Stirnberg, Rüdiger; Huijbers, Willem; Brenner, Daniel; Poser, Benedikt A; Breteler, Monique; Stöcker, Tony

2017-12-01

State-of-the-art simultaneous-multi-slice (SMS-)EPI and 3D-EPI share several properties that benefit functional MRI acquisition. Both sequences employ equivalent parallel imaging undersampling with controlled aliasing to achieve high temporal sampling rates. As a volumetric imaging sequence, 3D-EPI offers additional means of acceleration complementary to 2D-CAIPIRINHA sampling, such as fast water excitation and elliptical sampling. We performed an application-oriented comparison between a tailored, six-fold CAIPIRINHA-accelerated 3D-EPI protocol at 530 ms temporal and 2.4 mm isotropic spatial resolution and an SMS-EPI protocol with identical spatial and temporal resolution for whole-brain resting-state fMRI at 3 T. The latter required eight-fold slice acceleration to compensate for the lack of elliptical sampling and fast water excitation. Both sequences used vendor-supplied on-line image reconstruction. We acquired test/retest resting-state fMRI scans in ten volunteers, with simultaneous acquisition of cardiac and respiration data, subsequently used for optional physiological noise removal (nuisance regression). We found that the 3D-EPI protocol has significantly increased temporal signal-to-noise ratio throughout the brain as compared to the SMS-EPI protocol, especially when employing motion and nuisance regression. Both sequence types reliably identified known functional networks with stronger functional connectivity values for the 3D-EPI protocol. We conclude that the more time-efficient 3D-EPI primarily benefits from reduced parallel imaging noise due to a higher, actual k-space sampling density compared to SMS-EPI. The resultant BOLD sensitivity increase makes 3D-EPI a valuable alternative to SMS-EPI for whole-brain fMRI at 3 T, with voxel sizes well below 3 mm isotropic and sampling rates high enough to separate dominant cardiac signals from BOLD signals in the frequency domain. Copyright © 2017 Elsevier Inc. All rights reserved.

Markerless motion estimation for motion-compensated clinical brain imaging

NASA Astrophysics Data System (ADS)

Kyme, Andre Z.; Se, Stephen; Meikle, Steven R.; Fulton, Roger R.

2018-05-01

Motion-compensated brain imaging can dramatically reduce the artifacts and quantitative degradation associated with voluntary and involuntary subject head motion during positron emission tomography (PET), single photon emission computed tomography (SPECT) and computed tomography (CT). However, motion-compensated imaging protocols are not in widespread clinical use for these modalities. A key reason for this seems to be the lack of a practical motion tracking technology that allows for smooth and reliable integration of motion-compensated imaging protocols in the clinical setting. We seek to address this problem by investigating the feasibility of a highly versatile optical motion tracking method for PET, SPECT and CT geometries. The method requires no attached markers, relying exclusively on the detection and matching of distinctive facial features. We studied the accuracy of this method in 16 volunteers in a mock imaging scenario by comparing the estimated motion with an accurate marker-based method used in applications such as image guided surgery. A range of techniques to optimize performance of the method were also studied. Our results show that the markerless motion tracking method is highly accurate (<2 mm discrepancy against a benchmarking system) on an ethnically diverse range of subjects and, moreover, exhibits lower jitter and estimation of motion over a greater range than some marker-based methods. Our optimization tests indicate that the basic pose estimation algorithm is very robust but generally benefits from rudimentary background masking. Further marginal gains in accuracy can be achieved by accounting for non-rigid motion of features. Efficiency gains can be achieved by capping the number of features used for pose estimation provided that these features adequately sample the range of head motion encountered in the study. These proof-of-principle data suggest that markerless motion tracking is amenable to motion-compensated brain imaging and holds good promise for a practical implementation in clinical PET, SPECT and CT systems.

SU-F-R-11: Designing Quality and Safety Informatics Through Implementation of a CT Radiation Dose Monitoring Program

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

Wilson, JM; Samei, E; Departments of Physics, Electrical and Computer Engineering, and Biomedical Engineering, and Medical Physics Graduate Program, Duke University, Durham, NC

2016-06-15

Purpose: Recent legislative and accreditation requirements have driven rapid development and implementation of CT radiation dose monitoring solutions. Institutions must determine how to improve quality, safety, and consistency of their clinical performance. The purpose of this work was to design a strategy and meaningful characterization of results from an in-house, clinically-deployed dose monitoring solution. Methods: A dose monitoring platform was designed by our imaging physics group that focused on extracting protocol parameters, dose metrics, and patient demographics and size. Compared to most commercial solutions, which focus on individual exam alerts and global thresholds, the program sought to characterize overall consistencymore » and targeted thresholds based on eight analytic interrogations. Those were based on explicit questions related to protocol application, national benchmarks, protocol and size-specific dose targets, operational consistency, outliers, temporal trends, intra-system variability, and consistent use of electronic protocols. Using historical data since the start of 2013, 95% and 99% intervals were used to establish yellow and amber parameterized dose alert thresholds, respectively, as a function of protocol, scanner, and size. Results: Quarterly reports have been generated for three hospitals for 3 quarters of 2015 totaling 27880, 28502, 30631 exams, respectively. Four adult and two pediatric protocols were higher than external institutional benchmarks. Four protocol dose levels were being inconsistently applied as a function of patient size. For the three hospitals, the minimum and maximum amber outlier percentages were [1.53%,2.28%], [0.76%,1.8%], [0.94%,1.17%], respectively. Compared with the electronic protocols, 10 protocols were found to be used with some inconsistency. Conclusion: Dose monitoring can satisfy requirements with global alert thresholds and patient dose records, but the real value is in optimizing patient-specific protocols, balancing image quality trade-offs that dose-reduction strategies promise, and improving the performance and consistency of a clinical operation. Data plots that capture patient demographics and scanner performance demonstrate that value.« less

[PET/CT: protocol aspects and legal controversies].

PubMed

Gorospe Sarasúa, L; Vicente Bártulos, A; González Gordaliza, C; García Poza, J; Lourido García, D; Jover Díaz, R

2008-01-01

The combination of positron emission tomography (PET) and computed tomography (CT) in a single scanner (PET/CT) allows anatomic and metabolic images to be fused and correlated with a high degree of accuracy; this represents a very important landmark in the history of medicine and especially in the area of diagnostic imaging. Nevertheless, the implementation, startup, and operation of a PET/CT scanner presents particularly interesting challenges, because it involves the integration of two well-established and consolidated techniques (CT and PET, which provide complementary information) that have traditionally been carried out in the context of two different specialties (radiology and nuclear medicine). The rapid diffusion of this new integrated technology raises a series of questions related to the optimal protocols for image acquisition, the supervision of the examinations, image interpretation, and reporting, as well as questions related to the legal competence and responsibility of the specialists involved in a PET/CT study. The objective of this article is to approach these aspects from a constructive perspective and to stimulate the dialog between the specialties of radiology and nuclear medicine, with the aim of maximizing the diagnostic potential of PET/CT and thus of providing better care for patients.

Comparison of three-dimensional visualization techniques for depicting the scala vestibuli and scala tympani of the cochlea by using high-resolution MR imaging.

PubMed

Hans, P; Grant, A J; Laitt, R D; Ramsden, R T; Kassner, A; Jackson, A

1999-08-01

Cochlear implantation requires introduction of a stimulating electrode array into the scala vestibuli or scala tympani. Although these structures can be separately identified on many high-resolution scans, it is often difficult to ascertain whether these channels are patent throughout their length. The aim of this study was to determine whether an optimized combination of an imaging protocol and a visualization technique allows routine 3D rendering of the scala vestibuli and scala tympani. A submillimeter T2 fast spin-echo imaging sequence was designed to optimize the performance of 3D visualization methods. The spatial resolution was determined experimentally using primary images and 3D surface and volume renderings from eight healthy subjects. These data were used to develop the imaging sequence and to compare the quality and signal-to-noise dependency of four data visualization algorithms: maximum intensity projection, ray casting with transparent voxels, ray casting with opaque voxels, and isosurface rendering. The ability of these methods to produce 3D renderings of the scala tympani and scala vestibuli was also examined. The imaging technique was used in five patients with sensorineural deafness. Visualization techniques produced optimal results in combination with an isotropic volume imaging sequence. Clinicians preferred the isosurface-rendered images to other 3D visualizations. Both isosurface and ray casting displayed the scala vestibuli and scala tympani throughout their length. Abnormalities were shown in three patients, and in one of these, a focal occlusion of the scala tympani was confirmed at surgery. Three-dimensional images of the scala vestibuli and scala tympani can be routinely produced. The combination of an MR sequence optimized for use with isosurface rendering or ray-casting algorithms can produce 3D images with greater spatial resolution and anatomic detail than has been possible previously.

High throughput, detailed, cell-specific neuroanatomy of dendritic spines using microinjection and confocal microscopy

PubMed Central

Dumitriu, Dani; Rodriguez, Alfredo; Morrison, John H.

2012-01-01

Morphological features such as size, shape and density of dendritic spines have been shown to reflect important synaptic functional attributes and potential for plasticity. Here we describe in detail a protocol for obtaining detailed morphometric analysis of spines using microinjection of fluorescent dyes, high resolution confocal microscopy, deconvolution and image analysis using NeuronStudio. Recent technical advancements include better preservation of tissue resulting in prolonged ability to microinject, and algorithmic improvements that compensate for the residual Z-smear inherent in all optical imaging. Confocal imaging parameters were probed systematically for the identification of both optimal resolution as well as highest efficiency. When combined, our methods yield size and density measurements comparable to serial section transmission electron microscopy in a fraction of the time. An experiment containing 3 experimental groups with 8 subjects in each can take as little as one month if optimized for speed, or approximately 4 to 5 months if the highest resolution and morphometric detail is sought. PMID:21886104

Investigation of Readout RF Pulse Impact on the Chemical Exchange Saturation Transfer Spectrum

PubMed Central

Huang, Sheng-Min; Jan, Meei-Ling; Liang, Hsin-Chin; Chang, Chia-Hao; Wu, Yi-Chun; Tsai, Shang-Yueh; Wang, Fu-Nien

2015-01-01

Chemical exchange saturation transfer magnetic resonance imaging (CEST-MRI) is capable of both microenvironment and molecular imaging. The optimization of scanning parameters is important since the CEST effect is sensitive to factors such as saturation power and field homogeneity. The aim of this study was to determine if the CEST effect would be altered by changing the length of readout RF pulses. Both theoretical computer simulation and phantom experiments were performed to examine the influence of readout RF pulses. Our results showed that the length of readout RF pulses has unremarkable impact on the Z-spectrum and CEST effect in both computer simulation and phantom experiment. Moreover, we demonstrated that multiple refocusing RF pulses used in rapid acquisition with relaxation enhancement (RARE) sequence induced no obvious saturation transfer contrast. Therefore, readout RF pulse has negligible effect on CEST Z-spectrum and the optimization of readout RF pulse length can be disregarded in CEST imaging protocol. PMID:26455576

SU-E-I-81: Assessment of CT Radiation Dose and Image Quality for An Automated Tube Potential Selection Algorithm Using Adult Anthropomorphic and ACR Phantoms

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

Mahmood, U; Erdi, Y; Wang, W

Purpose: To assess the impact of General Electrics (GE) automated tube potential algorithm, kV assist (kVa) on radiation dose and image quality, with an emphasis on optimizing protocols based on noise texture. Methods: Radiation dose was assessed by inserting optically stimulated luminescence dosimeters (OSLs) throughout the body of an adult anthropomorphic phantom (CIRS). The baseline protocol was: 120 kVp, Auto mA (180 to 380 mA), noise index (NI) = 14, adaptive iterative statistical reconstruction (ASiR) of 20%, 0.8s rotation time. Image quality was evaluated by calculating the contrast to noise ratio (CNR) and noise power spectrum (NPS) from the ACRmore » CT accreditation phantom. CNRs were calculated according to the steps described in ACR CT phantom testing document. NPS was determined by taking the 3D FFT of the uniformity section of the ACR phantom. NPS and CNR were evaluated with and without kVa and for all available adaptive iterative statistical reconstruction (ASiR) settings, ranging from 0 to 100%. Each NPS was also evaluated for its peak frequency difference (PFD) with respect to the baseline protocol. Results: The CNR for the adult male was found to decrease from CNR = 0.912 ± 0.045 for the baseline protocol without kVa to a CNR = 0.756 ± 0.049 with kVa activated. When compared against the baseline protocol, the PFD at ASiR of 40% yielded a decrease in noise magnitude as realized by the increase in CNR = 0.903 ± 0.023. The difference in the central liver dose with and without kVa was found to be 0.07%. Conclusion: Dose reduction was insignificant in the adult phantom. As determined by NPS analysis, ASiR of 40% produced images with similar noise texture to the baseline protocol. However, the CNR at ASiR of 40% with kVa fails to meet the current ACR CNR passing requirement of 1.0.« less

Exploring silver as a contrast agent for contrast-enhanced dual-energy X-ray breast imaging

PubMed Central

Tsourkas, A; Maidment, A D A

2014-01-01

Objective: Through prior monoenergetic modelling, we have identified silver as a potential alternative to iodine in dual-energy (DE) X-ray breast imaging. The purpose of this study was to compare the performance of silver and iodine contrast agents in a commercially available DE imaging system through a quantitative analysis of signal difference-to-noise ratio (SDNR). Methods: A polyenergetic simulation algorithm was developed to model the signal intensity and noise. The model identified the influence of various technique parameters on SDNR. The model was also used to identify the optimal imaging techniques for silver and iodine, so that the two contrast materials could be objectively compared. Results: The major influences on the SDNR were the low-energy dose fraction and breast thickness. An increase in the value of either of these parameters resulted in a decrease in SDNR. The SDNR for silver was on average 43% higher than that for iodine when imaged at their respective optimal conditions, and 40% higher when both were imaged at the optimal conditions for iodine. Conclusion: A silver contrast agent should provide benefit over iodine, even when translated to the clinic without modification of imaging system or protocol. If the system were slightly modified to reflect the lower k-edge of silver, the difference in SDNR between the two materials would be increased. Advances in knowledge: These data are the first to demonstrate the suitability of silver as a contrast material in a clinical contrast-enhanced DE image acquisition system. PMID:24998157

Clinical experience with a high-performance ATM-connected DICOM archive for cardiology

NASA Astrophysics Data System (ADS)

Solomon, Harry P.

1997-05-01

A system to archive large image sets, such as cardiac cine runs, with near realtime response must address several functional and performance issues, including efficient use of a high performance network connection with standard protocols, an architecture which effectively integrates both short- and long-term mass storage devices, and a flexible data management policy which allows optimization of image distribution and retrieval strategies based on modality and site-specific operational use. Clinical experience with such as archive has allowed evaluation of these systems issues and refinement of a traffic model for cardiac angiography.

Hippocampal unified multi-atlas network (HUMAN): protocol and scale validation of a novel segmentation tool.

PubMed

Amoroso, N; Errico, R; Bruno, S; Chincarini, A; Garuccio, E; Sensi, F; Tangaro, S; Tateo, A; Bellotti, R

2015-11-21

In this study we present a novel fully automated Hippocampal Unified Multi-Atlas-Networks (HUMAN) algorithm for the segmentation of the hippocampus in structural magnetic resonance imaging. In multi-atlas approaches atlas selection is of crucial importance for the accuracy of the segmentation. Here we present an optimized method based on the definition of a small peri-hippocampal region to target the atlas learning with linear and non-linear embedded manifolds. All atlases were co-registered to a data driven template resulting in a computationally efficient method that requires only one test registration. The optimal atlases identified were used to train dedicated artificial neural networks whose labels were then propagated and fused to obtain the final segmentation. To quantify data heterogeneity and protocol inherent effects, HUMAN was tested on two independent data sets provided by the Alzheimer's Disease Neuroimaging Initiative and the Open Access Series of Imaging Studies. HUMAN is accurate and achieves state-of-the-art performance (Dice[Formula: see text] and Dice[Formula: see text]). It is also a robust method that remains stable when applied to the whole hippocampus or to sub-regions (patches). HUMAN also compares favorably with a basic multi-atlas approach and a benchmark segmentation tool such as FreeSurfer.

Hippocampal unified multi-atlas network (HUMAN): protocol and scale validation of a novel segmentation tool

NASA Astrophysics Data System (ADS)

Amoroso, N.; Errico, R.; Bruno, S.; Chincarini, A.; Garuccio, E.; Sensi, F.; Tangaro, S.; Tateo, A.; Bellotti, R.; Alzheimers Disease Neuroimaging Initiative,the

2015-11-01

In this study we present a novel fully automated Hippocampal Unified Multi-Atlas-Networks (HUMAN) algorithm for the segmentation of the hippocampus in structural magnetic resonance imaging. In multi-atlas approaches atlas selection is of crucial importance for the accuracy of the segmentation. Here we present an optimized method based on the definition of a small peri-hippocampal region to target the atlas learning with linear and non-linear embedded manifolds. All atlases were co-registered to a data driven template resulting in a computationally efficient method that requires only one test registration. The optimal atlases identified were used to train dedicated artificial neural networks whose labels were then propagated and fused to obtain the final segmentation. To quantify data heterogeneity and protocol inherent effects, HUMAN was tested on two independent data sets provided by the Alzheimer’s Disease Neuroimaging Initiative and the Open Access Series of Imaging Studies. HUMAN is accurate and achieves state-of-the-art performance (Dice{{}\\text{ADNI}} =0.929+/- 0.003 and Dice{{}\\text{OASIS}} =0.869+/- 0.002 ). It is also a robust method that remains stable when applied to the whole hippocampus or to sub-regions (patches). HUMAN also compares favorably with a basic multi-atlas approach and a benchmark segmentation tool such as FreeSurfer.

High-performance dual-energy imaging with a flat-panel detector: imaging physics from blackboard to benchtop to bedside

NASA Astrophysics Data System (ADS)

Siewerdsen, J. H.; Shkumat, N. A.; Dhanantwari, A. C.; Williams, D. B.; Richard, S.; Daly, M. J.; Paul, N. S.; Moseley, D. J.; Jaffray, D. A.; Yorkston, J.; Van Metter, R.

2006-03-01

The application of high-performance flat-panel detectors (FPDs) to dual-energy (DE) imaging offers the potential for dramatically improved detection and characterization of subtle lesions through reduction of "anatomical noise," with applications ranging from thoracic imaging to image-guided interventions. In this work, we investigate DE imaging performance from first principles of image science to preclinical implementation, including: 1.) generalized task-based formulation of NEQ and detectability as a guide to system optimization; 2.) measurements of imaging performance on a DE imaging benchtop; and 3.) a preclinical system developed in our laboratory for cardiac-gated DE chest imaging in a research cohort of 160 patients. Theoretical and benchtop studies directly guide clinical implementation, including the advantages of double-shot versus single-shot DE imaging, the value of differential added filtration between low- and high-kVp projections, and optimal selection of kVp pairs, filtration, and dose allocation. Evaluation of task-based NEQ indicates that the detectability of subtle lung nodules in double-shot DE imaging can exceed that of single-shot DE imaging by a factor of 4 or greater. Filter materials are investigated that not only harden the high-kVp beam (e.g., Cu or Ag) but also soften the low-kVp beam (e.g., Ce or Gd), leading to significantly increased contrast in DE images. A preclinical imaging system suitable for human studies has been constructed based upon insights gained from these theoretical and experimental studies. An important component of the system is a simple and robust means of cardiac-gated DE image acquisition, implemented here using a fingertip pulse oximeter. Timing schemes that provide cardiac-gated image acquisition on the same or successive heartbeats is described. Preclinical DE images to be acquired under research protocol will afford valuable testing of optimal deployment, facilitate the development of DE CAD, and support comparison of DE diagnostic imaging performance to low-dose CT and radiography.

Optimization of Nonambulant Mass Casualty Decontamination Protocols as Part of an Initial or Specialist Operational Response to Chemical Incidents.

PubMed

Chilcott, Robert P; Mitchell, Hannah; Matar, Hazem

2018-05-30

The UK's Initial Operational Response (IOR) is a new process for improving the survival of multiple casualties following a chemical, biological, radiological or nuclear incident. Whilst the introduction of IOR represents a patient-focused response for ambulant casualties, there is currently no provision for disrobe and dry decontamination of nonambulant casualties. Moreover, the current specialist operational response (SOR) protocol for nonambulant casualty decontamination (also referred to as "clinical decontamination") has not been subject to rigorous evaluation or development. Therefore, the aim of this study was to confirm the effectiveness of putatively optimized dry (IOR) and wet (SOR) protocols for nonambulant decontamination in human volunteers. Dry and wet decontamination protocols were objectively evaluated using human volunteers. Decontamination effectiveness was quantified by liquid chromatography-mass spectrometry analysis of the recovery of a chemical warfare agent simulant (methylsalicylate) from skin and hair of volunteers, with whole-body fluorescence imaging to quantify the skin distribution of residual simulant. Both the dry and wet decontamination processes were rapid (3 and 4 min, respectively) and were effective in removing simulant from the hair and skin of volunteers, with no observable adverse effects related to skin surface spreading of contaminant. Further studies are required to assess the combined effectiveness of dry and wet decontamination under more realistic conditions and to develop appropriate operational procedures that ensure the safety of first responders.

Cloud Optimized Image Format and Compression

NASA Astrophysics Data System (ADS)

Becker, P.; Plesea, L.; Maurer, T.

2015-04-01

Cloud based image storage and processing requires revaluation of formats and processing methods. For the true value of the massive volumes of earth observation data to be realized, the image data needs to be accessible from the cloud. Traditional file formats such as TIF and NITF were developed in the hay day of the desktop and assumed fast low latency file access. Other formats such as JPEG2000 provide for streaming protocols for pixel data, but still require a server to have file access. These concepts no longer truly hold in cloud based elastic storage and computation environments. This paper will provide details of a newly evolving image storage format (MRF) and compression that is optimized for cloud environments. Although the cost of storage continues to fall for large data volumes, there is still significant value in compression. For imagery data to be used in analysis and exploit the extended dynamic range of the new sensors, lossless or controlled lossy compression is of high value. Compression decreases the data volumes stored and reduces the data transferred, but the reduced data size must be balanced with the CPU required to decompress. The paper also outlines a new compression algorithm (LERC) for imagery and elevation data that optimizes this balance. Advantages of the compression include its simple to implement algorithm that enables it to be efficiently accessed using JavaScript. Combing this new cloud based image storage format and compression will help resolve some of the challenges of big image data on the internet.

SU-G-206-08: How Should Focal Spot Be Chosen for Optimized CT Imaging with Dose Modulation?

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

Bache, S; Liu, X; Rong, J

Purpose: To choose the preferred focal spot for achieving optimized CT image quality with balanced tube heating considerations. Methods: An anthropomorphic pelvic phantom was scanned using a GE Discovery CT750 HD at 120 and 140kVp, 0.8s rotation time, and pitch of 0.984. “Smart mA” was enabled to simulate a routine abdomen–pelvis CT scan. Permissible mA values at 120 and 140 kVp were obtained from the Serial Load Rating table (for mimicking a busy CT clinical operation) in the scanner Technical Reference Manual. At each kVp station and two Noise Index levels, the mA Upper Limit was set above/below the permissiblemore » mA values. Scanned mA values and focal spot (FS) used were obtained from the DICOM header of each image, and the FS-mA relationship was analyzed. For visual confirmation beyond recorded FS information, a CatPhan with a fat-ring attached for mimicking patient size/shape was scanned at 120kVp. A group of radiologists/physicists compared a pair of CatPhan images qualitatively. Lastly, a number of patient cases were evaluated to confirm the FS-mA relationship. Results: When preset Upper Limit values were above the permissible mA values, the Large FS (labeled 1.2) was used in scans, even if the maximum scanned mA values were much lower than the permissible values at both 120 and 140 kVp. Otherwise the Small FS (labeled 0.7) was used. Visual evaluation of the high contrast module of CatPhan and additional analysis of patient cases further confirmed that the preset Upper Limit determines which focal spot is to be used, not the actual maximum mA value to be scanned. Conclusion: Specific FS can be selected by setting up appropriate mA Upper Limit in a protocol. CT protocols could be optimized by selecting appropriate FS for improving patient image quality, especially benefiting the small size and pediatric patients.« less

MR imaging for diagnostic evaluation of encephalopathy in the newborn.

PubMed

Shroff, Manohar M; Soares-Fernandes, João P; Whyte, Hilary; Raybaud, Charles

2010-05-01

Magnetic resonance (MR) imaging is used with increasing frequency to evaluate the neonatal brain because it can provide important diagnostic and prognostic information that is needed for optimal treatment and appropriate counseling. Special care must be taken in preparing encephalopathic neonates for an MR study, transporting them from the intensive care unit, monitoring their vital signs, and optimizing MR sequences and protocols. Moreover, to accurately interpret the findings, specific knowledge is needed about the normal MR imaging appearances of the physiologic processes of myelination, cell migration, and sulcation, as well as patterns of injury, in the neonatal brain at various stages of gestational development. Hypoxic-ischemic injury, the most common cause of neonatal encephalopathy, has characteristic appearances that depend on the severity and duration of the insult as well as the stage of brain development. Diffusion-weighted MR imaging and MR spectroscopy depict abnormalities earlier than do conventional MR imaging sequences. However, diffusion-weighted imaging, if performed in the first 24 hours after the insult, might lead to underestimation of the extent of injury. When the MR findings are atypical, the differential diagnosis of neonatal encephalopathy also should include congenital and metabolic disorders and infectious diseases. Despite recent advances in the MR imaging-based characterization of these conditions, the clinical history must be borne in mind to achieve an accurate diagnosis.

Radiographic protocol and normal anatomy of the hind feet in the white rhinoceros (Ceratotherium simum).

PubMed

Dudley, Robert J; Wood, Simon P; Hutchinson, John R; Weller, Renate

2015-01-01

Foot pathology is a common and important health concern in captive rhinoceroses worldwide, but osteopathologies are rarely diagnosed, partly because of a lack of radiographic protocols. Here, we aimed to develop the first radiographic protocol for rhinoceros feet and describe the radiographic anatomy of the white rhinoceros (Ceratotherium simum) hind foot (pes). Computed tomographic images were obtained of nine cadaver pedes from seven different white rhinoceroses and assessed for pathology. A single foot deemed free of pathology was radiographed using a range of different projections and exposures to determine the best protocol. 3D models were produced from the CT images and were displayed with the real radiographs to describe the normal radiographic anatomy of the white rhinoceros pes. An optimal radiographic projection was determined for each bone in the rhinoceros pes focusing on highlighting areas where pathology has been previously described. The projections deemed to be most useful were D60Pr-PlDiO (digit III), D45Pr45M-PlDiLO (digit II), and D40Pr35L-PlDiLO (digit IV). The primary beam was centered 5-7 cm proximal to the cuticle on the digit of interest. Articular surfaces, ridges, grooves, tubercles, processes and fossae were identified. The radiographic protocol we have developed along with the normal radiographic anatomy we have described will allow for more accessible and effective diagnosis of white rhinoceros foot osteopathologies. © 2014 American College of Veterinary Radiology.

Evaluation of a dedicated MDCT protocol using iterative image reconstruction after cervical spine trauma.

PubMed

Geyer, L L; Körner, M; Hempel, R; Deak, Z; Mueck, F G; Linsenmaier, U; Reiser, M F; Wirth, S

2013-07-01

To evaluate radiation exposure for 64-row computed tomography (CT) of the cervical spine comparing two optimized protocols using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR), respectively. Sixty-seven studies using FBP (scanner 1) were retrospectively compared with 80 studies using ASIR (scanner 2). The key scanning parameters were identical (120 kV dose modulation, 64 × 0.625 mm collimation, pitch 0.531:1). In protocol 2, the noise index (NI) was increased from 5 to 25, and ASIR and the high-definition (HD) mode were used. The scan length, CT dose index (CTDI), and dose-length product (DLP) were recorded. The image quality was analysed subjectively by using a three-point scale (0; 1; 2), and objectively by using a region of interest (ROI) analysis. Mann-Whitney U and Wilcoxon's test were used. In the FBP group, the mean CTDI was 21.43 mGy, mean scan length 186.3 mm, and mean DLP 441.15 mGy cm. In the ASIR group, the mean CTDI was 9.57 mGy, mean scan length 195.21 mm, and mean DLP 204.23 mGy cm. The differences were significant for CTDI and DLP (p < 0.001) and scan length (p = 0.01). There was no significant difference in the subjective image quality (p > 0.05). The estimated mean effective dose decreased from 2.38 mSv (FBP) to 1.10 mSv (ASIR). The radiation dose of 64-row MDCT can be reduced to a level comparable to plain radiography without loss of subjective image quality by implementation of ASIR in a dedicated cervical spine trauma protocol. These results might contribute to an improved relative risk-to-benefit ratio and support the justification of CT as a first-line imaging tool to evaluate cervical spine trauma. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Outcomes of Optimized over Standard Protocol of Rabbit Antithymocyte Globulin for Severe Aplastic Anemia: A Single-Center Experience

PubMed Central

Ge, Meili; Shao, Yingqi; Huang, Jinbo; Huang, Zhendong; Zhang, Jing; Nie, Neng; Zheng, Yizhou

2013-01-01

Background Previous reports showed that outcome of rabbit antithymocyte globulin (rATG) was not satisfactory as the first-line therapy for severe aplastic anemia (SAA). We explored a modifying schedule of administration of rATG. Design and Methods Outcomes of a cohort of 175 SAA patients, including 51 patients administered with standard protocol (3.55 mg/kg/d for 5 days) and 124 cases with optimized protocol (1.97 mg/kg/d for 9 days) of rATG plus cyclosporine (CSA), were analyzed retrospectively. Results Of all 175 patients, response rates at 3 and 6 months were 36.6% and 56.0%, respectively. 51 cases received standard protocol had poor responses at 3 (25.5%) and 6 months (41.2%). However, 124 patients received optimized protocol had better responses at 3 (41.1%, P = 0.14) and 6 (62.1%, P = 0.01). Higher incidences of infection (57.1% versus 37.9%, P = 0.02) and early mortality (17.9% versus 0.8%, P<0.001) occurred in patients received standard protocol compared with optimized protocol. The 5-year overall survival in favor of the optimized over standard rATG protocol (76.0% versus. 50.3%, P<0.001) was observed. By multivariate analysis, optimized protocol (RR = 2.21, P = 0.04), response at 3 months (RR = 10.31, P = 0.03) and shorter interval (<23 days) between diagnosis and initial dose of rATG (RR = 5.35, P = 0.002) were independent favorable predictors of overall survival. Conclusions Optimized instead of standard rATG protocol in combination with CSA remained efficacious as a first-line immunosuppressive regimen for SAA. PMID:23554855

Neuronal Tracing with Magnetic Labels: NMR Imaging Methods, Preliminary Results, and New Optimized Coils.

NASA Astrophysics Data System (ADS)

Ghosh, Pratik

1992-01-01

The investigations focussed on in vivo NMR imaging studies of magnetic particles with and within neural cells. NMR imaging methods, both Fourier transform and projection reconstruction, were implemented and new protocols were developed to perform "Neuronal Tracing with Magnetic Labels" on small animal brains. Having performed the preliminary experiments with neuronal tracing, new optimized coils and experimental set-up were devised. A novel gradient coil technology along with new rf-coils were implemented, and optimized for future use with small animals in them. A new magnetic labelling procedure was developed that allowed labelling of billions of cells with ultra -small magnetite particles in a short time. The relationships among the viability of such cells, the amount of label and the contrast in the images were studied as quantitatively as possible. Intracerebral grafting of magnetite labelled fetal rat brain cells made it possible for the first time to attempt monitoring in vivo the survival, differentiation, and possible migration of both host and grafted cells in the host rat brain. This constituted the early steps toward future experiments that may lead to the monitoring of human brain grafts of fetal brain cells. Preliminary experiments with direct injection of horse radish peroxidase-conjugated magnetite particles into neurons, followed by NMR imaging, revealed a possible non-invasive alternative, allowing serial study of the dynamic transport pattern of tracers in single living animals. New gradient coils were built by using parallel solid-conductor ribbon cables that could be wrapped easily and quickly. Rapid rise times provided by these coils allowed implementation of fast imaging methods. Optimized rf-coil circuit development made it possible to understand better the sample-coil properties and the associated trade -offs in cases of small but conducting samples.

Optimization of a sample processing protocol for recovery of Bacillus anthracis spores from soil

USGS Publications Warehouse

Silvestri, Erin E.; Feldhake, David; Griffin, Dale; Lisle, John T.; Nichols, Tonya L.; Shah, Sanjiv; Pemberton, A; Schaefer III, Frank W

2016-01-01

Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps. Optimization of the protocol included: identifying an ideal extraction diluent, variation in the number of wash steps, variation in the initial centrifugation speed, sonication and shaking mechanisms. The optimized protocol was demonstrated at two laboratories in order to evaluate the recovery of spores from loamy and sandy soils. The new protocol demonstrated an improved limit of detection for loamy and sandy soils over the non-optimized protocol with an approximate matrix limit of detection at 14 spores/g of soil. There were no significant differences overall between the two laboratories for either soil type, suggesting that the processing protocol will be robust enough to use at multiple laboratories while achieving comparable recoveries.

MO-E-18A-01: Imaging: Best Practices In Pediatric Imaging

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

Willis, C; Strauss, K; MacDougall, R

This imaging educational program will focus on solutions to common pediatric imaging challenges. The speakers will present collective knowledge on best practices in pediatric imaging from their experience at dedicated children's hospitals. Areas of focus will include general radiography, the use of manual and automatic dose management in computed tomography, and enterprise-wide radiation dose management in the pediatric practice. The educational program will begin with a discussion of the complexities of exposure factor control in pediatric projection radiography. Following this introduction will be two lectures addressing the challenges of computed tomography (CT) protocol optimization in the pediatric population. The firstmore » will address manual CT protocol design in order to establish a managed radiation dose for any pediatric exam on any CT scanner. The second CT lecture will focus on the intricacies of automatic dose modulation in pediatric imaging with an emphasis on getting reliable results in algorithmbased technique selection. The fourth and final lecture will address the key elements needed to developing a comprehensive radiation dose management program for the pediatric environment with particular attention paid to new regulations and obligations of practicing medical physicists. Learning Objectives: To understand how general radiographic techniques can be optimized using exposure indices in order to improve pediatric radiography. To learn how to establish diagnostic dose reference levels for pediatric patients as a function of the type of examination, patient size, and individual design characteristics of the CT scanner. To learn how to predict the patient's radiation dose prior to the exam and manually adjust technique factors if necessary to match the patient's dose to the department's established dose reference levels. To learn how to utilize manufacturer-provided automatic dose modulation technology to consistently achieve patient doses within the department's established size-based diagnostic reference range. To understand the key components of an enterprise-wide pediatric dose management program that integrates the expanding responsibilities of medial physicists in the new era of dose monitoring.« less

Simulation of transmission electron microscope images of biological specimens.

PubMed

Rullgård, H; Ofverstedt, L-G; Masich, S; Daneholt, B; Oktem, O

2011-09-01

We present a new approach to simulate electron cryo-microscope images of biological specimens. The framework for simulation consists of two parts; the first is a phantom generator that generates a model of a specimen suitable for simulation, the second is a transmission electron microscope simulator. The phantom generator calculates the scattering potential of an atomic structure in aqueous buffer and allows the user to define the distribution of molecules in the simulated image. The simulator includes a well defined electron-specimen interaction model based on the scalar Schrödinger equation, the contrast transfer function for optics, and a noise model that includes shot noise as well as detector noise including detector blurring. To enable optimal performance, the simulation framework also includes a calibration protocol for setting simulation parameters. To test the accuracy of the new framework for simulation, we compare simulated images to experimental images recorded of the Tobacco Mosaic Virus (TMV) in vitreous ice. The simulated and experimental images show good agreement with respect to contrast variations depending on dose and defocus. Furthermore, random fluctuations present in experimental and simulated images exhibit similar statistical properties. The simulator has been designed to provide a platform for development of new instrumentation and image processing procedures in single particle electron microscopy, two-dimensional crystallography and electron tomography with well documented protocols and an open source code into which new improvements and extensions are easily incorporated. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Spectral optimization for micro-CT

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

Hupfer, Martin; Nowak, Tristan; Brauweiler, Robert

2012-06-15

Purpose: To optimize micro-CT protocols with respect to x-ray spectra and thereby reduce radiation dose at unimpaired image quality. Methods: Simulations were performed to assess image contrast, noise, and radiation dose for different imaging tasks. The figure of merit used to determine the optimal spectrum was the dose-weighted contrast-to-noise ratio (CNRD). Both optimal photon energy and tube voltage were considered. Three different types of filtration were investigated for polychromatic x-ray spectra: 0.5 mm Al, 3.0 mm Al, and 0.2 mm Cu. Phantoms consisted of water cylinders of 20, 32, and 50 mm in diameter with a central insert of 9more » mm which was filled with different contrast materials: an iodine-based contrast medium (CM) to mimic contrast-enhanced (CE) imaging, hydroxyapatite to mimic bone structures, and water with reduced density to mimic soft tissue contrast. Validation measurements were conducted on a commercially available micro-CT scanner using phantoms consisting of water-equivalent plastics. Measurements on a mouse cadaver were performed to assess potential artifacts like beam hardening and to further validate simulation results. Results: The optimal photon energy for CE imaging was found at 34 keV. For bone imaging, optimal energies were 17, 20, and 23 keV for the 20, 32, and 50 mm phantom, respectively. For density differences, optimal energies varied between 18 and 50 keV for the 20 and 50 mm phantom, respectively. For the 32 mm phantom and density differences, CNRD was found to be constant within 2.5% for the energy range of 21-60 keV. For polychromatic spectra and CMs, optimal settings were 50 kV with 0.2 mm Cu filtration, allowing for a dose reduction of 58% compared to the optimal setting for 0.5 mm Al filtration. For bone imaging, optimal tube voltages were below 35 kV. For soft tissue imaging, optimal tube settings strongly depended on phantom size. For 20 mm, low voltages were preferred. For 32 mm, CNRD was found to be almost independent of tube voltage. For 50 mm, voltages larger than 50 kV were preferred. For all three phantom sizes stronger filtration led to notable dose reduction for soft tissue imaging. Validation measurements were found to match simulations well, with deviations being less than 10%. Mouse measurements confirmed simulation results. Conclusions: Optimal photon energies and tube settings strongly depend on both phantom size and imaging task at hand. For in vivo CE imaging and density differences, strong filtration and voltages of 50-65 kV showed good overall results. For soft tissue imaging of animals the size of a rat or larger, voltages higher than 65 kV allow to greatly reduce scan times while maintaining dose efficiency. For imaging of bone structures, usage of only minimum filtration and low tube voltages of 40 kV and below allow exploiting the high contrast of bone at very low energies. Therefore, a combination of two filtrations could prove beneficial for micro-CT: a soft filtration allowing for bone imaging at low voltages, and a variable stronger filtration (e.g., 0.2 mm Cu) for soft tissue and contrast-enhanced imaging.« less

Evaluation of an accelerated 3D SPACE sequence with compressed sensing and free-stop scan mode for imaging of the knee.

PubMed

Henninger, B; Raithel, E; Kranewitter, C; Steurer, M; Jaschke, W; Kremser, C

2018-05-01

To prospectively evaluate a prototypical 3D turbo-spin-echo proton-density-weighted sequence with compressed sensing and free-stop scan mode for preventing motion artefacts (3D-PD-CS-SPACE free-stop) for knee imaging in a clinical setting. 80 patients underwent 3T magnetic resonance imaging (MRI) of the knee with our 2D routine protocol and with 3D-PD-CS-SPACE free-stop. In case of a scan-stop caused by motion (images are calculated nevertheless) the sequence was repeated without free-stop mode. All scans were evaluated by 2 radiologists concerning image quality of the 3D-PD-CS-SPACE (with and without free-stop). Important knee structures were further assessed in a lesion based analysis and compared to our reference 2D-PD-fs sequences. Image quality of the 3D-PD-CS-SPACE free-stop was found optimal in 47/80, slightly compromised in 21/80, moderately in 10/80 and severely in 2/80. In 29/80, the free-stop scan mode stopped the 3D-PD-CS-SPACE due to subject motion with a slight increase of image quality at longer effective acquisition times. Compared to the 3D-PD-CS-SPACE with free-stop, the image quality of the acquired 3D-PD-CS-SPACE without free-stop was found equal in 6/29, slightly improved in 13/29, improved with equal contours in 8/29, and improved with sharper contours in 2/29. The lesion based analysis showed a high agreement between the results from the 3D-PD-CS-SPACE free-stop and our 2D-PD-fs routine protocol (overall agreement 96.25%-100%, Cohen's Kappa 0.883-1, p < 0.001). 3D-PD-CS-SPACE free-stop is a reliable alternative for standard 2D-PD-fs protocols with acceptable acquisition times. Copyright © 2018 Elsevier B.V. All rights reserved.

SU-D-12A-06: A Comprehensive Parameter Analysis for Low Dose Cone-Beam CT Reconstruction

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

Lu, W; Southern Medical University, Guangzhou; Yan, H

Purpose: There is always a parameter in compressive sensing based iterative reconstruction (IR) methods low dose cone-beam CT (CBCT), which controls the weight of regularization relative to data fidelity. A clear understanding of the relationship between image quality and parameter values is important. The purpose of this study is to investigate this subject based on experimental data and a representative advanced IR algorithm using Tight-frame (TF) regularization. Methods: Three data sets of a Catphan phantom acquired at low, regular and high dose levels are used. For each tests, 90 projections covering a 200-degree scan range are used for reconstruction. Threemore » different regions-of-interest (ROIs) of different contrasts are used to calculate contrast-to-noise ratios (CNR) for contrast evaluation. A single point structure is used to measure modulation transfer function (MTF) for spatial-resolution evaluation. Finally, we analyze CNRs and MTFs to study the relationship between image quality and parameter selections. Results: It was found that: 1) there is no universal optimal parameter. The optimal parameter value depends on specific task and dose level. 2) There is a clear trade-off between CNR and resolution. The parameter for the best CNR is always smaller than that for the best resolution. 3) Optimal parameters are also dose-specific. Data acquired under a high dose protocol require less regularization, yielding smaller optimal parameter values. 4) Comparing with conventional FDK images, TF-based CBCT images are better under a certain optimally selected parameters. The advantages are more obvious for low dose data. Conclusion: We have investigated the relationship between image quality and parameter values in the TF-based IR algorithm. Preliminary results indicate optimal parameters are specific to both the task types and dose levels, providing guidance for selecting parameters in advanced IR algorithms. This work is supported in part by NIH (1R01CA154747-01)« less

What is the optimal way to prepare a Bell state using measurement and feedback?

NASA Astrophysics Data System (ADS)

Martin, Leigh; Sayrafi, Mahrud; Whaley, K. Birgitta

2017-12-01

Recent work has shown that the use of quantum feedback can significantly enhance both the speed and success rate of measurement-based remote entanglement generation, but it is generally unknown what feedback protocols are optimal for these tasks. Here we consider two common measurements that are capable of projecting into pairwise entangled states, namely half- and full-parity measurements of two qubits, and determine in each case a globally optimal protocol for generation of entanglement. For the half-parity measurement, we rederive a previously described protocol using more general methods and prove that it is globally optimal for several figures of merit, including maximal concurrence or fidelity and minimal time to reach a specified concurrence or fidelity. For the full-parity measurement, we derive a protocol for rapid entanglement generation related to that of (Hill, Ralph, Phys. Rev. A 77, 014305), and then map the dynamics of the concurrence of the state to the Bloch vector length of an effective qubit. This mapping allows us to prove several optimality results for feedback protocols with full-parity measurements. We further show that our full-parity protocol transfers entanglement optimally from one qubit to the other amongst all measurement-based schemes. The methods developed here will be useful for deriving feedback protocols and determining their optimality properties in many other quantum systems subject to measurement and unitary operations.

Validation of a Monte Carlo simulation of the Philips Allegro/GEMINI PET systems using GATE

NASA Astrophysics Data System (ADS)

Lamare, F.; Turzo, A.; Bizais, Y.; Cheze LeRest, C.; Visvikis, D.

2006-02-01

A newly developed simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop a Monte Carlo simulation of a fully three-dimensional (3D) clinical PET scanner. The Philips Allegro/GEMINI PET systems were simulated in order to (a) allow a detailed study of the parameters affecting the system's performance under various imaging conditions, (b) study the optimization and quantitative accuracy of emission acquisition protocols for dynamic and static imaging, and (c) further validate the potential of GATE for the simulation of clinical PET systems. A model of the detection system and its geometry was developed. The accuracy of the developed detection model was tested through the comparison of simulated and measured results obtained with the Allegro/GEMINI systems for a number of NEMA NU2-2001 performance protocols including spatial resolution, sensitivity and scatter fraction. In addition, an approximate model of the system's dead time at the level of detected single events and coincidences was developed in an attempt to simulate the count rate related performance characteristics of the scanner. The developed dead-time model was assessed under different imaging conditions using the count rate loss and noise equivalent count rates performance protocols of standard and modified NEMA NU2-2001 (whole body imaging conditions) and NEMA NU2-1994 (brain imaging conditions) comparing simulated with experimental measurements obtained with the Allegro/GEMINI PET systems. Finally, a reconstructed image quality protocol was used to assess the overall performance of the developed model. An agreement of <3% was obtained in scatter fraction, with a difference between 4% and 10% in the true and random coincidence count rates respectively, throughout a range of activity concentrations and under various imaging conditions, resulting in <8% differences between simulated and measured noise equivalent count rates performance. Finally, the image quality validation study revealed a good agreement in signal-to-noise ratio and contrast recovery coefficients for a number of different volume spheres and two different (clinical level based) tumour-to-background ratios. In conclusion, these results support the accurate modelling of the Philips Allegro/GEMINI PET systems using GATE in combination with a dead-time model for the signal flow description, which leads to an agreement of <10% in coincidence count rates under different imaging conditions and clinically relevant activity concentration levels.

Normalization of cortical thickness measurements across different T1 magnetic resonance imaging protocols by novel W-Score standardization.

PubMed

Chung, Jinyong; Yoo, Kwangsun; Lee, Peter; Kim, Chan Mi; Roh, Jee Hoon; Park, Ji Eun; Kim, Sang Joon; Seo, Sang Won; Shin, Jeong-Hyeon; Seong, Joon-Kyung; Jeong, Yong

2017-10-01

The use of different 3D T1-weighted magnetic resonance (T1 MR) imaging protocols induces image incompatibility across multicenter studies, negating the many advantages of multicenter studies. A few methods have been developed to address this problem, but significant image incompatibility still remains. Thus, we developed a novel and convenient method to improve image compatibility. W-score standardization creates quality reference values by using a healthy group to obtain normalized disease values. We developed a protocol-specific w-score standardization to control the protocol effect, which is applied to each protocol separately. We used three data sets. In dataset 1, brain T1 MR images of normal controls (NC) and patients with Alzheimer's disease (AD) from two centers, acquired with different T1 MR protocols, were used (Protocol 1 and 2, n = 45/group). In dataset 2, data from six subjects, who underwent MRI with two different protocols (Protocol 1 and 2), were used with different repetition times, echo times, and slice thicknesses. In dataset 3, T1 MR images from a large number of healthy normal controls (Protocol 1: n = 148, Protocol 2: n = 343) were collected for w-score standardization. The protocol effect and disease effect on subjects' cortical thickness were analyzed before and after the application of protocol-specific w-score standardization. As expected, different protocols resulted in differing cortical thickness measurements in both NC and AD subjects. Different measurements were obtained for the same subject when imaged with different protocols. Multivariate pattern difference between measurements was observed between the protocols. Classification accuracy between two protocols was nearly 90%. After applying protocol-specific w-score standardization, the differences between the protocols substantially decreased. Most importantly, protocol-specific w-score standardization reduced both univariate and multivariate differences in the images while maintaining the AD disease effect. Compared to conventional regression methods, our method showed the best performance for in terms of controlling the protocol effect while preserving disease information. Protocol-specific w-score standardization effectively resolved the concerns of conventional regression methods. It showed the best performance for improving the compatibility of a T1 MR post-processed feature, cortical thickness. Copyright © 2017 Elsevier Inc. All rights reserved.

Monte Carlo simulations in Nuclear Medicine

NASA Astrophysics Data System (ADS)

Loudos, George K.

2007-11-01

Molecular imaging technologies provide unique abilities to localise signs of disease before symptoms appear, assist in drug testing, optimize and personalize therapy, and assess the efficacy of treatment regimes for different types of cancer. Monte Carlo simulation packages are used as an important tool for the optimal design of detector systems. In addition they have demonstrated potential to improve image quality and acquisition protocols. Many general purpose (MCNP, Geant4, etc) or dedicated codes (SimSET etc) have been developed aiming to provide accurate and fast results. Special emphasis will be given to GATE toolkit. The GATE code currently under development by the OpenGATE collaboration is the most accurate and promising code for performing realistic simulations. The purpose of this article is to introduce the non expert reader to the current status of MC simulations in nuclear medicine and briefly provide examples of current simulated systems, and present future challenges that include simulation of clinical studies and dosimetry applications.

dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system.

PubMed

Anizan, Nadège; Carlier, Thomas; Hindorf, Cecilia; Barbet, Jacques; Bardiès, Manuel

2012-02-13

Noninvasive multimodality imaging is essential for preclinical evaluation of the biodistribution and pharmacokinetics of radionuclide therapy and for monitoring tumor response. Imaging with nonstandard positron-emission tomography [PET] isotopes such as 124I is promising in that context but requires accurate activity quantification. The decay scheme of 124I implies an optimization of both acquisition settings and correction processing. The PET scanner investigated in this study was the Inveon PET/CT system dedicated to small animal imaging. The noise equivalent count rate [NECR], the scatter fraction [SF], and the gamma-prompt fraction [GF] were used to determine the best acquisition parameters for mouse- and rat-sized phantoms filled with 124I. An image-quality phantom as specified by the National Electrical Manufacturers Association NU 4-2008 protocol was acquired and reconstructed with two-dimensional filtered back projection, 2D ordered-subset expectation maximization [2DOSEM], and 3DOSEM with maximum a posteriori [3DOSEM/MAP] algorithms, with and without attenuation correction, scatter correction, and gamma-prompt correction (weighted uniform distribution subtraction). Optimal energy windows were established for the rat phantom (390 to 550 keV) and the mouse phantom (400 to 590 keV) by combining the NECR, SF, and GF results. The coincidence time window had no significant impact regarding the NECR curve variation. Activity concentration of 124I measured in the uniform region of an image-quality phantom was underestimated by 9.9% for the 3DOSEM/MAP algorithm with attenuation and scatter corrections, and by 23% with the gamma-prompt correction. Attenuation, scatter, and gamma-prompt corrections decreased the residual signal in the cold insert. The optimal energy windows were chosen with the NECR, SF, and GF evaluation. Nevertheless, an image quality and an activity quantification assessment were required to establish the most suitable reconstruction algorithm and corrections for 124I small animal imaging.

Optimization of wireless sensor networks based on chicken swarm optimization algorithm

NASA Astrophysics Data System (ADS)

Wang, Qingxi; Zhu, Lihua

2017-05-01

In order to reduce the energy consumption of wireless sensor network and improve the survival time of network, the clustering routing protocol of wireless sensor networks based on chicken swarm optimization algorithm was proposed. On the basis of LEACH agreement, it was improved and perfected that the points on the cluster and the selection of cluster head using the chicken group optimization algorithm, and update the location of chicken which fall into the local optimum by Levy flight, enhance population diversity, ensure the global search capability of the algorithm. The new protocol avoided the die of partial node of intensive using by making balanced use of the network nodes, improved the survival time of wireless sensor network. The simulation experiments proved that the protocol is better than LEACH protocol on energy consumption, also is better than that of clustering routing protocol based on particle swarm optimization algorithm.

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid

PubMed Central

Farokh Payam, Amir; Piantanida, Luca; Cafolla, Clodomiro; Voïtchovsky, Kislon

2016-01-01

Atomic force microscopy (AFM) has become a well-established technique for nanoscale imaging of samples in air and in liquid. Recent studies have shown that when operated in amplitude-modulation (tapping) mode, atomic or molecular-level resolution images can be achieved over a wide range of soft and hard samples in liquid. In these situations, small oscillation amplitudes (SAM-AFM) enhance the resolution by exploiting the solvated liquid at the surface of the sample. Although the technique has been successfully applied across fields as diverse as materials science, biology and biophysics and surface chemistry, obtaining high-resolution images in liquid can still remain challenging for novice users. This is partly due to the large number of variables to control and optimize such as the choice of cantilever, the sample preparation, and the correct manipulation of the imaging parameters. Here, we present a protocol for achieving high-resolution images of hard and soft samples in fluid using SAM-AFM on a commercial instrument. Our goal is to provide a step-by-step practical guide to achieving high-resolution images, including the cleaning and preparation of the apparatus and the sample, the choice of cantilever and optimization of the imaging parameters. For each step, we explain the scientific rationale behind our choices to facilitate the adaptation of the methodology to every user's specific system. PMID:28060262

SU-F-J-178: A Computer Simulation Model Observer for Task-Based Image Quality Assessment in Radiation Therapy

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

Dolly, S; Mutic, S; Anastasio, M

Purpose: Traditionally, image quality in radiation therapy is assessed subjectively or by utilizing physically-based metrics. Some model observers exist for task-based medical image quality assessment, but almost exclusively for diagnostic imaging tasks. As opposed to disease diagnosis, the task for image observers in radiation therapy is to utilize the available images to design and deliver a radiation dose which maximizes patient disease control while minimizing normal tissue damage. The purpose of this study was to design and implement a new computer simulation model observer to enable task-based image quality assessment in radiation therapy. Methods: A modular computer simulation framework wasmore » developed to resemble the radiotherapy observer by simulating an end-to-end radiation therapy treatment. Given images and the ground-truth organ boundaries from a numerical phantom as inputs, the framework simulates an external beam radiation therapy treatment and quantifies patient treatment outcomes using the previously defined therapeutic operating characteristic (TOC) curve. As a preliminary demonstration, TOC curves were calculated for various CT acquisition and reconstruction parameters, with the goal of assessing and optimizing simulation CT image quality for radiation therapy. Sources of randomness and bias within the system were analyzed. Results: The relationship between CT imaging dose and patient treatment outcome was objectively quantified in terms of a singular value, the area under the TOC (AUTOC) curve. The AUTOC decreases more rapidly for low-dose imaging protocols. AUTOC variation introduced by the dose optimization algorithm was approximately 0.02%, at the 95% confidence interval. Conclusion: A model observer has been developed and implemented to assess image quality based on radiation therapy treatment efficacy. It enables objective determination of appropriate imaging parameter values (e.g. imaging dose). Framework flexibility allows for incorporation of additional modules to include any aspect of the treatment process, and therefore has great potential for both assessment and optimization within radiation therapy.« less

Estimating weak ratiometric signals in imaging data. II. Meta-analysis with multiple, dual-channel datasets.

PubMed

Sornborger, Andrew; Broder, Josef; Majumder, Anirban; Srinivasamoorthy, Ganesh; Porter, Erika; Reagin, Sean S; Keith, Charles; Lauderdale, James D

2008-09-01

Ratiometric fluorescent indicators are used for making quantitative measurements of a variety of physiological variables. Their utility is often limited by noise. This is the second in a series of papers describing statistical methods for denoising ratiometric data with the aim of obtaining improved quantitative estimates of variables of interest. Here, we outline a statistical optimization method that is designed for the analysis of ratiometric imaging data in which multiple measurements have been taken of systems responding to the same stimulation protocol. This method takes advantage of correlated information across multiple datasets for objectively detecting and estimating ratiometric signals. We demonstrate our method by showing results of its application on multiple, ratiometric calcium imaging experiments.

Visual-search model observer for assessing mass detection in CT

NASA Astrophysics Data System (ADS)

Karbaschi, Zohreh; Gifford, Howard C.

2017-03-01

Our aim is to devise model observers (MOs) to evaluate acquisition protocols in medical imaging. To optimize protocols for human observers, an MO must reliably interpret images containing quantum and anatomical noise under aliasing conditions. In this study of sampling parameters for simulated lung CT, the lesion-detection performance of human observers was compared with that of visual-search (VS) observers, a channelized nonprewhitening (CNPW) observer, and a channelized Hoteling (CH) observer. Scans of a mathematical torso phantom modeled single-slice parallel-hole CT with varying numbers of detector pixels and angular projections. Circular lung lesions had a fixed radius. Twodimensional FBP reconstructions were performed. A localization ROC study was conducted with the VS, CNPW and human observers, while the CH observer was applied in a location-known ROC study. Changing the sampling parameters had negligible effect on the CNPW and CH observers, whereas several VS observers demonstrated a sensitivity to sampling artifacts that was in agreement with how the humans performed.

In Vitro Culturing and Live Imaging of Drosophila Egg Chambers: A History and Adaptable Method.

PubMed

Peters, Nathaniel C; Berg, Celeste A

2016-01-01

The development of the Drosophila egg chamber encompasses a myriad of diverse germline and somatic events, and as such, the egg chamber has become a widely used and influential developmental model. Advantages of this system include physical accessibility, genetic tractability, and amenability to microscopy and live culturing, the last of which is the focus of this chapter. To provide adequate context, we summarize the structure of the Drosophila ovary and egg chamber, the morphogenetic events of oogenesis, the history of egg-chamber live culturing, and many of the important discoveries that this culturing has afforded. Subsequently, we discuss various culturing methods that have facilitated analyses of different stages of egg-chamber development and different types of cells within the egg chamber, and we present an optimized protocol for live culturing Drosophila egg chambers.We designed this protocol for culturing late-stage Drosophila egg chambers and live imaging epithelial tube morphogenesis, but with appropriate modifications, it can be used to culture egg chambers of any stage. The protocol employs a liquid-permeable, weighted "blanket" to gently hold egg chambers against the coverslip in a glass-bottomed culture dish so the egg chambers can be imaged on an inverted microscope. This setup provides a more buffered, stable, culturing environment than previously published methods by using a larger volume of culture media, but the setup is also compatible with small volumes. This chapter should aid researchers in their efforts to culture and live-image Drosophila egg chambers, further augmenting the impressive power of this model system.

In vitro culturing and live imaging of Drosophila egg chambers: A history and adaptable method

PubMed Central

Peters, Nathaniel C.; Berg, Celeste A.

2017-01-01

Summary/Abstract The development of the Drosophila egg chamber encompasses a myriad of diverse germline and somatic events, and as such, the egg chamber has become a widely used and influential developmental model. Advantages of this system include physical accessibility, genetic tractability, and amenability to microscopy and live culturing, the last of which is the focus of this chapter. To provide adequate context, we summarize the structure of the Drosophila ovary and egg chamber, the morphogenetic events of oogenesis, the history of egg-chamber live culturing, and many of the important discoveries that this culturing has afforded. Subsequently, we discuss various culturing methods that have facilitated analyses of different stages of egg-chamber development and different types of cells within the egg chamber, and we present an optimized protocol for live culturing Drosophila egg chambers. We designed this protocol for culturing late-stage Drosophila egg chambers and live imaging epithelial tube morphogenesis, but with appropriate modifications it can be used to culture egg chambers of any stage. The protocol employs a liquid-permeable, weighted, “blanket” to gently hold egg chambers against the coverslip in a glass-bottomed culture dish so the egg chambers can be imaged on an inverted microscope. This setup provides a more buffered, stable culturing environment than previously published methods by using a larger volume of culture media, but the setup is also compatible with small volumes. This chapter should aid researchers in their efforts to culture and live image Drosophila egg chambers, further augmenting the impressive power of this model system. PMID:27557572

SU-E-J-113: The Influence of Optimizing Pediatric CT Simulator Protocols On the Treatment Dose Calculation in Radiotherapy

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

Zhang, Y; Zhang, J; Hu, Q

2014-06-01

Purpose: To investigate the possibility of applying optimized scanning protocols for pediatric CT simulation by quantifying the dosimetric inaccuracy introduced by using a fixed HU to density conversion. Methods: The images of a CIRS electron density reference phantom (Model 062) were acquired by a Siemens CT simulator (Sensation Open) using the following settings of tube voltage and beam current: 120 kV/190mA (the reference protocol used to calibrate CT for our treatment planning system (TPS)); Fixed 190mA combined with all available kV: 80, 100, and 140; fixed 120 kV and various current from 37 to 444 mA (scanner extremes) with intervalmore » of 30 mA. To avoid the HU uncertainty of point sampling in the various inserts of known electron densities, the mean CT numbers of the central cylindrical volume were calculated using DICOMan software. The doses per 100 MU to the reference point (SAD=100cm, Depth=10cm, Field=10X10cm, 6MV photon beam) in a virtual cubic phantom (30X30X30cm) were calculated using Eclipse TPS (calculation model: AcurosXB-11031) by assigning the CT numbers to HU of typical materials acquired by various protocols. Results: For the inserts of densities less than muscle, CT number fluctuations of all protocols were within the tolerance of 10 HU as accepted by AAPM-TG66. For more condensed materials, fixed kV yielded stable HU with any mA combination where largest disparities were found in 1750mg/cc insert: HU{sub reference}=1801(106.6cGy), HU{sub minimum}=1799 (106.6cGy, error{sub dose}=0.00%), HU{sub maximum}=1815 (106.8cGy, error{sub dose}=0.19%). Yet greater disagreements were observed with increasing density when kV was modified: HU{sub minimum}=1646 (104.5cGy, error{sub dose}=- 1.97%), HU{sub maximum}=2487 (116.4cGy, error{sub dose}=9.19%) in 1750mg/cc insert. Conclusion: Without affecting treatment dose calculation, personalized mA optimization of CT simulator can be conducted by fixing kV for a better cost-effectiveness of imaging dose and quality especially for children. Unless recalibrated, kV should be constant for all anatomical sites if diagnostic CT scanner is used as a simulator. This work was partially supported by Capital Medical Development Scientific Research Fund of China.« less

SU-E-I-23: A General KV Constrained Optimization of CNR for CT Abdominal Imaging

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

Weir, V; Zhang, J

Purpose: While Tube current modulation has been well accepted for CT dose reduction, kV adjusting in clinical settings is still at its early stage. This is mainly due to the limited kV options of most current CT scanners. kV adjusting can potentially reduce radiation dose and optimize image quality. This study is to optimize CT abdomen imaging acquisition based on the assumption of a continuous kV, with the goal to provide the best contrast to noise ratio (CNR). Methods: For a given dose (CTDIvol) level, the CNRs at different kV and pitches were measured with an ACR GAMMEX phantom. Themore » phantom was scanned in a Siemens Sensation 64 scanner and a GE VCT 64 scanner. A constrained mathematical optimization was used to find the kV which led to the highest CNR for the anatomy and pitch setting. Parametric equations were obtained from polynomial fitting of plots of kVs vs CNRs. A suitable constraint region for optimization was chosen. Subsequent optimization yielded a peak CNR at a particular kV for different collimations and pitch setting. Results: The constrained mathematical optimization approach yields kV of 114.83 and 113.46, with CNRs of 1.27 and 1.11 at the pitch of 1.2 and 1.4, respectively, for the Siemens Sensation 64 scanner with the collimation of 32 x 0.625mm. An optimized kV of 134.25 and 1.51 CNR is obtained for a GE VCT 64 slice scanner with a collimation of 32 x 0.625mm and a pitch of 0.969. At 0.516 pitch and 32 x 0.625 mm an optimized kV of 133.75 and a CNR of 1.14 was found for the GE VCT 64 slice scanner. Conclusion: CNR in CT image acquisition can be further optimized with a continuous kV option instead of current discrete or fixed kV settings. A continuous kV option is a key for individualized CT protocols.« less

An optimized immunohistochemistry protocol for detecting the guidance cue Netrin-1 in neural tissue.

PubMed

Salameh, Samer; Nouel, Dominique; Flores, Cecilia; Hoops, Daniel

2018-01-01

Netrin-1, an axon guidance protein, is difficult to detect using immunohistochemistry. We performed a multi-step, blinded, and controlled protocol optimization procedure to establish an efficient and effective fluorescent immunohistochemistry protocol for characterizing Netrin-1 expression. Coronal mouse brain sections were used to test numerous antigen retrieval methods and combinations thereof in order to optimize the stain quality of a commercially available Netrin-1 antibody. Stain quality was evaluated by experienced neuroanatomists for two criteria: signal intensity and signal-to-noise ratio. After five rounds of testing protocol variants, we established a modified immunohistochemistry protocol that produced a Netrin-1 signal with good signal intensity and a high signal-to-noise ratio. The key protocol modifications are as follows: •Use phosphate buffer (PB) as the blocking solution solvent.•Use 1% sodium dodecyl sulfate (SDS) treatment for antigen retrieval. The original protocol was optimized for use with the Netrin-1 antibody produced by Novus Biologicals. However, we subsequently further modified the protocol to work with the antibody produced by Abcam. The Abcam protocol uses PBS as the blocking solution solvent and adds a citrate buffer antigen retrieval step.

Multicenter evaluation of stress-first myocardial perfusion image triage by nuclear technologists and automated quantification.

PubMed

Chaudhry, Waseem; Hussain, Nasir; Ahlberg, Alan W; Croft, Lori B; Fernandez, Antonio B; Parker, Mathew W; Swales, Heather H; Slomka, Piotr J; Henzlova, Milena J; Duvall, W Lane

2017-06-01

A stress-first myocardial perfusion imaging (MPI) protocol saves time, is cost effective, and decreases radiation exposure. A limitation of this protocol is the requirement for physician review of the stress images to determine the need for rest images. This hurdle could be eliminated if an experienced technologist and/or automated computer quantification could make this determination. Images from consecutive patients who were undergoing a stress-first MPI with attenuation correction at two tertiary care medical centers were prospectively reviewed independently by a technologist and cardiologist blinded to clinical and stress test data. Their decision on the need for rest imaging along with automated computer quantification of perfusion results was compared with the clinical reference standard of an assessment of perfusion images by a board-certified nuclear cardiologist that included clinical and stress test data. A total of 250 patients (mean age 61 years and 55% female) who underwent a stress-first MPI were studied. According to the clinical reference standard, 42 (16.8%) and 208 (83.2%) stress-first images were interpreted as "needing" and "not needing" rest images, respectively. The technologists correctly classified 229 (91.6%) stress-first images as either "needing" (n = 28) or "not needing" (n = 201) rest images. Their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 66.7%, 96.6%, 80.0%, and 93.5%, respectively. An automated stress TPD score ≥1.2 was associated with optimal sensitivity and specificity and correctly classified 179 (71.6%) stress-first images as either "needing" (n = 31) or "not needing" (n = 148) rest images. Its sensitivity, specificity, PPV, and NPV were 73.8%, 71.2%, 34.1%, and 93.1%, respectively. In a model whereby the computer or technologist could correct for the other's incorrect classification, 242 (96.8%) stress-first images were correctly classified. The composite sensitivity, specificity, PPV, and NPV were 83.3%, 99.5%, 97.2%, and 96.7%, respectively. Technologists and automated quantification software had a high degree of agreement with the clinical reference standard for determining the need for rest images in a stress-first imaging protocol. Utilizing an experienced technologist and automated systems to screen stress-first images could expand the use of stress-first MPI to sites where the cardiologist is not immediately available for interpretation.

Quantitative evaluation of multi-parametric MR imaging marker changes post-laser interstitial ablation therapy (LITT) for epilepsy

NASA Astrophysics Data System (ADS)

Tiwari, Pallavi; Danish, Shabbar; Wong, Stephen; Madabhushi, Anant

2013-03-01

Laser-induced interstitial thermal therapy (LITT) has recently emerged as a new, less invasive alternative to craniotomy for treating epilepsy; which allows for focussed delivery of laser energy monitored in real time by MRI, for precise removal of the epileptogenic foci. Despite being minimally invasive, the effects of laser ablation on the epileptogenic foci (reflected by changes in MR imaging markers post-LITT) are currently unknown. In this work, we present a quantitative framework for evaluating LITT-related changes by quantifying per-voxel changes in MR imaging markers which may be more reflective of local treatment related changes (TRC) that occur post-LITT, as compared to the standard volumetric analysis which involves monitoring a more global volume change across pre-, and post-LITT MRI. Our framework focuses on three objectives: (a) development of temporal MRI signatures that characterize TRC corresponding to patients with seizure freedom by comparing differences in MR imaging markers and monitoring them over time, (b) identification of the optimal time point when early LITT induced effects (such as edema and mass effect) subside by monitoring TRC at subsequent time-points post-LITT, and (c) identification of contributions of individual MRI protocols towards characterizing LITT-TRC for epilepsy by identifying MR markers that change most dramatically over time and employ individual contributions to create a more optimal weighted MP-MRI temporal profile that can better characterize TRC compared to any individual imaging marker. A cohort of patients were monitored at different time points post-LITT via MP-MRI involving T1-w, T2-w, T2-GRE, T2-FLAIR, and apparent diffusion coefficient (ADC) protocols. Post affine registration of individual MRI protocols to a reference MRI protocol pre-LITT, differences in individual MR markers are computed on a per-voxel basis, at different time-points with respect to baseline (pre-LITT) MRI as well as across subsequent time-points. A time-dependent MRI profile corresponding to successful (seizure-free) is then created that captures changes in individual MR imaging markers over time. Our preliminary analysis on two patient studies suggests that (a) LITT related changes (attributed to swelling and edema) appear to subside within 4-weeks post-LITT, (b) ADC may be more sensitive for evaluating early TRC (up to 3-months), and T1-w may be more sensitive in evaluating early delayed TRC (1-month, 3-months), while T2-w and T2-FLAIR appeared to be more sensitive in identifying late TRC (around 6-months post-LITT) compared to the other MRI protocols under evaluation. T2-GRE was found to be only nominally sensitive in identifying TRC at any follow-up time-point post-LITT. The framework presented in this work thus serves as an important precursor to a comprehensive treatment evaluation framework that can be used to identify sensitive MR markers corresponding to patient response (seizure-freedom or seizure recurrence), with an ultimate objective of making prognostic predictions about patient outcome post-LITT.

Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

PubMed Central

Yao, Xinwen; Gan, Yu; Marboe, Charles C.; Hendon, Christine P.

2016-01-01

Abstract. We present an ultrahigh-resolution spectral domain optical coherence tomography (OCT) system in 800 nm with a low-noise supercontinuum source (SC) optimized for myocardial imaging. The system was demonstrated to have an axial resolution of 2.72  μm with a large imaging depth of 1.78 mm and a 6-dB falloff range of 0.89 mm. The lateral resolution (5.52  μm) was compromised to enhance the image penetration required for myocardial imaging. The noise of the SC source was analyzed extensively and an imaging protocol was proposed for SC-based OCT imaging with appreciable contrast. Three-dimensional datasets were acquired ex vivo on the endocardium side of tissue specimens from different chambers of fresh human and swine hearts. With the increased resolution and contrast, features such as elastic fibers, Purkinje fibers, and collagen fiber bundles were observed. The correlation between the structural information revealed in the OCT images and tissue pathology was discussed as well. PMID:27001162

Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Yao, Xinwen; Gan, Yu; Marboe, Charles C.; Hendon, Christine P.

2016-06-01

We present an ultrahigh-resolution spectral domain optical coherence tomography (OCT) system in 800 nm with a low-noise supercontinuum source (SC) optimized for myocardial imaging. The system was demonstrated to have an axial resolution of 2.72 μm with a large imaging depth of 1.78 mm and a 6-dB falloff range of 0.89 mm. The lateral resolution (5.52 μm) was compromised to enhance the image penetration required for myocardial imaging. The noise of the SC source was analyzed extensively and an imaging protocol was proposed for SC-based OCT imaging with appreciable contrast. Three-dimensional datasets were acquired ex vivo on the endocardium side of tissue specimens from different chambers of fresh human and swine hearts. With the increased resolution and contrast, features such as elastic fibers, Purkinje fibers, and collagen fiber bundles were observed. The correlation between the structural information revealed in the OCT images and tissue pathology was discussed as well.

Accelerated whole brain intracranial vessel wall imaging using black blood fast spin echo with compressed sensing (CS-SPACE).

PubMed

Zhu, Chengcheng; Tian, Bing; Chen, Luguang; Eisenmenger, Laura; Raithel, Esther; Forman, Christoph; Ahn, Sinyeob; Laub, Gerhard; Liu, Qi; Lu, Jianping; Liu, Jing; Hess, Christopher; Saloner, David

2018-06-01

Develop and optimize an accelerated, high-resolution (0.5 mm isotropic) 3D black blood MRI technique to reduce scan time for whole-brain intracranial vessel wall imaging. A 3D accelerated T 1 -weighted fast-spin-echo prototype sequence using compressed sensing (CS-SPACE) was developed at 3T. Both the acquisition [echo train length (ETL), under-sampling factor] and reconstruction parameters (regularization parameter, number of iterations) were first optimized in 5 healthy volunteers. Ten patients with a variety of intracranial vascular disease presentations (aneurysm, atherosclerosis, dissection, vasculitis) were imaged with SPACE and optimized CS-SPACE, pre and post Gd contrast. Lumen/wall area, wall-to-lumen contrast ratio (CR), enhancement ratio (ER), sharpness, and qualitative scores (1-4) by two radiologists were recorded. The optimized CS-SPACE protocol has ETL 60, 20% k-space under-sampling, 0.002 regularization factor with 20 iterations. In patient studies, CS-SPACE and conventional SPACE had comparable image scores both pre- (3.35 ± 0.85 vs. 3.54 ± 0.65, p = 0.13) and post-contrast (3.72 ± 0.58 vs. 3.53 ± 0.57, p = 0.15), but the CS-SPACE acquisition was 37% faster (6:48 vs. 10:50). CS-SPACE agreed with SPACE for lumen/wall area, ER measurements and sharpness, but marginally reduced the CR. In the evaluation of intracranial vascular disease, CS-SPACE provides a substantial reduction in scan time compared to conventional T 1 -weighted SPACE while maintaining good image quality.

Abbreviated breast magnetic resonance protocol: Value of high-resolution temporal dynamic sequence to improve lesion characterization.

PubMed

Oldrini, Guillaume; Fedida, Benjamin; Poujol, Julie; Felblinger, Jacques; Trop, Isabelle; Henrot, Philippe; Darai, Emile; Thomassin-Naggara, Isabelle

2017-10-01

To evaluate the added value of ULTRAFAST-MR sequence to an abbreviated FAST protocol in comparison with FULL protocol to distinguish benign from malignant lesions in a population of women, regardless of breast MR imaging indication. From March 10th to September 22th, 2014, we retrospectively included a total of 70 consecutive patients with 106 histologically proven lesions (58 malignant and 48 benign) who underwent breast MR imaging for preoperative breast staging (n=38), high-risk screening (n=7), problem solving (n=18), and nipple discharge (n=4) with 12 time resolved imaging of contrast kinetics (TRICKS) acquisitions during contrast inflow interleaved in a regular high-resolution dynamic MRI protocol (FULL protocol). Two readers scored MR exams as either positive or negative and described significant lesions according to Bi-RADS lexicon with a TRICKS images (ULTRAFAST), an abbreviated protocol (FAST) and all images (FULL protocol). Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for each protocol and compared with McNemar's test. For all readers, the combined FAST-ULTRAFAST protocol significantly improved the reading with a specificity of 83.3% and 70.8% in comparison with FAST protocol or FULL protocol, respectively, without change in sensitivity. By adding ULTRAFAST protocol to FAST protocol, readers 1 and 2 were able to correctly change the diagnosis in 22.9% (11/48) and 10.4% (5/48) of benign lesions, without missing any malignancy, respectively. Both interpretation and image acquisition times for combined FAST-ULTRAFAST protocol and FAST protocol were shorter compared to FULL protocol (p<0.001). Compared to FULL protocol, adding ULTRAFAST to FAST protocol improves specificity, mainly in correctly reclassifying benign masses and reducing interpretation and acquisition time, without decreasing sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

TH-A-BRF-05: MRI of Individual Lymph Nodes to Guide Regional Breast Radiotherapy

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

Heijst, T van; Asselen, B van; Lagendijk, J

2014-06-15

Purpose: In regional radiotherapy (RT) for breast-cancer patients, direct visualization of individual lymph nodes (LNs) may reduce target volumes and Result in lower toxicity (i.e. reduced radiation pneumonitis, arm edema, arm morbidity), relative to standard CT-based delineations. To this end, newly designed magnetic resonance imaging (MRI) sequences were optimized and assessed qualitatively and quantitatively. Methods: In ten healthy female volunteers, a scanning protocol was developed and optimized. Coronal images were acquired in supine RT position positioned on a wedge board on a 1.5 T Ingenia (Philips) wide-bore MRI. In four volunteers the optimized MRI protocol was applied, including a 3-dimensionalmore » (3D) T1-weighted (T1w) fast-field-echo (FFE). T2w sequences, including 3D FFE, 3D and 2D fast spin echo (FSE), and diffusion-weighted single-shot echo-planar imaging (DWI) were also performed. Several fatsuppression techniques were used. Qualitative evaluation parameters included LN contrast, motion susceptibility, visibility of anatomical structures, and fat suppression. The number of visible axillary and supraclavicular LNs was also determined. Results: T1 FFE, insensitive to motion, lacked contrast of LNs, which often blended in with soft tissue and blood. T2 FFE showed high contrast, but some LNs were obscured due to motion. Both 2D and 3D FSE were motion-insensitive having high contrast, although some blood remained visible. 2D FSE showed more anatomical details, while in 3D FSE, some blurring occurred. DWI showed high LN contrast, but suffered from geometric distortions and low resolution. Fat suppression by mDixon was the most reliable in regions with magnetic-field inhomogeneities. The FSE sequences showed the highest sensitivity for LN detection. Conclusion: MRI of regional LNs was achieved in volunteers. The FSE techniques were robust and the most sensitive. Our optimized MRI sequences can facilitate direct delineation of individual LNs. This can Result in smaller target volumes and reduced toxicity in regional RT compared to standard CT planning.« less

TH-E-209-00: Radiation Dose Monitoring and Protocol Management

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

NONE

Radiation dose monitoring solutions have opened up new opportunities for medical physicists to be more involved in modern clinical radiology practices. In particular, with the help of comprehensive radiation dose data, data-driven protocol management and informed case follow up are now feasible. Significant challenges remain however and the problems faced by medical physicists are highly heterogeneous. Imaging systems from multiple vendors and a wide range of vintages co-exist in the same department and employ data communication protocols that are not fully standardized or implemented making harmonization complex. Many different solutions for radiation dose monitoring have been implemented by imaging facilitiesmore » over the past few years. Such systems are based on commercial software, home-grown IT solutions, manual PACS data dumping, etc., and diverse pathways can be used to bring the data to impact clinical practice. The speakers will share their experiences with creating or tailoring radiation dose monitoring/management systems and procedures over the past few years, which vary significantly in design and scope. Topics to cover: (1) fluoroscopic dose monitoring and high radiation event handling from a large academic hospital; (2) dose monitoring and protocol optimization in pediatric radiology; and (3) development of a home-grown IT solution and dose data analysis framework. Learning Objectives: Describe the scope and range of radiation dose monitoring and protocol management in a modern radiology practice Review examples of data available from a variety of systems and how it managed and conveyed. Reflect on the role of the physicist in radiation dose awareness.« less

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

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

Yan, Hao; Folkerts, Michael; Jiang, Steve B., E-mail: xun.jia@utsouthwestern.edu, E-mail: steve.jiang@UTSouthwestern.edu

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 inventedmore » 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. Conclusions: High-quality 4D-CBCT imaging based on the clinically standard 1-min 3D CBCT scanning protocol is feasible via the proposed hybrid reconstruction algorithm.« less

Evaluation of image registration in PET/CT of the liver and recommendations for optimized imaging.

PubMed

Vogel, Wouter V; van Dalen, Jorn A; Wiering, Bas; Huisman, Henkjan; Corstens, Frans H M; Ruers, Theo J M; Oyen, Wim J G

2007-06-01

Multimodality PET/CT of the liver can be performed with an integrated (hybrid) PET/CT scanner or with software fusion of dedicated PET and CT. Accurate anatomic correlation and good image quality of both modalities are important prerequisites, regardless of the applied method. Registration accuracy is influenced by breathing motion differences on PET and CT, which may also have impact on (attenuation correction-related) artifacts, especially in the upper abdomen. The impact of these issues was evaluated for both hybrid PET/CT and software fusion, focused on imaging of the liver. Thirty patients underwent hybrid PET/CT, 20 with CT during expiration breath-hold (EB) and 10 with CT during free breathing (FB). Ten additional patients underwent software fusion of dedicated PET and dedicated expiration breath-hold CT (SF). The image registration accuracy was evaluated at the location of liver borders on CT and uncorrected PET images and at the location of liver lesions. Attenuation-correction artifacts were evaluated by comparison of liver borders on uncorrected and attenuation-corrected PET images. CT images were evaluated for the presence of breathing artifacts. In EB, 40% of patients had an absolute registration error of the diaphragm in the craniocaudal direction of >1 cm (range, -16 to 44 mm), and 45% of lesions were mispositioned >1 cm. In 50% of cases, attenuation-correction artifacts caused a deformation of the liver dome on PET of >1 cm. Poor compliance to breath-hold instructions caused CT artifacts in 55% of cases. In FB, 30% had registration errors of >1 cm (range, -4 to 16 mm) and PET artifacts were less extensive, but all CT images had breathing artifacts. As SF allows independent alignment of PET and CT, no registration errors or artifacts of >1 cm of the diaphragm occurred. Hybrid PET/CT of the liver may have significant registration errors and artifacts related to breathing motion. The extent of these issues depends on the selected breathing protocol and the speed of the CT scanner. No protocol or scanner can guarantee perfect image fusion. On the basis of these findings, recommendations were formulated with regard to scanner requirements, breathing protocols, and reporting.

Experimental considerations for fast kurtosis imaging.

PubMed

Hansen, Brian; Lund, Torben E; Sangill, Ryan; Stubbe, Ebbe; Finsterbusch, Jürgen; Jespersen, Sune Nørhøj

2016-11-01

The clinical use of kurtosis imaging is impeded by long acquisitions and postprocessing. Recently, estimation of mean kurtosis tensor W¯ and mean diffusivity ( D¯) was made possible from 13 distinct diffusion weighted MRI acquisitions (the 1-3-9 protocol) with simple postprocessing. Here, we analyze the effects of noise and nonideal diffusion encoding, and propose a new correction strategy. We also present a 1-9-9 protocol with increased robustness to experimental imperfections and minimal additional scan time. This refinement does not affect computation time and also provides a fast estimate of fractional anisotropy (FA). 1-3-9/1-9-9 data are acquired in rat and human brains, and estimates of D¯, FA, W¯ from human brains are compared with traditional estimates from an extensive diffusion kurtosis imaging data set. Simulations are used to evaluate the influence of noise and diffusion encodings deviating from the scheme, and the performance of the correction strategy. Optimal b-values are determined from simulations and data. Accuracy and precision in D¯ and W¯ are comparable to nonlinear least squares estimation, and is improved with the 1-9-9 protocol. The compensation strategy vastly improves parameter estimation in nonideal data. The framework offers a robust and compact method for estimating several diffusion metrics. The protocol is easily implemented. Magn Reson Med 76:1455-1468, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Epi-Fluorescence Microscopy

PubMed Central

Webb, Donna J.; Brown, Claire M.

2012-01-01

Epi-fluorescence microscopy is available in most life sciences research laboratories, and when optimized can be a central laboratory tool. In this chapter, the epi-fluorescence light path is introduced and the various components are discussed in detail. Recommendations are made for incident lamp light sources, excitation and emission filters, dichroic mirrors, objective lenses, and charge-coupled device (CCD) cameras in order to obtain the most sensitive epi-fluorescence microscope. The even illumination of metal-halide lamps combined with new “hard” coated filters and mirrors, a high resolution monochrome CCD camera, and a high NA objective lens are all recommended for high resolution and high sensitivity fluorescence imaging. Recommendations are also made for multicolor imaging with the use of monochrome cameras, motorized filter turrets, individual filter cubes, and corresponding dyes that are the best choice for sensitive, high resolution multicolor imaging. Images should be collected using Nyquist sampling and should be corrected for background intensity contributions and nonuniform illumination across the field of view. Photostable fluorescent probes and proteins that absorb a lot of light (i.e., high extinction co-efficients) and generate a lot of fluorescence signal (i.e., high quantum yields) are optimal. A neuronal immune-fluorescence labeling protocol is also presented. Finally, in order to maximize the utility of sensitive wide-field microscopes and generate the highest resolution images with high signal-to-noise, advice for combining wide-field epi-fluorescence imaging with restorative image deconvolution is presented. PMID:23026996

Test-Retest Repeatability of Myocardial Blood Flow Measurements using Rubidium-82 Positron Emission Tomography

NASA Astrophysics Data System (ADS)

Efseaff, Matthew

Rubidium-82 positron emission tomography (PET) imaging has been proposed for routine myocardial blood flow (MBF) quantification. Few studies have investigated the test-retest repeatability of this method. Same-day repeatability of rest MBF imaging was optimized with a highly automated analysis program using image-derived input functions and a dual spillover correction (SOC). The effects of heterogeneous tracer infusion profiles and subject hemodynamics on test-retest repeatability were investigated at rest and during hyperemic stress. Factors affecting rest MBF repeatability included gender, suspected coronary artery disease, and dual SOC (p < 0.001). The best repeatability coefficient for same-day rest MBF was 0.20 mL/min/g using a six-minute scan-time, iterative reconstruction, dual SOC, resting rate-pressure-product (RPP) adjustment, and a left atrium image-derived input function. The serial study repeatabilities of the optimized protocol in subjects with homogeneous RPPs and tracer infusion profiles was 0.19 and 0.53 mL/min/g at rest and stress, and 0.95 for stress / rest myocardial flow reserve (MFR). Subjects with heterogeneous tracer infusion profiles and hemodynamic conditions had significantly less repeatable MBF measurements at rest, stress, and stress/rest flow reserve (p < 0.05).

Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses.

PubMed

Roth, Christian J; Becher, Tobias; Frerichs, Inéz; Weiler, Norbert; Wall, Wolfgang A

2017-04-01

Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EIT" module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling. NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results obtained in an acute respiratory distress syndrome patient show the potential of this approach for personalized computationally guided optimization of mechanical ventilation in future. Copyright © 2017 the American Physiological Society.

Optimized labeling of membrane proteins for applications to super-resolution imaging in confined cellular environments using monomeric streptavidin.

PubMed

Chamma, Ingrid; Rossier, Olivier; Giannone, Grégory; Thoumine, Olivier; Sainlos, Matthieu

2017-04-01

Recent progress in super-resolution imaging (SRI) has created a strong need to improve protein labeling with probes of small size that minimize the target-to-label distance, increase labeling density, and efficiently penetrate thick biological tissues. This protocol describes a method for labeling genetically modified proteins incorporating a small biotin acceptor peptide with a 3-nm fluorescent probe, monomeric streptavidin. We show how to express, purify, and conjugate the probe to organic dyes with different fluorescent properties, and how to label selectively biotinylated membrane proteins for SRI techniques (point accumulation in nanoscale topography (PAINT), stimulated emission depletion (STED), stochastic optical reconstruction microscopy (STORM)). This method is complementary to the previously described anti-GFP-nanobody/SNAP-tag strategies, with the main advantage being that it requires only a short 15-amino-acid tag, and can thus be used with proteins resistant to fusion with large tags and for multicolor imaging. The protocol requires standard molecular biology/biochemistry equipment, making it easily accessible for laboratories with only basic skills in cell biology and biochemistry. The production/purification/conjugation steps take ∼5 d, and labeling takes a few minutes to an hour.

MO-B-BRB-01: Optimize Treatment Planning Process in Clinical Environment

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

Feng, W.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

MO-B-BRB-00: Optimizing the Treatment Planning Process

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

NONE

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

MO-B-BRB-03: Systems Engineering Tools for Treatment Planning Process Optimization in Radiation Medicine

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

Kapur, A.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

Automated prescription of oblique brain 3D magnetic resonance spectroscopic imaging.

PubMed

Ozhinsky, Eugene; Vigneron, Daniel B; Chang, Susan M; Nelson, Sarah J

2013-04-01

Two major difficulties encountered in implementing Magnetic Resonance Spectroscopic Imaging (MRSI) in a clinical setting are limited coverage and difficulty in prescription. The goal of this project was to automate completely the process of 3D PRESS MRSI prescription, including placement of the selection box, saturation bands and shim volume, while maximizing the coverage of the brain. The automated prescription technique included acquisition of an anatomical MRI image, optimization of the oblique selection box parameters, optimization of the placement of outer-volume suppression saturation bands, and loading of the calculated parameters into a customized 3D MRSI pulse sequence. To validate the technique and compare its performance with existing protocols, 3D MRSI data were acquired from six exams from three healthy volunteers. To assess the performance of the automated 3D MRSI prescription for patients with brain tumors, the data were collected from 16 exams from 8 subjects with gliomas. This technique demonstrated robust coverage of the tumor, high consistency of prescription and very good data quality within the T2 lesion. Copyright © 2012 Wiley Periodicals, Inc.

Performance evaluation of a retrofit digital detector-based mammography system.

PubMed

Marshall, Nicholas W; van Ongeval, Chantal; Bosmans, Hilde

2016-02-01

A retrofit flat panel detector was integrated with a GE DMR+ analog mammography system and characterized using detective quantum efficiency (DQE). Technical system performance was evaluated using the European Guidelines protocol, followed by a limited evaluation of clinical image quality for 20 cases using image quality criteria in the European Guidelines. Optimal anode/filter selections were established using signal difference-to-noise ratio measurements. Only small differences in peak DQE were seen between the three anode/filter settings, with an average value of 0.53. For poly(methyl methacrylate) (PMMA) thicknesses above 60 mm, the Rh/Rh setting was the optimal anode/filter setting. The system required a mean glandular dose of 0.54 mGy at 30 kV Rh/Rh to reach the Acceptable gold thickness limit for 0.1 mm details. Imaging performance of the retrofit unit with the GE DMR+ is notably better than of powder based computed radiography systems and is comparable to current flat panel FFDM systems. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Characterization of tissue-simulating phantom materials for ultrasound-guided needle procedures

NASA Astrophysics Data System (ADS)

Buchanan, Susan; Moore, John; Lammers, Deanna; Baxter, John; Peters, Terry

2012-02-01

Needle biopsies are standard protocols that are commonly performed under ultrasound (US) guidance or computed tomography (CT)1. Vascular access such as central line insertions, and many spinal needle therapies also rely on US guidance. Phantoms for these procedures are crucial as both training tools for clinicians and research tools for developing new guidance systems. Realistic imaging properties and material longevity are critical qualities for needle guidance phantoms. However, current commercially available phantoms for use with US guidance have many limitations, the most detrimental of which include harsh needle tracks obfuscating US images and a membrane comparable to human skin that does not allow seepage of inner media. To overcome these difficulties, we tested a variety of readily available media and membranes to evaluate optimal materials to fit our current needs. It was concluded that liquid hand soap was the best medium, as it instantly left no needle tracks, had an acceptable depth of US penetration and portrayed realistic imaging conditions, while because of its low leakage, low cost, acceptable durability and transparency, the optimal membrane was 10 gauge vinyl.

Protein cage assisted metal-protein nanocomposite synthesis: Optimization of loading conditions

NASA Astrophysics Data System (ADS)

Sana, Barindra; Calista, Marcia; Lim, Sierin

2012-11-01

Ferritin is an iron-storage protein in most living systems with a cage-like structure. It has inherent property to form metallic nanocore within its cavity. The metallic core formed within the Archaeoglobus fulgidus ferritin cavity is stabilized by modulating the protein structure by site directed mutagenesis. Encapsulation protocol of various metals within the engineered ferritin cage (AfFtn-AA) is optimized. Dense metallic cores are visualized using electron microscopy and the bound metal was quantified by ICP-spectrometry. The AfFtn-AA is loaded with up to about 350 cobalt, 2000 chromium, and as high as 7000 iron atoms, separately. The metal-protein nanocomposites formed by encapsulation of cobalt, chromium, and iron are studied. Magnetic resonance imaging of the agarose embedded nanocomposites shows brightening of T1-weighted images and signal loss of T2-weighted images with increasing concentration of the nanocomposites. Shortening of magnetic relaxation times in the presence of the nanocomposites confirm their ability to enhance magnetic relaxation rate and suggests that the nanocomposites have potential application as MRI contrast agent.

Improving the efficiency of single and multiple teleportation protocols based on the direct use of partially entangled states

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

Fortes, Raphael; Rigolin, Gustavo, E-mail: rigolin@ifi.unicamp.br

We push the limits of the direct use of partially pure entangled states to perform quantum teleportation by presenting several protocols in many different scenarios that achieve the optimal efficiency possible. We review and put in a single formalism the three major strategies known to date that allow one to use partially entangled states for direct quantum teleportation (no distillation strategies permitted) and compare their efficiencies in real world implementations. We show how one can improve the efficiency of many direct teleportation protocols by combining these techniques. We then develop new teleportation protocols employing multipartite partially entangled states. The threemore » techniques are also used here in order to achieve the highest efficiency possible. Finally, we prove the upper bound for the optimal success rate for protocols based on partially entangled Bell states and show that some of the protocols here developed achieve such a bound. -- Highlights: •Optimal direct teleportation protocols using directly partially entangled states. •We put in a single formalism all strategies of direct teleportation. •We extend these techniques for multipartite partially entangle states. •We give upper bounds for the optimal efficiency of these protocols.« less

Coding and transmission of subband coded images on the Internet

NASA Astrophysics Data System (ADS)

Wah, Benjamin W.; Su, Xiao

2001-09-01

Subband-coded images can be transmitted in the Internet using either the TCP or the UDP protocol. Delivery by TCP gives superior decoding quality but with very long delays when the network is unreliable, whereas delivery by UDP has negligible delays but with degraded quality when packets are lost. Although images are delivered currently over the Internet by TCP, we study in this paper the use of UDP to deliver multi-description reconstruction-based subband-coded images. First, in order to facilitate recovery from UDP packet losses, we propose a joint sender-receiver approach for designing optimized reconstruction-based subband transform (ORB-ST) in multi-description coding (MDC). Second, we carefully evaluate the delay-quality trade-offs between the TCP delivery of SDC images and the UDP and combined TCP/UDP delivery of MDC images. Experimental results show that our proposed ORB-ST performs well in real Internet tests, and UDP and combined TCP/UDP delivery of MDC images provide a range of attractive alternatives to TCP delivery.

A Genetic Algorithm for the Generation of Packetization Masks for Robust Image Communication

PubMed Central

Zapata-Quiñones, Katherine; Duran-Faundez, Cristian; Gutiérrez, Gilberto; Lecuire, Vincent; Arredondo-Flores, Christopher; Jara-Lipán, Hugo

2017-01-01

Image interleaving has proven to be an effective solution to provide the robustness of image communication systems when resource limitations make reliable protocols unsuitable (e.g., in wireless camera sensor networks); however, the search for optimal interleaving patterns is scarcely tackled in the literature. In 2008, Rombaut et al. presented an interesting approach introducing a packetization mask generator based in Simulated Annealing (SA), including a cost function, which allows assessing the suitability of a packetization pattern, avoiding extensive simulations. In this work, we present a complementary study about the non-trivial problem of generating optimal packetization patterns. We propose a genetic algorithm, as an alternative to the cited work, adopting the mentioned cost function, then comparing it to the SA approach and a torus automorphism interleaver. In addition, we engage the validation of the cost function and provide results attempting to conclude about its implication in the quality of reconstructed images. Several scenarios based on visual sensor networks applications were tested in a computer application. Results in terms of the selected cost function and image quality metric PSNR show that our algorithm presents similar results to the other approaches. Finally, we discuss the obtained results and comment about open research challenges. PMID:28452934

Tissue segmentation of computed tomography images using a Random Forest algorithm: a feasibility study

NASA Astrophysics Data System (ADS)

Polan, Daniel F.; Brady, Samuel L.; Kaufman, Robert A.

2016-09-01

There is a need for robust, fully automated whole body organ segmentation for diagnostic CT. This study investigates and optimizes a Random Forest algorithm for automated organ segmentation; explores the limitations of a Random Forest algorithm applied to the CT environment; and demonstrates segmentation accuracy in a feasibility study of pediatric and adult patients. To the best of our knowledge, this is the first study to investigate a trainable Weka segmentation (TWS) implementation using Random Forest machine-learning as a means to develop a fully automated tissue segmentation tool developed specifically for pediatric and adult examinations in a diagnostic CT environment. Current innovation in computed tomography (CT) is focused on radiomics, patient-specific radiation dose calculation, and image quality improvement using iterative reconstruction, all of which require specific knowledge of tissue and organ systems within a CT image. The purpose of this study was to develop a fully automated Random Forest classifier algorithm for segmentation of neck-chest-abdomen-pelvis CT examinations based on pediatric and adult CT protocols. Seven materials were classified: background, lung/internal air or gas, fat, muscle, solid organ parenchyma, blood/contrast enhanced fluid, and bone tissue using Matlab and the TWS plugin of FIJI. The following classifier feature filters of TWS were investigated: minimum, maximum, mean, and variance evaluated over a voxel radius of 2 n , (n from 0 to 4), along with noise reduction and edge preserving filters: Gaussian, bilateral, Kuwahara, and anisotropic diffusion. The Random Forest algorithm used 200 trees with 2 features randomly selected per node. The optimized auto-segmentation algorithm resulted in 16 image features including features derived from maximum, mean, variance Gaussian and Kuwahara filters. Dice similarity coefficient (DSC) calculations between manually segmented and Random Forest algorithm segmented images from 21 patient image sections, were analyzed. The automated algorithm produced segmentation of seven material classes with a median DSC of 0.86  ±  0.03 for pediatric patient protocols, and 0.85  ±  0.04 for adult patient protocols. Additionally, 100 randomly selected patient examinations were segmented and analyzed, and a mean sensitivity of 0.91 (range: 0.82-0.98), specificity of 0.89 (range: 0.70-0.98), and accuracy of 0.90 (range: 0.76-0.98) were demonstrated. In this study, we demonstrate that this fully automated segmentation tool was able to produce fast and accurate segmentation of the neck and trunk of the body over a wide range of patient habitus and scan parameters.

Optimization of brain PET imaging for a multicentre trial: the French CATI experience.

PubMed

Habert, Marie-Odile; Marie, Sullivan; Bertin, Hugo; Reynal, Moana; Martini, Jean-Baptiste; Diallo, Mamadou; Kas, Aurélie; Trébossen, Régine

2016-12-01

CATI is a French initiative launched in 2010 to handle the neuroimaging of a large cohort of subjects recruited for an Alzheimer's research program called MEMENTO. This paper presents our test protocol and results obtained for the 22 PET centres (overall 13 different scanners) involved in the MEMENTO cohort. We determined acquisition parameters using phantom experiments prior to patient studies, with the aim of optimizing PET quantitative values to the highest possible per site, while reducing, if possible, variability across centres. Jaszczak's and 3D-Hoffman's phantom measurements were used to assess image spatial resolution (ISR), recovery coefficients (RC) in hot and cold spheres, and signal-to-noise ratio (SNR). For each centre, the optimal reconstruction parameters were chosen as those maximizing ISR and RC without a noticeable decrease in SNR. Point-spread-function (PSF) modelling reconstructions were discarded. The three figures of merit extracted from the images reconstructed with optimized parameters and routine schemes were compared, as were volumes of interest ratios extracted from Hoffman acquisitions. The net effect of the 3D-OSEM reconstruction parameter optimization was investigated on a subset of 18 scanners without PSF modelling reconstruction. Compared to the routine parameters of the 22 PET centres, average RC in the two smallest hot and cold spheres and average ISR remained stable or were improved with the optimized reconstruction, at the expense of slight SNR degradation, while the dispersion of values was reduced. For the subset of scanners without PSF modelling, the mean RC of the smallest hot sphere obtained with the optimized reconstruction was significantly higher than with routine reconstruction. The putamen and caudate-to-white matter ratios measured on 3D-Hoffman acquisitions of all centres were also significantly improved by the optimization, while the variance was reduced. This study provides guidelines for optimizing quantitative results for multicentric PET neuroimaging trials.

Multi-exponential analysis of magnitude MR images using a quantitative multispectral edge-preserving filter.

PubMed

Bonny, Jean Marie; Boespflug-Tanguly, Odile; Zanca, Michel; Renou, Jean Pierre

2003-03-01

A solution for discrete multi-exponential analysis of T(2) relaxation decay curves obtained in current multi-echo imaging protocol conditions is described. We propose a preprocessing step to improve the signal-to-noise ratio and thus lower the signal-to-noise ratio threshold from which a high percentage of true multi-exponential detection is detected. It consists of a multispectral nonlinear edge-preserving filter that takes into account the signal-dependent Rician distribution of noise affecting magnitude MR images. Discrete multi-exponential decomposition, which requires no a priori knowledge, is performed by a non-linear least-squares procedure initialized with estimates obtained from a total least-squares linear prediction algorithm. This approach was validated and optimized experimentally on simulated data sets of normal human brains.

Optimal protocols for slowly driven quantum systems.

PubMed

Zulkowski, Patrick R; DeWeese, Michael R

2015-09-01

The design of efficient quantum information processing will rely on optimal nonequilibrium transitions of driven quantum systems. Building on a recently developed geometric framework for computing optimal protocols for classical systems driven in finite time, we construct a general framework for optimizing the average information entropy for driven quantum systems. Geodesics on the parameter manifold endowed with a positive semidefinite metric correspond to protocols that minimize the average information entropy production in finite time. We use this framework to explicitly compute the optimal entropy production for a simple two-state quantum system coupled to a heat bath of bosonic oscillators, which has applications to quantum annealing.

Optimization of the Energy Window for PETbox4, a Preclinical PET Tomograph With a Small Inner Diameter

NASA Astrophysics Data System (ADS)

Gu, Z.; Bao, Q.; Taschereau, R.; Wang, H.; Bai, B.; Chatziioannou, A. F.

2014-06-01

Small animal positron emission tomography (PET) systems are often designed by employing close geometry configurations. Due to the different characteristics caused by geometrical factors, these tomographs require data acquisition protocols that differ from those optimized for conventional large diameter ring systems. In this work we optimized the energy window for data acquisitions with PETbox4, a 50 mm detector separation (box-like geometry) pre-clinical PET scanner, using the Geant4 Application for Tomographic Emission (GATE). The fractions of different types of events were estimated using a voxelized phantom including a mouse as well as its supporting chamber, mimicking a realistic mouse imaging environment. Separate code was developed to extract additional information about the gamma interactions for more accurate event type classification. Three types of detector backscatter events were identified in addition to the trues, phantom scatters and randoms. The energy window was optimized based on the noise equivalent count rate (NECR) and scatter fraction (SF) with lower-level discriminators (LLD) corresponding to energies from 150 keV to 450 keV. The results were validated based on the calculated image uniformity, spillover ratio (SOR) and recovery coefficient (RC) from physical measurements using the National Electrical Manufacturers Association (NEMA) NU-4 image quality phantom. These results indicate that when PETbox4 is operated with a more narrow energy window (350-650 keV), detector backscatter rejection is unnecessary. For the NEMA NU-4 image quality phantom, the SOR for the water chamber decreases by about 45% from 15.1% to 8.3%, and the SOR for the air chamber decreases by 31% from 12.0% to 8.3% at the LLDs of 150 and 350 keV, without obvious change in uniformity, further supporting the simulation based optimization. The optimization described in this work is not limited to PETbox4, but also applicable or helpful to other small inner diameter geometry scanners.

Improving Biomaterials Imaging for Nanotechnology: Rapid Methods for Protein Localization at Ultrastructural Level.

PubMed

Cano-Garrido, Olivia; Garcia-Fruitós, Elena; Villaverde, Antonio; Sánchez-Chardi, Alejandro

2018-04-01

The preparation of biological samples for electron microscopy is material- and time-consuming because it is often based on long protocols that also may produce artifacts. Protein labeling for transmission electron microscopy (TEM) is such an example, taking several days. However, for protein-based nanotechnology, high resolution imaging techniques are unique and crucial tools for studying the spatial distribution of these molecules, either alone or as components of biomaterials. In this paper, we tested two new short methods of immunolocalization for TEM, and compared them with a standard protocol in qualitative and quantitative approaches by using four protein-based nanoparticles. We reported a significant increase of labeling per area of nanoparticle in both new methodologies (H = 19.811; p < 0.001) with all the model antigens tested: GFP (H = 22.115; p < 0.001), MMP-2 (H = 19.579; p < 0.001), MMP-9 (H = 7.567; p < 0.023), and IFN-γ (H = 62.110; p < 0.001). We also found that the most suitable protocol for labeling depends on the nanoparticle's tendency to aggregate. Moreover, the shorter methods reduce artifacts, time (by 30%), residues, and reagents hindering, losing, or altering antigens, and obtaining a significant increase of protein localization (of about 200%). Overall, this study makes a step forward in the development of optimized protocols for the nanoscale localization of peptides and proteins within new biomaterials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Musculoskeletal MRI at 3.0 T and 7.0 T: a comparison of relaxation times and image contrast.

PubMed

Jordan, Caroline D; Saranathan, Manojkumar; Bangerter, Neal K; Hargreaves, Brian A; Gold, Garry E

2013-05-01

The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T. We measured the T₁ and T₂ relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T₁ relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T₂ relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T₁ and T₂ measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency. The T₁ relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T₂ relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T₂-weighted FSE, and 3D-FSE-Cube. The T₁ and T₂ changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The applied research of MRI with ASSET-EPI-FLAIR combined with 3D TOF MRA sequences in the assessment of patients with acute cerebral infarction.

PubMed

Lin, Zhichao; Guo, Zexiong; Qiu, Lin; Yang, Wanyoug; Lin, Mingxia

2016-12-01

Background To extend the time window for thrombolysis, reducing the time for diagnosis and detection of acute cerebral infarction seems to be warranted. Purpose To evaluate the feasibility of implementing an array spatial sensitivity technique (ASSET)-echo-planar imaging (EPI)-fluid attenuated inversion recovery (FLAIR) (AE-FLAIR) sequence into an acute cerebral infarction magnetic resonance (MR) evaluation protocol, and to assess the diagnostic value of AE-FLAIR combined with three-dimensional time-of-flight MR angiography (3D TOF MRA). Material and Methods A total of 100 patients (68 men, 32 women; age range, 44-82 years) with acute cerebral infarction, including 50 consecutive uncooperative and 50 cooperative patients, were evaluated with T1-weighted (T1W) imaging, T2-weighted (T2W) imaging, FLAIR, diffusion-weighted imaging (DWI), 3D TOF, EPI-FLAIR, and AE-FLAIR. Conventional FLAIR, EPI-FLAIR, and AE-FLAIR were assessed by two observers independently for image quality. The optimized group (AE-FLAIR and 3D TOF) and the control group (T1W imaging, T2W imaging, conventional FLAIR, DWI, and 3D TOF) were compared for evaluation time and diagnostic accuracy. Results One hundred and twenty-five lesions were detected and images having adequate diagnostic image quality were in 73% of conventional FLAIR, 62% of EPI-FLAIR, and 89% of AE-FLAIR. The detection time was 12 ± 1 min with 76% accuracy and 4 ± 0.5 min with 100% accuracy in the control and the optimized groups, respectively. Inter-observer agreements of κ = 0.78 and κ = 0.81 were for the optimized group and control group, respectively. Conclusion With reduced acquisition time and better image quality, AE-FLAIR combined with 3D TOF may be used as a rapid diagnosis tool in patients with acute cerebral infarction, especially in uncooperative patients.

Evaluation of training nurses to perform semi-automated three-dimensional left ventricular ejection fraction using a customised workstation-based training protocol.

PubMed

Guppy-Coles, Kristyan B; Prasad, Sandhir B; Smith, Kym C; Hillier, Samuel; Lo, Ada; Atherton, John J

2015-06-01

We aimed to determine the feasibility of training cardiac nurses to evaluate left ventricular function utilising a semi-automated, workstation-based protocol on three dimensional echocardiography images. Assessment of left ventricular function by nurses is an attractive concept. Recent developments in three dimensional echocardiography coupled with border detection assistance have reduced inter- and intra-observer variability and analysis time. This could allow abbreviated training of nurses to assess cardiac function. A comparative, diagnostic accuracy study evaluating left ventricular ejection fraction assessment utilising a semi-automated, workstation-based protocol performed by echocardiography-naïve nurses on previously acquired three dimensional echocardiography images. Nine cardiac nurses underwent two brief lectures about cardiac anatomy, physiology and three dimensional left ventricular ejection fraction assessment, before a hands-on demonstration in 20 cases. We then selected 50 cases from our three dimensional echocardiography library based on optimal image quality with a broad range of left ventricular ejection fractions, which was quantified by two experienced sonographers and the average used as the comparator for the nurses. Nurses independently measured three dimensional left ventricular ejection fraction using the Auto lvq package with semi-automated border detection. The left ventricular ejection fraction range was 25-72% (70% with a left ventricular ejection fraction <55%). All nurses showed excellent agreement with the sonographers. Minimal intra-observer variability was noted on both short-term (same day) and long-term (>2 weeks later) retest. It is feasible to train nurses to measure left ventricular ejection fraction utilising a semi-automated, workstation-based protocol on previously acquired three dimensional echocardiography images. Further study is needed to determine the feasibility of training nurses to acquire three dimensional echocardiography images on real-world patients to measure left ventricular ejection fraction. Nurse-performed evaluation of left ventricular function could facilitate the broader application of echocardiography to allow cost-effective screening and monitoring for left ventricular dysfunction in high-risk populations. © 2014 John Wiley & Sons Ltd.

Evaluation of DICOM viewer software for workflow integration in clinical trials

NASA Astrophysics Data System (ADS)

Haak, Daniel; Page, Charles E.; Kabino, Klaus; Deserno, Thomas M.

2015-03-01

The digital imaging and communications in medicine (DICOM) protocol is nowadays the leading standard for capture, exchange and storage of image data in medical applications. A broad range of commercial, free, and open source software tools supporting a variety of DICOM functionality exists. However, different from patient's care in hospital, DICOM has not yet arrived in electronic data capture systems (EDCS) for clinical trials. Due to missing integration, even just the visualization of patient's image data in electronic case report forms (eCRFs) is impossible. Four increasing levels for integration of DICOM components into EDCS are conceivable, raising functionality but also demands on interfaces with each level. Hence, in this paper, a comprehensive evaluation of 27 DICOM viewer software projects is performed, investigating viewing functionality as well as interfaces for integration. Concerning general, integration, and viewing requirements the survey involves the criteria (i) license, (ii) support, (iii) platform, (iv) interfaces, (v) two-dimensional (2D) and (vi) three-dimensional (3D) image viewing functionality. Optimal viewers are suggested for applications in clinical trials for 3D imaging, hospital communication, and workflow. Focusing on open source solutions, the viewers ImageJ and MicroView are superior for 3D visualization, whereas GingkoCADx is advantageous for hospital integration. Concerning workflow optimization in multi-centered clinical trials, we suggest the open source viewer Weasis. Covering most use cases, an EDCS and PACS interconnection with Weasis is suggested.

Preliminary pilot fMRI study of neuropostural optimization with a noninvasive asymmetric radioelectric brain stimulation protocol in functional dysmetria

PubMed Central

Mura, Marco; Castagna, Alessandro; Fontani, Vania; Rinaldi, Salvatore

2012-01-01

Purpose This study assessed changes in functional dysmetria (FD) and in brain activation observable by functional magnetic resonance imaging (fMRI) during a leg flexion-extension motor task following brain stimulation with a single radioelectric asymmetric conveyer (REAC) pulse, according to the precisely defined neuropostural optimization (NPO) protocol. Population and methods Ten healthy volunteers were assessed using fMRI conducted during a simple motor task before and immediately after delivery of a single REAC-NPO pulse. The motor task consisted of a flexion-extension movement of the legs with the knees bent. FD signs and brain activation patterns were compared before and after REAC-NPO. Results A single 250-millisecond REAC-NPO treatment alleviated FD, as evidenced by patellar asymmetry during a sit-up motion, and modulated activity patterns in the brain, particularly in the cerebellum, during the performance of the motor task. Conclusion Activity in brain areas involved in motor control and coordination, including the cerebellum, is altered by administration of a REAC-NPO treatment and this effect is accompanied by an alleviation of FD. PMID:22536071

7T Magnetization Transfer and Chemical Exchange Saturation Transfer MRI of Cortical Gray Matter: Can We Detect Neurochemical and Macromolecular Abnormalities?

DTIC Science & Technology

2014-10-21

measures working memory • Trail making test (both A and B): measures planning/executive function • "Black Box” (choice reaction time, critical flicker ...associated with SIR imaging. The former of these was mitigated by developing a novel B+ and !1B insensitive in- version composite pulse (Fig. 2) and...employing a low-flip angle TFE readout; the latter was mitigated by the efficiency of the TFE readout along with additional protocol optimization

Accurate tissue characterization in low-dose CT imaging with pure iterative reconstruction.

PubMed

Murphy, Kevin P; McLaughlin, Patrick D; Twomey, Maria; Chan, Vincent E; Moloney, Fiachra; Fung, Adrian J; Chan, Faimee E; Kao, Tafline; O'Neill, Siobhan B; Watson, Benjamin; O'Connor, Owen J; Maher, Michael M

2017-04-01

We assess the ability of low-dose hybrid iterative reconstruction (IR) and 'pure' model-based IR (MBIR) images to maintain accurate Hounsfield unit (HU)-determined tissue characterization. Standard-protocol (SP) and low-dose modified-protocol (MP) CTs were contemporaneously acquired in 34 Crohn's disease patients referred for CT. SP image reconstruction was via the manufacturer's recommendations (60% FBP, filtered back projection; 40% ASiR, Adaptive Statistical iterative Reconstruction; SP-ASiR40). MP data sets underwent four reconstructions (100% FBP; 40% ASiR; 70% ASiR; MBIR). Three observers measured tissue volumes using HU thresholds for fat, soft tissue and bone/contrast on each data set. Analysis was via SPSS. Inter-observer agreement was strong for 1530 datapoints (rs > 0.9). MP-MBIR tissue volume measurement was superior to other MP reconstructions and closely correlated with the reference SP-ASiR40 images for all tissue types. MP-MBIR superiority was most marked for fat volume calculation - close SP-ASiR40 and MP-MBIR Bland-Altman plot correlation was seen with the lowest average difference (336 cm 3 ) when compared with other MP reconstructions. Hounsfield unit-determined tissue volume calculations from MP-MBIR images resulted in values comparable to SP-ASiR40 calculations and values that are superior to MP-ASiR images. Accuracy of estimation of volume of tissues (e.g. fat) using segmentation software on low-dose CT images appears optimal when reconstructed with pure IR. © 2016 The Royal Australian and New Zealand College of Radiologists.

Dynamic Hierarchical Energy-Efficient Method Based on Combinatorial Optimization for Wireless Sensor Networks.

PubMed

Chang, Yuchao; Tang, Hongying; Cheng, Yongbo; Zhao, Qin; Yuan, Baoqing Li andXiaobing

2017-07-19

Routing protocols based on topology control are significantly important for improving network longevity in wireless sensor networks (WSNs). Traditionally, some WSN routing protocols distribute uneven network traffic load to sensor nodes, which is not optimal for improving network longevity. Differently to conventional WSN routing protocols, we propose a dynamic hierarchical protocol based on combinatorial optimization (DHCO) to balance energy consumption of sensor nodes and to improve WSN longevity. For each sensor node, the DHCO algorithm obtains the optimal route by establishing a feasible routing set instead of selecting the cluster head or the next hop node. The process of obtaining the optimal route can be formulated as a combinatorial optimization problem. Specifically, the DHCO algorithm is carried out by the following procedures. It employs a hierarchy-based connection mechanism to construct a hierarchical network structure in which each sensor node is assigned to a special hierarchical subset; it utilizes the combinatorial optimization theory to establish the feasible routing set for each sensor node, and takes advantage of the maximum-minimum criterion to obtain their optimal routes to the base station. Various results of simulation experiments show effectiveness and superiority of the DHCO algorithm in comparison with state-of-the-art WSN routing algorithms, including low-energy adaptive clustering hierarchy (LEACH), hybrid energy-efficient distributed clustering (HEED), genetic protocol-based self-organizing network clustering (GASONeC), and double cost function-based routing (DCFR) algorithms.

SU-E-I-82: Improving CT Image Quality for Radiation Therapy Using Iterative Reconstruction Algorithms and Slightly Increasing Imaging Doses

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

Noid, G; Chen, G; Tai, A

2014-06-01

Purpose: Iterative reconstruction (IR) algorithms are developed to improve CT image quality (IQ) by reducing noise without diminishing spatial resolution or contrast. For CT in radiation therapy (RT), slightly increasing imaging dose to improve IQ may be justified if it can substantially enhance structure delineation. The purpose of this study is to investigate and to quantify the IQ enhancement as a result of increasing imaging doses and using IR algorithms. Methods: CT images were acquired for phantoms, built to evaluate IQ metrics including spatial resolution, contrast and noise, with a variety of imaging protocols using a CT scanner (Definition ASmore » Open, Siemens) installed inside a Linac room. Representative patients were scanned once the protocols were optimized. Both phantom and patient scans were reconstructed using the Sinogram Affirmed Iterative Reconstruction (SAFIRE) and the Filtered Back Projection (FBP) methods. IQ metrics of the obtained CTs were compared. Results: IR techniques are demonstrated to preserve spatial resolution as measured by the point spread function and reduce noise in comparison to traditional FBP. Driven by the reduction in noise, the contrast to noise ratio is doubled by adopting the highest SAFIRE strength. As expected, increasing imaging dose reduces noise for both SAFIRE and FBP reconstructions. The contrast to noise increases from 3 to 5 by increasing the dose by a factor of 4. Similar IQ improvement was observed on the CTs for selected patients with pancreas and prostrate cancers. Conclusion: The IR techniques produce a measurable enhancement to CT IQ by reducing the noise. Increasing imaging dose further reduces noise independent of the IR techniques. The improved CT enables more accurate delineation of tumors and/or organs at risk during RT planning and delivery guidance.« less

Zoom Reconstruction Tool: Evaluation of Image Quality and Influence on the Diagnosis of Root Fracture.

PubMed

Queiroz, Polyane Mazucatto; Santaella, Gustavo Machado; Capelozza, Ana Lúcia Alvares; Rosalen, Pedro Luiz; Freitas, Deborah Queiroz; Haiter-Neto, Francisco

2018-04-01

This study evaluated the image quality and the diagnosis of root fractures when using the Zoom Reconstruction tool (J Morita, Kyoto, Japan). A utility wax phantom with a metal sample inside was used for objective evaluation, and a mandible with 27 single-rooted teeth (with and without obturation and with and without vertical or horizontal fractures) was used for diagnostic evaluation. The images were acquired in 3 protocols: protocol 1, field of view (FOV) of 4 × 4 cm and a voxel size of 0.08 mm; protocol 2, FOV of 10 × 10 cm and a voxel size of 0.2 mm; and protocol 3, Zoom Reconstruction of images from protocol 2 (FOV of 4 × 4 cm and a voxel size of 0.08 mm). The objective evaluation was achieved by measuring the image noise, and the diagnosis of fractures was performed by 3 evaluators. The area under the receiver operating characteristic curve was used to calculate accuracy, and analysis of variance compared the accuracy and image quality of the protocols. Regarding quality, protocol 1 was superior to protocol 2 (P < .0001) and Zoom Reconstruction (P < .0001). Additionally, images of protocol 2 presented less noise than the Zoom Reconstruction image (P < .0001); however, for diagnosis, Zoom Reconstruction was superior in relation to protocol 2 (P = .011) and did not differ from protocol 1 (P = .228) for the diagnosis of a vertical root fracture in filled teeth. The Zoom Reconstruction tool allows better accuracy for vertical root fracture detection in filled teeth, making it possible to obtain a higher-resolution image from a lower-resolution examination without having to expose the patient to more radiation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Preliminary experimental results from a MARS Micro-CT system.

PubMed

He, Peng; Yu, Hengyong; Thayer, Patrick; Jin, Xin; Xu, Qiong; Bennett, James; Tappenden, Rachael; Wei, Biao; Goldstein, Aaron; Renaud, Peter; Butler, Anthony; Butler, Phillip; Wang, Ge

2012-01-01

The Medipix All Resolution System (MARS) system is a commercial spectral/multi-energy micro-CT scanner designed and assembled by the MARS Bioimaging, Ltd. in New Zealand. This system utilizes the state-of-the-art Medipix photon-counting, energy-discriminating detector technology developed by a collaboration at European Organization for Nuclear Research (CERN). In this paper, we report our preliminary experimental results using this system, including geometrical alignment, photon energy characterization, protocol optimization, and spectral image reconstruction. We produced our scan datasets with a multi-material phantom, and then applied ordered subset-simultaneous algebraic reconstruction technique (OS-SART) to reconstruct images in different energy ranges and principal component analysis (PCA) to evaluate spectral deviation among the energy ranges.

LesionTracker: Extensible Open-Source Zero-Footprint Web Viewer for Cancer Imaging Research and Clinical Trials.

PubMed

Urban, Trinity; Ziegler, Erik; Lewis, Rob; Hafey, Chris; Sadow, Cheryl; Van den Abbeele, Annick D; Harris, Gordon J

2017-11-01

Oncology clinical trials have become increasingly dependent upon image-based surrogate endpoints for determining patient eligibility and treatment efficacy. As therapeutics have evolved and multiplied in number, the tumor metrics criteria used to characterize therapeutic response have become progressively more varied and complex. The growing intricacies of image-based response evaluation, together with rising expectations for rapid and consistent results reporting, make it difficult for site radiologists to adequately address local and multicenter imaging demands. These challenges demonstrate the need for advanced cancer imaging informatics tools that can help ensure protocol-compliant image evaluation while simultaneously promoting reviewer efficiency. LesionTracker is a quantitative imaging package optimized for oncology clinical trial workflows. The goal of the project is to create an open source zero-footprint viewer for image analysis that is designed to be extensible as well as capable of being integrated into third-party systems for advanced imaging tools and clinical trials informatics platforms. Cancer Res; 77(21); e119-22. ©2017 AACR . ©2017 American Association for Cancer Research.

Nanogels as imaging agents for modalities spanning the electromagnetic spectrum.

PubMed

Chan, Minnie; Almutairi, Adah

2016-01-21

In the past few decades, advances in imaging equipment and protocols have expanded the role of imaging in in vivo diagnosis and disease management, especially in cancer. Traditional imaging agents have rapid clearance and low specificity for disease detection. To improve accuracy in disease identification, localization and assessment, novel nanomaterials are frequently explored as imaging agents to achieve high detection specificity and sensitivity. A promising material for this purpose are hydrogel nanoparticles, whose high hydrophilicity, biocompatibility, and tunable size in the nanometer range make them ideal for imaging. These nanogels (10 to 200 nm) can circumvent uptake by the reticuloendothelial system, allowing longer circulation times than small molecules. In addition, their size/surface properties can be further tailored to optimize their pharmacokinetics for imaging of a particular disease. Herein, we provide a comprehensive review of nanogels as imaging agents in various modalities with sources of signal spanning the electromagnetic spectrum, including MRI, NIR, UV-vis, and PET. Many materials and formulation methods will be reviewed to highlight the versatility of nanogels as imaging agents.

Optimization of SPECT-CT Hybrid Imaging Using Iterative Image Reconstruction for Low-Dose CT: A Phantom Study

PubMed Central

Grosser, Oliver S.; Kupitz, Dennis; Ruf, Juri; Czuczwara, Damian; Steffen, Ingo G.; Furth, Christian; Thormann, Markus; Loewenthal, David; Ricke, Jens; Amthauer, Holger

2015-01-01

Background Hybrid imaging combines nuclear medicine imaging such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) with computed tomography (CT). Through this hybrid design, scanned patients accumulate radiation exposure from both applications. Imaging modalities have been the subject of long-term optimization efforts, focusing on diagnostic applications. It was the aim of this study to investigate the influence of an iterative CT image reconstruction algorithm (ASIR) on the image quality of the low-dose CT images. Methodology/Principal Findings Examinations were performed with a SPECT-CT scanner with standardized CT and SPECT-phantom geometries and CT protocols with systematically reduced X-ray tube currents. Analyses included image quality with respect to photon flux. Results were compared to the standard FBP reconstructed images. The general impact of the CT-based attenuation maps used during SPECT reconstruction was examined for two SPECT phantoms. Using ASIR for image reconstructions, image noise was reduced compared to FBP reconstructions for the same X-ray tube current. The Hounsfield unit (HU) values reconstructed by ASIR were correlated to the FBP HU values(R2 ≥ 0.88) and the contrast-to-noise ratio (CNR) was improved by ASIR. However, for a phantom with increased attenuation, the HU values shifted for low X-ray tube currents I ≤ 60 mA (p ≤ 0.04). In addition, the shift of the HU values was observed within the attenuation corrected SPECT images for very low X-ray tube currents (I ≤ 20 mA, p ≤ 0.001). Conclusion/Significance In general, the decrease in X-ray tube current up to 30 mA in combination with ASIR led to a reduction of CT-related radiation exposure without a significant decrease in image quality. PMID:26390216

MO-FG-209-05: Towards a Feature-Based Anthropomorphic Model Observer

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

Avanaki, A.

2016-06-15

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

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

Graff, C.

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins

PubMed Central

Niikura, Yohei; Kitagawa, Katsumi

2016-01-01

"Centromeres" and "kinetochores" refer to the site where chromosomes associate with the spindle during cell division. Direct visualization of centromere-kinetochore proteins during the cell cycle remains a fundamental tool in investigating the mechanism(s) of these proteins. Advanced imaging methods in fluorescence microscopy provide remarkable resolution of centromere-kinetochore components and allow direct observation of specific molecular components of the centromeres and kinetochores. In addition, methods of indirect immunofluorescent (IIF) staining using specific antibodies are crucial to these observations. However, despite numerous reports about IIF protocols, few discussed in detail problems of specific centromere-kinetochore proteins.1-4 Here we report optimized protocols to stain endogenous centromere-kinetochore proteins in human cells by using paraformaldehyde fixation and IIF staining. Furthermore, we report protocols to detect Flag-tagged exogenous CENP-A proteins in human cells subjected to acetone or methanol fixation. These methods are useful in detecting and quantifying endogenous centromere-kinetochore proteins and Flag-tagged CENP-A proteins, including those in human cells. PMID:26967065

Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs.

PubMed

Sensakovic, William F; O'Dell, M Cody; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura

2016-10-01

Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA(2) by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image processing can significantly impact image quality when settings are left near default values.

Automated Prescription of Oblique Brain 3D MRSI

PubMed Central

Ozhinsky, Eugene; Vigneron, Daniel B.; Chang, Susan M.; Nelson, Sarah J.

2012-01-01

Two major difficulties encountered in implementing Magnetic Resonance Spectroscopic Imaging (MRSI) in a clinical setting are limited coverage and difficulty in prescription. The goal of this project was to completely automate the process of 3D PRESS MRSI prescription, including placement of the selection box, saturation bands and shim volume, while maximizing the coverage of the brain. The automated prescription technique included acquisition of an anatomical MRI image, optimization of the oblique selection box parameters, optimization of the placement of OVS saturation bands, and loading of the calculated parameters into a customized 3D MRSI pulse sequence. To validate the technique and compare its performance with existing protocols, 3D MRSI data were acquired from 6 exams from 3 healthy volunteers. To assess the performance of the automated 3D MRSI prescription for patients with brain tumors, the data were collected from 16 exams from 8 subjects with gliomas. This technique demonstrated robust coverage of the tumor, high consistency of prescription and very good data quality within the T2 lesion. PMID:22692829

Optimization of Brain T2 Mapping Using Standard CPMG Sequence In A Clinical Scanner

NASA Astrophysics Data System (ADS)

Hnilicová, P.; Bittšanský, M.; Dobrota, D.

2014-04-01

In magnetic resonance imaging, transverse relaxation time (T2) mapping is a useful quantitative tool enabling enhanced diagnostics of many brain pathologies. The aim of our study was to test the influence of different sequence parameters on calculated T2 values, including multi-slice measurements, slice position, interslice gap, echo spacing, and pulse duration. Measurements were performed using standard multi-slice multi-echo CPMG imaging sequence on a 1.5 Tesla routine whole body MR scanner. We used multiple phantoms with different agarose concentrations (0 % to 4 %) and verified the results on a healthy volunteer. It appeared that neither the pulse duration, the size of interslice gap nor the slice shift had any impact on the T2. The measurement accuracy was increased with shorter echo spacing. Standard multi-slice multi-echo CPMG protocol with the shortest echo spacing, also the smallest available interslice gap (100 % of slice thickness) and shorter pulse duration was found to be optimal and reliable for calculating T2 maps in the human brain.

Multicenter evaluation of stress-first myocardial perfusion image triage by nuclear technologists and automated quantification

PubMed Central

Chaudhry, Waseem; Hussain, Nasir; Ahlberg, Alan W.; Croft, Lori B.; Fernandez, Antonio B.; Parker, Mathew W.; Swales, Heather H.; Slomka, Piotr J.; Henzlova, Milena J.; Duvall, W. Lane

2016-01-01

Background A stress-first myocardial perfusion imaging (MPI) protocol saves time, is cost effective, and decreases radiation exposure. A limitation of this protocol is the requirement for physician review of the stress images to determine the need for rest images. This hurdle could be eliminated if an experienced technologist and/or automated computer quantification could make this determination. Methods Images from consecutive patients who were undergoing a stress-first MPI with attenuation correction at two tertiary care medical centers were prospectively reviewed independently by a technologist and cardiologist blinded to clinical and stress test data. Their decision on the need for rest imaging along with automated computer quantification of perfusion results was compared with the clinical reference standard of an assessment of perfusion images by a board-certified nuclear cardiologist that included clinical and stress test data. Results A total of 250 patients (mean age 61 years and 55% female) who underwent a stress-first MPI were studied. According to the clinical reference standard, 42 (16.8%) and 208 (83.2%) stress-first images were interpreted as “needing” and “not needing” rest images, respectively. The technologists correctly classified 229 (91.6%) stress-first images as either “needing” (n = 28) or “not needing” (n = 201) rest images. Their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 66.7%, 96.6%, 80.0%, and 93.5%, respectively. An automated stress TPD score ≥1.2 was associated with optimal sensitivity and specificity and correctly classified 179 (71.6%) stress-first images as either “needing” (n = 31) or “not needing” (n = 148) rest images. Its sensitivity, specificity, PPV, and NPV were 73.8%, 71.2%, 34.1%, and 93.1%, respectively. In a model whereby the computer or technologist could correct for the other's incorrect classification, 242 (96.8%) stress-first images were correctly classified. The composite sensitivity, specificity, PPV, and NPV were 83.3%, 99.5%, 97.2%, and 96.7%, respectively. Conclusion Technologists and automated quantification software had a high degree of agreement with the clinical reference standard for determining the need for rest images in a stress-first imaging protocol. Utilizing an experienced technologist and automated systems to screen stress-first images could expand the use of stress-first MPI to sites where the cardiologist is not immediately available for interpretation. PMID:26566774

Thin isotropic FLAIR MR images at 1.5T increase the yield of focal cortical dysplasia transmantle sign detection in frontal lobe epilepsy.

PubMed

Kokkinos, Vasileios; Kallifatidis, Alexandros; Kapsalaki, Eftychia Z; Papanikolaou, Nikolaos; Garganis, Kyriakos

2017-05-01

The transmantle sign is a distinctive imaging marker of focal cortical dysplasia (FCD) type II in frontal lobe epilepsy (FLE), which is revealed predominantly by fluid-attenuation inversion recovery (FLAIR) sequences. Although the transmantle sign detection yield is high by routine imaging protocols for epilepsy at 3T, most centers around the world have access to 1.5T MR technology and FLE patients often receive negative imaging reports. This study investigates the optimization of transmantle detection yield at 1.5T by introducing a 3D thin-slice isotropic FLAIR sequence in the epilepsy imaging protocol. Twenty FLE patients underwent diagnostic imaging for epilepsy with typical 2D thick-slice (3.0mm) coronal FLAIR sequences and a 3D thin-slice (1.0mm) isotropic FLAIR sequences at 1.5T, and transmantle sign detection yields and thickness measurements were derived. The 2D thick-slice FLAIR detected a transmantle sign in seven (35.0%) patients. The 3D isotropic thin-slice FLAIR detected a transmantle sign in eleven (55.0%) patients, thereby increasing the transmantle sign detection yield by 57.4%. The mean transmantle sign thickness by thick images was 12.3mm, by thin images was 8.9mm, and in the patients undetected by thick FLAIR was 3.5mm. This study showed that the extratemporal transmantle sign in FLE patients can be thin enough to be missed by thick-slice FLAIR sequences at 1.5T. By introducing 3D thin-slice isotropic FLAIR, false-negative reports can be reduced without reference for higher MR field structural scanning or other modalities, and more FLE patients can benefit from epilepsy surgery candidacy. Copyright © 2017 Elsevier B.V. All rights reserved.

Complex-based OCT angiography algorithm recovers microvascular information better than amplitude- or phase-based algorithms in phase-stable systems

NASA Astrophysics Data System (ADS)

Xu, Jingjiang; Song, Shaozhen; Li, Yuandong; Wang, Ruikang K.

2018-01-01

Optical coherence tomography angiography (OCTA) is increasingly becoming a popular inspection tool for biomedical imaging applications. By exploring the amplitude, phase and complex information available in OCT signals, numerous algorithms have been proposed that contrast functional vessel networks within microcirculatory tissue beds. However, it is not clear which algorithm delivers optimal imaging performance. Here, we investigate systematically how amplitude and phase information have an impact on the OCTA imaging performance, to establish the relationship of amplitude and phase stability with OCT signal-to-noise ratio (SNR), time interval and particle dynamics. With either repeated A-scan or repeated B-scan imaging protocols, the amplitude noise increases with the increase of OCT SNR; however, the phase noise does the opposite, i.e. it increases with the decrease of OCT SNR. Coupled with experimental measurements, we utilize a simple Monte Carlo (MC) model to simulate the performance of amplitude-, phase- and complex-based algorithms for OCTA imaging, the results of which suggest that complex-based algorithms deliver the best performance when the phase noise is  <  ~40 mrad. We also conduct a series of in vivo vascular imaging in animal models and human retina to verify the findings from the MC model through assessing the OCTA performance metrics of vessel connectivity, image SNR and contrast-to-noise ratio. We show that for all the metrics assessed, the complex-based algorithm delivers better performance than either the amplitude- or phase-based algorithms for both the repeated A-scan and the B-scan imaging protocols, which agrees well with the conclusion drawn from the MC simulations.

Complex-based OCT angiography algorithm recovers microvascular information better than amplitude- or phase-based algorithms in phase-stable systems.

PubMed

Xu, Jingjiang; Song, Shaozhen; Li, Yuandong; Wang, Ruikang K

2017-12-19

Optical coherence tomography angiography (OCTA) is increasingly becoming a popular inspection tool for biomedical imaging applications. By exploring the amplitude, phase and complex information available in OCT signals, numerous algorithms have been proposed that contrast functional vessel networks within microcirculatory tissue beds. However, it is not clear which algorithm delivers optimal imaging performance. Here, we investigate systematically how amplitude and phase information have an impact on the OCTA imaging performance, to establish the relationship of amplitude and phase stability with OCT signal-to-noise ratio (SNR), time interval and particle dynamics. With either repeated A-scan or repeated B-scan imaging protocols, the amplitude noise increases with the increase of OCT SNR; however, the phase noise does the opposite, i.e. it increases with the decrease of OCT SNR. Coupled with experimental measurements, we utilize a simple Monte Carlo (MC) model to simulate the performance of amplitude-, phase- and complex-based algorithms for OCTA imaging, the results of which suggest that complex-based algorithms deliver the best performance when the phase noise is  <  ~40 mrad. We also conduct a series of in vivo vascular imaging in animal models and human retina to verify the findings from the MC model through assessing the OCTA performance metrics of vessel connectivity, image SNR and contrast-to-noise ratio. We show that for all the metrics assessed, the complex-based algorithm delivers better performance than either the amplitude- or phase-based algorithms for both the repeated A-scan and the B-scan imaging protocols, which agrees well with the conclusion drawn from the MC simulations.

A guide for effective anatomical vascularization studies: useful ex vivo methods for both CT and MRI imaging before dissection.

PubMed

Renard, Yohann; Hossu, Gabriela; Chen, Bailiang; Krebs, Marine; Labrousse, Marc; Perez, Manuela

2018-01-01

The objective of this study was to develop a simple and useful injection protocol for imaging cadaveric vascularization and dissection. Mixtures of contrast agent and cast product should provide adequate contrast for two types of ex vivo imaging (MRI and CT) and should harden to allow gross dissection of the injected structures. We tested the most popular contrast agents and cast products, and selected the optimal mixture composition based on their availability and ease of use. All mixtures were first tested in vitro to adjust dilution parameters of each contrast agent and to fine-tune MR imaging acquisition sequences. Mixtures were then injected in 24 pig livers and one human pancreas for MR and computed tomography (CT) imaging before anatomical dissection. Colorized latex, gadobutrol and barite mixture met the above objective. Mixtures composed of copper sulfate (CuSO 4 ) gadoxetic acid (for MRI) and iodine (for CT) gave an inhomogeneous signal or extravasation of the contrast agent. Agar did not harden sufficiently for gross dissection but appears useful for CT and magnetic resonance imaging (MRI) studies without dissection. Silicone was very hard to inject but achieved the goals of the study. Resin is particularly difficult to use but could replace latex as an alternative for corrosion instead of dissection. This injection protocol allows CT and MRI images to be obtained of cadaveric vascularization and anatomical casts in the same anatomic specimen. Post-imaging processing software allow easy 3D reconstruction of complex anatomical structures using this technique. Applications are numerous, e.g. surgical training, teaching methods, postmortem anatomic studies, pathologic studies, and forensic diagnoses. © 2017 Anatomical Society.

Broken symmetry in a two-qubit quantum control landscape

NASA Astrophysics Data System (ADS)

Bukov, Marin; Day, Alexandre G. R.; Weinberg, Phillip; Polkovnikov, Anatoli; Mehta, Pankaj; Sels, Dries

2018-05-01

We analyze the physics of optimal protocols to prepare a target state with high fidelity in a symmetrically coupled two-qubit system. By varying the protocol duration, we find a discontinuous phase transition, which is characterized by a spontaneous breaking of a Z2 symmetry in the functional form of the optimal protocol, and occurs below the quantum speed limit. We study in detail this phase and demonstrate that even though high-fidelity protocols come degenerate with respect to their fidelity, they lead to final states of different entanglement entropy shared between the qubits. Consequently, while globally both optimal protocols are equally far away from the target state, one is locally closer than the other. An approximate variational mean-field theory which captures the physics of the different phases is developed.

Image quality of mean temporal arterial and mean temporal portal venous phase images calculated from low dose dynamic volume perfusion CT datasets in patients with hepatocellular carcinoma and pancreatic cancer.

PubMed

Wang, X; Henzler, T; Gawlitza, J; Diehl, S; Wilhelm, T; Schoenberg, S O; Jin, Z Y; Xue, H D; Smakic, A

2016-11-01

Dynamic volume perfusion CT (dVPCT) provides valuable information on tissue perfusion in patients with hepatocellular carcinoma (HCC) and pancreatic cancer. However, currently dVPCT is often performed in addition to conventional CT acquisitions due to the limited morphologic image quality of dose optimized dVPCT protocols. The aim of this study was to prospectively compare objective and subjective image quality, lesion detectability and radiation dose between mean temporal arterial (mTA) and mean temporal portal venous (mTPV) images calculated from low dose dynamic volume perfusion CT (dVPCT) datasets with linearly blended 120-kVp arterial and portal venous datasets in patients with HCC and pancreatic cancer. All patients gave written informed consent for this institutional review board-approved HIPAA compliant study. 27 consecutive patients (18 men, 9 women, mean age, 69.1 years±9.4) with histologically proven HCC or suspected pancreatic cancer were prospectively enrolled. The study CT protocol included a dVPCT protocol performed with 70 or 80kVp tube voltage (18 spiral acquisitions, 71.2s total acquisition times) and standard dual-energy (90/150kVpSn) arterial and portal venous acquisition performed 25min after the dVPCT. The mTA and mTPV images were manually reconstructed from the 3 to 5 best visually selected single arterial and 3 to 5 best single portal venous phases dVPCT dataset. The linearly blended 120-kVp images were calculated from dual-energy CT (DECT) raw data. Image noise, SNR, and CNR of the liver, abdominal aorta (AA) and main portal vein (PV) were compared between the mTA/mTPV and the linearly blended 120-kVp dual-energy arterial and portal venous datasets, respectively. Subjective image quality was evaluated by two radiologists regarding subjective image noise, sharpness and overall diagnostic image quality using a 5-point Likert Scale. In addition, liver lesion detectability was performed for each liver segment by the two radiologists using the linearly blended120-kVp arterial and portal venous datasets as the reference standard. Image noise, SNR and CNR values of the mTA and mTPV were significantly higher when compared to the corresponding linearly blended arterial and portal venous 120-kVp datasets (all p<0.001) except for image noise within the PV in the portal venous phases (p=0.136). image quality of mTA and mTPV were rated significantly better when compared to the linearly blended 120-kVp arterial and portal venous datasets. Both readers were able to detect all liver lesions found on the linearly blended 120-kVp arterial and portal venous datasets using the mTA and mTPV datasets. The effective radiation dose of the dVPCT was 27.6mSv for the 80kVp protocol and 14.5mSv for the 70kVp protocol. The mean effective radiation dose for the linearly blended 120-kVp arterial and portal venous CT protocol together of the upper abdomen was 5.60mSv±1.48mSv. Our preliminary data suggest that subjective and objective image quality of mTA and mTPV datasets calculated from low-kVp dVPCT datasets is non-inferior when compared to linearly blended 120-kVp arterial and portal venous acquisitions in patients with HCC and pancreatic cancer. Thus, dVPCT could be used as a stand-alone imaging technique without additionally performed conventional arterial and portal venous CT acquisitions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Spine labeling in MRI via regularized distribution matching.

PubMed

Hojjat, Seyed-Parsa; Ayed, Ismail; Garvin, Gregory J; Punithakumar, Kumaradevan

2017-11-01

This study investigates an efficient (nearly real-time) two-stage spine labeling algorithm that removes the need for an external training while being applicable to different types of MRI data and acquisition protocols. Based solely on the image being labeled (i.e., we do not use training data), the first stage aims at detecting potential vertebra candidates following the optimization of a functional containing two terms: (i) a distribution-matching term that encodes contextual information about the vertebrae via a density model learned from a very simple user input, which amounts to a point (mouse click) on a predefined vertebra; and (ii) a regularization constraint, which penalizes isolated candidates in the solution. The second stage removes false positives and identifies all vertebrae and discs by optimizing a geometric constraint, which embeds generic anatomical information on the interconnections between neighboring structures. Based on generic knowledge, our geometric constraint does not require external training. We performed quantitative evaluations of the algorithm over a data set of 90 mid-sagittal MRI images of the lumbar spine acquired from 45 different subjects. To assess the flexibility of the algorithm, we used both T1- and T2-weighted images for each subject. A total of 990 structures were automatically detected/labeled and compared to ground-truth annotations by an expert. On the T2-weighted data, we obtained an accuracy of 91.6% for the vertebrae and 89.2% for the discs. On the T1-weighted data, we obtained an accuracy of 90.7% for the vertebrae and 88.1% for the discs. Our algorithm removes the need for external training while being applicable to different types of MRI data and acquisition protocols. Based on the current testing data, a subject-specific model density and generic anatomical information, our method can achieve competitive performances when applied to T1- and T2-weighted MRI images.

High performance MRI simulations of motion on multi-GPU systems.

PubMed

Xanthis, Christos G; Venetis, Ioannis E; Aletras, Anthony H

2014-07-04

MRI physics simulators have been developed in the past for optimizing imaging protocols and for training purposes. However, these simulators have only addressed motion within a limited scope. The purpose of this study was the incorporation of realistic motion, such as cardiac motion, respiratory motion and flow, within MRI simulations in a high performance multi-GPU environment. Three different motion models were introduced in the Magnetic Resonance Imaging SIMULator (MRISIMUL) of this study: cardiac motion, respiratory motion and flow. Simulation of a simple Gradient Echo pulse sequence and a CINE pulse sequence on the corresponding anatomical model was performed. Myocardial tagging was also investigated. In pulse sequence design, software crushers were introduced to accommodate the long execution times in order to avoid spurious echoes formation. The displacement of the anatomical model isochromats was calculated within the Graphics Processing Unit (GPU) kernel for every timestep of the pulse sequence. Experiments that would allow simulation of custom anatomical and motion models were also performed. Last, simulations of motion with MRISIMUL on single-node and multi-node multi-GPU systems were examined. Gradient Echo and CINE images of the three motion models were produced and motion-related artifacts were demonstrated. The temporal evolution of the contractility of the heart was presented through the application of myocardial tagging. Better simulation performance and image quality were presented through the introduction of software crushers without the need to further increase the computational load and GPU resources. Last, MRISIMUL demonstrated an almost linear scalable performance with the increasing number of available GPU cards, in both single-node and multi-node multi-GPU computer systems. MRISIMUL is the first MR physics simulator to have implemented motion with a 3D large computational load on a single computer multi-GPU configuration. The incorporation of realistic motion models, such as cardiac motion, respiratory motion and flow may benefit the design and optimization of existing or new MR pulse sequences, protocols and algorithms, which examine motion related MR applications.

Dynamic Hierarchical Energy-Efficient Method Based on Combinatorial Optimization for Wireless Sensor Networks

PubMed Central

Tang, Hongying; Cheng, Yongbo; Zhao, Qin; Li, Baoqing; Yuan, Xiaobing

2017-01-01

Routing protocols based on topology control are significantly important for improving network longevity in wireless sensor networks (WSNs). Traditionally, some WSN routing protocols distribute uneven network traffic load to sensor nodes, which is not optimal for improving network longevity. Differently to conventional WSN routing protocols, we propose a dynamic hierarchical protocol based on combinatorial optimization (DHCO) to balance energy consumption of sensor nodes and to improve WSN longevity. For each sensor node, the DHCO algorithm obtains the optimal route by establishing a feasible routing set instead of selecting the cluster head or the next hop node. The process of obtaining the optimal route can be formulated as a combinatorial optimization problem. Specifically, the DHCO algorithm is carried out by the following procedures. It employs a hierarchy-based connection mechanism to construct a hierarchical network structure in which each sensor node is assigned to a special hierarchical subset; it utilizes the combinatorial optimization theory to establish the feasible routing set for each sensor node, and takes advantage of the maximum–minimum criterion to obtain their optimal routes to the base station. Various results of simulation experiments show effectiveness and superiority of the DHCO algorithm in comparison with state-of-the-art WSN routing algorithms, including low-energy adaptive clustering hierarchy (LEACH), hybrid energy-efficient distributed clustering (HEED), genetic protocol-based self-organizing network clustering (GASONeC), and double cost function-based routing (DCFR) algorithms. PMID:28753962

In vivo PET/CT in a human glioblastoma chicken chorioallantoic membrane model: a new tool for oncology and radiotracer development.

PubMed

Warnock, Geoff; Turtoi, Andrei; Blomme, Arnaud; Bretin, Florian; Bahri, Mohamed Ali; Lemaire, Christian; Libert, Lionel Cyrille; Seret, Alain E J J; Luxen, André; Castronovo, Vincenzo; Plenevaux, Alain R E G

2013-10-01

For many years the laboratory mouse has been used as the standard model for in vivo oncology research, particularly in the development of novel PET tracers, but the growth of tumors on chicken chorioallantoic membrane (CAM) provides a more rapid, low cost, and ethically sustainable alternative. For the first time, to our knowledge, we demonstrate the feasibility of in vivo PET and CT imaging in a U87 glioblastoma tumor model on chicken CAM, with the aim of applying this model for screening of novel PET tracers. U87 glioblastoma cells were implanted on the CAM at day 11 after fertilization and imaged at day 18. A small-animal imaging cell was used to maintain incubation and allow anesthesia using isoflurane. Radiotracers were injected directly into the exposed CAM vasculature. Sodium (18)F-fluoride was used to validate the imaging protocol, demonstrating that image-degrading motion can be removed with anesthesia. Tumor glucose metabolism was imaged using (18)F-FDG, and tumor protein synthesis was imaged using 2-(18)F-fluoro-l-tyrosine. Anatomic images were obtained by contrast-enhanced CT, facilitating clear delineation of the tumor, delineation of tracer uptake in tumor versus embryo, and accurate volume measurements. PET imaging of tumor glucose metabolism and protein synthesis was successfully demonstrated in the CAM U87 glioblastoma model. Catheterization of CAM blood vessels facilitated dynamic imaging of glucose metabolism with (18)F-FDG and demonstrated the ability to study PET tracer uptake over time in individual tumors, and CT imaging improved the accuracy of tumor volume measurements. We describe the novel application of PET/CT in the CAM tumor model, with optimization of typical imaging protocols. PET imaging in this valuable tumor model could prove particularly useful for rapid, high-throughput screening of novel radiotracers.

Evaluation of automatic image quality assessment in chest CT - A human cadaver study.

PubMed

Franck, Caro; De Crop, An; De Roo, Bieke; Smeets, Peter; Vergauwen, Merel; Dewaele, Tom; Van Borsel, Mathias; Achten, Eric; Van Hoof, Tom; Bacher, Klaus

2017-04-01

The evaluation of clinical image quality (IQ) is important to optimize CT protocols and to keep patient doses as low as reasonably achievable. Considering the significant amount of effort needed for human observer studies, automatic IQ tools are a promising alternative. The purpose of this study was to evaluate automatic IQ assessment in chest CT using Thiel embalmed cadavers. Chest CT's of Thiel embalmed cadavers were acquired at different exposures. Clinical IQ was determined by performing a visual grading analysis. Physical-technical IQ (noise, contrast-to-noise and contrast-detail) was assessed in a Catphan phantom. Soft and sharp reconstructions were made with filtered back projection and two strengths of iterative reconstruction. In addition to the classical IQ metrics, an automatic algorithm was used to calculate image quality scores (IQs). To be able to compare datasets reconstructed with different kernels, the IQs values were normalized. Good correlations were found between IQs and the measured physical-technical image quality: noise (ρ=-1.00), contrast-to-noise (ρ=1.00) and contrast-detail (ρ=0.96). The correlation coefficients between IQs and the observed clinical image quality of soft and sharp reconstructions were 0.88 and 0.93, respectively. The automatic scoring algorithm is a promising tool for the evaluation of thoracic CT scans in daily clinical practice. It allows monitoring of the image quality of a chest protocol over time, without human intervention. Different reconstruction kernels can be compared after normalization of the IQs. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

CAIPIRINHA accelerated SPACE enables 10-min isotropic 3D TSE MRI of the ankle for optimized visualization of curved and oblique ligaments and tendons.

PubMed

Kalia, Vivek; Fritz, Benjamin; Johnson, Rory; Gilson, Wesley D; Raithel, Esther; Fritz, Jan

2017-09-01

To test the hypothesis that a fourfold CAIPIRINHA accelerated, 10-min, high-resolution, isotropic 3D TSE MRI prototype protocol of the ankle derives equal or better quality than a 20-min 2D TSE standard protocol. Following internal review board approval and informed consent, 3-Tesla MRI of the ankle was obtained in 24 asymptomatic subjects including 10-min 3D CAIPIRINHA SPACE TSE prototype and 20-min 2D TSE standard protocols. Outcome variables included image quality and visibility of anatomical structures using 5-point Likert scales. Non-parametric statistical testing was used. P values ≤0.001 were considered significant. Edge sharpness, contrast resolution, uniformity, noise, fat suppression and magic angle effects were without statistical difference on 2D and 3D TSE images (p > 0.035). Fluid was mildly brighter on intermediate-weighted 2D images (p < 0.001), whereas 3D images had substantially less partial volume, chemical shift and no pulsatile-flow artifacts (p < 0.001). Oblique and curved planar 3D images resulted in mildly-to-substantially improved visualization of joints, spring, bifurcate, syndesmotic, collateral and sinus tarsi ligaments, and tendons (p < 0.001, respectively). 3D TSE MRI with CAIPIRINHA acceleration enables high-spatial resolution oblique and curved planar MRI of the ankle and visualization of ligaments, tendons and joints equally well or better than a more time-consuming anisotropic 2D TSE MRI. • High-resolution 3D TSE MRI improves visualization of ankle structures. • Limitations of current 3D TSE MRI include long scan times. • 3D CAIPIRINHA SPACE allows now a fourfold-accelerated data acquisition. • 3D CAIPIRINHA SPACE enables high-spatial-resolution ankle MRI within 10 min. • 10-min 3D CAIPIRINHA SPACE produces equal-or-better quality than 20-min 2D TSE.

CT Dose Optimization in Pediatric Radiology: A Multiyear Effort to Preserve the Benefits of Imaging While Reducing the Risks.

PubMed

Greenwood, Taylor J; Lopez-Costa, Rodrigo I; Rhoades, Patrick D; Ramírez-Giraldo, Juan C; Starr, Matthew; Street, Mandie; Duncan, James; McKinstry, Robert C

2015-01-01

The marked increase in radiation exposure from medical imaging, especially in children, has caused considerable alarm and spurred efforts to preserve the benefits but reduce the risks of imaging. Applying the principles of the Image Gently campaign, data-driven process and quality improvement techniques such as process mapping and flowcharting, cause-and-effect diagrams, Pareto analysis, statistical process control (control charts), failure mode and effects analysis, "lean" or Six Sigma methodology, and closed feedback loops led to a multiyear program that has reduced overall computed tomographic (CT) examination volume by more than fourfold and concurrently decreased radiation exposure per CT study without compromising diagnostic utility. This systematic approach involving education, streamlining access to magnetic resonance imaging and ultrasonography, auditing with comparison with benchmarks, applying modern CT technology, and revising CT protocols has led to a more than twofold reduction in CT radiation exposure between 2005 and 2012 for patients at the authors' institution while maintaining diagnostic utility. (©)RSNA, 2015.

Implementation of remote monitoring and managing switches

NASA Astrophysics Data System (ADS)

Leng, Junmin; Fu, Guo

2010-12-01

In order to strengthen the safety performance of the network and provide the big convenience and efficiency for the operator and the manager, the system of remote monitoring and managing switches has been designed and achieved using the advanced network technology and present network resources. The fast speed Internet Protocol Cameras (FS IP Camera) is selected, which has 32-bit RSIC embedded processor and can support a number of protocols. An Optimal image compress algorithm Motion-JPEG is adopted so that high resolution images can be transmitted by narrow network bandwidth. The architecture of the whole monitoring and managing system is designed and implemented according to the current infrastructure of the network and switches. The control and administrative software is projected. The dynamical webpage Java Server Pages (JSP) development platform is utilized in the system. SQL (Structured Query Language) Server database is applied to save and access images information, network messages and users' data. The reliability and security of the system is further strengthened by the access control. The software in the system is made to be cross-platform so that multiple operating systems (UNIX, Linux and Windows operating systems) are supported. The application of the system can greatly reduce manpower cost, and can quickly find and solve problems.

New Protocol for Skin Landmark Registration in Image-Guided Neurosurgery: Technical Note.

PubMed

Gerard, Ian J; Hall, Jeffery A; Mok, Kelvin; Collins, D Louis

2015-09-01

Newer versions of the commercial Medtronic StealthStation allow the use of only 8 landmark pairs for patient-to-image registration as opposed to 9 landmarks in older systems. The choice of which landmark pair to drop in these newer systems can have an effect on the quality of the patient-to-image registration. To investigate 4 landmark registration protocols based on 8 landmark pairs and compare the resulting registration accuracy with a 9-landmark protocol. Four different protocols were tested on both phantoms and patients. Two of the protocols involved using 4 ear landmarks and 4 facial landmarks and the other 2 involved using 3 ear landmarks and 5 facial landmarks. Both the fiducial registration error and target registration error were evaluated for each of the different protocols to determine any difference between them and the 9-landmark protocol. No difference in fiducial registration error was found between any of the 8-landmark protocols and the 9-landmark protocol. A significant decrease (P < .05) in target registration error was found when using a protocol based on 4 ear landmarks and 4 facial landmarks compared with the other protocols based on 3 ear landmarks. When using 8 landmarks to perform the patient-to-image registration, the protocol using 4 ear landmarks and 4 facial landmarks greatly outperformed the other 8-landmark protocols and 9-landmark protocol, resulting in the lowest target registration error.

Towards a five-minute comprehensive cardiac MR examination using highly accelerated parallel imaging with a 32-element coil array: feasibility and initial comparative evaluation.

PubMed

Xu, Jian; Kim, Daniel; Otazo, Ricardo; Srichai, Monvadi B; Lim, Ruth P; Axel, Leon; Mcgorty, Kelly Anne; Niendorf, Thoralf; Sodickson, Daniel K

2013-07-01

To evaluate the feasibility and perform initial comparative evaluations of a 5-minute comprehensive whole-heart magnetic resonance imaging (MRI) protocol with four image acquisition types: perfusion (PERF), function (CINE), coronary artery imaging (CAI), and late gadolinium enhancement (LGE). This study protocol was Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board-approved. A 5-minute comprehensive whole-heart MRI examination protocol (Accelerated) using 6-8-fold-accelerated volumetric parallel imaging was incorporated into and compared with a standard 2D clinical routine protocol (Standard). Following informed consent, 20 patients were imaged with both protocols. Datasets were reviewed for image quality using a 5-point Likert scale (0 = non-diagnostic, 4 = excellent) in blinded fashion by two readers. Good image quality with full whole-heart coverage was achieved using the accelerated protocol, particularly for CAI, although significant degradations in quality, as compared with traditional lengthy examinations, were observed for the other image types. Mean total scan time was significantly lower for the Accelerated as compared to Standard protocols (28.99 ± 4.59 min vs. 1.82 ± 0.05 min, P < 0.05). Overall image quality for the Standard vs. Accelerated protocol was 3.67 ± 0.29 vs. 1.5 ± 0.51 (P < 0.005) for PERF, 3.48 ± 0.64 vs. 2.6 ± 0.68 (P < 0.005) for CINE, 2.35 ± 1.01 vs. 2.48 ± 0.68 (P = 0.75) for CAI, and 3.67 ± 0.42 vs. 2.67 ± 0.84 (P < 0.005) for LGE. Diagnostic image quality for Standard vs. Accelerated protocols was 20/20 (100%) vs. 10/20 (50%) for PERF, 20/20 (100%) vs. 18/20 (90%) for CINE, 18/20 (90%) vs. 18/20 (90%) for CAI, and 20/20 (100%) vs. 18/20 (90%) for LGE. This study demonstrates the technical feasibility and promising image quality of 5-minute comprehensive whole-heart cardiac examinations, with simplified scan prescription and high spatial and temporal resolution enabled by highly parallel imaging technology. The study also highlights technical hurdles that remain to be addressed. Although image quality remained diagnostic for most scan types, the reduced image quality of PERF, CINE, and LGE scans in the Accelerated protocol remain a concern. Copyright © 2012 Wiley Periodicals, Inc.

Three-dimensional image technology in forensic anthropology: Assessing the validity of biological profiles derived from CT-3D images of the skeleton

NASA Astrophysics Data System (ADS)

Garcia de Leon Valenzuela, Maria Julia

This project explores the reliability of building a biological profile for an unknown individual based on three-dimensional (3D) images of the individual's skeleton. 3D imaging technology has been widely researched for medical and engineering applications, and it is increasingly being used as a tool for anthropological inquiry. While the question of whether a biological profile can be derived from 3D images of a skeleton with the same accuracy as achieved when using dry bones has been explored, bigger sample sizes, a standardized scanning protocol and more interobserver error data are needed before 3D methods can become widely and confidently used in forensic anthropology. 3D images of Computed Tomography (CT) scans were obtained from 130 innominate bones from Boston University's skeletal collection (School of Medicine). For each bone, both 3D images and original bones were assessed using the Phenice and Suchey-Brooks methods. Statistical analysis was used to determine the agreement between 3D image assessment versus traditional assessment. A pool of six individuals with varying experience in the field of forensic anthropology scored a subsample (n = 20) to explore interobserver error. While a high agreement was found for age and sex estimation for specimens scored by the author, the interobserver study shows that observers found it difficult to apply standard methods to 3D images. Higher levels of experience did not result in higher agreement between observers, as would be expected. Thus, a need for training in 3D visualization before applying anthropological methods to 3D bones is suggested. Future research should explore interobserver error using a larger sample size in order to test the hypothesis that training in 3D visualization will result in a higher agreement between scores. The need for the development of a standard scanning protocol focusing on the optimization of 3D image resolution is highlighted. Applications for this research include the possibility of digitizing skeletal collections in order to expand their use and for deriving skeletal collections from living populations and creating population-specific standards. Further research for the development of a standard scanning and processing protocol is needed before 3D methods in forensic anthropology are considered as reliable tools for generating biological profiles.

Enabling Histopathological Annotations on Immunofluorescent Images through Virtualization of Hematoxylin and Eosin

PubMed Central

Lahiani, Amal; Klaiman, Eldad; Grimm, Oliver

2018-01-01

Context: Medical diagnosis and clinical decisions rely heavily on the histopathological evaluation of tissue samples, especially in oncology. Historically, classical histopathology has been the gold standard for tissue evaluation and assessment by pathologists. The most widely and commonly used dyes in histopathology are hematoxylin and eosin (H&E) as most malignancies diagnosis is largely based on this protocol. H&E staining has been used for more than a century to identify tissue characteristics and structures morphologies that are needed for tumor diagnosis. In many cases, as tissue is scarce in clinical studies, fluorescence imaging is necessary to allow staining of the same specimen with multiple biomarkers simultaneously. Since fluorescence imaging is a relatively new technology in the pathology landscape, histopathologists are not used to or trained in annotating or interpreting these images. Aims, Settings and Design: To allow pathologists to annotate these images without the need for additional training, we designed an algorithm for the conversion of fluorescence images to brightfield H&E images. Subjects and Methods: In this algorithm, we use fluorescent nuclei staining to reproduce the hematoxylin information and natural tissue autofluorescence to reproduce the eosin information avoiding the necessity to specifically stain the proteins or intracellular structures with an additional fluorescence stain. Statistical Analysis Used: Our method is based on optimizing a transform function from fluorescence to H&E images using least mean square optimization. Results: It results in high quality virtual H&E digital images that can easily and efficiently be analyzed by pathologists. We validated our results with pathologists by making them annotate tumor in real and virtual H&E whole slide images and we obtained promising results. Conclusions: Hence, we provide a solution that enables pathologists to assess tissue and annotate specific structures based on multiplexed fluorescence images. PMID:29531846

Enabling Histopathological Annotations on Immunofluorescent Images through Virtualization of Hematoxylin and Eosin.

PubMed

Lahiani, Amal; Klaiman, Eldad; Grimm, Oliver

2018-01-01

Medical diagnosis and clinical decisions rely heavily on the histopathological evaluation of tissue samples, especially in oncology. Historically, classical histopathology has been the gold standard for tissue evaluation and assessment by pathologists. The most widely and commonly used dyes in histopathology are hematoxylin and eosin (H&E) as most malignancies diagnosis is largely based on this protocol. H&E staining has been used for more than a century to identify tissue characteristics and structures morphologies that are needed for tumor diagnosis. In many cases, as tissue is scarce in clinical studies, fluorescence imaging is necessary to allow staining of the same specimen with multiple biomarkers simultaneously. Since fluorescence imaging is a relatively new technology in the pathology landscape, histopathologists are not used to or trained in annotating or interpreting these images. To allow pathologists to annotate these images without the need for additional training, we designed an algorithm for the conversion of fluorescence images to brightfield H&E images. In this algorithm, we use fluorescent nuclei staining to reproduce the hematoxylin information and natural tissue autofluorescence to reproduce the eosin information avoiding the necessity to specifically stain the proteins or intracellular structures with an additional fluorescence stain. Our method is based on optimizing a transform function from fluorescence to H&E images using least mean square optimization. It results in high quality virtual H&E digital images that can easily and efficiently be analyzed by pathologists. We validated our results with pathologists by making them annotate tumor in real and virtual H&E whole slide images and we obtained promising results. Hence, we provide a solution that enables pathologists to assess tissue and annotate specific structures based on multiplexed fluorescence images.

Impact of 4D image quality on the accuracy of target definition.

PubMed

Nielsen, Tine Bjørn; Hansen, Christian Rønn; Westberg, Jonas; Hansen, Olfred; Brink, Carsten

2016-03-01

Delineation accuracy of target shape and position depends on the image quality. This study investigates whether the image quality on standard 4D systems has an influence comparable to the overall delineation uncertainty. A moving lung target was imaged using a dynamic thorax phantom on three different 4D computed tomography (CT) systems and a 4D cone beam CT (CBCT) system using pre-defined clinical scanning protocols. Peak-to-peak motion and target volume were registered using rigid registration and automatic delineation, respectively. A spatial distribution of the imaging uncertainty was calculated as the distance deviation between the imaged target and the true target shape. The measured motions were smaller than actual motions. There were volume differences of the imaged target between respiration phases. Imaging uncertainties of >0.4 cm were measured in the motion direction which showed that there was a large distortion of the imaged target shape. Imaging uncertainties of standard 4D systems are of similar size as typical GTV-CTV expansions (0.5-1 cm) and contribute considerably to the target definition uncertainty. Optimising and validating 4D systems is recommended in order to obtain the most optimal imaged target shape.

Phantom for assessment of fat suppression in large field-of-view diffusion-weighted magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Winfield, J. M.; Douglas, N. H. M.; deSouza, N. M.; Collins, D. J.

2014-05-01

We present the development and application of a phantom for assessment and optimization of fat suppression over a large field-of-view in diffusion-weighted magnetic resonance imaging at 1.5 T and 3 T. A Perspex cylinder (inner diameter 185 mm, height 300 mm) which contains a second cylinder (inner diameter 140 mm) was constructed. The inner cylinder was filled with water doped with copper sulphate and sodium chloride and the annulus was filled with corn oil, which closely matches the spectrum and longitudinal relaxation times of subcutaneous abdominal fat. Placement of the phantom on the couch at 45° to the z-axis presented an elliptical cross-section, which was of a similar size and shape to axial abdominal images. The use of a phantom for optimization of fat suppression allowed quantitative comparison between studies without the differences introduced by variability between human subjects. We have demonstrated that the phantom is suitable for selection of inversion delay times, spectral adiabatic inversion recovery delays and assessment of combinatorial methods of fat suppression. The phantom is valuable in protocol development and the assessment of new techniques, particularly in multi-centre trials.

Optimization of coronary attenuation in coronary computed tomography angiography using diluted contrast material.

PubMed

Kawaguchi, Naoto; Kurata, Akira; Kido, Teruhito; Nishiyama, Yoshiko; Kido, Tomoyuki; Miyagawa, Masao; Ogimoto, Akiyoshi; Mochizuki, Teruhito

2014-01-01

The purpose of this study was to evaluate a personalized protocol with diluted contrast material (CM) for coronary computed tomography angiography (CTA). One hundred patients with suspected coronary artery disease underwent retrospective electrocardiogram-gated coronary CTA on a 256-slice multidetector-row CT scanner. In the diluted CM protocol (n=50), the optimal scan timing and CM dilution rate were determined by the timing bolus scan, with 20% CM dilution (5ml/s during 10s) being considered suitable to achieve the target arterial attenuation of 350 Hounsfield units (HU). In the body weight (BW)-adjusted protocol (n=50, 222mg iodine/kg), only the optimal scan timing was determined by the timing bolus scan. The injection rate and volume in the timing bolus scan and real scan were identical between the 2 protocols. We compared the means and variations in coronary attenuation between the 2 protocols. Coronary attenuation (mean±SD) in the diluted CM and BW-adjusted protocols was 346.1±23.9 HU and 298.8±45.2 HU, respectively. The diluted CM protocol provided significantly higher coronary attenuation and lower variance than did the BW-adjusted protocol (P<0.05, in each). The diluted CM protocol facilitates more uniform attenuation on coronary CTA in comparison with the BW-adjusted protocol.  

Three-dimensional brain MRI for DBS patients within ultra-low radiofrequency power limits.

PubMed

Sarkar, Subhendra N; Papavassiliou, Efstathios; Hackney, David B; Alsop, David C; Shih, Ludy C; Madhuranthakam, Ananth J; Busse, Reed F; La Ruche, Susan; Bhadelia, Rafeeque A

2014-04-01

For patients with deep brain stimulators (DBS), local absorbed radiofrequency (RF) power is unknown and is much higher than what the system estimates. We developed a comprehensive, high-quality brain magnetic resonance imaging (MRI) protocol for DBS patients utilizing three-dimensional (3D) magnetic resonance sequences at very low RF power. Six patients with DBS were imaged (10 sessions) using a transmit/receive head coil at 1.5 Tesla with modified 3D sequences within ultra-low specific absorption rate (SAR) limits (0.1 W/kg) using T2 , fast fluid-attenuated inversion recovery (FLAIR) and T1 -weighted image contrast. Tissue signal and tissue contrast from the low-SAR images were subjectively and objectively compared with routine clinical images of six age-matched controls. Low-SAR images of DBS patients demonstrated tissue contrast comparable to high-SAR images and were of diagnostic quality except for slightly reduced signal. Although preliminary, we demonstrated diagnostic quality brain MRI with optimized, volumetric sequences in DBS patients within very conservative RF safety guidelines offering a greater safety margin. © 2014 International Parkinson and Movement Disorder Society.

Cone beam computed tomography in veterinary dentistry.

PubMed

Van Thielen, Bert; Siguenza, Francis; Hassan, Bassam

2012-01-01

The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal reconstructions were created using specialized software. Image quality and visibility of anatomical landmarks were subjectively assessed by two observers. Good image quality was obtained for the MPR para-sagittal reconstructions through multiple teeth. The image quality of the panoramic reconstructions of dogs was moderate while the panoramic reconstructions of cats were poor since the images were associated with an increased noise level. Segmental panoramic reconstructions of the mouth seem to be useful for studying the dental anatomy especially in dogs. The results of this study using human dental CBCT technology demonstrate the potential of this scanning technology in veterinary medicine. Unfortunately, the moderate image quality obtained with the CBCT technique reported here seems to be inferior to the diagnostic image quality obtained from 2-dimensional dental radiographs. Further research is required to optimize scanning and reconstruction protocols for veterinary applications.

TH-E-209-01: Fluoroscopic Dose Monitoring and Patient Follow-Up Program at Massachusetts General Hospital

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

Liu, B.

2016-06-15

Radiation dose monitoring solutions have opened up new opportunities for medical physicists to be more involved in modern clinical radiology practices. In particular, with the help of comprehensive radiation dose data, data-driven protocol management and informed case follow up are now feasible. Significant challenges remain however and the problems faced by medical physicists are highly heterogeneous. Imaging systems from multiple vendors and a wide range of vintages co-exist in the same department and employ data communication protocols that are not fully standardized or implemented making harmonization complex. Many different solutions for radiation dose monitoring have been implemented by imaging facilitiesmore » over the past few years. Such systems are based on commercial software, home-grown IT solutions, manual PACS data dumping, etc., and diverse pathways can be used to bring the data to impact clinical practice. The speakers will share their experiences with creating or tailoring radiation dose monitoring/management systems and procedures over the past few years, which vary significantly in design and scope. Topics to cover: (1) fluoroscopic dose monitoring and high radiation event handling from a large academic hospital; (2) dose monitoring and protocol optimization in pediatric radiology; and (3) development of a home-grown IT solution and dose data analysis framework. Learning Objectives: Describe the scope and range of radiation dose monitoring and protocol management in a modern radiology practice Review examples of data available from a variety of systems and how it managed and conveyed. Reflect on the role of the physicist in radiation dose awareness.« less

A Power-Optimized Cooperative MAC Protocol for Lifetime Extension in Wireless Sensor Networks.

PubMed

Liu, Kai; Wu, Shan; Huang, Bo; Liu, Feng; Xu, Zhen

2016-10-01

In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with higher channel gain and sufficient residual energy help a sender relay its data packets to its recipient is employed to achieve this objective. We first propose a transmission power optimization algorithm to prolong network lifetime by optimizing the transmission powers of the sender and its cooperative nodes to maximize their minimum residual energy after their data packet transmissions. Based on it, we propose a corresponding power-optimized cooperative MAC protocol. A cooperative node contention mechanism is designed to ensure that the sender can effectively select a group of cooperative nodes with the lowest energy consumption and the best channel quality for cooperative transmissions, thus further improving the energy efficiency. Simulation results show that compared to typical MAC protocol with direct transmissions and energy-efficient cooperative MAC protocol, the proposed cooperative MAC protocol can efficiently improve the energy efficiency and extend the network lifetime.

A Power-Optimized Cooperative MAC Protocol for Lifetime Extension in Wireless Sensor Networks

PubMed Central

Liu, Kai; Wu, Shan; Huang, Bo; Liu, Feng; Xu, Zhen

2016-01-01

In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with higher channel gain and sufficient residual energy help a sender relay its data packets to its recipient is employed to achieve this objective. We first propose a transmission power optimization algorithm to prolong network lifetime by optimizing the transmission powers of the sender and its cooperative nodes to maximize their minimum residual energy after their data packet transmissions. Based on it, we propose a corresponding power-optimized cooperative MAC protocol. A cooperative node contention mechanism is designed to ensure that the sender can effectively select a group of cooperative nodes with the lowest energy consumption and the best channel quality for cooperative transmissions, thus further improving the energy efficiency. Simulation results show that compared to typical MAC protocol with direct transmissions and energy-efficient cooperative MAC protocol, the proposed cooperative MAC protocol can efficiently improve the energy efficiency and extend the network lifetime. PMID:27706079

Heritability estimates on resting state fMRI data using ENIGMA analysis pipeline.

PubMed

Adhikari, Bhim M; Jahanshad, Neda; Shukla, Dinesh; Glahn, David C; Blangero, John; Reynolds, Richard C; Cox, Robert W; Fieremans, Els; Veraart, Jelle; Novikov, Dmitry S; Nichols, Thomas E; Hong, L Elliot; Thompson, Paul M; Kochunov, Peter

2018-01-01

Big data initiatives such as the Enhancing NeuroImaging Genetics through Meta-Analysis consortium (ENIGMA), combine data collected by independent studies worldwide to achieve more generalizable estimates of effect sizes and more reliable and reproducible outcomes. Such efforts require harmonized image analyses protocols to extract phenotypes consistently. This harmonization is particularly challenging for resting state fMRI due to the wide variability of acquisition protocols and scanner platforms; this leads to site-to-site variance in quality, resolution and temporal signal-to-noise ratio (tSNR). An effective harmonization should provide optimal measures for data of different qualities. We developed a multi-site rsfMRI analysis pipeline to allow research groups around the world to process rsfMRI scans in a harmonized way, to extract consistent and quantitative measurements of connectivity and to perform coordinated statistical tests. We used the single-modality ENIGMA rsfMRI preprocessing pipeline based on modelfree Marchenko-Pastur PCA based denoising to verify and replicate resting state network heritability estimates. We analyzed two independent cohorts, GOBS (Genetics of Brain Structure) and HCP (the Human Connectome Project), which collected data using conventional and connectomics oriented fMRI protocols, respectively. We used seed-based connectivity and dual-regression approaches to show that the rsfMRI signal is consistently heritable across twenty major functional network measures. Heritability values of 20-40% were observed across both cohorts.

Optimization of oligonucleotide arrays and RNA amplification protocols for analysis of transcript structure and alternative splicing.

PubMed

Castle, John; Garrett-Engele, Phil; Armour, Christopher D; Duenwald, Sven J; Loerch, Patrick M; Meyer, Michael R; Schadt, Eric E; Stoughton, Roland; Parrish, Mark L; Shoemaker, Daniel D; Johnson, Jason M

2003-01-01

Microarrays offer a high-resolution means for monitoring pre-mRNA splicing on a genomic scale. We have developed a novel, unbiased amplification protocol that permits labeling of entire transcripts. Also, hybridization conditions, probe characteristics, and analysis algorithms were optimized for detection of exons, exon-intron edges, and exon junctions. These optimized protocols can be used to detect small variations and isoform mixtures, map the tissue specificity of known human alternative isoforms, and provide a robust, scalable platform for high-throughput discovery of alternative splicing.

Optimization of oligonucleotide arrays and RNA amplification protocols for analysis of transcript structure and alternative splicing

PubMed Central

Castle, John; Garrett-Engele, Phil; Armour, Christopher D; Duenwald, Sven J; Loerch, Patrick M; Meyer, Michael R; Schadt, Eric E; Stoughton, Roland; Parrish, Mark L; Shoemaker, Daniel D; Johnson, Jason M

2003-01-01

Microarrays offer a high-resolution means for monitoring pre-mRNA splicing on a genomic scale. We have developed a novel, unbiased amplification protocol that permits labeling of entire transcripts. Also, hybridization conditions, probe characteristics, and analysis algorithms were optimized for detection of exons, exon-intron edges, and exon junctions. These optimized protocols can be used to detect small variations and isoform mixtures, map the tissue specificity of known human alternative isoforms, and provide a robust, scalable platform for high-throughput discovery of alternative splicing. PMID:14519201

Protocols for Image Processing based Underwater Inspection of Infrastructure Elements

NASA Astrophysics Data System (ADS)

O'Byrne, Michael; Ghosh, Bidisha; Schoefs, Franck; Pakrashi, Vikram

2015-07-01

Image processing can be an important tool for inspecting underwater infrastructure elements like bridge piers and pile wharves. Underwater inspection often relies on visual descriptions of divers who are not necessarily trained in specifics of structural degradation and the information may often be vague, prone to error or open to significant variation of interpretation. Underwater vehicles, on the other hand can be quite expensive to deal with for such inspections. Additionally, there is now significant encouragement globally towards the deployment of more offshore renewable wind turbines and wave devices and the requirement for underwater inspection can be expected to increase significantly in the coming years. While the merit of image processing based assessment of the condition of underwater structures is understood to a certain degree, there is no existing protocol on such image based methods. This paper discusses and describes an image processing protocol for underwater inspection of structures. A stereo imaging image processing method is considered in this regard and protocols are suggested for image storage, imaging, diving, and inspection. A combined underwater imaging protocol is finally presented which can be used for a variety of situations within a range of image scenes and environmental conditions affecting the imaging conditions. An example of detecting marine growth is presented of a structure in Cork Harbour, Ireland.

MR efficiency using automated MRI-desktop eProtocol

NASA Astrophysics Data System (ADS)

Gao, Fei; Xu, Yanzhe; Panda, Anshuman; Zhang, Min; Hanson, James; Su, Congzhe; Wu, Teresa; Pavlicek, William; James, Judy R.

2017-03-01

MRI protocols are instruction sheets that radiology technologists use in routine clinical practice for guidance (e.g., slice position, acquisition parameters etc.). In Mayo Clinic Arizona (MCA), there are over 900 MR protocols (ranging across neuro, body, cardiac, breast etc.) which makes maintaining and updating the protocol instructions a labor intensive effort. The task is even more challenging given different vendors (Siemens, GE etc.). This is a universal problem faced by all the hospitals and/or medical research institutions. To increase the efficiency of the MR practice, we designed and implemented a web-based platform (eProtocol) to automate the management of MRI protocols. It is built upon a database that automatically extracts protocol information from DICOM compliant images and provides a user-friendly interface to the technologists to create, edit and update the protocols. Advanced operations such as protocol migrations from scanner to scanner and capability to upload Multimedia content were also implemented. To the best of our knowledge, eProtocol is the first MR protocol automated management tool used clinically. It is expected that this platform will significantly improve the radiology operations efficiency including better image quality and exam consistency, fewer repeat examinations and less acquisition errors. These protocols instructions will be readily available to the technologists during scans. In addition, this web-based platform can be extended to other imaging modalities such as CT, Mammography, and Interventional Radiology and different vendors for imaging protocol management.

Optimization of Saanen sperm genes amplification: evaluation of standardized protocols in genetically uncharacterized rural goats reared under a subtropical environment.

PubMed

Barbour, Elie K; Saade, Maya F; Sleiman, Fawwak T; Hamadeh, Shady K; Mouneimne, Youssef; Kassaifi, Zeina; Kayali, Ghazi; Harakeh, Steve; Jaber, Lina S; Shaib, Houssam A

2012-10-01

The purpose of this research is to optimize quantitatively the amplification of specific sperm genes in reference genomically characterized Saanen goat and to evaluate the standardized protocols applicability on sperms of uncharacterized genome of rural goats reared under subtropical environment for inclusion in future selection programs. The optimization of the protocols in Saanen sperms included three production genes (growth hormone (GH) exons 2, 3, and 4, αS1-casein (CSN1S1), and α-lactalbumin) and two health genes (MHC class II DRB and prion (PrP)). The optimization was based on varying the primers concentrations and the inclusion of a PCR cosolvent (Triton X). The impact of the studied variables on statistically significant increase in the yield of amplicons was noticed in four out of five (80%) optimized protocols, namely in those related to GH, CSN1S1, α-lactalbumin, and PrP genes (P < 0.05). There was no significant difference in the yield of amplicons related to MHC class II DRB gene, regardless of the variables used (P > 0.05). The applicability of the optimized protocols of Saanen sperm genes on amplification of uncharacterized rural goat sperms revealed a 100% success in tested individuals for amplification of GH, CSN1S1, α-lactalbumin, and MHC class II DRB genes and a 75% success for the PrP gene. The significant success in applicability of the Saanen quantitatively optimized protocols to other uncharacterized genome of rural goats allows for their inclusion in future selection, targeting the sustainability of this farming system in a subtropical environment and the improvement of the farmers livelihood.

Median prior constrained TV algorithm for sparse view low-dose CT reconstruction.

PubMed

Liu, Yi; Shangguan, Hong; Zhang, Quan; Zhu, Hongqing; Shu, Huazhong; Gui, Zhiguo

2015-05-01

It is known that lowering the X-ray tube current (mAs) or tube voltage (kVp) and simultaneously reducing the total number of X-ray views (sparse view) is an effective means to achieve low-dose in computed tomography (CT) scan. However, the associated image quality by the conventional filtered back-projection (FBP) usually degrades due to the excessive quantum noise. Although sparse-view CT reconstruction algorithm via total variation (TV), in the scanning protocol of reducing X-ray tube current, has been demonstrated to be able to result in significant radiation dose reduction while maintain image quality, noticeable patchy artifacts still exist in reconstructed images. In this study, to address the problem of patchy artifacts, we proposed a median prior constrained TV regularization to retain the image quality by introducing an auxiliary vector m in register with the object. Specifically, the approximate action of m is to draw, in each iteration, an object voxel toward its own local median, aiming to improve low-dose image quality with sparse-view projection measurements. Subsequently, an alternating optimization algorithm is adopted to optimize the associative objective function. We refer to the median prior constrained TV regularization as "TV_MP" for simplicity. Experimental results on digital phantoms and clinical phantom demonstrated that the proposed TV_MP with appropriate control parameters can not only ensure a higher signal to noise ratio (SNR) of the reconstructed image, but also its resolution compared with the original TV method. Copyright © 2015 Elsevier Ltd. All rights reserved.

An image-based approach to understanding the physics of MR artifacts.

PubMed

Morelli, John N; Runge, Val M; Ai, Fei; Attenberger, Ulrike; Vu, Lan; Schmeets, Stuart H; Nitz, Wolfgang R; Kirsch, John E

2011-01-01

As clinical magnetic resonance (MR) imaging becomes more versatile and more complex, it is increasingly difficult to develop and maintain a thorough understanding of the physical principles that govern the changing technology. This is particularly true for practicing radiologists, whose primary obligation is to interpret clinical images and not necessarily to understand complex equations describing the underlying physics. Nevertheless, the physics of MR imaging plays an important role in clinical practice because it determines image quality, and suboptimal image quality may hinder accurate diagnosis. This article provides an image-based explanation of the physics underlying common MR imaging artifacts, offering simple solutions for remedying each type of artifact. Solutions that have emerged from recent technologic advances with which radiologists may not yet be familiar are described in detail. Types of artifacts discussed include those resulting from voluntary and involuntary patient motion, magnetic susceptibility, magnetic field inhomogeneities, gradient nonlinearity, standing waves, aliasing, chemical shift, and signal truncation. With an improved awareness and understanding of these artifacts, radiologists will be better able to modify MR imaging protocols so as to optimize clinical image quality, allowing greater confidence in diagnosis. Copyright © RSNA, 2011.

Self-Configuration and Self-Optimization Process in Heterogeneous Wireless Networks

PubMed Central

Guardalben, Lucas; Villalba, Luis Javier García; Buiati, Fábio; Sobral, João Bosco Mangueira; Camponogara, Eduardo

2011-01-01

Self-organization in Wireless Mesh Networks (WMN) is an emergent research area, which is becoming important due to the increasing number of nodes in a network. Consequently, the manual configuration of nodes is either impossible or highly costly. So it is desirable for the nodes to be able to configure themselves. In this paper, we propose an alternative architecture for self-organization of WMN based on Optimized Link State Routing Protocol (OLSR) and the ad hoc on demand distance vector (AODV) routing protocols as well as using the technology of software agents. We argue that the proposed self-optimization and self-configuration modules increase the throughput of network, reduces delay transmission and network load, decreases the traffic of HELLO messages according to network’s scalability. By simulation analysis, we conclude that the self-optimization and self-configuration mechanisms can significantly improve the performance of OLSR and AODV protocols in comparison to the baseline protocols analyzed. PMID:22346584

Self-configuration and self-optimization process in heterogeneous wireless networks.

PubMed

Guardalben, Lucas; Villalba, Luis Javier García; Buiati, Fábio; Sobral, João Bosco Mangueira; Camponogara, Eduardo

2011-01-01

Self-organization in Wireless Mesh Networks (WMN) is an emergent research area, which is becoming important due to the increasing number of nodes in a network. Consequently, the manual configuration of nodes is either impossible or highly costly. So it is desirable for the nodes to be able to configure themselves. In this paper, we propose an alternative architecture for self-organization of WMN based on Optimized Link State Routing Protocol (OLSR) and the ad hoc on demand distance vector (AODV) routing protocols as well as using the technology of software agents. We argue that the proposed self-optimization and self-configuration modules increase the throughput of network, reduces delay transmission and network load, decreases the traffic of HELLO messages according to network's scalability. By simulation analysis, we conclude that the self-optimization and self-configuration mechanisms can significantly improve the performance of OLSR and AODV protocols in comparison to the baseline protocols analyzed.

Imaging Human Brain Perfusion with Inhaled Hyperpolarized 129Xe MR Imaging.

PubMed

Rao, Madhwesha R; Stewart, Neil J; Griffiths, Paul D; Norquay, Graham; Wild, Jim M

2018-02-01

Purpose To evaluate the feasibility of directly imaging perfusion of human brain tissue by using magnetic resonance (MR) imaging with inhaled hyperpolarized xenon 129 ( 129 Xe). Materials and Methods In vivo imaging with 129 Xe was performed in three healthy participants. The combination of a high-yield spin-exchange optical pumping 129 Xe polarizer, custom-built radiofrequency coils, and an optimized gradient-echo MR imaging protocol was used to achieve signal sensitivity sufficient to directly image hyperpolarized 129 Xe dissolved in the human brain. Conventional T1-weighted proton (hydrogen 1 [ 1 H]) images and perfusion images by using arterial spin labeling were obtained for comparison. Results Images of 129 Xe uptake were obtained with a signal-to-noise ratio of 31 ± 9 and demonstrated structural similarities to the gray matter distribution on conventional T1-weighted 1 H images and to perfusion images from arterial spin labeling. Conclusion Hyperpolarized 129 Xe MR imaging is an injection-free means of imaging the perfusion of cerebral tissue. The proposed method images the uptake of inhaled xenon gas to the extravascular brain tissue compartment across the intact blood-brain barrier. This level of sensitivity is not readily available with contemporary MR imaging methods. © RSNA, 2017.

Atlas-based analysis of cardiac shape and function: correction of regional shape bias due to imaging protocol for population studies.

PubMed

Medrano-Gracia, Pau; Cowan, Brett R; Bluemke, David A; Finn, J Paul; Kadish, Alan H; Lee, Daniel C; Lima, Joao A C; Suinesiaputra, Avan; Young, Alistair A

2013-09-13

Cardiovascular imaging studies generate a wealth of data which is typically used only for individual study endpoints. By pooling data from multiple sources, quantitative comparisons can be made of regional wall motion abnormalities between different cohorts, enabling reuse of valuable data. Atlas-based analysis provides precise quantification of shape and motion differences between disease groups and normal subjects. However, subtle shape differences may arise due to differences in imaging protocol between studies. A mathematical model describing regional wall motion and shape was used to establish a coordinate system registered to the cardiac anatomy. The atlas was applied to data contributed to the Cardiac Atlas Project from two independent studies which used different imaging protocols: steady state free precession (SSFP) and gradient recalled echo (GRE) cardiovascular magnetic resonance (CMR). Shape bias due to imaging protocol was corrected using an atlas-based transformation which was generated from a set of 46 volunteers who were imaged with both protocols. Shape bias between GRE and SSFP was regionally variable, and was effectively removed using the atlas-based transformation. Global mass and volume bias was also corrected by this method. Regional shape differences between cohorts were more statistically significant after removing regional artifacts due to imaging protocol bias. Bias arising from imaging protocol can be both global and regional in nature, and is effectively corrected using an atlas-based transformation, enabling direct comparison of regional wall motion abnormalities between cohorts acquired in separate studies.

The preparation of Drosophila embryos for live-imaging using the hanging drop protocol.

PubMed

Reed, Bruce H; McMillan, Stephanie C; Chaudhary, Roopali

2009-03-13

Green fluorescent protein (GFP)-based timelapse live-imaging is a powerful technique for studying the genetic regulation of dynamic processes such as tissue morphogenesis, cell-cell adhesion, or cell death. Drosophila embryos expressing GFP are readily imaged using either stereoscopic or confocal microscopy. A goal of any live-imaging protocol is to minimize detrimental effects such as dehydration and hypoxia. Previous protocols for preparing Drosophila embryos for live-imaging analysis have involved placing dechorionated embryos in halocarbon oil and sandwiching them between a halocarbon gas-permeable membrane and a coverslip. The introduction of compression through mounting embryos in this manner represents an undesirable complication for any biomechanical-based analysis of morphogenesis. Our method, which we call the hanging drop protocol, results in excellent viability of embryos during live imaging and does not require that embryos be compressed. Briefly, the hanging drop protocol involves the placement of embryos in a drop of halocarbon oil that is suspended from a coverslip, which is, in turn, fixed in position over a humid chamber. In addition to providing gas exchange and preventing dehydration, this arrangement takes advantage of the buoyancy of embryos in halocarbon oil to prevent them from drifting out of position during timelapse acquisition. This video describes in detail how to collect and prepare Drosophila embryos for live imaging using the hanging drop protocol. This protocol is suitable for imaging dechorionated embryos using stereomicroscopy or any upright compound fluorescence microscope.

TU-G-204-04: A Unified Strategy for Bi-Factorial Optimization of Radiation Dose and Contrast Dose in CT Imaging

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

Sahbaee, P; Zhang, Y; Solomon, J

Purpose: To substantiate the interdependency of contrast dose, radiation dose, and image quality in CT towards the patient- specific optimization of the imaging protocols Methods: The study deployed two phantom platforms. A variable sized (12, 18, 23, 30, 37 cm) phantom (Mercury-3.0) containing an iodinated insert (8.5 mgI/ml) was imaged on a representative CT scanner at multiple CTDI values (0.7–22.6 mGy). The contrast and noise were measured from the reconstructed images for each phantom diameter. Linearly related to iodine-concentration, contrast-to-noise ratio (CNR), were calculated for 16 iodine-concentration levels (0–8.5 mgI/ml). The analysis was extended to a recently developed suit ofmore » 58 virtual human models (5D XCAT) with added contrast dynamics. Emulating a contrast-enhanced abdominal image procedure and targeting a peak-enhancement in aorta, each XCAT phantom was “imaged” using a simulation platform (CatSim, GE). 3D surfaces for each patient/size established the relationship between iodine-concentration, dose, and CNR. The ratios of change in iodine-concentration versus dose (IDR) to yield a constant change in CNR were calculated for each patient size. Results: Mercury phantom results show the image-quality size- dependence on CTDI and IC levels. For desired image-quality values, the iso-contour-lines reflect the trade off between contrast-material and radiation doses. For a fixed iodine-concentration (4 mgI/mL), the IDR values for low (1.4 mGy) and high (11.5 mGy) dose levels were 1.02, 1.07, 1.19, 1.65, 1.54, and 3.14, 3.12, 3.52, 3.76, 4.06, respectively across five sizes. The simulation data from XCAT models confirmed the empirical results from Mercury phantom. Conclusion: The iodine-concentration, image quality, and radiation dose are interdependent. The understanding of the relationships between iodine-concentration, image quality, and radiation dose will allow for a more comprehensive optimization of CT imaging devices and techniques, providing the methodology to balance iodine-concentration and dose based on patient’s attributes.« less

In vivo High Angular Resolution Diffusion-Weighted Imaging of Mouse Brain at 16.4 Tesla

PubMed Central

Alomair, Othman I.; Brereton, Ian M.; Smith, Maree T.; Galloway, Graham J.; Kurniawan, Nyoman D.

2015-01-01

Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T 1 and shorter T 2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM) diseases. PMID:26110770

SU-E-I-06: Measurement of Skin Dose from Dental Cone-Beam CT Scans.

PubMed

Akyalcin, S; English, J; Abramovitch, K; Rong, J

2012-06-01

To directly measure skin dose using point-dosimeters from dental cone-beam CT (CBCT) scans. To compare the results among three different dental CBCT scanners and compare the CBCT results with those from a conventional panoramic and cephalomic dental imaging system. A head anthropomorphic phantom was used with nanoDOT dosimeters attached to specified anatomic landmarks of selected radiosensitive tissues of interest. To ensure reliable measurement results, three dosimeters were used for each location. The phantom was scanned under various modes of operation and scan protocols for typical dental exams on three dental CBCT systems plus a conventional dental imaging system. The Landauer OSL nanoDOT dosimeters were calibrated under the same imaging condition as the head phantom scan protocols, and specifically for each of the imaging systems. Using nanoDOT dosimeters, skin doses at several positions on the surface of an adult head anthropomorphic phantom were measured for clinical dental imaging. The measured skin doses ranged from 0.04 to 4.62mGy depending on dosimeter positions and imaging systems. The highest dose location was at the parotid surface for all three CBCT scanners. The surface doses to the locations of the eyes were ∼4.0mGy, well below the 500mGy threshold for possibly causing cataract development. The results depend on x-ray tube output (kVp and mAs) and also are sensitive to SFOV. Comparing to the conventional dental imaging system operated in panoramic and cephalometric modes, doses from all three CBCT systems were at least an order of magnitude higher. No image artifact was caused by presence of nanoDOT dosimeters in the head phantom images. Direct measurements of skin dose using nanoDOT dosimeters provided accurate skin dose values without any image artifacts. The results of skin dose measurements serve as dose references in guiding future dose optimization efforts in dental CBCT imaging. © 2012 American Association of Physicists in Medicine.

Kilovoltage cone-beam CT: Comparative dose and image quality evaluations in partial and full-angle scan protocols

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

Kim, Sangroh; Yoo, Sua; Yin Fangfang

2010-07-15

Purpose: To assess imaging dose of partial and full-angle kilovoltage CBCT scan protocols and to evaluate image quality for each protocol. Methods: The authors obtained the CT dose index (CTDI) of the kilovoltage CBCT protocols in an on-board imager by ion chamber (IC) measurements and Monte Carlo (MC) simulations. A total of six new CBCT scan protocols were evaluated: Standard-dose head (100 kVp, 151 mA s, partial-angle), low-dose head (100 kVp, 75 mA s, partial-angle), high-quality head (100 kVp, 754 mA s, partial-angle), pelvis (125 kVp, 706 mA s, full-angle), pelvis spotlight (125 kVp, 752 mA s, partial-angle), and low-dosemore » thorax (110 kVp, 271 mA s, full-angle). Using the point dose method, various CTDI values were calculated by (1) the conventional weighted CTDI (CTDI{sub w}) calculation and (2) Bakalyar's method (CTDI{sub wb}). The MC simulations were performed to obtain the CTDI{sub w} and CTDI{sub wb}, as well as from (3) central slice averaging (CTDI{sub 2D}) and (4) volume averaging (CTDI{sub 3D}) techniques. The CTDI values of the new protocols were compared to those of the old protocols (full-angle CBCT protocols). Image quality of the new protocols was evaluated following the CBCT image quality assurance (QA) protocol [S. Yoo et al., ''A quality assurance program for the on-board imager registered ,'' Med. Phys. 33(11), 4431-4447 (2006)] testing Hounsfield unit (HU) linearity, spatial linearity/resolution, contrast resolution, and HU uniformity. Results: The CTDI{sub w} were found as 6.0, 3.2, 29.0, 25.4, 23.8, and 7.7 mGy for the new protocols, respectively. The CTDI{sub w} and CTDI{sub wb} differed within +3% between IC measurements and MC simulations. Method (2) results were within {+-}12% of method (1). In MC simulations, the CTDI{sub w} and CTDI{sub wb} were comparable to the CTDI{sub 2D} and CTDI{sub 3D} with the differences ranging from -4.3% to 20.6%. The CTDI{sub 3D} were smallest among all the CTDI values. CTDI{sub w} of the new protocols were found as {approx}14 times lower for standard head scan and 1.8 times lower for standard body scan than the old protocols, respectively. In the image quality QA tests, all the protocols except low-dose head and low-dose thorax protocols were within the tolerance in the HU verification test. The HU value for the two protocols was always higher than the nominal value. All the protocols passed the spatial linearity/resolution and HU uniformity tests. In the contrast resolution test, only high-quality head and pelvis scan protocols were within the tolerance. In addition, crescent effect was found in the partial-angle scan protocols. Conclusions: The authors found that CTDI{sub w} of the new CBCT protocols has been significantly reduced compared to the old protocols with acceptable image quality. The CTDI{sub w} values in the point dose method were close to the volume averaging method within 9%-21% for all the CBCT scan protocols. The Bakalyar's method produced more accurate dose estimation within 14%. The HU inaccuracy from low-dose head and low-dose thorax protocols can render incorrect dose results in the treatment planning system. When high soft-tissue contrast data are desired, high-quality head or pelvis scan protocol is recommended depending on the imaging area. The point dose method can be applicable to estimate CBCT dose with reasonable accuracy in the clinical environment.« less

Solvent replacement for green processing.

PubMed Central

Sherman, J; Chin, B; Huibers, P D; Garcia-Valls, R; Hatton, T A

1998-01-01

The implementation of the Montreal Protocol, the Clean Air Act, and the Pollution Prevention Act of 1990 has resulted in increased awareness of organic solvent use in chemical processing. The advances made in the search to find "green" replacements for traditional solvents are reviewed, with reference to solvent alternatives for cleaning, coatings, and chemical reaction and separation processes. The development of solvent databases and computational methods that aid in the selection and/or design of feasible or optimal environmentally benign solvent alternatives for specific applications is also discussed. Images Figure 2 Figure 3 PMID:9539018

Lens dose in routine head CT: comparison of different optimization methods with anthropomorphic phantoms.

PubMed

Nikupaavo, Ulla; Kaasalainen, Touko; Reijonen, Vappu; Ahonen, Sanna-Mari; Kortesniemi, Mika

2015-01-01

The purpose of this study was to study different optimization methods for reducing eye lens dose in head CT. Two anthropomorphic phantoms were scanned with a routine head CT protocol for evaluation of the brain that included bismuth shielding, gantry tilting, organ-based tube current modulation, or combinations of these techniques. Highsensitivity metal oxide semiconductor field effect transistor dosimeters were used to measure local equivalent doses in the head region. The relative changes in image noise and contrast were determined by ROI analysis. The mean absorbed lens doses varied from 4.9 to 19.7 mGy and from 10.8 to 16.9 mGy in the two phantoms. The most efficient method for reducing lens dose was gantry tilting, which left the lenses outside the primary radiation beam, resulting in an approximately 75% decrease in lens dose. Image noise decreased, especially in the anterior part of the brain. The use of organ-based tube current modulation resulted in an approximately 30% decrease in lens dose. However, image noise increased as much as 30% in the posterior and central parts of the brain. With bismuth shields, it was possible to reduce lens dose as much as 25%. Our results indicate that gantry tilt, when possible, is an effective method for reducing exposure of the eye lenses in CT of the brain without compromising image quality. Measurements in two different phantoms showed how patient geometry affects the optimization. When lenses can only partially be cropped outside the primary beam, organ-based tube current modulation or bismuth shields can be useful in lens dose reduction.

Cone beam computed tomography in implant dentistry: recommendations for clinical use.

PubMed

Jacobs, Reinhilde; Salmon, Benjamin; Codari, Marina; Hassan, Bassam; Bornstein, Michael M

2018-05-15

In implant dentistry, three-dimensional (3D) imaging can be realised by dental cone beam computed tomography (CBCT), offering volumetric data on jaw bones and teeth with relatively low radiation doses and costs. The latter may explain why the market has been steadily growing since the first dental CBCT system appeared two decades ago. More than 85 different CBCT devices are currently available and this exponential growth has created a gap between scientific evidence and existing CBCT machines. Indeed, research for one CBCT machine cannot be automatically applied to other systems. Supported by a narrative review, recommendations for justified and optimized CBCT imaging in oral implant dentistry are provided. The huge range in dose and diagnostic image quality requires further optimization and justification prior to clinical use. Yet, indications in implant dentistry may go beyond diagnostics. In fact, the inherent 3D datasets may further allow surgical planning and transfer to surgery via 3D printing or navigation. Nonetheless, effective radiation doses of distinct dental CBCT machines and protocols may largely vary with equivalent doses ranging between 2 to 200 panoramic radiographs, even for similar indications. Likewise, such variation is also noticed for diagnostic image quality, which reveals a massive variability amongst CBCT technologies and exposure protocols. For anatomical model making, the so-called segmentation accuracy may reach up to 200 μm, but considering wide variations in machine performance, larger inaccuracies may apply. This also holds true for linear measures, with accuracies of 200 μm being feasible, while sometimes fivefold inaccuracy levels may be reached. Diagnostic image quality may also be dramatically hampered by patient factors, such as motion and metal artefacts. Apart from radiodiagnostic possibilities, CBCT may offer a huge therapeutic potential, related to surgical guides and further prosthetic rehabilitation. Those additional opportunities may surely clarify part of the success of using CBCT for presurgical implant planning and its transfer to surgery and prosthetic solutions. Hence, dental CBCT could be justified for presurgical diagnosis, preoperative planning and peroperative transfer for oral implant rehabilitation, whilst striving for optimisation of CBCT based machine-dependent, patient-specific and indication-oriented variables.

Informatics in radiology: use of CouchDB for document-based storage of DICOM objects.

PubMed

Rascovsky, Simón J; Delgado, Jorge A; Sanz, Alexander; Calvo, Víctor D; Castrillón, Gabriel

2012-01-01

Picture archiving and communication systems traditionally have depended on schema-based Structured Query Language (SQL) databases for imaging data management. To optimize database size and performance, many such systems store a reduced set of Digital Imaging and Communications in Medicine (DICOM) metadata, discarding informational content that might be needed in the future. As an alternative to traditional database systems, document-based key-value stores recently have gained popularity. These systems store documents containing key-value pairs that facilitate data searches without predefined schemas. Document-based key-value stores are especially suited to archive DICOM objects because DICOM metadata are highly heterogeneous collections of tag-value pairs conveying specific information about imaging modalities, acquisition protocols, and vendor-supported postprocessing options. The authors used an open-source document-based database management system (Apache CouchDB) to create and test two such databases; CouchDB was selected for its overall ease of use, capability for managing attachments, and reliance on HTTP and Representational State Transfer standards for accessing and retrieving data. A large database was created first in which the DICOM metadata from 5880 anonymized magnetic resonance imaging studies (1,949,753 images) were loaded by using a Ruby script. To provide the usual DICOM query functionality, several predefined "views" (standard queries) were created by using JavaScript. For performance comparison, the same queries were executed in both the CouchDB database and a SQL-based DICOM archive. The capabilities of CouchDB for attachment management and database replication were separately assessed in tests of a similar, smaller database. Results showed that CouchDB allowed efficient storage and interrogation of all DICOM objects; with the use of information retrieval algorithms such as map-reduce, all the DICOM metadata stored in the large database were searchable with only a minimal increase in retrieval time over that with the traditional database management system. Results also indicated possible uses for document-based databases in data mining applications such as dose monitoring, quality assurance, and protocol optimization. RSNA, 2012

Intelligent QoS routing algorithm based on improved AODV protocol for Ad Hoc networks

NASA Astrophysics Data System (ADS)

Huibin, Liu; Jun, Zhang

2016-04-01

Mobile Ad Hoc Networks were playing an increasingly important part in disaster reliefs, military battlefields and scientific explorations. However, networks routing difficulties are more and more outstanding due to inherent structures. This paper proposed an improved cuckoo searching-based Ad hoc On-Demand Distance Vector Routing protocol (CSAODV). It elaborately designs the calculation methods of optimal routing algorithm used by protocol and transmission mechanism of communication-package. In calculation of optimal routing algorithm by CS Algorithm, by increasing QoS constraint, the found optimal routing algorithm can conform to the requirements of specified bandwidth and time delay, and a certain balance can be obtained among computation spending, bandwidth and time delay. Take advantage of NS2 simulation software to take performance test on protocol in three circumstances and validate the feasibility and validity of CSAODV protocol. In results, CSAODV routing protocol is more adapt to the change of network topological structure than AODV protocol, which improves package delivery fraction of protocol effectively, reduce the transmission time delay of network, reduce the extra burden to network brought by controlling information, and improve the routing efficiency of network.

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

PubMed Central

Zhang, Rongxiao; Gladstone, David J.; Williams, Benjamin B.; Glaser, Adam K.; Pogue, Brian W.; Jarvis, Lesley A.

2016-01-01

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, composite images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R2 = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R2 = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments. PMID:26843259

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

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

Andreozzi, Jacqueline M., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org; Glaser, Adam K.; Zhang, Rongxiao

2016-02-15

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, compositemore » images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R{sup 2} = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R{sup 2} = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments.« less

Intravenous Ketamine Infusions for Neuropathic Pain Management: A Promising Therapy in Need of Optimization.

PubMed

Maher, Dermot P; Chen, Lucy; Mao, Jianren

2017-02-01

Intravenous ketamine infusions have been used extensively to treat often-intractable neuropathic pain conditions. Because there are many widely divergent ketamine infusion protocols described in the literature, the variation in these protocols presents a challenge for direct comparison of one protocol with another and in discerning an optimal protocol. Careful examination of the published literature suggests that ketamine infusions can be useful to treat neuropathic pain and that certain characteristics of ketamine infusions may be associated with better clinical outcomes. Increased duration of relief from neuropathic pain is associated with (1) higher total infused doses of ketamine; (2) prolonged infusion durations, although the rate of infusion does not appear to be a factor; and (3) coadministration of adjunct medications such as midazolam and/or clonidine that mitigate some of the unpleasant psychomimetic side effects. However, there are few studies designed to optimize ketamine infusion protocols by defining what an effective infusion protocol entails with regard to a respective neuropathic pain condition. Therefore, despite common clinical practice, the current state of the literature leaves the use of ketamine infusions without meaningful guidance from high-quality comparative evidence. The objectives of this topical review are to (1) analyze the available clinical evidence related to ketamine infusion protocols and (2) call for clinical studies to identify optimal ketamine infusion protocols tailored for individual neuropathic pain conditions. The Oxford Center for Evidence-Based Medicine classification for levels of evidence was used to stratify the grades of clinical recommendation for each infusion variable studied.

Optimal approach to quantum communication using dynamic programming.

PubMed

Jiang, Liang; Taylor, Jacob M; Khaneja, Navin; Lukin, Mikhail D

2007-10-30

Reliable preparation of entanglement between distant systems is an outstanding problem in quantum information science and quantum communication. In practice, this has to be accomplished by noisy channels (such as optical fibers) that generally result in exponential attenuation of quantum signals at large distances. A special class of quantum error correction protocols, quantum repeater protocols, can be used to overcome such losses. In this work, we introduce a method for systematically optimizing existing protocols and developing more efficient protocols. Our approach makes use of a dynamic programming-based searching algorithm, the complexity of which scales only polynomially with the communication distance, letting us efficiently determine near-optimal solutions. We find significant improvements in both the speed and the final-state fidelity for preparing long-distance entangled states.

TH-C-18A-08: A Management Tool for CT Dose Monitoring, Analysis, and Protocol Review

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

Wang, J; Chan, F; Newman, B

2014-06-15

Purpose: To develop a customizable tool for enterprise-wide managing of CT protocols and analyzing radiation dose information of CT exams for a variety of quality control applications Methods: All clinical CT protocols implemented on the 11 CT scanners at our institution were extracted in digital format. The original protocols had been preset by our CT management team. A commercial CT dose tracking software (DoseWatch,GE healthcare,WI) was used to collect exam information (exam date, patient age etc.), scanning parameters, and radiation doses for all CT exams. We developed a Matlab-based program (MathWorks,MA) with graphic user interface which allows to analyze themore » scanning protocols with the actual dose estimates, and compare the data to national (ACR,AAPM) and internal reference values for CT quality control. Results: The CT protocol review portion of our tool allows the user to look up the scanning and image reconstruction parameters of any protocol on any of the installed CT systems among about 120 protocols per scanner. In the dose analysis tool, dose information of all CT exams (from 05/2013 to 02/2014) was stratified on a protocol level, and within a protocol down to series level, i.e. each individual exposure event. This allows numerical and graphical review of dose information of any combination of scanner models, protocols and series. The key functions of the tool include: statistics of CTDI, DLP and SSDE, dose monitoring using user-set CTDI/DLP/SSDE thresholds, look-up of any CT exam dose data, and CT protocol review. Conclusion: our inhouse CT management tool provides radiologists, technologists and administration a first-hand near real-time enterprise-wide knowledge on CT dose levels of different exam types. Medical physicists use this tool to manage CT protocols, compare and optimize dose levels across different scanner models. It provides technologists feedback on CT scanning operation, and knowledge on important dose baselines and thresholds.« less

How to make optimal use of maximal multipartite entanglement in clock synchronization

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

Ren, Changliang; Hofmann, Holger F.

2014-12-04

We introduce a multi-party quantum clock synchronization protocol that makes optimal use of the maximal multipartite entanglement of GHZ-type states. The measurement statistics of the protocol are analyzed and the efficiency is evaluated.

SPOT: Optimization Tool for Network Adaptable Security

NASA Astrophysics Data System (ADS)

Ksiezopolski, Bogdan; Szalachowski, Pawel; Kotulski, Zbigniew

Recently we have observed the growth of the intelligent application especially with its mobile character, called e-anything. The implementation of these applications provides guarantee of security requirements of the cryptographic protocols which are used in the application. Traditionally the protocols have been configured with the strongest possible security mechanisms. Unfortunately, when the application is used by means of the mobile devices, the strongest protection can lead to the denial of services for them. The solution of this problem is introducing the quality of protection models which will scale the protection level depending on the actual threat level. In this article we would like to introduce the application which manages the protection level of the processes in the mobile environment. The Security Protocol Optimizing Tool (SPOT) optimizes the cryptographic protocol and defines the protocol version appropriate to the actual threat level. In this article the architecture of the SPOT is presented with a detailed description of the included modules.

Paperless protocoling of CT and MRI requests at an outpatient imaging center.

PubMed

Bassignani, Matthew J; Dierolf, David A; Roberts, David L; Lee, Steven

2010-04-01

We created our imaging center (IC) to move outpatient imaging from our busy inpatient imaging suite off-site to a location that is more inviting to ambulatory patients. Nevertheless, patients scanned at our IC still represent the depth and breadth of illness complexity seen with our tertiary care population. Thus, we protocol exams on an individualized basis to ensure that the referring clinician's question is fully answered by the exam performed. Previously, paper based protocoling was a laborious process for all those involved where the IC business office would fax the requests to various reading rooms for protocoling by the subspecialist radiologists who are 3 miles away at the main hospital. Once protocoled, reading room coordinators would fax back the protocoled request to the IC technical area in preparation for the next day's scheduled exams. At any breakdown in this process (e.g., lost paperwork), patient exams were delayed and clinicians and patients became upset. To improve this process, we developed a paper free process whereby protocoling is accomplished through scanning of exam requests into our PACS. Using the common worklist functionality found in most PACS, we created "protocoling worklists" that contain these scanned documents. Radiologists protocol these studies in the PACS worklist (with the added benefit of having all imaging and report data available), and subsequently, the technologists can see and act on the protocols they find in PACS. This process has significantly decreased interruptions in our busy reading rooms and decreased rework of IC staff.

Optimal acquisition and modeling parameters for accurate assessment of low Ktrans blood-brain barrier permeability using dynamic contrast-enhanced MRI.

PubMed

Barnes, Samuel R; Ng, Thomas S C; Montagne, Axel; Law, Meng; Zlokovic, Berislav V; Jacobs, Russell E

2016-05-01

To determine optimal parameters for acquisition and processing of dynamic contrast-enhanced MRI (DCE-MRI) to detect small changes in near normal low blood-brain barrier (BBB) permeability. Using a contrast-to-noise ratio metric (K-CNR) for Ktrans precision and accuracy, the effects of kinetic model selection, scan duration, temporal resolution, signal drift, and length of baseline on the estimation of low permeability values was evaluated with simulations. The Patlak model was shown to give the highest K-CNR at low Ktrans . The Ktrans transition point, above which other models yielded superior results, was highly dependent on scan duration and tissue extravascular extracellular volume fraction (ve ). The highest K-CNR for low Ktrans was obtained when Patlak model analysis was combined with long scan times (10-30 min), modest temporal resolution (<60 s/image), and long baseline scans (1-4 min). Signal drift as low as 3% was shown to affect the accuracy of Ktrans estimation with Patlak analysis. DCE acquisition and modeling parameters are interdependent and should be optimized together for the tissue being imaged. Appropriately optimized protocols can detect even the subtlest changes in BBB integrity and may be used to probe the earliest changes in neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis. © 2015 Wiley Periodicals, Inc.

Cranial nerve contrast using nerve-specific fluorophores improved by paired-agent imaging with indocyanine green as a control agent

NASA Astrophysics Data System (ADS)

Torres, Veronica C.; Vuong, Victoria D.; Wilson, Todd; Wewel, Joshua; Byrne, Richard W.; Tichauer, Kenneth M.

2017-09-01

Nerve preservation during surgery is critical because damage can result in significant morbidity. This remains a challenge especially for skull base surgeries where cranial nerves (CNs) are involved because visualization and access are particularly poor in that location. We present a paired-agent imaging method to enhance identification of CNs using nerve-specific fluorophores. Two myelin-targeting imaging agents were evaluated, Oxazine 4 and Rhodamine 800, and coadministered with a control agent, indocyanine green, either intravenously or topically in rats. Fluorescence imaging was performed on excised brains ex vivo, and nerve contrast was evaluated via paired-agent ratiometric data analysis. Although contrast was improved among all experimental groups using paired-agent imaging compared to conventional, solely targeted imaging, Oxazine 4 applied directly exhibited the greatest enhancement, with a minimum 3 times improvement in CNs delineation. This work highlights the importance of accounting for nonspecific signal of targeted agents, and demonstrates that paired-agent imaging is one method capable of doing so. Although staining, rinsing, and imaging protocols need to be optimized, these findings serve as a demonstration for the potential use of paired-agent imaging to improve contrast of CNs, and consequently, surgical outcome.

Color standardization and optimization in whole slide imaging.

PubMed

Yagi, Yukako

2011-03-30

Standardization and validation of the color displayed by digital slides is an important aspect of digital pathology implementation. While the most common reason for color variation is the variance in the protocols and practices in the histology lab, the color displayed can also be affected by variation in capture parameters (for example, illumination and filters), image processing and display factors in the digital systems themselves. We have been developing techniques for color validation and optimization along two paths. The first was based on two standard slides that are scanned and displayed by the imaging system in question. In this approach, one slide is embedded with nine filters with colors selected especially for H&E stained slides (looking like tiny Macbeth color chart); the specific color of the nine filters were determined in our previous study and modified for whole slide imaging (WSI). The other slide is an H&E stained mouse embryo. Both of these slides were scanned and the displayed images were compared to a standard. The second approach was based on our previous multispectral imaging research. As a first step, the two slide method (above) was used to identify inaccurate display of color and its cause, and to understand the importance of accurate color in digital pathology. We have also improved the multispectral-based algorithm for more consistent results in stain standardization. In near future, the results of the two slide and multispectral techniques can be combined and will be widely available. We have been conducting a series of researches and developing projects to improve image quality to establish Image Quality Standardization. This paper discusses one of most important aspects of image quality - color.

Tube focal spot size and power capability impact image quality in the evaluation of intracoronary stents

NASA Astrophysics Data System (ADS)

Cesmeli, Erdogan; Berry, Joel L.; Carr, J. J.

2005-04-01

Proliferation of coronary stent deployment for treatment of coronary heart disease (CHD) creates a need for imaging-based follow-up examinations to assess patency. Technological improvements in multi-detector computer tomography (MDCT) make it a potential non-invasive alternative to coronary catheterization for evaluation of stent patency; however, image quality with MDCT varies based on the size and composition of the stent. We studied the role of tube focal spot size and power in the optimization of image quality in a stationary phantom. A standard uniform physical phantom with a tubular insert was used where coronary stents (4 mm in diameter) were deployed in a tube filled with contrast to simulate a typical imaging condition observed in clinical practice. We utilized different commercially available stents and scanned them with different tube voltage and current settings (LightSpeed Pro16, GE Healthcare Technologies, Waukesha, WI, USA). The scanner used different focal spot size depending on the power load and thus allowed us to assess the combined effect of the focal spot size and the power. A radiologist evaluated the resulting images in terms of image quality and artifacts. For all stents, we found that the small focal spot size yielded better image quality and reduced artifacts. In general, higher power capability for the given focal spot size improved the signal-to-noise ratio in the images allowing improved assessment. Our preliminary study in a non-moving phantom suggests that a CT scanner that can deliver the same power on a small focal spot size is better suited to have an optimized scan protocol for reliable stent assessment.

A review of biomedical multiphoton microscopy and its laser sources

NASA Astrophysics Data System (ADS)

Lefort, Claire

2017-10-01

Multiphoton microscopy (MPM) has been the subject of major development efforts for about 25 years for imaging biological specimens at micron scale and presented as an elegant alternative to classical fluorescence methods such as confocal microscopy. In this topical review, the main interests and technical requirements of MPM are addressed with a focus on the crucial role of excitation source for optimization of multiphoton processes. Then, an overview of the different sources successfully demonstrated in literature for MPM is presented, and their physical parameters are inventoried. A classification of these sources in function with their ability to optimize multiphoton processes is proposed, following a protocol found in literature. Starting from these considerations, a suggestion of a possible identikit of the ideal laser source for MPM concludes this topical review. Dedicated to Martin.

[Intranet applications in radiology].

PubMed

Knopp, M V; von Hippel, G M; Koch, T; Knopp, M A

2000-01-01

The aim of the paper is to present the conceptual basis and capabilities of intranet applications in radiology. The intranet, which is the local brother of the internet can be readily realized using existing computer components and a network. All current computer operating systems support intranet applications which allow hard and software independent communication of text, images, video and sound with the use of browser software without dedicated programs on the individual personal computers. Radiological applications for text communication e.g. department specific bulletin boards and access to examination protocols; use of image communication for viewing and limited processing and documentation of radiological images can be achieved on decentralized PCs as well as speech communication for dictation, distribution of dictation and speech recognition. The intranet helps to optimize the organizational efficiency and cost effectiveness in the daily work of radiological departments in outpatients and hospital settings. The general interest in internet and intranet technology will guarantee its continuous development.

State of the art: dual-energy CT of the abdomen.

PubMed

Marin, Daniele; Boll, Daniel T; Mileto, Achille; Nelson, Rendon C

2014-05-01

Recent technologic advances in computed tomography (CT)--enabling the nearly simultaneous acquisition of clinical images using two different x-ray energy spectra--have sparked renewed interest in dual-energy CT. By interrogating the unique characteristics of different materials at different x-ray energies, dual-energy CT can be used to provide quantitative information about tissue composition, overcoming the limitations of attenuation-based conventional single-energy CT imaging. In the past few years, intensive research efforts have been devoted to exploiting the unique and powerful opportunities of dual-energy CT for a variety of clinical applications. This has led to CT protocol modifications for radiation dose reduction, improved diagnostic performance for detection and characterization of diseases, as well as image quality optimization. In this review, the authors discuss the basic principles, instrumentation and design, examples of current clinical applications in the abdomen and pelvis, and future opportunities of dual-energy CT.

Potential Projective Material on the Rorschach: Comparing Comprehensive System Protocols to Their Modeled R-Optimized Administration Counterparts.

PubMed

Pianowski, Giselle; Meyer, Gregory J; Villemor-Amaral, Anna Elisa de

2016-01-01

Exner ( 1989 ) and Weiner ( 2003 ) identified 3 types of Rorschach codes that are most likely to contain personally relevant projective material: Distortions, Movement, and Embellishments. We examine how often these types of codes occur in normative data and whether their frequency changes for the 1st, 2nd, 3rd, 4th, or last response to a card. We also examine the impact on these variables of the Rorschach Performance Assessment System's (R-PAS) statistical modeling procedures that convert the distribution of responses (R) from Comprehensive System (CS) administered protocols to match the distribution of R found in protocols obtained using R-optimized administration guidelines. In 2 normative reference databases, the results indicated that about 40% of responses (M = 39.25) have 1 type of code, 15% have 2 types, and 1.5% have all 3 types, with frequencies not changing by response number. In addition, there were no mean differences in the original CS and R-optimized modeled records (M Cohen's d = -0.04 in both databases). When considered alongside findings showing minimal differences between the protocols of people randomly assigned to CS or R-optimized administration, the data suggest R-optimized administration should not alter the extent to which potential projective material is present in a Rorschach protocol.

SU-E-I-68: Practical Considerations On Implementation of the Image Gently Pediatric CT Protocols

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

Zhang, J; Adams, C; Lumby, C

Purpose: One limitation associated with the Image Gently pediatric CT protocols is practical implementation of the recommended manual techniques. Inconsistency as a result of different practice is a possibility among technologist. An additional concern is the added risk of data error that would result in over or underexposure. The Automatic Exposure Control (AEC) features automatically reduce radiation for children. However, they do not work efficiently for the patients of very small size and relative large size. This study aims to implement the Image Gently pediatric CT protocols in the practical setting while maintaining the use of AEC features for pediatricmore » patients of varying size. Methods: Anthropomorphological abdomen phantoms were scanned in a CT scanner using the Image Gently pediatric protocols, the AEC technique with a fixed adult baseline, and automatic protocols with various baselines. The baselines were adjusted corresponding to patient age, weight and posterioranterior thickness to match the Image Gently pediatric CT manual techniques. CTDIvol was recorded for each examination. Image noise was measured and recorded for image quality comparison. Clinical images were evaluated by pediatric radiologists. Results: By adjusting vendor default baselines used in the automatic techniques, radiation dose and image quality can match those of the Image Gently manual techniques. In practice, this can be achieved by dividing pediatric patients into three major groups for technologist reference: infant, small child, and large child. Further division can be done but will increase the number of CT protocols. For each group, AEC can efficiently adjust acquisition techniques for children. This implementation significantly overcomes the limitation of the Image Gently manual techniques. Conclusion: Considering the effectiveness in clinical practice, Image Gently Pediatric CT protocols can be implemented in accordance with AEC techniques, with adjusted baselines, to achieve the goal of providing the most appropriate radiation dose for pediatric patients of varying sizes.« less

Optimizing Variational Quantum Algorithms Using Pontryagin’s Minimum Principle

DOE PAGES

Yang, Zhi -Cheng; Rahmani, Armin; Shabani, Alireza; ...

2017-05-18

We use Pontryagin’s minimum principle to optimize variational quantum algorithms. We show that for a fixed computation time, the optimal evolution has a bang-bang (square pulse) form, both for closed and open quantum systems with Markovian decoherence. Our findings support the choice of evolution ansatz in the recently proposed quantum approximate optimization algorithm. Focusing on the Sherrington-Kirkpatrick spin glass as an example, we find a system-size independent distribution of the duration of pulses, with characteristic time scale set by the inverse of the coupling constants in the Hamiltonian. The optimality of the bang-bang protocols and the characteristic time scale ofmore » the pulses provide an efficient parametrization of the protocol and inform the search for effective hybrid (classical and quantum) schemes for tackling combinatorial optimization problems. Moreover, we find that the success rates of our optimal bang-bang protocols remain high even in the presence of weak external noise and coupling to a thermal bath.« less

Optimizing Variational Quantum Algorithms Using Pontryagin’s Minimum Principle

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

Yang, Zhi -Cheng; Rahmani, Armin; Shabani, Alireza

We use Pontryagin’s minimum principle to optimize variational quantum algorithms. We show that for a fixed computation time, the optimal evolution has a bang-bang (square pulse) form, both for closed and open quantum systems with Markovian decoherence. Our findings support the choice of evolution ansatz in the recently proposed quantum approximate optimization algorithm. Focusing on the Sherrington-Kirkpatrick spin glass as an example, we find a system-size independent distribution of the duration of pulses, with characteristic time scale set by the inverse of the coupling constants in the Hamiltonian. The optimality of the bang-bang protocols and the characteristic time scale ofmore » the pulses provide an efficient parametrization of the protocol and inform the search for effective hybrid (classical and quantum) schemes for tackling combinatorial optimization problems. Moreover, we find that the success rates of our optimal bang-bang protocols remain high even in the presence of weak external noise and coupling to a thermal bath.« less

Live imaging of mitosis in the developing mouse embryonic cortex.

PubMed

Pilaz, Louis-Jan; Silver, Debra L

2014-06-04

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-α-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

Adaptive hybrid optimal quantum control for imprecisely characterized systems.

PubMed

Egger, D J; Wilhelm, F K

2014-06-20

Optimal quantum control theory carries a huge promise for quantum technology. Its experimental application, however, is often hindered by imprecise knowledge of the input variables, the quantum system's parameters. We show how to overcome this by adaptive hybrid optimal control, using a protocol named Ad-HOC. This protocol combines open- and closed-loop optimal control by first performing a gradient search towards a near-optimal control pulse and then an experimental fidelity estimation with a gradient-free method. For typical settings in solid-state quantum information processing, adaptive hybrid optimal control enhances gate fidelities by an order of magnitude, making optimal control theory applicable and useful.

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

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

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

1984-01-01

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

The value and throughput of rest Thallium-201/stress Technetium -99m sestamibi dual-isotope myocardial SPECT.

PubMed

Okudan, Berna; Smitherman, Thomas C

2004-06-01

Myocardial perfusion scintigraphy is an established method in cardiology for the diagnosis and evaluation of coronary artery disease (CAD). Thallium-201 and Tc-99m sestamibi myocardial perfusion imaging has been widely accepted as non-invasive diagnostic procedure for detection of CAD, risk stratification and myocardial viability assessment. But, standard Tl-201 redistribution and same day or 2-day rest/stress Tc-99m sestamibi protocols are time-consuming. Hence, the dual isotope rest thallium-201/stress technetium-99m sestamibi gated single-photon emission tomography protocol has gained increasing popularity for these applications. Combining the use of thallium-201 with technetium-99m agents permits optimal image resolution and simultaneous assessment of viability. Dual-isotope imaging may be separate or simultaneous acquisition set-up. The more rapid completion of these studies is appreciated as an advantage by patients, technologists, interpreting and referring physicians, nurses and hospital management. Simultaneous imaging has the potential advantages of precise pixel registration and artifacts, if present, are identical in both thallium and sestamibi, and require only one set of imaging. Also, there are some disadvantages of spillover of activity from the Tc-99m to the Tl-201 window. Fortunately, despite this problem it can be overcome. Separate acquisition dual isotope also has some disadvantages. Difference in defect resolution in attenuation and scatter between T-201 and Tc-99m sestamibi potentially results in interpretation problems. But, studies about cost-effectiveness of dual isotope imaging showed that some selective elimination of the rest studies may decrease the cost of the nuclear procedures and should be considered in the current care health system.

Quantitative CT: technique dependence of volume estimation on pulmonary nodules

NASA Astrophysics Data System (ADS)

Chen, Baiyu; Barnhart, Huiman; Richard, Samuel; Colsher, James; Amurao, Maxwell; Samei, Ehsan

2012-03-01

Current estimation of lung nodule size typically relies on uni- or bi-dimensional techniques. While new three-dimensional volume estimation techniques using MDCT have improved size estimation of nodules with irregular shapes, the effect of acquisition and reconstruction parameters on accuracy (bias) and precision (variance) of the new techniques has not been fully investigated. To characterize the volume estimation performance dependence on these parameters, an anthropomorphic chest phantom containing synthetic nodules was scanned and reconstructed with protocols across various acquisition and reconstruction parameters. Nodule volumes were estimated by a clinical lung analysis software package, LungVCAR. Precision and accuracy of the volume assessment were calculated across the nodules and compared between protocols via a generalized estimating equation analysis. Results showed that the precision and accuracy of nodule volume quantifications were dependent on slice thickness, with different dependences for different nodule characteristics. Other parameters including kVp, pitch, and reconstruction kernel had lower impact. Determining these technique dependences enables better volume quantification via protocol optimization and highlights the importance of consistent imaging parameters in sequential examinations.

Two examples of indication specific radiation dose calculations in dental CBCT and Multidetector CT scanners.

PubMed

Stratis, Andreas; Zhang, Guozhi; Lopez-Rendon, Xochitl; Politis, Constantinus; Hermans, Robert; Jacobs, Reinhilde; Bogaerts, Ria; Shaheen, Eman; Bosmans, Hilde

2017-09-01

To calculate organ doses and estimate the effective dose for justification purposes in patients undergoing orthognathic treatment planning purposes and temporal bone imaging in dental cone beam CT (CBCT) and Multidetector CT (MDCT) scanners. The radiation dose to the ICRP reference male voxel phantom was calculated for dedicated orthognathic treatment planning acquisitions via Monte Carlo simulations in two dental CBCT scanners, Promax 3D Max (Planmeca, FI) and NewTom VGi evo (QR s.r.l, IT) and in Somatom Definition Flash (Siemens, DE) MDCT scanner. For temporal bone imaging, radiation doses were calculated via MC simulations for a CBCT protocol in NewTom 5G (QR s.r.l, IT) and with the use of a software tool (CT-expo) for Somatom Force (Siemens, DE). All procedures had been optimized at the acceptance tests of the devices. For orthognathic protocols, dental CBCT scanners deliver lower doses compared to MDCT scanners. The estimated effective dose (ED) was 0.32mSv for a normal resolution operation mode in Promax 3D Max, 0.27mSv in VGi-evo and 1.18mSv in the Somatom Definition Flash. For temporal bone protocols, the Somatom Force resulted in an estimated ED of 0.28mSv while for NewTom 5G the ED was 0.31 and 0.22mSv for monolateral and bilateral imaging respectively. Two clinical exams which are carried out with both a CBCT or a MDCT scanner were compared in terms of radiation dose. Dental CBCT scanners deliver lower doses for orthognathic patients whereas for temporal bone procedures the doses were similar. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Brain imaging predictors and the international study to predict optimized treatment for depression: study protocol for a randomized controlled trial

PubMed Central

2013-01-01

Background Approximately 50% of patients with major depressive disorder (MDD) do not respond optimally to antidepressant treatments. Given this is a large proportion of the patient population, pretreatment tests that predict which patients will respond to which types of treatment could save time, money and patient burden. Brain imaging offers a means to identify treatment predictors that are grounded in the neurobiology of the treatment and the pathophysiology of MDD. Methods/Design The international Study to Predict Optimized Treatment in Depression is a multi-center, parallel model, randomized clinical trial with an embedded imaging sub-study to identify such predictors. We focus on brain circuits implicated in major depressive disorder and its treatment. In the full trial, depressed participants are randomized to receive escitalopram, sertraline or venlafaxine-XR (open-label). They are assessed using standardized multiple clinical, cognitive-emotional behavioral, electroencephalographic and genetic measures at baseline and at eight weeks post-treatment. Overall, 2,016 depressed participants (18 to 65 years old) will enter the study, of whom a target of 10% will be recruited into the brain imaging sub-study (approximately 67 participants in each treatment arm) and 67 controls. The imaging sub-study is conducted at the University of Sydney and at Stanford University. Structural studies include high-resolution three-dimensional T1-weighted, diffusion tensor and T2/Proton Density scans. Functional studies include standardized functional magnetic resonance imaging (MRI) with three cognitive tasks (auditory oddball, a continuous performance task, and Go-NoGo) and two emotion tasks (unmasked conscious and masked non-conscious emotion processing tasks). After eight weeks of treatment, the functional MRI is repeated with the above tasks. We will establish the methods in the first 30 patients. Then we will identify predictors in the first half (n = 102), test the findings in the second half, and then extend the analyses to the total sample. Trial registration International Study to Predict Optimized Treatment - in Depression (iSPOT-D). ClinicalTrials.gov, NCT00693849. PMID:23866851

Brain imaging predictors and the international study to predict optimized treatment for depression: study protocol for a randomized controlled trial.

PubMed

Grieve, Stuart M; Korgaonkar, Mayuresh S; Etkin, Amit; Harris, Anthony; Koslow, Stephen H; Wisniewski, Stephen; Schatzberg, Alan F; Nemeroff, Charles B; Gordon, Evian; Williams, Leanne M

2013-07-18

Approximately 50% of patients with major depressive disorder (MDD) do not respond optimally to antidepressant treatments. Given this is a large proportion of the patient population, pretreatment tests that predict which patients will respond to which types of treatment could save time, money and patient burden. Brain imaging offers a means to identify treatment predictors that are grounded in the neurobiology of the treatment and the pathophysiology of MDD. The international Study to Predict Optimized Treatment in Depression is a multi-center, parallel model, randomized clinical trial with an embedded imaging sub-study to identify such predictors. We focus on brain circuits implicated in major depressive disorder and its treatment. In the full trial, depressed participants are randomized to receive escitalopram, sertraline or venlafaxine-XR (open-label). They are assessed using standardized multiple clinical, cognitive-emotional behavioral, electroencephalographic and genetic measures at baseline and at eight weeks post-treatment. Overall, 2,016 depressed participants (18 to 65 years old) will enter the study, of whom a target of 10% will be recruited into the brain imaging sub-study (approximately 67 participants in each treatment arm) and 67 controls. The imaging sub-study is conducted at the University of Sydney and at Stanford University. Structural studies include high-resolution three-dimensional T1-weighted, diffusion tensor and T2/Proton Density scans. Functional studies include standardized functional magnetic resonance imaging (MRI) with three cognitive tasks (auditory oddball, a continuous performance task, and Go-NoGo) and two emotion tasks (unmasked conscious and masked non-conscious emotion processing tasks). After eight weeks of treatment, the functional MRI is repeated with the above tasks. We will establish the methods in the first 30 patients. Then we will identify predictors in the first half (n=102), test the findings in the second half, and then extend the analyses to the total sample. International Study to Predict Optimized Treatment--in Depression (iSPOT-D). ClinicalTrials.gov, NCT00693849.

Quantitative assessment on coronary computed tomography angiography (CCTA) image quality: comparisons between genders and different tube voltage settings.

PubMed

Chian, Teo Chee; Nassir, Norziana Mat; Ibrahim, Mohd Izuan; Yusof, Ahmad Khairuddin Md; Sabarudin, Akmal

2017-02-01

This study was carried out to quantify and compare the quantitative image quality of coronary computed tomography angiography (CCTA) between genders as well as between different tube voltages scan protocols. Fifty-five cases of CCTA were collected retrospectively and all images including reformatted axial images at systolic and diastolic phases as well as images with curved multi planar reformation (cMPR) were obtained. Quantitative image quality including signal intensity, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of right coronary artery (RCA), left anterior descending artery (LAD), left circumflex artery (LCx) and left main artery (LM) were quantified using Analyze 12.0 software. Six hundred and fifty-seven coronary arteries were evaluated. There were no significant differences in any quantitative image quality parameters between genders. 100 kilovoltage peak (kVp) scanning protocol produced images with significantly higher signal intensity compared to 120 kVp scanning protocol (P<0.001) in all coronary arteries in all types of images. Higher SNR was also observed in 100 kVp scan protocol in all coronary arteries except in LCx where 120 kVp showed better SNR than 100 kVp. There were no significant differences in image quality of CCTA between genders and different tube voltages. Lower tube voltage (100 kVp) scanning protocol is recommended in clinical practice to reduce the radiation dose to patient.

A retrospective comparison of smart prep and test bolus multi-detector CT pulmonary angiography protocols

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

Suckling, Tara; Smith, Tony; Reed, Warren

2013-06-15

Optimal arterial opacification is crucial in imaging the pulmonary arteries using computed tomography (CT). This poses the challenge of precisely timing data acquisition to coincide with the transit of the contrast bolus through the pulmonary vasculature. The aim of this quality assurance exercise was to investigate if a change in CT pulmonary angiography (CTPA) scanning protocol resulted in improved opacification of the pulmonary arteries. Comparison was made between the smart prep protocol (SPP) and the test bolus protocol (TBP) for opacification in the pulmonary trunk. A total of 160 CTPA examinations (80 using each protocol) performed between January 2010 andmore » February 2011 were assessed retrospectively. CT attenuation coefficients were measured in Hounsfield Units (HU) using regions of interest at the level of the pulmonary trunk. The average pixel value, standard deviation (SD), maximum, and minimum were recorded. For each of these variables a mean value was then calculated and compared for these two CTPA protocols. Minimum opacification of 200 HU was achieved in 98% of the TBP sample but only 90% of the SPP sample. The average CT attenuation over the pulmonary trunk for the SPP was 329 (SD = ±21) HU, whereas for the TBP it was 396 (SD = ±22) HU (P = 0.0017). The TBP also recorded higher maximum (P = 0.0024) and minimum (P = 0.0039) levels of opacification. This study has found that a TBP resulted in significantly better opacification of the pulmonary trunk than the SPP.« less

The performance of magnetic resonance imaging in the detection of triangular fibrocartilage complex injury: a meta-analysis.

PubMed

Wang, Z X; Chen, S L; Wang, Q Q; Liu, B; Zhu, J; Shen, J

2015-06-01

The aim of this study was to evaluate the accuracy of magnetic resonance imaging in the detection of triangular fibrocartilage complex injury through a meta-analysis. A comprehensive literature search was conducted before 1 April 2014. All studies comparing magnetic resonance imaging results with arthroscopy or open surgery findings were reviewed, and 25 studies that satisfied the eligibility criteria were included. Data were pooled to yield pooled sensitivity and specificity, which were respectively 0.83 and 0.82. In detection of central and peripheral tears, magnetic resonance imaging had respectively a pooled sensitivity of 0.90 and 0.88 and a pooled specificity of 0.97 and 0.97. Six high-quality studies using Ringler's recommended magnetic resonance imaging parameters were selected for analysis to determine whether optimal imaging protocols yielded better results. The pooled sensitivity and specificity of these six studies were 0.92 and 0.82, respectively. The overall accuracy of magnetic resonance imaging was acceptable. For peripheral tears, the pooled data showed a relatively high accuracy. Magnetic resonance imaging with appropriate parameters are an ideal method for diagnosing different types of triangular fibrocartilage complex tears. © The Author(s) 2015.

Compliance with AAPM Practice Guideline 1.a: CT Protocol Management and Review — from the perspective of a university hospital

PubMed Central

Bour, Robert K.; Pozniak, Myron; Ranallo, Frank N.

2015-01-01

The purpose of this paper is to describe our experience with the AAPM Medical Physics Practice Guideline 1.a: “CT Protocol Management and Review Practice Guideline”. Specifically, we will share how our institution's quality management system addresses the suggestions within the AAPM practice report. We feel this paper is needed as it was beyond the scope of the AAPM practice guideline to provide specific details on fulfilling individual guidelines. Our hope is that other institutions will be able to emulate some of our practices and that this article would encourage other types of centers (e.g., community hospitals) to share their methodology for approaching CT protocol optimization and quality control. Our institution had a functioning CT protocol optimization process, albeit informal, since we began using CT. Recently, we made our protocol development and validation process compliant with a number of the ISO 9001:2008 clauses and this required us to formalize the roles of the members of our CT protocol optimization team. We rely heavily on PACS‐based IT solutions for acquiring radiologist feedback on the performance of our CT protocols and the performance of our CT scanners in terms of dose (scanner output) and the function of the automatic tube current modulation. Specific details on our quality management system covering both quality control and ongoing optimization have been provided. The roles of each CT protocol team member have been defined, and the critical role that IT solutions provides for the management of files and the monitoring of CT protocols has been reviewed. In addition, the invaluable role management provides by being a champion for the project has been explained; lack of a project champion will mitigate the efforts of a CT protocol optimization team. Meeting the guidelines set forth in the AAPM practice guideline was not inherently difficult, but did, in our case, require the cooperation of radiologists, technologists, physicists, IT, administrative staff, and hospital management. Some of the IT solutions presented in this paper are novel and currently unique to our institution. PACS number: 87.57.Q PMID:26103176

Experience with Delay-Tolerant Networking from Orbit

NASA Technical Reports Server (NTRS)

Ivancic, W.; Eddy, W. M.; Stewart, D.; Wood, L.; Northam, J.; Jackson, C.

2010-01-01

We describe the first use from space of the Bundle Protocol for Delay-Tolerant Networking (DTN) and lessons learned from experiments made and experience gained with this protocol. The Disaster Monitoring Constellation (DMC), constructed by Surrey Satellite Technology Ltd (SSTL), is a multiple-satellite Earth-imaging low-Earth-orbit sensor network in which recorded image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store-and-forward of images with capture and later download gives each satellite the characteristics of a node in a disruption-tolerant network. Originally developed for the Interplanetary Internet, DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a bundle architecture and protocol. The DMC is technically advanced in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation s UK-DMC satellite. Earth images are downloaded from the satellites using a custom IP-based high-speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with the use of DTNRG bundle concepts onboard the UK-DMC satellite, by examining how Saratoga can be used as a DTN convergence layer to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. Our practical experience with the first successful use of the DTNRG Bundle Protocol in a space environment gives us insights into the design of the Bundle Protocol and enables us to identify issues that must be addressed before wider deployment of the Bundle Protocol. Published in 2010 by John Wiley & Sons, Ltd. KEY WORDS: Internet; UK-DMC; satellite; Delay-Tolerant Networking (DTN); Bundle Protocol

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

PubMed

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

2016-07-01

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

Carb-3 is the superior anti-CD15 monoclonal antibody for immunohistochemistry.

PubMed

Røge, Rasmus; Nielsen, Søren; Vyberg, Mogens

2014-07-01

Immunohistochemical detection of CD15 is important in the diagnosis of Hodgkin lymphoma and may play a role in the classification of renal cell tumors (RCTs). In the NordiQC external quality assessment scheme, 4 CD15 tests, each with 71 to 121 participating laboratories, showed that 24% to 50% of the stains were insufficient. This was mainly because of very low primary antibody (Ab) concentration and insufficient heat-induced epitope retrieval, whereas the Ab clone performance seemed of little importance. The purpose of this study was to evaluate the performance of the most commonly used CD15 Abs on the basis of vendor-recommended and in-house optimized protocols. Multitissue blocks with 199 specimens including various malignant lymphomas, RCTs, and normal tissues were stained with 3 different concentrated (conc) CD15 Ab clones Carb-3, MMA, and BY87 according to predetermined in-house optimized protocols on 2 automated immunostaining platforms. Carb-3 and MMA were also applied in ready-to-use (RTU) formats utilized according to vendor protocols. Extension and intensity of stains was determined using the H-score method. Clone Carb-3-conc gave with an in-house optimized protocol the highest H-scores in Hodgkin lymphoma, RCTs, and normal kidney tissue. Clones Carb-3-RTU and MMA-conc gave slightly lower scores, whereas clones MMA-RTU and BY87-conc gave the lowest scores and a large proportion of false-negative reactions. For all concentrated Abs, in-house optimized protocols resulted in increased sensitivity and improved overall staining results compared with vendor-recommended protocols. The importance of Ab selection and protocol optimization in immunohistochemical laboratories is emphasized.

MO-D-213-06: Quantitative Image Quality Metrics Are for Physicists, Not Radiologists: How to Communicate to Your Radiologists Using Their Language

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

Szczykutowicz, T; Rubert, N; Ranallo, F

Purpose: A framework for explaining differences in image quality to non-technical audiences in medial imaging is needed. Currently, this task is something that is learned “on the job.” The lack of a formal methodology for communicating optimal acquisition parameters into the clinic effectively mitigates many technological advances. As a community, medical physicists need to be held responsible for not only advancing image science, but also for ensuring its proper use in the clinic. This work outlines a framework that bridges the gap between the results from quantitative image quality metrics like detectability, MTF, and NPS and their effect on specificmore » anatomical structures present in diagnostic imaging tasks. Methods: Specific structures of clinical importance were identified for a body, an extremity, a chest, and a temporal bone protocol. Using these structures, quantitative metrics were used to identify the parameter space that should yield optimal image quality constrained within the confines of clinical logistics and dose considerations. The reading room workflow for presenting the proposed changes for imaging each of these structures is presented. The workflow consists of displaying images for physician review consisting of different combinations of acquisition parameters guided by quantitative metrics. Examples of using detectability index, MTF, NPS, noise and noise non-uniformity are provided. During review, the physician was forced to judge the image quality solely on those features they need for diagnosis, not on the overall “look” of the image. Results: We found that in many cases, use of this framework settled mis-agreements between physicians. Once forced to judge images on the ability to detect specific structures inter reader agreement was obtained. Conclusion: This framework will provide consulting, research/industrial, or in-house physicists with clinically relevant imaging tasks to guide reading room image review. This framework avoids use of the overall “look” or “feel” to dictate acquisition parameter selection. Equipment grants GE Healthcare.« less

Thoracic-abdominal imaging with a novel dual-layer spectral detector CT: intra-individual comparison of image quality and radiation dose with 128-row single-energy acquisition.

PubMed

Haneder, Stefan; Siedek, Florian; Doerner, Jonas; Pahn, Gregor; Grosse Hokamp, Nils; Maintz, David; Wybranski, Christian

2018-01-01

Background A novel, multi-energy, dual-layer spectral detector computed tomography (SDCT) is commercially available now with the vendor's claim that it yields the same or better quality of polychromatic, conventional CT images like modern single-energy CT scanners without any radiation dose penalty. Purpose To intra-individually compare the quality of conventional polychromatic CT images acquired with a dual-layer spectral detector (SDCT) and the latest generation 128-row single-energy-detector (CT128) from the same manufacturer. Material and Methods Fifty patients underwent portal-venous phase, thoracic-abdominal CT scans with the SDCT and prior CT128 imaging. The SDCT scanning protocol was adapted to yield a similar estimated dose length product (DLP) as the CT128. Patient dose optimization by automatic tube current modulation and CT image reconstruction with a state-of-the-art iterative algorithm were identical on both scanners. CT image contrast-to-noise ratio (CNR) was compared between the SDCT and CT128 in different anatomic structures. Image quality and noise were assessed independently by two readers with 5-point-Likert-scales. Volume CT dose index (CTDI vol ), and DLP were recorded and normalized to 68 cm acquisition length (DLP 68 ). Results The SDCT yielded higher mean CNR values of 30.0% ± 2.0% (26.4-32.5%) in all anatomic structures ( P < 0.001) and excellent scores for qualitative parameters surpassing the CT128 (all P < 0.0001) with substantial inter-rater agreement (κ ≥ 0.801). Despite adapted scan protocols the SDCT yielded lower values for CTDI vol (-10.1 ± 12.8%), DLP (-13.1 ± 13.9%), and DLP 68 (-15.3 ± 16.9%) than the CT128 (all P < 0.0001). Conclusion The SDCT scanner yielded better CT image quality compared to the CT128 and lower radiation dose parameters.

Electronic workflow for imaging in clinical research.

PubMed

Hedges, Rebecca A; Goodman, Danielle; Sachs, Peter B

2014-08-01

In the transition from paper to electronic workflow, the University of Colorado Health System's implementation of a new electronic health record system (EHR) forced all clinical groups to reevaluate their practices including the infrastructure surrounding clinical trials. Radiological imaging is an important piece of many clinical trials and requires a high level of consistency and standardization. With EHR implementation, paper orders were manually transcribed into the EHR, digitizing an inefficient work flow. A team of schedulers, radiologists, technologists, research personnel, and EHR analysts worked together to optimize the EHR to accommodate the needs of research imaging protocols. The transition to electronic workflow posed several problems: (1) there needed to be effective communication throughout the imaging process from scheduling to radiologist interpretation. (2) The exam ordering process needed to be automated to allow scheduling of specific research studies on specific equipment. (3) The billing process needed to be controlled to accommodate radiologists already supported by grants. (4) There needed to be functionality allowing exams to finalize automatically skipping the PACS and interpretation process. (5) There needed to be a way to alert radiologists that a specialized research interpretation was needed on a given exam. These issues were resolved through the optimization of the "visit type," allowing a high-level control of an exam at the time of scheduling. Additionally, we added columns and fields to work queues displaying grant identification numbers. The build solutions we implemented reduced the mistakes made and increased imaging quality and compliance.

OXSA: An open-source magnetic resonance spectroscopy analysis toolbox in MATLAB.

PubMed

Purvis, Lucian A B; Clarke, William T; Biasiolli, Luca; Valkovič, Ladislav; Robson, Matthew D; Rodgers, Christopher T

2017-01-01

In vivo magnetic resonance spectroscopy provides insight into metabolism in the human body. New acquisition protocols are often proposed to improve the quality or efficiency of data collection. Processing pipelines must also be developed to use these data optimally. Current fitting software is either targeted at general spectroscopy fitting, or for specific protocols. We therefore introduce the MATLAB-based OXford Spectroscopy Analysis (OXSA) toolbox to allow researchers to rapidly develop their own customised processing pipelines. The toolbox aims to simplify development by: being easy to install and use; seamlessly importing Siemens Digital Imaging and Communications in Medicine (DICOM) standard data; allowing visualisation of spectroscopy data; offering a robust fitting routine; flexibly specifying prior knowledge when fitting; and allowing batch processing of spectra. This article demonstrates how each of these criteria have been fulfilled, and gives technical details about the implementation in MATLAB. The code is freely available to download from https://github.com/oxsatoolbox/oxsa.

[Ballistic concepts and management of gunshot wounds at members].

PubMed

Fabeck, L; Hock, N; Goffin, J; Ngatchou, W

2017-01-01

Ballistic trauma is not the prerogative of battlefields and currently extends to civil environments. Any surgeon or emergency room can be faced with such trauma whose management requires an understanding of wound ballistics. The aim of this retrospective is reviewing the management of ballistic trauma within the C.H.U. Saint-Pierre hospital over a period of ten years. Data recorded included demographics data, lesions, clinical parameters, imaging, treatment and outcome. It appears that the wounds of the members have a low mortality rate but a significant rate of complications. Patients should be managed according to the ATLS protocol and according hemodynamic stability and location of the injury, benefit from imaging. Unstable patients will be operated in emergency, stable patients will be treated according to the extent of damage and the type of fracture either conservatively or by external fixator and intramedullary centromedullary. Debridement and antibiotics are recommended as a nerve exploration if there is a peripheral paralysis. The management of trauma in our sample appear not optimal in light of the literature especially in terms of setting the vascular point of debridement, antibiotic and nerve repair resulting in significant consequences. Two management protocols according to patients' hemodynamic status are offered.

Automated Slide Scanning and Segmentation in Fluorescently-labeled Tissues Using a Widefield High-content Analysis System.

PubMed

Poon, Candice C; Ebacher, Vincent; Liu, Katherine; Yong, Voon Wee; Kelly, John James Patrick

2018-05-03

Automated slide scanning and segmentation of fluorescently-labeled tissues is the most efficient way to analyze whole slides or large tissue sections. Unfortunately, many researchers spend large amounts of time and resources developing and optimizing workflows that are only relevant to their own experiments. In this article, we describe a protocol that can be used by those with access to a widefield high-content analysis system (WHCAS) to image any slide-mounted tissue, with options for customization within pre-built modules found in the associated software. Not originally intended for slide scanning, the steps detailed in this article make it possible to acquire slide scanning images in the WHCAS which can be imported into the associated software. In this example, the automated segmentation of brain tumor slides is demonstrated, but the automated segmentation of any fluorescently-labeled nuclear or cytoplasmic marker is possible. Furthermore, there are a variety of other quantitative software modules including assays for protein localization/translocation, cellular proliferation/viability/apoptosis, and angiogenesis that can be run. This technique will save researchers time and effort and create an automated protocol for slide analysis.

SU-F-I-16: Short Breast MRI with High-Resolution T2-Weighted and Dynamic Contrast Enhanced T1-Weighted Images

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

Ma, J; Son, J; Arun, B

Purpose: To develop and demonstrate a short breast (sb) MRI protocol that acquires both T2-weighted and dynamic contrast-enhanced T1-weighted images in approximately ten minutes. Methods: The sb-MRI protocol consists of two novel pulse sequences. The first is a flexible fast spin-echo triple-echo Dixon (FTED) sequence for high-resolution fat-suppressed T2-weighted imaging, and the second is a 3D fast dual-echo spoiled gradient sequence (FLEX) for volumetric fat-suppressed T1-weighted imaging before and post contrast agent injection. The flexible FTED sequence replaces each single readout during every echo-spacing period of FSE with three fast-switching bipolar readouts to produce three raw images in a singlemore » acquisition. These three raw images are then post-processed using a Dixon algorithm to generate separate water-only and fat-only images. The FLEX sequence acquires two echoes using dual-echo readout after each RF excitation and the corresponding images are post-processed using a similar Dixon algorithm to yield water-only and fat-only images. The sb-MRI protocol was implemented on a 3T MRI scanner and used for patients who had undergone concurrent clinical MRI for breast cancer screening. Results: With the same scan parameters (eg, spatial coverage, field of view, spatial and temporal resolution) as the clinical protocol, the total scan-time of the sb-MRI protocol (including the localizer, bilateral T2-weighted, and dynamic contrast-enhanced T1-weighted images) was 11 minutes. In comparison, the clinical breast MRI protocol took 43 minutes. Uniform fat suppression and high image quality were consistently achieved by sb-MRI. Conclusion: We demonstrated a sb-MRI protocol comprising both T2-weighted and dynamic contrast-enhanced T1-weighted images can be performed in approximately ten minutes. The spatial and temporal resolution of the images easily satisfies the current breast MRI accreditation guidelines by the American College of Radiology. The protocol has the potential of making breast MRI more widely accessible to and more tolerable by the patients. JMA is the inventor of United States patents that are owned by the University of Texas Board of Regents and currently licensed to GE Healthcare and Siemens Gmbh.« less

Analysis of power management and system latency in wireless sensor networks

NASA Astrophysics Data System (ADS)

Oswald, Matthew T.; Rohwer, Judd A.; Forman, Michael A.

2004-08-01

Successful power management in a wireless sensor network requires optimization of the protocols which affect energy-consumption on each node and the aggregate effects across the larger network. System optimization for a given deployment scenario requires an analysis and trade off of desired node and network features with their associated costs. The sleep protocol for an energy-efficient wireless sensor network for event detection, target classification, and target tracking developed at Sandia National Laboratories is presented. The dynamic source routing (DSR) algorithm is chosen to reduce network maintenance overhead, while providing a self-configuring and self-healing network architecture. A method for determining the optimal sleep time is developed and presented, providing reference data which spans several orders of magnitude. Message timing diagrams show, that a node in a five-node cluster, employing an optimal cyclic single-radio sleep protocol, consumes 3% more energy and incurs a 16-s increase latency than nodes employing the more complex dual-radio STEM protocol.

Continuous-variable quantum key distribution with a leakage from state preparation

NASA Astrophysics Data System (ADS)

Derkach, Ivan; Usenko, Vladyslav C.; Filip, Radim

2017-12-01

We address side-channel leakage in a trusted preparation station of continuous-variable quantum key distribution with coherent and squeezed states. We consider two different scenarios: multimode Gaussian modulation, directly accessible to an eavesdropper, or side-channel loss of the signal states prior to the modulation stage. We show the negative impact of excessive modulation on both the coherent- and squeezed-state protocols. The impact is more pronounced for squeezed-state protocols and may require optimization of squeezing in the case of noisy quantum channels. Further, we demonstrate that the coherent-state protocol is immune to side-channel signal state leakage prior to modulation, while the squeezed-state protocol is vulnerable to such attacks, becoming more sensitive to the noise in the channel. In the general case of noisy quantum channels the signal squeezing can be optimized to provide best performance of the protocol in the presence of side-channel leakage prior to modulation. Our results demonstrate that leakage from the trusted source in continuous-variable quantum key distribution should not be underestimated and squeezing optimization is needed to overcome coherent state protocols.

TH-E-209-03: Development of An In-House CT Dose Monitoring and Management System Based On Open-Source Software Resources -- Pearls and Pitfalls

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

Zhang, D.

Radiation dose monitoring solutions have opened up new opportunities for medical physicists to be more involved in modern clinical radiology practices. In particular, with the help of comprehensive radiation dose data, data-driven protocol management and informed case follow up are now feasible. Significant challenges remain however and the problems faced by medical physicists are highly heterogeneous. Imaging systems from multiple vendors and a wide range of vintages co-exist in the same department and employ data communication protocols that are not fully standardized or implemented making harmonization complex. Many different solutions for radiation dose monitoring have been implemented by imaging facilitiesmore » over the past few years. Such systems are based on commercial software, home-grown IT solutions, manual PACS data dumping, etc., and diverse pathways can be used to bring the data to impact clinical practice. The speakers will share their experiences with creating or tailoring radiation dose monitoring/management systems and procedures over the past few years, which vary significantly in design and scope. Topics to cover: (1) fluoroscopic dose monitoring and high radiation event handling from a large academic hospital; (2) dose monitoring and protocol optimization in pediatric radiology; and (3) development of a home-grown IT solution and dose data analysis framework. Learning Objectives: Describe the scope and range of radiation dose monitoring and protocol management in a modern radiology practice Review examples of data available from a variety of systems and how it managed and conveyed. Reflect on the role of the physicist in radiation dose awareness.« less

Imaging for understanding speech communication: Advances and challenges

NASA Astrophysics Data System (ADS)

Narayanan, Shrikanth

2005-04-01

Research in speech communication has relied on a variety of instrumentation methods to illuminate details of speech production and perception. One longstanding challenge has been the ability to examine real-time changes in the shaping of the vocal tract; a goal that has been furthered by imaging techniques such as ultrasound, movement tracking, and magnetic resonance imaging. The spatial and temporal resolution afforded by these techniques, however, has limited the scope of the investigations that could be carried out. In this talk, we focus on some recent advances in magnetic resonance imaging that allow us to perform near real-time investigations on the dynamics of vocal tract shaping during speech. Examples include Demolin et al. (2000) (4-5 images/second, ultra-fast turbo spin echo) and Mady et al. (2001,2002) (8 images/second, T1 fast gradient echo). A recent study by Narayanan et al. (2004) that used a spiral readout scheme to accelerate image acquisition has allowed for image reconstruction rates of 24 images/second. While these developments offer exciting prospects, a number of challenges lie ahead, including: (1) improving image acquisition protocols, hardware for enhancing signal-to-noise ratio, and optimizing spatial sampling; (2) acquiring quality synchronized audio; and (3) analyzing and modeling image data including cross-modality registration. [Work supported by NIH and NSF.

Network oriented radiological and medical archive

NASA Astrophysics Data System (ADS)

Ferraris, M.; Frixione, P.; Squarcia, S.

2001-10-01

In this paper the basic ideas of NORMA (Network Oriented Radiological and Medical Archive) are discussed. NORMA is an original project built by a team of physicists in collaboration with radiologists in order to select the best Treatment Planning in radiotherapy. It allows physicians and health physicists, working in different places, to discuss on interesting clinical cases visualizing the same diagnostic images, at the same time, and highlighting zones of interest (tumors and organs at risk). NORMA has a client/server architecture in order to be platform independent. Applying World Wide Web technologies, it can be easily used by people with no specific computer knowledge providing a verbose help to guide the user through the right steps of execution. The client side is an applet while the server side is a Java application. In order to optimize execution the project also includes a proprietary protocol, lying over TCP/IP suite, that organizes data exchanges and control messages. Diagnostic images are retrieved from a relational database or from a standard DICOM (Digital Images and COmmunications in Medicine) PACS through the DICOM-WWW gateway allowing connection of the usual Web browsers, used by the NORMA system, to DICOM applications via the HTTP protocol. Browser requests are sent to the gateway from the Web server through CGI (Common Gateway Interface). DICOM software translates the requests in DICOM messages and organizes the communication with the remote DICOM Application.

Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques

PubMed Central

Deshpande, Sudesh; Dhote, Deepak; Thakur, Kalpna; Pawar, Amol; Kumar, Rajesh; Kumar, Munish; Kulkarni, M. S.; Sharma, S. D.; Kannan, V.

2016-01-01

The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT) acquisition protocols of Varian's On-Board Imaging (OBI) system using optically stimulated luminescence dosimeter (OSLD) and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH]) of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8–3.2 mGy and 4.5–9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3–0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol. PMID:27651564

Ultrasound Imaging System Implementation and Ignition Protocol for the Microgravity Smoldering Combustion (MSC) Experiments

NASA Technical Reports Server (NTRS)

Walther, David C.; Anthenien, Ralph A.; Roslon, Mark; Fernandez-Pello, A. Carlos; Urban, David L.

1999-01-01

The Microgravity Smoldering Combustion (MSC) experiment is a study of the smolder characteristics of porous combustible materials in a microgravity environment. The objective of the study is to provide a better understanding of the controlling mechanisms of smolder, both in microgravity and normal earth gravity. Experiments have been conducted aboard the NASA Space Shuttle in the Get Away Special Canister (GAS-CAN), an apparatus requiring completely remote operation. Future GAS-CAN experiments will utilize an ultrasound imaging system (UIS) which has been incorporated into the MSC experimental apparatus. Thermocouples are currently used to measure temperature and reaction front velocities. A less intrusive method is desirable, however, as smolder is a very weak reaction and it has been found that heat transfer along the thermocouple is sufficient to affect the smolder reaction. It is expected that the UIS system will eventually replace the existing array of thermocouples as a non-intrusive technique without compromising data acquisition. The UIS measures line of sight permeability, providing information about the reaction front position and extent. Additionally, the ignition sequence of the MSC experiments has been optimized from previous experiments to provide longer periods of self-supported smolder. An ignition protocol of a fixed power to the igniter for a fixed time is now implemented. This, rather than a controlled temperature profile ignition protocol at the igniter surface, along with the UIS system, will allow for better study of the effect of gravity on a smolder reaction.

Optimization of Native and Formaldehyde iPOND Techniques for Use in Suspension Cells.

PubMed

Wiest, Nathaniel E; Tomkinson, Alan E

2017-01-01

The isolation of proteins on nascent DNA (iPOND) technique developed by the Cortez laboratory allows a previously unparalleled ability to examine proteins associated with replicating and newly synthesized DNA in mammalian cells. Both the original, formaldehyde-based iPOND technique and a more recent derivative, accelerated native iPOND (aniPOND), have mostly been performed in adherent cell lines. Here, we describe modifications to both protocols for use with suspension cell lines. These include cell culture, pulse, and chase conditions that optimize sample recovery in both protocols using suspension cells and several key improvements to the published aniPOND technique that reduce sample loss, increase signal to noise, and maximize sample recovery. Additionally, we directly and quantitatively compare the iPOND and aniPOND protocols to test the strengths and limitations of both. Finally, we present a detailed protocol to perform the optimized aniPOND protocol in suspension cell lines. © 2017 Elsevier Inc. All rights reserved.

Imaging intracellular protein dynamics by spinning disk confocal microscopy

PubMed Central

Stehbens, Samantha; Pemble, Hayley; Murrow, Lindsay; Wittmann, Torsten

2012-01-01

The palette of fluorescent proteins has grown exponentially over the last decade, and as a result live imaging of cells expressing fluorescently tagged proteins is becoming more and more main stream. Spinning disk confocal microscopy (SDC) is a high speed optical sectioning technique, and a method of choice to observe and analyze intracellular fluorescent protein dynamics at high spatial and temporal resolution. In an SDC system, a rapidly rotating pinhole disk generates thousands of points of light that scan the specimen simultaneously, which allows direct capture of the confocal image with low noise scientific grade cooled charged-coupled device (CCD) cameras, and can achieve frame rates of up 1000 frames per second. In this chapter we describe important components of a state-of-the-art spinning disk system optimized for live cell microscopy, and provide a rationale for specific design choices. We also give guidelines how other imaging techniques such as total internal reflection (TIRF) microscopy or spatially controlled photoactivation can be coupled with SDC imaging, and provide a short protocol on how to generate cell lines stably expressing fluorescently tagged proteins by lentivirus-mediated transduction. PMID:22264541

Model-based imaging of cardiac electrical function in human atria

NASA Astrophysics Data System (ADS)

Modre, Robert; Tilg, Bernhard; Fischer, Gerald; Hanser, Friedrich; Messnarz, Bernd; Schocke, Michael F. H.; Kremser, Christian; Hintringer, Florian; Roithinger, Franz

2003-05-01

Noninvasive imaging of electrical function in the human atria is attained by the combination of data from electrocardiographic (ECG) mapping and magnetic resonance imaging (MRI). An anatomical computer model of the individual patient is the basis for our computer-aided diagnosis of cardiac arrhythmias. Three patients suffering from Wolff-Parkinson-White syndrome, from paroxymal atrial fibrillation, and from atrial flutter underwent an electrophysiological study. After successful treatment of the cardiac arrhythmia with invasive catheter technique, pacing protocols with stimuli at several anatomical sites (coronary sinus, left and right pulmonary vein, posterior site of the right atrium, right atrial appendage) were performed. Reconstructed activation time (AT) maps were validated with catheter-based electroanatomical data, with invasively determined pacing sites, and with pacing at anatomical markers. The individual complex anatomical model of the atria of each patient in combination with a high-quality mesh optimization enables accurate AT imaging, resulting in a localization error for the estimated pacing sites within 1 cm. Our findings may have implications for imaging of atrial activity in patients with focal arrhythmias.

Reducing the Radiation Dose for CT Colonography: Effect of Low Tube Voltage and Iterative Reconstruction.

PubMed

Yamamura, Sadahiro; Oda, Seitaro; Imuta, Masanori; Utsunomiya, Daisuke; Yoshida, Morikatsu; Namimoto, Tomohiro; Yuki, Hideaki; Kidoh, Masafumi; Funama, Yoshinori; Baba, Hideo; Yamashita, Yasuyuki

2016-02-01

The purpose of this study was to assess the effect of a low-tube-voltage technique and iterative reconstruction (IR) on the radiation dose and image quality of computed tomography colonography (CTC). We studied 30 patients (14 women and 16 men; mean age, 64.5 ± 13.1 years; range, 39-90 years) with colorectal cancer referred for surgical treatment. All underwent CTC with fecal tagging under a standard 120-kVp protocol in the supine position and a 100-kVp protocol in the prone position. The 120-kVp images were reconstructed with filtered back projection (FBP). The 100-kVp images were postprocessed using FBP and a hybrid type of IR (adaptive iterative dose reduction 3D). The effective radiation dose (ED), image noise, and contrast-to-noise ratio (CNR) were compared among the three protocols. The visual image quality was scored on a four-point scale. The mean ED was significantly lower under the 100-kVp protocol than the 120-kVp protocol, resulting in a 27% radiation dose decrease (3.5 ± 2.0 vs 2.5 ± 1.5 mSv; P < .01). Image noise decreased by 48%, and the mean attenuation of tagged fluid increased from 452 to 558 HU on images acquired at 100 kVp with IR compared to that in the 120-kVp protocol; these differences were significant. The mean CNR was significantly higher under the 100 kVp with IR than the other two protocols. We found no significant differences in the visual scores for diagnostic utility between the 100 kVp with IR and the 120 kVp with FBP protocol (P = .10). Low-tube-voltage CTC reduced the radiation dose by approximately 27% while maintaining the image quality. Copyright © 2016 AUR. Published by Elsevier Inc. All rights reserved.

A secure cluster-based multipath routing protocol for WMSNs.

PubMed

Almalkawi, Islam T; Zapata, Manel Guerrero; Al-Karaki, Jamal N

2011-01-01

The new characteristics of Wireless Multimedia Sensor Network (WMSN) and its design issues brought by handling different traffic classes of multimedia content (video streams, audio, and still images) as well as scalar data over the network, make the proposed routing protocols for typical WSNs not directly applicable for WMSNs. Handling real-time multimedia data requires both energy efficiency and QoS assurance in order to ensure efficient utility of different capabilities of sensor resources and correct delivery of collected information. In this paper, we propose a Secure Cluster-based Multipath Routing protocol for WMSNs, SCMR, to satisfy the requirements of delivering different data types and support high data rate multimedia traffic. SCMR exploits the hierarchical structure of powerful cluster heads and the optimized multiple paths to support timeliness and reliable high data rate multimedia communication with minimum energy dissipation. Also, we present a light-weight distributed security mechanism of key management in order to secure the communication between sensor nodes and protect the network against different types of attacks. Performance evaluation from simulation results demonstrates a significant performance improvement comparing with existing protocols (which do not even provide any kind of security feature) in terms of average end-to-end delay, network throughput, packet delivery ratio, and energy consumption.

A Secure Cluster-Based Multipath Routing Protocol for WMSNs

PubMed Central

Almalkawi, Islam T.; Zapata, Manel Guerrero; Al-Karaki, Jamal N.

2011-01-01

The new characteristics of Wireless Multimedia Sensor Network (WMSN) and its design issues brought by handling different traffic classes of multimedia content (video streams, audio, and still images) as well as scalar data over the network, make the proposed routing protocols for typical WSNs not directly applicable for WMSNs. Handling real-time multimedia data requires both energy efficiency and QoS assurance in order to ensure efficient utility of different capabilities of sensor resources and correct delivery of collected information. In this paper, we propose a Secure Cluster-based Multipath Routing protocol for WMSNs, SCMR, to satisfy the requirements of delivering different data types and support high data rate multimedia traffic. SCMR exploits the hierarchical structure of powerful cluster heads and the optimized multiple paths to support timeliness and reliable high data rate multimedia communication with minimum energy dissipation. Also, we present a light-weight distributed security mechanism of key management in order to secure the communication between sensor nodes and protect the network against different types of attacks. Performance evaluation from simulation results demonstrates a significant performance improvement comparing with existing protocols (which do not even provide any kind of security feature) in terms of average end-to-end delay, network throughput, packet delivery ratio, and energy consumption. PMID:22163854

Optimizing spectral CT parameters for material classification tasks

NASA Astrophysics Data System (ADS)

Rigie, D. S.; La Rivière, P. J.

2016-06-01

In this work, we propose a framework for optimizing spectral CT imaging parameters and hardware design with regard to material classification tasks. Compared with conventional CT, many more parameters must be considered when designing spectral CT systems and protocols. These choices will impact material classification performance in a non-obvious, task-dependent way with direct implications for radiation dose reduction. In light of this, we adapt Hotelling Observer formalisms typically applied to signal detection tasks to the spectral CT, material-classification problem. The result is a rapidly computable metric that makes it possible to sweep out many system configurations, generating parameter optimization curves (POC’s) that can be used to select optimal settings. The proposed model avoids restrictive assumptions about the basis-material decomposition (e.g. linearity) and incorporates signal uncertainty with a stochastic object model. This technique is demonstrated on dual-kVp and photon-counting systems for two different, clinically motivated material classification tasks (kidney stone classification and plaque removal). We show that the POC’s predicted with the proposed analytic model agree well with those derived from computationally intensive numerical simulation studies.

Optimizing Spectral CT Parameters for Material Classification Tasks

PubMed Central

Rigie, D. S.; La Rivière, P. J.

2017-01-01

In this work, we propose a framework for optimizing spectral CT imaging parameters and hardware design with regard to material classification tasks. Compared with conventional CT, many more parameters must be considered when designing spectral CT systems and protocols. These choices will impact material classification performance in a non-obvious, task-dependent way with direct implications for radiation dose reduction. In light of this, we adapt Hotelling Observer formalisms typically applied to signal detection tasks to the spectral CT, material-classification problem. The result is a rapidly computable metric that makes it possible to sweep out many system configurations, generating parameter optimization curves (POC’s) that can be used to select optimal settings. The proposed model avoids restrictive assumptions about the basis-material decomposition (e.g. linearity) and incorporates signal uncertainty with a stochastic object model. This technique is demonstrated on dual-kVp and photon-counting systems for two different, clinically motivated material classification tasks (kidney stone classification and plaque removal). We show that the POC’s predicted with the proposed analytic model agree well with those derived from computationally intensive numerical simulation studies. PMID:27227430

TH-C-18A-12: Evaluation of the Impact of Body Size and Tube Output Limits in the Optimization of Fast Scanning with High-Pitch Dual Source CT

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

Ramirez Giraldo, J; Mileto, A.; Hurwitz, L.

2014-06-15

Purpose: To evaluate the impact of body size and tube power limits in the optimization of fast scanning with high-pitch dual source CT (DSCT). Methods: A previously validated MERCURY phantom, made of polyethylene, with circular cross-section of diameters 16, 23, 30 and 37cm, and connected through tapered sections, was scanned using a second generation DSCT system. The DSCT operates with two independently controlled x-ray tube generators offering up to 200 kW power reserve (100 kW per tube). The entire length of the phantom (42cm) was scanned with two protocols using: A)Standard single-source CT (SSCT) protocol with pitch of 0.8, andmore » B) DSCT protocol with high-pitch values ranging from 1.6 to 3.2 (0.2 steps). All scans used 120 kVp with 150 quality reference mAs using automatic exposure control. Scanner radiation output (CTDIvol) and effective mAs values were extracted retrospectively from DICOM files for each slice. Image noise was recorded. All variables were assessed relative to phantom diameter. Results: With standard-pitch SSCT, the scanner radiation output (and tube-current) were progressively adapted with increasing size, from 6 mGy (120 mAs) up to 15 mGy (270 mAs) from the thinnest (16cm) to the thickest diameter (37 cm), respectively. By comparison, using high-pitch (3.2), the scanner output was bounded at about 8 mGy (140 mAs), independent of phantom diameter. Although relative to standard-pitch, the high-pitch led to lower radiation output for the same scan, the image noise was higher, particularly for larger diameters. To match the radiation output adaptation of standard-pitch, a high-pitch mode of 1.6 was needed, with the advantage of scanning twice as fast. Conclusion: To maximize the benefits of fast scanning with high-pitch DSCT, the body size and tube power limits of the system need to be considered such that a good balance between speed of acquisition and image quality are warranted. JCRG is an employee of Siemens Medical Solutions USA Inc.« less

Feasibility of ASL spinal bone marrow perfusion imaging with optimized inversion time.

PubMed

Xing, Dong; Zha, Yunfei; Yan, Liyong; Wang, Kejun; Gong, Wei; Lin, Hui

2015-11-01

To assess the correlation between flow-sensitive alternating inversion recovery (FAIR) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the measurement of spinal bone marrow (SBM) perfusion; in addition, to assess for an optimized inversion time (TI) as well as the reproducibility of SBM FAIR perfusion. The optimized TI of a FAIR SBM perfusion experiment was carried out on 14 volunteers; two adjacent vertebral bodies were selected from each volunteer to measure the change of signal intensity (ΔM) and the signal-to-noise ratio (SNR) of FAIR perfusion MRI with five different TIs. Then, reproducibility of FAIR data from 10 volunteers was assessed by the reposition SBM FAIR experiments. Finally, FAIR and DCE-MRI were performed on 27 subjects. The correlation between the blood flow on FAIR (BFASL ) and perfusion-related parameters on DCE-MRI was evaluated. The maximum value of ΔM and SNR were 36.39 ± 12.53 and 2.38 ± 0.97, respectively; both were obtained when TI was near 1200 msec. There were no significant difference between the two successive measurements of SBM BFASL perfusion (P = 0.879), and the within-subject coefficients of variation (wCV) of the measurements was 3.28%. The BFASL showed a close correlation with K(trans) (P < 0.001) and Kep (P = 0.004), and no correlation with Ve (P = 0.082) was found. 1200 msec was the optimal TI for the SBM ASL perfusion image, which led to the maximum ΔM and a good quality perfusion image. The SBM FAIR perfusion scan protocol has good reproducibility, and as blood flow measurement on FAIR is reliable and closely related with the parameters on DCE-MRI, FAIR is feasible for measuring SBM blood flow. © 2015 Wiley Periodicals, Inc.

Quantitative assessment on coronary computed tomography angiography (CCTA) image quality: comparisons between genders and different tube voltage settings

PubMed Central

Chian, Teo Chee; Nassir, Norziana Mat; Ibrahim, Mohd Izuan; Yusof, Ahmad Khairuddin Md

2017-01-01

Background This study was carried out to quantify and compare the quantitative image quality of coronary computed tomography angiography (CCTA) between genders as well as between different tube voltages scan protocols. Methods Fifty-five cases of CCTA were collected retrospectively and all images including reformatted axial images at systolic and diastolic phases as well as images with curved multi planar reformation (cMPR) were obtained. Quantitative image quality including signal intensity, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of right coronary artery (RCA), left anterior descending artery (LAD), left circumflex artery (LCx) and left main artery (LM) were quantified using Analyze 12.0 software. Results Six hundred and fifty-seven coronary arteries were evaluated. There were no significant differences in any quantitative image quality parameters between genders. 100 kilovoltage peak (kVp) scanning protocol produced images with significantly higher signal intensity compared to 120 kVp scanning protocol (P<0.001) in all coronary arteries in all types of images. Higher SNR was also observed in 100 kVp scan protocol in all coronary arteries except in LCx where 120 kVp showed better SNR than 100 kVp. Conclusions There were no significant differences in image quality of CCTA between genders and different tube voltages. Lower tube voltage (100 kVp) scanning protocol is recommended in clinical practice to reduce the radiation dose to patient. PMID:28275559

Implementation of a 5-Minute Magnetic Resonance Imaging Screening Protocol for Prostate Cancer in Men With Elevated Prostate-Specific Antigen Before Biopsy.

PubMed

Weiss, Jakob; Martirosian, Petros; Notohamiprodjo, Mike; Kaufmann, Sascha; Othman, Ahmed E; Grosse, Ulrich; Nikolaou, Konstantin; Gatidis, Sergios

2018-03-01

The aims of this study were to establish a 5-minute magnetic resonance (MR) screening protocol for prostate cancer in men before biopsy and to evaluate effects on Prostate Imaging Reporting and Data System (PI-RADS) V2 scoring in comparison to a conventional, fully diagnostic multiparametric MR imaging (mpMRI) approach. Fifty-two patients with elevated prostate-specific antigen levels and without prior biopsy were prospectively included in this institutional review board-approved study. In all patients, an mpMRI protocol according to the PI-RADS recommendations was acquired on a 3 T MRI system. In addition, an accelerated diffusion-weighted imaging sequence was acquired using simultaneous multislice technique (DW-EPISMS). Two readers independently evaluated the images for the presence/absence of prostate cancer according to the PI-RADS criteria and for additional findings. In a first reading session, only the screening protocol consisting of axial T2-weighted and DW-EPISMS images was made available. In a subsequent reading session, the mpMRI protocol was assessed blinded to the results of the first reading, serving as reference standard. Both readers successfully established a final diagnosis according to the PI-RADS criteria in the screening and mpMRI protocol. Mean lesion size was 1.2 cm in the screening and 1.4 cm in the mpMRI protocol (P = 0.4) with 35% (18/52) of PI-RADS IV/V lesions. Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100% for both readers with no significant differences in comparison to the mpMRI standard (P = 1.0). In 3 patients, suspicious lymph nodes were reported as additional finding, which were equally detectable in the screening and mpMRI protocol. A 5-minute MR screening protocol for prostate cancer in men with elevated prostate-specific antigen levels before biopsy is applicable for clinical routine with similar diagnostic performance as the full diagnostic mpMRI approach.

Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies.

PubMed

Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John; Bonomo, Lorenzo

2015-09-01

The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging.

Visual grading characteristics and ordinal regression analysis during optimisation of CT head examinations.

PubMed

Zarb, Francis; McEntee, Mark F; Rainford, Louise

2015-06-01

To evaluate visual grading characteristics (VGC) and ordinal regression analysis during head CT optimisation as a potential alternative to visual grading assessment (VGA), traditionally employed to score anatomical visualisation. Patient images (n = 66) were obtained using current and optimised imaging protocols from two CT suites: a 16-slice scanner at the national Maltese centre for trauma and a 64-slice scanner in a private centre. Local resident radiologists (n = 6) performed VGA followed by VGC and ordinal regression analysis. VGC alone indicated that optimised protocols had similar image quality as current protocols. Ordinal logistic regression analysis provided an in-depth evaluation, criterion by criterion allowing the selective implementation of the protocols. The local radiology review panel supported the implementation of optimised protocols for brain CT examinations (including trauma) in one centre, achieving radiation dose reductions ranging from 24 % to 36 %. In the second centre a 29 % reduction in radiation dose was achieved for follow-up cases. The combined use of VGC and ordinal logistic regression analysis led to clinical decisions being taken on the implementation of the optimised protocols. This improved method of image quality analysis provided the evidence to support imaging protocol optimisation, resulting in significant radiation dose savings. • There is need for scientifically based image quality evaluation during CT optimisation. • VGC and ordinal regression analysis in combination led to better informed clinical decisions. • VGC and ordinal regression analysis led to dose reductions without compromising diagnostic efficacy.

Clock Scan Protocol for Image Analysis: ImageJ Plugins.

PubMed

Dobretsov, Maxim; Petkau, Georg; Hayar, Abdallah; Petkau, Eugen

2017-06-19

The clock scan protocol for image analysis is an efficient tool to quantify the average pixel intensity within, at the border, and outside (background) a closed or segmented convex-shaped region of interest, leading to the generation of an averaged integral radial pixel-intensity profile. This protocol was originally developed in 2006, as a visual basic 6 script, but as such, it had limited distribution. To address this problem and to join similar recent efforts by others, we converted the original clock scan protocol code into two Java-based plugins compatible with NIH-sponsored and freely available image analysis programs like ImageJ or Fiji ImageJ. Furthermore, these plugins have several new functions, further expanding the range of capabilities of the original protocol, such as analysis of multiple regions of interest and image stacks. The latter feature of the program is especially useful in applications in which it is important to determine changes related to time and location. Thus, the clock scan analysis of stacks of biological images may potentially be applied to spreading of Na + or Ca ++ within a single cell, as well as to the analysis of spreading activity (e.g., Ca ++ waves) in populations of synaptically-connected or gap junction-coupled cells. Here, we describe these new clock scan plugins and show some examples of their applications in image analysis.

J-Plus Web Portal

NASA Astrophysics Data System (ADS)

Civera Lorenzo, Tamara

2017-10-01

Brief presentation about the J-PLUS EDR data access web portal (http://archive.cefca.es/catalogues/jplus-edr) where the different services available to retrieve images and catalogues data have been presented.J-PLUS Early Data Release (EDR) archive includes two types of data: images and dual and single catalogue data which include parameters measured from images. J-PLUS web portal offers catalogue data and images through several different online data access tools or services each suited to a particular need. The different services offered are: Coverage map Sky navigator Object visualization Image search Cone search Object list search Virtual observatory services: Simple Cone Search Simple Image Access Protocol Simple Spectral Access Protocol Table Access Protocol

Computed tomographic venography for varicose veins of the lower extremities: prospective comparison of 80-kVp and conventional 120-kVp protocols.

PubMed

Cho, Eun-Suk; Kim, Joo Hee; Kim, Sungjun; Yu, Jeong-Sik; Chung, Jae-Joon; Yoon, Choon-Sik; Lee, Hyeon-Kyeong; Lee, Kyung Hee

2012-01-01

To prospectively investigate the feasibility of an 80-kilovolt (peak) (kVp) protocol in computed tomographic venography for varicose veins of the lower extremities by comparison with conventional 120-kVp protocol. Attenuation values and signal-to-noise ratio of iodine contrast medium (CM) were determined in a water phantom for 2 tube voltages (80 kVp and 120 kVp). Among 100 patients, 50 patients were scanned with 120 kVp and 150 effective milliampere second (mAs(eff)), and the other 50 patients were scanned with 80 kVp and 390 mAs(eff) after the administration of 1.7-mL/kg CM (370 mg of iodine per milliliter). The 2 groups were compared for venous attenuation, contrast-to-noise ratio, and subjective degree of venous enhancement, image noise, and overall diagnostic image quality. In the phantom, the attenuation value and signal-to-noise ratio value for iodine CM at 80 kVp were 63.8% and 33.0% higher, respectively, than those obtained at 120 kVp. The mean attenuation of the measured veins of the lower extremities was 148.3 Hounsfield units (HU) for the 80-kVp protocol and 94.8 HU for the 120-kVp protocol. Contrast-to-noise ratio was also significantly higher with the 80-kVp protocol. The overall diagnostic image quality of the 3-dimensional volume-rendered images was good with both protocols. The subjective score for venous enhancement was higher at the 80-kVp protocol. The mean volume computed tomography dose index of the 80-kVp (5.6 mGy) protocol was 23.3% lower than that of the 120-kVp (7.3 mGy) protocol. The use of the 80-kVp protocol improved overall venous attenuation, especially in perforating vein, and provided similarly high diagnostic image quality with a lower radiation dose when compared to the conventional 120-kVp protocol.

SU-E-J-06: Additional Imaging Guidance Dose to Patient Organs Resulting From X-Ray Tubes Used in CyberKnife Image Guidance System

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

Sullivan, A; Ding, G

Purpose: The use of image-guided radiation therapy (IGRT) has become increasingly common, but the additional radiation exposure resulting from repeated image guidance procedures raises concerns. Although there are many studies reporting imaging dose from different image guidance devices, imaging dose for the CyberKnife Robotic Radiosurgery System is not available. This study provides estimated organ doses resulting from image guidance procedures on the CyberKnife system. Methods: Commercially available Monte Carlo software, PCXMC, was used to calculate average organ doses resulting from x-ray tubes used in the CyberKnife system. There are seven imaging protocols with kVp ranging from 60 – 120 kVmore » and 15 mAs for treatment sites in the Cranium, Head and Neck, Thorax, and Abdomen. The output of each image protocol was measured at treatment isocenter. For each site and protocol, Adult body sizes ranging from anorexic to extremely obese were simulated since organ dose depends on patient size. Doses for all organs within the imaging field-of-view of each site were calculated for a single image acquisition from both of the orthogonal x-ray tubes. Results: Average organ doses were <1.0 mGy for every treatment site and imaging protocol. For a given organ, dose increases as kV increases or body size decreases. Higher doses are typically reported for skeletal components, such as the skull, ribs, or clavicles, than for softtissue organs. Typical organ doses due to a single exposure are estimated as 0.23 mGy to the brain, 0.29 mGy to the heart, 0.08 mGy to the kidneys, etc., depending on the imaging protocol and site. Conclusion: The organ doses vary with treatment site, imaging protocol and patient size. Although the organ dose from a single image acquisition resulting from two orthogonal beams is generally insignificant, the sum of repeated image acquisitions (>100) could reach 10–20 cGy for a typical treatment fraction.« less

CT dose minimization using personalized protocol optimization and aggressive bowtie

NASA Astrophysics Data System (ADS)

Wang, Hui; Yin, Zhye; Jin, Yannan; Wu, Mingye; Yao, Yangyang; Tao, Kun; Kalra, Mannudeep K.; De Man, Bruno

2016-03-01

In this study, we propose to use patient-specific x-ray fluence control to reduce the radiation dose to sensitive organs while still achieving the desired image quality (IQ) in the region of interest (ROI). The mA modulation profile is optimized view by view, based on the sensitive organs and the ROI, which are obtained from an ultra-low-dose volumetric CT scout scan [1]. We use a clinical chest CT scan to demonstrate the feasibility of the proposed concept: the breast region is selected as the sensitive organ region while the cardiac region is selected as IQ ROI. Two groups of simulations are performed based on the clinical CT dataset: (1) a constant mA scan adjusted based on the patient attenuation (120 kVp, 300 mA), which serves as baseline; (2) an optimized scan with aggressive bowtie and ROI centering combined with patient-specific mA modulation. The results shows that the combination of the aggressive bowtie and the optimized mA modulation can result in 40% dose reduction in the breast region, while the IQ in the cardiac region is maintained. More generally, this paper demonstrates the general concept of using a 3D scout scan for optimal scan planning.

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

PubMed

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

2017-07-01

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

Fast macromolecular proton fraction mapping of the human liver in vivo for quantitative assessment of hepatic fibrosis

PubMed Central

Yarnykh, Vasily L.; Tartaglione, Erica V.; Ioannou, George N.

2015-01-01

Macromolecular proton fraction (MPF) is a quantitative MRI parameter determining the magnetization transfer (MT) effect in tissues and defined as a relative amount of immobile macromolecular protons involved into magnetization exchange with mobile water protons. MPF has a potential for quantitative assessment of fibrous tissue due to intrinsically high MPF specific for collagen. The goal of this study was to investigate a relationship between histologically determined fibrosis stage and MPF in the liver parenchyma measured using a recently developed fast single-point clinically-targeted MPF mapping method. Optimal saturation parameters for single-point liver MPF measurements were determined from the analysis of liver Z-spectra in vivo based on the error propagation model. Sixteen patients with chronic hepatitis C viral infection underwent 3T MRI using an optimized liver MPF mapping protocol. Fourteen patients had prior liver biopsy with histologically staged fibrosis (METAVIR scores F0-F3), and two patients had clinically diagnosed cirrhosis (score F4 was assigned). The protocol included four breath-hold three-dimensional scans with 2×3×6 mm3 resolution and 10 transverse sections: 1) dynamic acquisition of MT-weighted and reference images; 2) dynamic acquisition of three images for variable flip angle T1 mapping; 3) dual-echo B0 map; and 4) actual flip-angle imaging B1 map. Average liver MPF was determined as the mode of MPF histograms. MPF was significantly increased in patients with clinically significant fibrosis (scores F2-F4, n=6) compared to patients with no or mild fibrosis (scores F0-F1, n=10): 6.49±0.36% vs. 5.94±0.26%, P<0.01 (Mann-Whitney test). MPF and fibrosis score were strongly positively correlated with the Spearman's rank correlation coefficient 0.80 (P<0.001). This study demonstrates the feasibility of fast MPF mapping of the human liver in vivo and confirms the hypothesis that MPF is increased in hepatic fibrosis and associated with fibrosis stage. MPF may be useful as a non-invasive imaging biomarker of hepatic fibrosis. PMID:26503401

High performance MRI simulations of motion on multi-GPU systems

PubMed Central

2014-01-01

Background MRI physics simulators have been developed in the past for optimizing imaging protocols and for training purposes. However, these simulators have only addressed motion within a limited scope. The purpose of this study was the incorporation of realistic motion, such as cardiac motion, respiratory motion and flow, within MRI simulations in a high performance multi-GPU environment. Methods Three different motion models were introduced in the Magnetic Resonance Imaging SIMULator (MRISIMUL) of this study: cardiac motion, respiratory motion and flow. Simulation of a simple Gradient Echo pulse sequence and a CINE pulse sequence on the corresponding anatomical model was performed. Myocardial tagging was also investigated. In pulse sequence design, software crushers were introduced to accommodate the long execution times in order to avoid spurious echoes formation. The displacement of the anatomical model isochromats was calculated within the Graphics Processing Unit (GPU) kernel for every timestep of the pulse sequence. Experiments that would allow simulation of custom anatomical and motion models were also performed. Last, simulations of motion with MRISIMUL on single-node and multi-node multi-GPU systems were examined. Results Gradient Echo and CINE images of the three motion models were produced and motion-related artifacts were demonstrated. The temporal evolution of the contractility of the heart was presented through the application of myocardial tagging. Better simulation performance and image quality were presented through the introduction of software crushers without the need to further increase the computational load and GPU resources. Last, MRISIMUL demonstrated an almost linear scalable performance with the increasing number of available GPU cards, in both single-node and multi-node multi-GPU computer systems. Conclusions MRISIMUL is the first MR physics simulator to have implemented motion with a 3D large computational load on a single computer multi-GPU configuration. The incorporation of realistic motion models, such as cardiac motion, respiratory motion and flow may benefit the design and optimization of existing or new MR pulse sequences, protocols and algorithms, which examine motion related MR applications. PMID:24996972

MO-B-BRB-02: Maintain the Quality of Treatment Planning for Time-Constraint Cases

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

Chang, J.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

Image processing tools dedicated to quantification in 3D fluorescence microscopy

NASA Astrophysics Data System (ADS)

Dieterlen, A.; De Meyer, A.; Colicchio, B.; Le Calvez, S.; Haeberlé, O.; Jacquey, S.

2006-05-01

3-D optical fluorescent microscopy now becomes an efficient tool for the volume investigation of living biological samples. Developments in instrumentation have permitted to beat off the conventional Abbe limit. In any case the recorded image can be described by the convolution equation between the original object and the Point Spread Function (PSF) of the acquisition system. Due to the finite resolution of the instrument, the original object is recorded with distortions and blurring, and contaminated by noise. This induces that relevant biological information cannot be extracted directly from raw data stacks. If the goal is 3-D quantitative analysis, then to assess optimal performance of the instrument and to ensure the data acquisition reproducibility, the system characterization is mandatory. The PSF represents the properties of the image acquisition system; we have proposed the use of statistical tools and Zernike moments to describe a 3-D PSF system and to quantify the variation of the PSF. This first step toward standardization is helpful to define an acquisition protocol optimizing exploitation of the microscope depending on the studied biological sample. Before the extraction of geometrical information and/or intensities quantification, the data restoration is mandatory. Reduction of out-of-focus light is carried out computationally by deconvolution process. But other phenomena occur during acquisition, like fluorescence photo degradation named "bleaching", inducing an alteration of information needed for restoration. Therefore, we have developed a protocol to pre-process data before the application of deconvolution algorithms. A large number of deconvolution methods have been described and are now available in commercial package. One major difficulty to use this software is the introduction by the user of the "best" regularization parameters. We have pointed out that automating the choice of the regularization level; also greatly improves the reliability of the measurements although it facilitates the use. Furthermore, to increase the quality and the repeatability of quantitative measurements a pre-filtering of images improves the stability of deconvolution process. In the same way, the PSF prefiltering stabilizes the deconvolution process. We have shown that Zemike polynomials can be used to reconstruct experimental PSF, preserving system characteristics and removing the noise contained in the PSF.

Three-input majority function as the unique optimal function for the bias amplification using nonlocal boxes

NASA Astrophysics Data System (ADS)

Mori, Ryuhei

2016-11-01

Brassard et al. [Phys. Rev. Lett. 96, 250401 (2006), 10.1103/PhysRevLett.96.250401] showed that shared nonlocal boxes with a CHSH (Clauser, Horne, Shimony, and Holt) probability greater than 3/+√{6 } 6 yield trivial communication complexity. There still exists a gap with the maximum CHSH probability 2/+√{2 } 4 achievable by quantum mechanics. It is an interesting open question to determine the exact threshold for the trivial communication complexity. Brassard et al.'s idea is based on recursive bias amplification by the three-input majority function. It was not obvious if another choice of function exhibits stronger bias amplification. We show that the three-input majority function is the unique optimal function, so that one cannot improve the threshold 3/+√{6 } 6 by Brassard et al.'s bias amplification. In this work, protocols for computing the function used for the bias amplification are restricted to be nonadaptive protocols or a particular adaptive protocol inspired by Pawłowski et al.'s protocol for information causality [Nature (London) 461, 1101 (2009), 10.1038/nature08400]. We first show an adaptive protocol inspired by Pawłowski et al.'s protocol, and then show that the adaptive protocol improves upon nonadaptive protocols. Finally, we show that the three-input majority function is the unique optimal function for the bias amplification if we apply the adaptive protocol to each step of the bias amplification.

Use of the Delay-Tolerant Networking Bundle Protocol from Space

NASA Technical Reports Server (NTRS)

Wood, Lloyd; Ivancic, William D.; Eddy, Wesley M.; Stewart, Dave; Northam, James; Jackson, Chris; daSilvaCuriel, Alex

2009-01-01

The Disaster Monitoring Constellation (DMC), constructed by Survey Satellite Technology Ltd (SSTL), is a multisatellite Earth-imaging low-Earth-orbit sensor network where captured image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store-and-forward of images with capture and later download gives each satellite the characteristics of a node in a Delay/Disruption Tolerant Network (DTN). Originally developed for the Interplanetary Internet, DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a bundle architecture and protocol. The DMC is currently unique in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation's UK-DMC satellite. Earth images are downloaded from the satellites using a custom IPbased high-speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with use of DTNRG bundle concepts onboard the UKDMC satellite, by examining how Saratoga can be used as a DTN convergence layer to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. This is the first successful use of the DTNRG Bundle Protocol in a space environment. We use our practical experience to examine the strengths and weaknesses of the Bundle Protocol for DTN use, paying attention to fragmentation, custody transfer, and reliability issues.

Ultrafast Brain MRI: Clinical Deployment and Comparison to Conventional Brain MRI at 3T.

PubMed

Prakkamakul, Supada; Witzel, Thomas; Huang, Susie; Boulter, Daniel; Borja, Maria J; Schaefer, Pamela; Rosen, Bruce; Heberlein, Keith; Ratai, Eva; Gonzalez, Gilberto; Rapalino, Otto

2016-09-01

To compare an ultrafast brain magnetic resonance imaging (MRI) protocol to the conventional protocol in motion-prone inpatient clinical settings. This retrospective study was HIPAA compliant and approved by the Institutional Review Board with waived inform consent. Fifty-nine inpatients (30 males, 29 females; mean age 55.1, range 23-93 years)who underwent 3-Tesla brain MRI using ultrafast and conventional protocols, both including five sequences, were included in the study. The total scan time for five ultrafast sequences was 4 minutes 59 seconds. The ideal conventional acquisition time was 10 minutes 32 seconds but the actual acquisition took 15-20 minutes. The average scan times for ultrafast localizers, T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR), diffusion-weighted, T2*-weighted sequences were 14, 41, 62, 96, 80, 6 seconds, respectively. Two blinded neuroradiologists independently assessed three aspects: (1) image quality, (2) gray-white matter (GM-WM) differentiation, and (3) diagnostic concordance for the detection of six clinically relevant imaging findings. Wilcoxon signed-rank test was used to compare image quality and GM-WM scores. Interobserver reproducibility was calculated. The ultrafast T1-weighted sequence demonstrated significantly better image quality (P = .005) and GM-WM differentiation (P < .001) compared to the conventional sequence. There was high agreement (>85%) between both protocols for the detection of mass-like lesion, hemorrhage, diffusion restriction, WM FLAIR hyperintensities, subarachnoid FLAIR hyperintensities, and hydrocephalus. The ultrafast protocol achieved at least comparable image quality and high diagnostic concordance compared to the conventional protocol. This fast protocol can be a viable option to replace the conventional protocol in motion-prone inpatient clinical settings. Copyright © 2016 by the American Society of Neuroimaging.

Distributed Cooperative Optimal Control for Multiagent Systems on Directed Graphs: An Inverse Optimal Approach.

PubMed

Zhang, Huaguang; Feng, Tao; Yang, Guang-Hong; Liang, Hongjing

2015-07-01

In this paper, the inverse optimal approach is employed to design distributed consensus protocols that guarantee consensus and global optimality with respect to some quadratic performance indexes for identical linear systems on a directed graph. The inverse optimal theory is developed by introducing the notion of partial stability. As a result, the necessary and sufficient conditions for inverse optimality are proposed. By means of the developed inverse optimal theory, the necessary and sufficient conditions are established for globally optimal cooperative control problems on directed graphs. Basic optimal cooperative design procedures are given based on asymptotic properties of the resulting optimal distributed consensus protocols, and the multiagent systems can reach desired consensus performance (convergence rate and damping rate) asymptotically. Finally, two examples are given to illustrate the effectiveness of the proposed methods.

Improving best-phase image quality in cardiac CT by motion correction with MAM optimization

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

Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl

2013-03-15

Purpose: Research in image reconstruction for cardiac CT aims at using motion correction algorithms to improve the image quality of the coronary arteries. The key to those algorithms is motion estimation, which is currently based on 3-D/3-D registration to align the structures of interest in images acquired in multiple heart phases. The need for an extended scan data range covering several heart phases is critical in terms of radiation dose to the patient and limits the clinical potential of the method. Furthermore, literature reports only slight quality improvements of the motion corrected images when compared to the most quiet phasemore » (best-phase) that was actually used for motion estimation. In this paper a motion estimation algorithm is proposed which does not require an extended scan range but works with a short scan data interval, and which markedly improves the best-phase image quality. Methods: Motion estimation is based on the definition of motion artifact metrics (MAM) to quantify motion artifacts in a 3-D reconstructed image volume. The authors use two different MAMs, entropy, and positivity. By adjusting the motion field parameters, the MAM of the resulting motion-compensated reconstruction is optimized using a gradient descent procedure. In this way motion artifacts are minimized. For a fast and practical implementation, only analytical methods are used for motion estimation and compensation. Both the MAM-optimization and a 3-D/3-D registration-based motion estimation algorithm were investigated by means of a computer-simulated vessel with a cardiac motion profile. Image quality was evaluated using normalized cross-correlation (NCC) with the ground truth template and root-mean-square deviation (RMSD). Four coronary CT angiography patient cases were reconstructed to evaluate the clinical performance of the proposed method. Results: For the MAM-approach, the best-phase image quality could be improved for all investigated heart phases, with a maximum improvement of the NCC value by 100% and of the RMSD value by 81%. The corresponding maximum improvements for the registration-based approach were 20% and 40%. In phases with very rapid motion the registration-based algorithm obtained better image quality, while the image quality of the MAM algorithm was superior in phases with less motion. The image quality improvement of the MAM optimization was visually confirmed for the different clinical cases. Conclusions: The proposed method allows a software-based best-phase image quality improvement in coronary CT angiography. A short scan data interval at the target heart phase is sufficient, no additional scan data in other cardiac phases are required. The algorithm is therefore directly applicable to any standard cardiac CT acquisition protocol.« less

High-Resolution 3T MR Imaging of the Triangular Fibrocartilage Complex

PubMed Central

von Borstel, Donald; Wang, Michael; Small, Kirstin; Nozaki, Taiki; Yoshioka, Hiroshi

2017-01-01

This study is intended as a review of 3Tesla (T) magnetic resonance (MR) imaging of the triangular fibrocartilage complex (TFCC). The recent advances in MR imaging, which includes high field strength magnets, multi-channel coils, and isotropic 3-dimensional (3D) sequences have enabled the visualization of precise TFCC anatomy with high spatial and contrast resolution. In addition to the routine wrist protocol, there are specific techniques used to optimize 3T imaging of the wrist; including driven equilibrium sequence (DRIVE), parallel imaging, and 3D imaging. The coil choice for 3T imaging of the wrist depends on a number of variables, and the proper coil design selection is critical for high-resolution wrist imaging with high signal and contrast-to-noise ratio. The TFCC is a complex structure and is composed of the articular disc (disc proper), the triangular ligament, the dorsal and volar radioulnar ligaments, the meniscus homologue, the ulnar collateral ligament (UCL), the extensor carpi ulnaris (ECU) tendon sheath, and the ulnolunate and ulnotriquetral ligaments. The Palmer classification categorizes TFCC lesions as traumatic (type 1) or degenerative (type 2). In this review article, we present clinical high-resolution MR images of normal TFCC anatomy and TFCC injuries with this classification system. PMID:27535592

High-Resolution 3T MR Imaging of the Triangular Fibrocartilage Complex.

PubMed

von Borstel, Donald; Wang, Michael; Small, Kirstin; Nozaki, Taiki; Yoshioka, Hiroshi

2017-01-10

This study is intended as a review of 3Tesla (T) magnetic resonance (MR) imaging of the triangular fibrocartilage complex (TFCC). The recent advances in MR imaging, which includes high field strength magnets, multi-channel coils, and isotropic 3-dimensional (3D) sequences have enabled the visualization of precise TFCC anatomy with high spatial and contrast resolution. In addition to the routine wrist protocol, there are specific techniques used to optimize 3T imaging of the wrist; including driven equilibrium sequence (DRIVE), parallel imaging, and 3D imaging. The coil choice for 3T imaging of the wrist depends on a number of variables, and the proper coil design selection is critical for high-resolution wrist imaging with high signal and contrast-to-noise ratio. The TFCC is a complex structure and is composed of the articular disc (disc proper), the triangular ligament, the dorsal and volar radioulnar ligaments, the meniscus homologue, the ulnar collateral ligament (UCL), the extensor carpi ulnaris (ECU) tendon sheath, and the ulnolunate and ulnotriquetral ligaments. The Palmer classification categorizes TFCC lesions as traumatic (type 1) or degenerative (type 2). In this review article, we present clinical high-resolution MR images of normal TFCC anatomy and TFCC injuries with this classification system.

Building Imaging Institutes of Patient Care Outcomes: Imaging as a Nidus for Innovation in Clinical Care, Research, and Education.

PubMed

Petrou, Myria; Cronin, Paul; Altaee, Duaa K; Kelly, Aine M; Foerster, Bradley R

2018-05-01

Traditionally, radiologists have been responsible for the protocol of imaging studies, imaging acquisition, supervision of imaging technologists, and interpretation and reporting of imaging findings. In this article, we outline how radiology needs to change and adapt to a role of providing value-based, integrated health-care delivery. We believe that the way to best serve our specialty and our patients is to undertake a fundamental paradigm shift in how we practice. We describe the need for imaging institutes centered on disease entities (eg, lung cancer, multiple sclerosis) to not only optimize clinical care and patient outcomes, but also spur the development of a new educational focus, which will increase opportunities for medical trainees and other health professionals. These institutes will also serve as unique environments for testing and implementing new technologies and for generating new ideas for research and health-care delivery. We propose that the imaging institutes focus on how imaging practices-including new innovations-improve patient care outcomes within a specific disease framework. These institutes will allow our specialty to lead patient care, provide the necessary infrastructure for state-of-the art-education of trainees, and stimulate innovative and clinically relevant research. Copyright © 2018 The Association of University Radiologists. All rights reserved.

Optimization of a Sample Processing Protocol for Recovery of ...

EPA Pesticide Factsheets

Journal Article Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps.

Establishment and optimization of NMR-based cell metabonomics study protocols for neonatal Sprague-Dawley rat cardiomyocytes.

PubMed

Zhang, Ming; Sun, Bo; Zhang, Qi; Gao, Rong; Liu, Qiao; Dong, Fangting; Fang, Haiqin; Peng, Shuangqing; Li, Famei; Yan, Xianzhong

2017-01-15

A quenching, harvesting, and extraction protocol was optimized for cardiomyocytes NMR metabonomics analysis in this study. Trypsin treatment and direct scraping cells in acetonitrile were compared for sample harvesting. The results showed trypsin treatment cause normalized concentration increasing of phosphocholine and metabolites leakage, since the trypsin-induced membrane broken and long term harvesting procedures. Then the intracellular metabolite extraction efficiency of methanol and acetonitrile were compared. As a result, washing twice with phosphate buffer, direct scraping cells and extracting with acetonitrile were chosen to prepare cardiomyocytes extracts samples for metabonomics studies. This optimized protocol is rapid, effective, and exhibits greater metabolite retention. Copyright © 2016 Elsevier Inc. All rights reserved.

International Image Concordance Study to Compare a Point of Care Tampon Colposcope to a Standard-of-Care Colposcope

PubMed Central

Mueller, Jenna L.; Asma, Elizabeth; Lam, Christopher T.; Krieger, Marlee S.; Gallagher, Jennifer E.; Erkanli, Alaattin; Hariprasad, Roopa; Malliga, J.S.; Muasher, Lisa C.; Mchome, Bariki; Oneko, Olola; Taylor, Peyton; Venegas, Gino; Wanyoro, Anthony; Mehrotra, Ravi; Schmitt, John W.; Ramanujam, Nimmi

2017-01-01

Objective Barriers to cervical cancer screening in low resource settings include lack of accessible high quality services, high cost, and the need for multiple visits. To address these challenges, we developed a low cost intra-vaginal optical cervical imaging device, the Point of Care Tampon (POCkeT) colposcope, and evaluated whether its performance is comparable to a standard-of-care colposcope. Methods There were two protocols, which included 44 and 18 patients respectively. For the first protocol, white light cervical images were collected in vivo, blinded by device, and sent electronically to 8 physicians from high, middle and low income countries. For the second protocol, green light images were also collected and sent electronically to the highest performing physician from the first protocol who has experience in both a high and low income country. For each image, physicians completed a survey assessing cervix characteristics and severity of precancerous lesions. Corresponding pathology was obtained for all image pairs. Results For the first protocol, average percent agreement between devices was 70% across all physicians. POCkeT and standard-of-care colposcope images had 37% and 51% percent agreement respectively with pathology for high-grade squamous intraepithelial lesions (HSILs). Investigation of HSIL POCkeT images revealed decreased visibility of vascularization and lack of contrast in lesion margins. After changes were made for the second protocol, the two devices achieved similar agreement to pathology for HSIL lesions (55%). Conclusions Based on the exploratory study, physician interpretation of cervix images acquired using a portable, low cost, POCkeT colposcope was comparable to a standard-of-care colposcope. PMID:28263237

Image guidance in prostate cancer - can offline corrections be an effective substitute for daily online imaging?

PubMed

Prasad, Devleena; Das, Pinaki; Saha, Niladri S; Chatterjee, Sanjoy; Achari, Rimpa; Mallick, Indranil

2014-01-01

This aim of this study was to determine if a less resource-intensive and established offline correction protocol - the No Action Level (NAL) protocol was as effective as daily online corrections of setup deviations in curative high-dose radiotherapy of prostate cancer. A total of 683 daily megavoltage CT (MVCT) or kilovoltage CT (kvCBCT) images of 30 patients with localized prostate cancer treated with intensity modulated radiotherapy were evaluated. Daily image-guidance was performed and setup errors in three translational axes recorded. The NAL protocol was simulated by using the mean shift calculated from the first five fractions and implemented on all subsequent treatments. Using the imaging data from the remaining fractions, the daily residual error (RE) was determined. The proportion of fractions where the RE was greater than 3,5 and 7 mm was calculated, and also the actual PTV margin that would be required if the offline protocol was followed. Using the NAL protocol reduced the systematic but not the random errors. Corrections made using the NAL protocol resulted in small and acceptable RE in the mediolateral (ML) and superoinferior (SI) directions with 46/533 (8.1%) and 48/533 (5%) residual shifts above 5 mm. However; residual errors greater than 5mm in the anteroposterior (AP) direction remained in 181/533 (34%) of fractions. The PTV margins calculated based on residual errors were 5mm, 5mm and 13 mm in the ML, SI and AP directions respectively. Offline correction using the NAL protocol resulted in unacceptably high residual errors in the AP direction, due to random uncertainties of rectal and bladder filling. Daily online imaging and corrections remain the standard image guidance policy for highly conformal radiotherapy of prostate cancer.

Ultralow dose dentomaxillofacial CT imaging and iterative reconstruction techniques: variability of Hounsfield units and contrast-to-noise ratio

PubMed Central

Bischel, Alexander; Stratis, Andreas; Kakar, Apoorv; Bosmans, Hilde; Jacobs, Reinhilde; Gassner, Eva-Maria; Puelacher, Wolfgang; Pauwels, Ruben

2016-01-01

Objective: The aim of this study was to evaluate whether application of ultralow dose protocols and iterative reconstruction technology (IRT) influence quantitative Hounsfield units (HUs) and contrast-to-noise ratio (CNR) in dentomaxillofacial CT imaging. Methods: A phantom with inserts of five types of materials was scanned using protocols for (a) a clinical reference for navigated surgery (CT dose index volume 36.58 mGy), (b) low-dose sinus imaging (18.28 mGy) and (c) four ultralow dose imaging (4.14, 2.63, 0.99 and 0.53 mGy). All images were reconstructed using: (i) filtered back projection (FBP); (ii) IRT: adaptive statistical iterative reconstruction-50 (ASIR-50), ASIR-100 and model-based iterative reconstruction (MBIR); and (iii) standard (std) and bone kernel. Mean HU, CNR and average HU error after recalibration were determined. Each combination of protocols was compared using Friedman analysis of variance, followed by Dunn's multiple comparison test. Results: Pearson's sample correlation coefficients were all >0.99. Ultralow dose protocols using FBP showed errors of up to 273 HU. Std kernels had less HU variability than bone kernels. MBIR reduced the error value for the lowest dose protocol to 138 HU and retained the highest relative CNR. ASIR could not demonstrate significant advantages over FBP. Conclusions: Considering a potential dose reduction as low as 1.5% of a std protocol, ultralow dose protocols and IRT should be further tested for clinical dentomaxillofacial CT imaging. Advances in knowledge: HU as a surrogate for bone density may vary significantly in CT ultralow dose imaging. However, use of std kernels and MBIR technology reduce HU error values and may retain the highest CNR. PMID:26859336

Influence of basis images and skull position on evaluation of cortical bone thickness in cone beam computed tomography.

PubMed

Nascimento, Monikelly do Carmo Chagas; Boscolo, Solange Maria de Almeida; Haiter-Neto, Francisco; Santos, Emanuela Carla Dos; Lambrichts, Ivo; Pauwels, Ruben; Jacobs, Reinhilde

2017-06-01

The aim of this study was to assess the influence of the number of basis images and the orientation of the skull on the evaluation of cortical alveolar bone in cone beam computed tomography (CBCT). Eleven skulls with a total of 59 anterior teeth were selected. CBCT images were acquired by using 4 protocols, by varying the rotation of the tube-detector arm and the orientation of the skull (protocol 1: 360°/0°; protocol 2: 180°/0°; protocol 3: 180°/90°; protocol 4: 180°/180°). Observers evaluated cortical bone as absent, thin, or thick. Direct observation of the skulls was used as the gold standard. Intra- and interobserver agreement, as well as agreement of scoring between the 3 bone thickness classifications, were calculated by using the κ statistic. The Wilcoxon signed-rank test was used to compare the 4 protocols. For lingual cortical bone, protocol 1 showed no statistical difference from the gold standard. Higher reliability was found in protocol 3 for absent (κ = 0.80) and thin (κ = 0.47) cortices, whereas for thick cortical bone, protocol 2 was more consistent (κ = 0.60). In buccal cortical bone, protocol 1 obtained the highest agreement for absent cortices (κ = 0.61), whereas protocol 4 was better for thin cortical plates (κ = 0.38) and protocol 2 for thick cortical plates (κ = 0.40). No consistent effect of the number of basis images or head orientation for visual detection of alveolar bone was detected, except for lingual cortical bone, for which full rotation scanning showed improved visualization. Copyright © 2017 Elsevier Inc. All rights reserved.

Automatic image hanging protocol for chest radiographs in PACS.

PubMed

Luo, Hui; Hao, Wei; Foos, David H; Cornelius, Craig W

2006-04-01

Chest radiography is one of the most widely used techniques in diagnostic imaging. It comprises at least one-third of all diagnostic radiographic procedures in hospitals. However, in the picture archive and communication system, images are often stored with the projection and orientation unknown or mislabeled, which causes inefficiency for radiologists' interpretation. To address this problem, an automatic hanging protocol for chest radiographs is presented. The method targets the most effective region in a chest radiograph, and extracts a set of size-, rotation-, and translation-invariant features from it. Then, a well-trained classifier is used to recognize the projection. The orientation of the radiograph is later identified by locating the neck, heart, and abdomen positions in the radiographs. Initial experiments are performed on the radiographs collected from daily routine chest exams in hospitals and show promising results. Using the presented protocol, 98.2% of all cases could be hung correctly on projection view (without protocol, 62%), and 96.1% had correct orientation (without protocol, 75%). A workflow study on the protocol also demonstrates a significant improvement in efficiency for image display.

Multiphoton Intravital Calcium Imaging.

PubMed

Cheetham, Claire E J

2018-06-26

Multiphoton intravital calcium imaging is a powerful technique that enables high-resolution longitudinal monitoring of cellular and subcellular activity hundreds of microns deep in the living organism. This unit addresses the application of 2-photon microscopy to imaging of genetically encoded calcium indicators (GECIs) in the mouse brain. The protocols in this unit enable real-time intravital imaging of intracellular calcium concentration simultaneously in hundreds of neurons, or at the resolution of single synapses, as mice respond to sensory stimuli or perform behavioral tasks. Protocols are presented for implantation of a cranial imaging window to provide optical access to the brain and for 2-photon image acquisition. Protocols for implantation of both open skull and thinned skull windows for single or multi-session imaging are described. © 2018 by John Wiley & Sons, Inc. © 2018 John Wiley & Sons, Inc.

Monitoring photodynamic therapy of head and neck malignancies with optical spectroscopies

PubMed Central

Sunar, Ulas

2013-01-01

In recent years there has been significant developments in photosensitizers (PSs), light sources and light delivery systems that have allowed decreasing the treatment time and skin phototoxicity resulting in more frequent use of photodynamic therapy (PDT) in the clinical settings. Compared to standard treatment approaches such as chemo-radiation and surgery, PDT has much reduced morbidity for head and neck malignancies and is becoming an alternative treatment option. It can be used as an adjunct therapy to other treatment modalities without any additive cumulative side effects. Surface illumination can be an option for pre-malignant and early-stage malignancies while interstitial treatment is for debulking of thick tumors in the head and neck region. PDT can achieve equivalent or greater efficacy in treating head and neck malignancies, suggesting that it may be considered as a first line therapy in the future. Despite progressive development, clinical PDT needs improvement in several topics for wider acceptance including standardization of protocols that involve the same administrated light and PS doses and establishing quantitative tools for PDT dosimetry planning and response monitoring. Quantitative measures such as optical parameters, PS concentration, tissue oxygenation and blood flow are essential for accurate PDT dosimetry as well as PDT response monitoring and assessing therapy outcome. Unlike conventional imaging modalities like magnetic resonance imaging, novel optical imaging techniques can quantify PDT-related parameters without any contrast agent administration and enable real-time assessment during PDT for providing fast feedback to clinicians. Ongoing developments in optical imaging offer the promise of optimization of PDT protocols with improved outcomes. PMID:24303476

WE-G-19A-01: Radiologists and Medical Physicists: Working Together to Achieve Common Goals

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

Jones, A; Ma, J; Steele, J

It is vitally important that medical physicists understand the clinical questions that radiologists are trying to answer with patient images. Knowledge of the types of information the radiologist needs helps medical physicists configure imaging protocols that appropriately balance radiation dose, time, and image quality. The ability to communicate with radiologists and understand medical terminology, anatomy, and physiology is key to creating such imaging protocols. In this session, radiologists will present clinical cases and describe the information they are seeking in the clinical images. Medical physicists will then discuss how imaging protocols are configured. Learning Objectives: Understand the types of informationmore » that radiologists seek in medical images. Apply this understanding in configuring the imaging equipment to deliver this information. Develop strategies for working with physician colleagues.« less

Design and Analysis of Optimization Algorithms to Minimize Cryptographic Processing in BGP Security Protocols.

PubMed

Sriram, Vinay K; Montgomery, Doug

2017-07-01

The Internet is subject to attacks due to vulnerabilities in its routing protocols. One proposed approach to attain greater security is to cryptographically protect network reachability announcements exchanged between Border Gateway Protocol (BGP) routers. This study proposes and evaluates the performance and efficiency of various optimization algorithms for validation of digitally signed BGP updates. In particular, this investigation focuses on the BGPSEC (BGP with SECurity extensions) protocol, currently under consideration for standardization in the Internet Engineering Task Force. We analyze three basic BGPSEC update processing algorithms: Unoptimized, Cache Common Segments (CCS) optimization, and Best Path Only (BPO) optimization. We further propose and study cache management schemes to be used in conjunction with the CCS and BPO algorithms. The performance metrics used in the analyses are: (1) routing table convergence time after BGPSEC peering reset or router reboot events and (2) peak-second signature verification workload. Both analytical modeling and detailed trace-driven simulation were performed. Results show that the BPO algorithm is 330% to 628% faster than the unoptimized algorithm for routing table convergence in a typical Internet core-facing provider edge router.

Single-source dual-energy spectral multidetector CT of pancreatic adenocarcinoma: optimization of energy level viewing significantly increases lesion contrast.

PubMed

Patel, B N; Thomas, J V; Lockhart, M E; Berland, L L; Morgan, D E

2013-02-01

To evaluate lesion contrast in pancreatic adenocarcinoma patients using spectral multidetector computed tomography (MDCT) analysis. The present institutional review board-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant retrospective study evaluated 64 consecutive adults with pancreatic adenocarcinoma examined using a standardized, multiphasic protocol on a single-source, dual-energy MDCT system. Pancreatic phase images (35 s) were acquired in dual-energy mode; unenhanced and portal venous phases used standard MDCT. Lesion contrast was evaluated on an independent workstation using dual-energy analysis software, comparing tumour to non-tumoural pancreas attenuation (HU) differences and tumour diameter at three energy levels: 70 keV; individual subject-optimized viewing energy level (based on the maximum contrast-to-noise ratio, CNR); and 45 keV. The image noise was measured for the same three energies. Differences in lesion contrast, diameter, and noise between the different energy levels were analysed using analysis of variance (ANOVA). Quantitative differences in contrast gain between 70 keV and CNR-optimized viewing energies, and between CNR-optimized and 45 keV were compared using the paired t-test. Thirty-four women and 30 men (mean age 68 years) had a mean tumour diameter of 3.6 cm. The median optimized energy level was 50 keV (range 40-77). The mean ± SD lesion contrast values (non-tumoural pancreas - tumour attenuation) were: 57 ± 29, 115 ± 70, and 146 ± 74 HU (p = 0.0005); the lengths of the tumours were: 3.6, 3.3, and 3.1 cm, respectively (p = 0.026); and the contrast to noise ratios were: 24 ± 7, 39 ± 12, and 59 ± 17 (p = 0.0005) for 70 keV, the optimized energy level, and 45 keV, respectively. For individuals, the mean ± SD contrast gain from 70 keV to the optimized energy level was 59 ± 45 HU; and the mean ± SD contrast gain from the optimized energy level to 45 keV was 31 ± 25 HU (p = 0.007). Significantly increased pancreatic lesion contrast was noted at lower viewing energies using spectral MDCT. Individual patient CNR-optimized energy level images have the potential to improve lesion conspicuity. Copyright © 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Optimal Adenosine Stress for Maximum Stress Perfusion, Coronary Flow Reserve, and Pixel Distribution of Coronary Flow Capacity by Kolmogorov-Smirnov Analysis.

PubMed

Kitkungvan, Danai; Lai, Dejian; Zhu, Hongjian; Roby, Amanda E; Johnson, Nils P; Steptoe, Derek D; Patel, Monica B; Kirkeeide, Richard; Gould, K Lance

2017-02-01

Different adenosine stress imaging protocols have not been systemically validated for absolute myocardial perfusion and coronary flow reserve (CFR) by positron emission tomography, where submaximal stress precludes assessing physiological severity of coronary artery disease. In 127 volunteers, serial rest-stress positron emission tomography scans using rubidium-82 with various adenosine infusion protocols identified (1) the protocol with maximum stress perfusion and CFR, (2) test-retest precision in same subject, (3) stress perfusion and CFR after adenosine compared with dipyridamole, (4) heterogeneity of coronary flow capacity combining stress perfusion and CFR, and (5) potential relevance for patients with risk factors or coronary artery disease. The adenosine 6-minute infusion with rubidium-82 injection at 3 minutes caused CFR that was significantly 15.7% higher than the 4-minute adenosine infusion with rubidium-82 injection at 2 minutes and significantly more homogeneous by Kolmogorov-Smirnov analysis for histograms of 1344 pixel range of perfusion in paired positron emission tomographies. In a coronary artery disease cohort separate from volunteers of this study, compared with the 3/6-minute protocol, the 2/4-minute adenosine protocol would potentially have changed 332 of 1732 (19%) positron emission tomographies at low-risk physiological severity CFR ≥2.3 to CFR <2.0, thereby implying high-risk quantitative severity potentially appropriate for interventions but because of suboptimal stress of the 2/4 protocol in some patients. The 6-minute adenosine infusion with rubidium-82 activation at 3 minutes produced CFR that averaged 15.7% higher than that in the 2/4-minute protocol, thereby potentially providing essential information for personalized management in some patients. © 2017 American Heart Association, Inc.

CCSDS File Delivery Protocol (CFDP): Why it's Useful and How it Works

NASA Technical Reports Server (NTRS)

Ray, Tim

2003-01-01

Reliable delivery of data products is often required across space links. For example, a NASA mission will require reliable delivery of images produced by an on-board detector. Many missions have their own (unique) way of accomplishing this, requiring custom software. Many missions also require manual operations (e.g. the telemetry receiver software keeps track of what data is missing, and a person manually inputs the appropriate commands to request retransmissions). The Consultative Committee for Space Data Systems (CCSDS) developed the CCSDS File Delivery Protocol (CFDP) specifically for this situation. CFDP is an international standard communication protocol that provides reliable delivery of data products. It is designed for use across space links. It will work well if run over the widely used CCSDS Telemetry and Telecommand protocols. However, it can be run over any protocol, and will work well as long as the underlying protocol delivers a reasonable portion of the data. The CFDP receiver will autonomously determine what data is missing, and request retransmissions as needed. The CFDP sender will autonomously perform the requested transmissions. When the entire data product is delivered, the CFDP receiver will let the CFDP sender know that the transaction has completed successfully. The result is that custom software becomes standard, and manual operations become autonomous. This paper will consider various ways of achieving reliable file delivery, explain why CFDP is the optimal choice for use over space links, explain how the core protocol works, and give some guidance on how to best utilize CFDP within various mission scenarios. It will also touch on additional features of CFDP, as well as other uses for CFDP (e.g. the loading of on-board memory and tables).

When tractography meets tracer injections: a systematic study of trends and variation sources of diffusion-based connectivity.

PubMed

Aydogan, Dogu Baran; Jacobs, Russell; Dulawa, Stephanie; Thompson, Summer L; Francois, Maite Christi; Toga, Arthur W; Dong, Hongwei; Knowles, James A; Shi, Yonggang

2018-04-16

Tractography is a powerful technique capable of non-invasively reconstructing the structural connections in the brain using diffusion MRI images, but the validation of tractograms is challenging due to lack of ground truth. Owing to recent developments in mapping the mouse brain connectome, high-resolution tracer injection-based axonal projection maps have been created and quickly adopted for the validation of tractography. Previous studies using tracer injections mainly focused on investigating the match in projections and optimal tractography protocols. Being a complicated technique, however, tractography relies on multiple stages of operations and parameters. These factors introduce large variabilities in tractograms, hindering the optimization of protocols and making the interpretation of results difficult. Based on this observation, in contrast to previous studies, in this work we focused on quantifying and ranking the amount of performance variation introduced by these factors. For this purpose, we performed over a million tractography experiments and studied the variability across different subjects, injections, anatomical constraints and tractography parameters. By using N-way ANOVA analysis, we show that all tractography parameters are significant and importantly performance variations with respect to the differences in subjects are comparable to the variations due to tractography parameters, which strongly underlines the importance of fully documenting the tractography protocols in scientific experiments. We also quantitatively show that inclusion of anatomical constraints is the most significant factor for improving tractography performance. Although this critical factor helps reduce false positives, our analysis indicates that anatomy-informed tractography still fails to capture a large portion of axonal projections.

Assessment of Ovarian Cancer Tumors Treated with Intraperitoneal Cisplatin Therapy by Nanoscopic X-ray Fluorescence Imaging

NASA Astrophysics Data System (ADS)

Laforce, Brecht; Carlier, Charlotte; Vekemans, Bart; Villanova, Julie; Tucoulou, Rémi; Ceelen, Wim; Vincze, Laszlo

2016-07-01

Ovarian cancer is amongst the most common types of cancer in women, with a relatively low overall cure rate of approximately 30%. This is therefore an important incentive to urge for further research in order to maximize the chances of survival for these patients. Intraperitoneal chemotherapy with Cisplatin is an effective treatement for ovarian cancer; however, many questions still remain concerning the ideal treatment protocol and tumor resistance towards the drug, which should be resolved for optimal application of this therapy. For the first time in-vivo grown tumors treated with both hyper- and normothermic intraperitoneal chemotherapy have been studied using nano-XRF spectroscopy to examine the platinum (Pt) distribution within the analyzed tissues. These measurements prove Pt resides predominantly outsides the cancer cells in the stroma of the tissue. These findings indicate the resistance mechanism of the cancer cells prevents Cisplatin from diffusing through their cell membranes. This is an important addition to the existing knowledge on the resistance mechanism providing insights which might help to overcome this effect. In our aim to find the optimal treatment protocol, no significant differences were found between the two examined procedures. A more extensive data set will be needed to draw definite conclusions.

Low contrast detection in abdominal CT: comparing single-slice and multi-slice tasks

NASA Astrophysics Data System (ADS)

Ba, Alexandre; Racine, Damien; Viry, Anaïs.; Verdun, Francis R.; Schmidt, Sabine; Bochud, François O.

2017-03-01

Image quality assessment is crucial for the optimization of computed tomography (CT) protocols. Human and mathematical model observers are increasingly used for the detection of low contrast signal in abdominal CT, but are frequently limited to the use of a single image slice. Another limitation is that most of them only consider the detection of a signal embedded in a uniform background phantom. The purpose of this paper was to test if human observer performance is significantly different in CT images read in single or multiple slice modes and if these differences are the same for anatomical and uniform clinical images. We investigated detection performance and scrolling trends of human observers of a simulated liver lesion embedded in anatomical and uniform CT backgrounds. Results show that observers don't take significantly benefit of additional information provided in multi-slice reading mode. Regarding the background, performances are moderately higher for uniform than for anatomical images. Our results suggest that for low contrast detection in abdominal CT, the use of multi-slice model observers would probably only add a marginal benefit. On the other hand, the quality of a CT image is more accurately estimated with clinical anatomical backgrounds.

Advances in Imaging and Management Trends of Traumatic Aortic Injuries.

PubMed

Nagpal, Prashant; Mullan, Brian F; Sen, Indrani; Saboo, Sachin S; Khandelwal, Ashish

2017-05-01

Acute traumatic aortic injury (ATAI) is a life-threatening injury. CT is the imaging tool of choice, and the knowledge of direct and indirect signs of injury, grading system, and current management protocol helps the emergency radiologist to better identify and classify the injury and provide additional details that can impact management options. Newer dual-source CT technology with ultrafast acquisition speed has also influenced the appropriate protocol for imaging in patients with suspected ATAI. This review highlights the imaging protocol in patients with blunt trauma, CT appearance and grading systems of ATAI, management options, and the role of the multidisciplinary team in the management of these patients. We also briefly review the current literature on the definition, treatment, and follow-up protocol in patients with minimal aortic injury.

Optimizing Equivalence-Based Instruction: Effects of Training Protocols on Equivalence Class Formation

ERIC Educational Resources Information Center

Fienup, Daniel M.; Wright, Nicole A.; Fields, Lanny

2015-01-01

Two experiments evaluated the effects of the simple-to-complex and simultaneous training protocols on the formation of academically relevant equivalence classes. The simple-to-complex protocol intersperses derived relations probes with training baseline relations. The simultaneous protocol conducts all training trials and test trials in separate…

Magnetic resonance imaging of the inner ear by using a hybrid radiofrequency coil at 7 T

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Nam; Heo, Phil; Kim, Young-Bo; Han, Gyu-Cheol

2015-01-01

Visualization of the membranous structures of the inner ear has been limited to the detection of the normal fluid signal intensity within the bony labyrinth by using magnetic resonance imaging (MRI) equipped with a 1.5 Tesla (T) magnet. High-field (HF) MRI has been available for more than a decade, and numerous studies have documented its significant advantages over conventional MRI with regards to its use in basic scientific research and routine clinical assessments. No previous studies of the inner ear by using HF MRI have been reported, in part because high-quality resolution of mastoid pneumatization is challenging due to artifacts generated in the HF environment and insufficient performance of radiofrequency (RF) coils. Therefore, a hybrid RF coil with integrated circuitry was developed at 7 T and was targeted for anatomical imaging to achieve a high resolution image of the structure of the human inner ear, excluding the bony portion. The inner-ear's structure is composed of soft tissues containing hydrogen ions and includes the membranous labyrinth, endolymphatic space, perilymphatic space, and cochlear-vestibular nerves. Visualization of the inner-ear's anatomy was performed in-vivo with a custom-designed hybrid RF coil and a specific imaging protocol based on an interpolated breath-held examination sequence. The comparative signal intensity value at 30-mm away from the phantom side was 88% higher for the hybrid RF coil and 24% higher for the 8-channel transmit/receive (Tx/Rx) coil than for the commercial birdcage coil. The optimized MRI protocol employed a hybrid RF coil because it enabled high-resolution imaging of the inner-ear's anatomy and accurate mapping of structures including the cochlea and the semicircular canals. These results indicate that 7 T MRI achieves high spatial resolution visualization of the inner-ear's anatomy. Therefore, MRI imaging using a hybrid RF coil at 7 T could provide a powerful tool for clinical investigations of petrous pathologies of the inner ear.

The development and role of megavoltage cone beam computerized tomography in radiation oncology

NASA Astrophysics Data System (ADS)

Morin, Olivier

External beam radiation therapy has now the ability to deliver doses that conform tightly to a tumor volume. The steep dose gradients planned in these treatments make it increasingly important to reproduce the patient position and anatomy at each treatment fraction. For this reason, considerable research now focuses on in-room three-dimensional imaging. This thesis describes the first clinical megavoltage cone beam computed tomography (MVCBCT) system, which utilizes a conventional linear accelerator equipped with an amorphous silicon flat panel detector. The document covers the system development and investigation of its clinical applications over the last 4-5 years. The physical performance of the system was evaluated and optimized for soft-tissue contrast resolution leading to recommendations of imaging protocols to use for specific clinical applications and body sites. MVCBCT images can resolve differences of 5% in electron density for a mean dose of 9 cGy. Hence, the image quality of this system is sufficient to differentiate some soft-tissue structures. The absolute positioning accuracy with MVCBCT is better than 1 mm. The accuracy of isodose lines calculated using MVCBCT images of head and neck patients is within 3% and 3 mm. The system shows excellent stability in image quality, CT# calibration, radiation exposure and absolute positioning over a period of 8 months. A procedure for MVCBCT quality assurance was developed. In our clinic, MVCBCT has been used to detect non rigid spinal cord distortions, to position a patient with a paraspinous tumor close to metallic hardware, to position prostate cancer patients using gold markers or soft-tissue landmarks, to monitor head and neck anatomical changes and their dosimetric consequences, and to complement the convention CT for treatment planning in presence of metallic implants. MVCBCT imaging is changing the clinical practice of our department by increasingly revealing patient-specific errors. New verification protocols are being developed to minimize those errors thus moving the practice of radiation therapy one step closer to personalized medicine.

80-kVp CT Using Iterative Reconstruction in Image Space Algorithm for the Detection of Hypervascular Hepatocellular Carcinoma: Phantom and Initial Clinical Experience

PubMed Central

Hur, Saebeom; Kim, Soo Jin; Park, Ji Hoon; Han, Joon Koo; Choi, Byung Ihn

2012-01-01

Objective To investigate whether the low-tube-voltage (80-kVp), intermediate-tube-current (340-mAs) MDCT using the Iterative Reconstruction in Image Space (IRIS) algorithm improves lesion-to-liver contrast at reduced radiation dosage while maintaining acceptable image noise in the detection of hepatocellular carcinomas (HCC) in thin (mean body mass index, 24 ± 0.4 kg/m2) adults. Subjects and Methods A phantom simulating the liver with HCC was scanned at 50-400 mAs for 80, 100, 120 and 140-kVp. In addition, fifty patients with HCC who underwent multiphasic liver CT using dual-energy (80-kVp and 140-kVp) arterial scans were enrolled. Virtual 120-kVP scans (protocol A) and 80-kVp scans (protocol B) of the late arterial phase were reconstructed with filtered back-projection (FBP), while corresponding 80-kVp scans were reconstructed with IRIS (protocol C). Contrast-to-noise ratio (CNR) of HCCs and abdominal organs were assessed quantitatively, whereas lesion conspicuity, image noise, and overall image quality were assessed qualitatively. Results IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study. In the quantitative patient study, protocol C helped improve CNR by 51% and 172% than protocols A and B (p < 0.001), respectively, at equivalent radiation dosage. In the qualitative study, protocol C acquired the highest score for lesion conspicuity albeit with an inferior score to protocol A for overall image quality (p < 0.001). Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C. Conclusion CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP. PMID:22438682

Can magnetic resonance imaging at 3.0-Tesla reliably detect patients with endometriosis? Initial results.

PubMed

Thomeer, Maarten G; Steensma, Anneke B; van Santbrink, Evert J; Willemssen, Francois E; Wielopolski, Piotr A; Hunink, Myriam G; Spronk, Sandra; Laven, Joop S; Krestin, Gabriel P

2014-04-01

The aim of this study was to determine whether an optimized 3.0-Tesla magnetic resonance imaging (MRI) protocol is sensitive and specific enough to detect patients with endometriosis. This was a prospective cohort study with consecutive patients. Forty consecutive patients with clinical suspicion of endometriosis underwent 3.0-Tesla MRI, including a T2-weighted high-resolution fast spin echo sequence (spatial resolution=0.75 ×1.2 ×1.5 mm³) and a 3D T1-weighted high-resolution gradient echo sequence (spatial resolution=0.75 ×1.2 × 2.0 mm³). Two radiologists reviewed the dataset with consensus reading. During laparoscopy, which was used as reference standard, all lesions were characterized according to the revised criteria of the American Fertility Society. Patient-level and region-level sensitivities and specificities and lesion-level sensitivities were calculated. Patient-level sensitivity was 42% for stage I (5/12) and 100% for stages II, III and IV (25/25). Patient-level specificity for all stages was 100% (3/3). The region-level sensitivity and specificity was 63% and 97%, respectively. The sensitivity per lesion was 61% (90% for deep lesions, 48% for superficial lesions and 100% for endometriomata). The detection rate of obliteration of the cul-the-sac was 100% (10/10) with no false positive findings. The interreader agreement was substantial to perfect (kappa=1 per patient, 0.65 per lesion and 0.71 for obliteration of the cul-the-sac). An optimized 3.0-Tesla MRI protocol is accurate in detecting stage II to stage IV endometriosis. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

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

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

NONE

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 applicationsmore » 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.« less

7-T magnetic resonance imaging of the inner ear's anatomy by using dual four-element radiofrequency coil arrays and the VIBE sequence

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Nam; Heo, Phil; Kim, Young-Bo; Han, Gyu-Cheol

2015-02-01

An ultra-high-field magnetic resonance (MR) scanner and a specially-optimized radiofrequency (RF) coil and sequence protocol are required to obtain high-resolution images of the inner ear that can noninvasively confirm pathologic diagnoses. In phantom studies, the MR signal distribution of the gradient echo MR images generated by using a customized RF coil was compared with that of a commercial volume coil. The MR signal intensity of the customized RF coil decreases rapidly from near the RF coil plane toward the exterior of the phantom. However, the signal sensitivity of this coil is superior on both sides of the phantom, corresponding to the petrous pyramid. In in-vivo 7-T MR imaging, a customized RF coil and a volumetric-interpolated breath-hold examination imaging sequence are employed for visualization of the inner ear's structure. The entire membranous portion of the cochlear and the three semicircular canals, including the ductus reunions, oval window, and round window with associated nervous tissue, were clearly depicted with sufficient spatial coverage for adequate inspection of the surrounding anatomy. Developments from a new perspective to inner ear imaging using the 7-T modality could lead to further improved image sensitivity and, thus, enable ultra-structural MR imaging.

GRAPE: a graphical pipeline environment for image analysis in adaptive magnetic resonance imaging.

PubMed

Gabr, Refaat E; Tefera, Getaneh B; Allen, William J; Pednekar, Amol S; Narayana, Ponnada A

2017-03-01

We present a platform, GRAphical Pipeline Environment (GRAPE), to facilitate the development of patient-adaptive magnetic resonance imaging (MRI) protocols. GRAPE is an open-source project implemented in the Qt C++ framework to enable graphical creation, execution, and debugging of real-time image analysis algorithms integrated with the MRI scanner. The platform provides the tools and infrastructure to design new algorithms, and build and execute an array of image analysis routines, and provides a mechanism to include existing analysis libraries, all within a graphical environment. The application of GRAPE is demonstrated in multiple MRI applications, and the software is described in detail for both the user and the developer. GRAPE was successfully used to implement and execute three applications in MRI of the brain, performed on a 3.0-T MRI scanner: (i) a multi-parametric pipeline for segmenting the brain tissue and detecting lesions in multiple sclerosis (MS), (ii) patient-specific optimization of the 3D fluid-attenuated inversion recovery MRI scan parameters to enhance the contrast of brain lesions in MS, and (iii) an algebraic image method for combining two MR images for improved lesion contrast. GRAPE allows graphical development and execution of image analysis algorithms for inline, real-time, and adaptive MRI applications.

Accumulative Difference Image Protocol for Particle Tracking in Fluorescence Microscopy Tested in Mouse Lymphonodes

PubMed Central

Villa, Carlo E.; Caccia, Michele; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Rivolta, Ilaria; Miserocchi, Giuseppe; Gorletta, Tatiana; Zanoni, Ivan; Granucci, Francesca; Chirico, Giuseppe

2010-01-01

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done. PMID:20808918

Accumulative difference image protocol for particle tracking in fluorescence microscopy tested in mouse lymphonodes.

PubMed

Villa, Carlo E; Caccia, Michele; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Rivolta, Ilaria; Miserocchi, Giuseppe; Gorletta, Tatiana; Zanoni, Ivan; Granucci, Francesca; Chirico, Giuseppe

2010-08-17

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done.

Biplane interventional pediatric system with cone‐beam CT: dose and image quality characterization for the default protocols

PubMed Central

Vañó, Eliseo; Alejo, Luis; Ubeda, Carlos; Gutiérrez‐Larraya, Federico; Garayoa, Julia

2016-01-01

The aim of this study was to assess image quality and radiation dose of a biplane angiographic system with cone‐beam CT (CBCT) capability tuned for pediatric cardiac procedures. The results of this study can be used to explore dose reduction techniques. For pulsed fluoroscopy and cine modes, polymethyl methacrylate phantoms of various thicknesses and a Leeds TOR 18‐FG test object were employed. Various fields of view (FOV) were selected. For CBCT, the study employed head and body dose phantoms, Catphan 504, and an anthropomorphic cardiology phantom. The study also compared two 3D rotational angiography protocols. The entrance surface air kerma per frame increases by a factor of 3–12 when comparing cine and fluoroscopy frames. The biggest difference in the signal‐to‐noise ratio between fluoroscopy and cine modes occurs at FOV 32 cm because fluoroscopy is acquired at a 1440×1440 pixel matrix size and in unbinned mode, whereas cine is acquired at 720×720 pixels and in binned mode. The high‐contrast spatial resolution of cine is better than that of fluoroscopy, except for FOV 32 cm, because fluoroscopy mode with 32 cm FOV is unbinned. Acquiring CBCT series with a 16 cm head phantom using the standard dose protocol results in a threefold dose increase compared with the low‐dose protocol. Although the amount of noise present in the images acquired with the low‐dose protocol is much higher than that obtained with the standard mode, the images present better spatial resolution. A 1 mm diameter rod with 250 Hounsfield units can be distinguished in reconstructed images with an 8 mm slice width. Pediatric‐specific protocols provide lower doses while maintaining sufficient image quality. The system offers a novel 3D imaging mode. The acquisition of CBCT images results in increased doses administered to the patients, but also provides further diagnostic information contained in the volumetric images. The assessed CBCT protocols provide images that are noisy, but with very good spatial resolution. PACS number(s): 87.59.‐e, 87.59.‐C, 87.59.‐cf, 87.59.Dj, 87.57. uq PMID:27455474

Biplane interventional pediatric system with cone-beam CT: dose and image quality characterization for the default protocols.

PubMed

Corredoira, Eva; Vañó, Eliseo; Alejo, Luis; Ubeda, Carlos; Gutiérrez-Larraya, Federico; Garayoa, Julia

2016-07-08

The aim of this study was to assess image quality and radiation dose of a biplane angiographic system with cone-beam CT (CBCT) capability tuned for pediatric cardiac procedures. The results of this study can be used to explore dose reduction techniques. For pulsed fluoroscopy and cine modes, polymethyl methacrylate phantoms of various thicknesses and a Leeds TOR 18-FG test object were employed. Various fields of view (FOV) were selected. For CBCT, the study employed head and body dose phantoms, Catphan 504, and an anthropomorphic cardiology phantom. The study also compared two 3D rotational angiography protocols. The entrance surface air kerma per frame increases by a factor of 3-12 when comparing cine and fluoroscopy frames. The biggest difference in the signal-to- noise ratio between fluoroscopy and cine modes occurs at FOV 32 cm because fluoroscopy is acquired at a 1440 × 1440 pixel matrix size and in unbinned mode, whereas cine is acquired at 720 × 720 pixels and in binned mode. The high-contrast spatial resolution of cine is better than that of fluoroscopy, except for FOV 32 cm, because fluoroscopy mode with 32 cm FOV is unbinned. Acquiring CBCT series with a 16 cm head phantom using the standard dose protocol results in a threefold dose increase compared with the low-dose protocol. Although the amount of noise present in the images acquired with the low-dose protocol is much higher than that obtained with the standard mode, the images present better spatial resolution. A 1 mm diameter rod with 250 Hounsfield units can be distinguished in reconstructed images with an 8 mm slice width. Pediatric-specific protocols provide lower doses while maintaining sufficient image quality. The system offers a novel 3D imaging mode. The acquisition of CBCT images results in increased doses administered to the patients, but also provides further diagnostic information contained in the volumetric images. The assessed CBCT protocols provide images that are noisy, but with very good spatial resolution. © 2016 The Authors.

Near-optimal protocols in complex nonequilibrium transformations

DOE PAGES

Gingrich, Todd R.; Rotskoff, Grant M.; Crooks, Gavin E.; ...

2016-08-29

The development of sophisticated experimental means to control nanoscale systems has motivated efforts to design driving protocols that minimize the energy dissipated to the environment. Computational models are a crucial tool in this practical challenge. In this paper, we describe a general method for sampling an ensemble of finite-time, nonequilibrium protocols biased toward a low average dissipation. In addition, we show that this scheme can be carried out very efficiently in several limiting cases. As an application, we sample the ensemble of low-dissipation protocols that invert the magnetization of a 2D Ising model and explore how the diversity of themore » protocols varies in response to constraints on the average dissipation. In this example, we find that there is a large set of protocols with average dissipation close to the optimal value, which we argue is a general phenomenon.« less

A novel approach for quantitative harmonization in PET.

PubMed

Namías, M; Bradshaw, T; Menezes, V O; Machado, M A D; Jeraj, R

2018-05-04

Positron emission tomography (PET) imaging allows for measurement of activity concentrations of a given radiotracer in vivo. The quantitative capabilities of PET imaging are particularly important in the context of monitoring response to treatment, where quantitative changes in tracer uptake could be used as a biomarker of treatment response. Reconstruction algorithms and settings have a significant impact on PET quantification. In this work we introduce a novel harmonization methodology requiring only a simple cylindrical phantom and show that it can match the performance of more complex harmonization approaches based on phantoms with spherical inserts. Resolution and noise measurements from cylindrical phantoms are used to simulate the spherical inserts from NEMA image quality phantoms. An optimization algorithm was used to find the optimal smoothing filters for the simulated NEMA phantom images to identify those that best harmonized the PET scanners. Our methodology was tested on seven different PET models from two manufacturers installed at five institutions. Our methodology is able to predict contrast recovery coefficients (CRCs) from NEMA phantoms with errors within  ±5.2% for CRCmax and  ±3.7% for CRCmean (limits of agreement  =  95%). After applying the proposed harmonization protocol, all the CRC values were within the tolerances from EANM. Quantitative harmonization in compliance with the EARL FDG-PET/CT accreditation program is achieved in a simpler way, without the need of NEMA phantoms. This may lead to simplified scanner harmonization workflows more accessible to smaller institutions.

CRISPR/Cas9-mediated knock-in of an optimized TetO repeat for live cell imaging of endogenous loci.

PubMed

Tasan, Ipek; Sustackova, Gabriela; Zhang, Liguo; Kim, Jiah; Sivaguru, Mayandi; HamediRad, Mohammad; Wang, Yuchuan; Genova, Justin; Ma, Jian; Belmont, Andrew S; Zhao, Huimin

2018-06-15

Nuclear organization has an important role in determining genome function; however, it is not clear how spatiotemporal organization of the genome relates to functionality. To elucidate this relationship, a method for tracking any locus of interest is desirable. Recently clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) or transcription activator-like effectors were adapted for imaging endogenous loci; however, they are mostly limited to visualization of repetitive regions. Here, we report an efficient and scalable method named SHACKTeR (Short Homology and CRISPR/Cas9-mediated Knock-in of a TetO Repeat) for live cell imaging of specific chromosomal regions without the need for a pre-existing repetitive sequence. SHACKTeR requires only two modifications to the genome: CRISPR/Cas9-mediated knock-in of an optimized TetO repeat and its visualization by TetR-EGFP expression. Our simplified knock-in protocol, utilizing short homology arms integrated by polymerase chain reaction, was successful at labeling 10 different loci in HCT116 cells. We also showed the feasibility of knock-in into lamina-associated, heterochromatin regions, demonstrating that these regions prefer non-homologous end joining for knock-in. Using SHACKTeR, we were able to observe DNA replication at a specific locus by long-term live cell imaging. We anticipate the general applicability and scalability of our method will enhance causative analyses between gene function and compartmentalization in a high-throughput manner.

Effect of automated tube voltage selection, integrated circuit detector and advanced iterative reconstruction on radiation dose and image quality of 3rd generation dual-source aortic CT angiography: An intra-individual comparison.

PubMed

Mangold, Stefanie; De Cecco, Carlo N; Wichmann, Julian L; Canstein, Christian; Varga-Szemes, Akos; Caruso, Damiano; Fuller, Stephen R; Bamberg, Fabian; Nikolaou, Konstantin; Schoepf, U Joseph

2016-05-01

To compare, on an intra-individual basis, the effect of automated tube voltage selection (ATVS), integrated circuit detector and advanced iterative reconstruction on radiation dose and image quality of aortic CTA studies using 2nd and 3rd generation dual-source CT (DSCT). We retrospectively evaluated 32 patients who had undergone CTA of the entire aorta with both 2nd generation DSCT at 120kV using filtered back projection (FBP) (protocol 1) and 3rd generation DSCT using ATVS, an integrated circuit detector and advanced iterative reconstruction (protocol 2). Contrast-to-noise ratio (CNR) was calculated. Image quality was subjectively evaluated using a five-point scale. Radiation dose parameters were recorded. All studies were considered of diagnostic image quality. CNR was significantly higher with protocol 2 (15.0±5.2 vs 11.0±4.2; p<.0001). Subjective image quality analysis revealed no significant differences for evaluation of attenuation (p=0.08501) but image noise was rated significantly lower with protocol 2 (p=0.0005). Mean tube voltage and effective dose were 94.7±14.1kV and 6.7±3.9mSv with protocol 2; 120±0kV and 11.5±5.2mSv with protocol 1 (p<0.0001, respectively). Aortic CTA performed with 3rd generation DSCT, ATVS, integrated circuit detector, and advanced iterative reconstruction allow a substantial reduction of radiation exposure while improving image quality in comparison to 120kV imaging with FBP. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Impact of uncertain head tissue conductivity in the optimization of transcranial direct current stimulation for an auditory target

NASA Astrophysics Data System (ADS)

Schmidt, Christian; Wagner, Sven; Burger, Martin; van Rienen, Ursula; Wolters, Carsten H.

2015-08-01

Objective. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modify neural excitability. Using multi-array tDCS, we investigate the influence of inter-individually varying head tissue conductivity profiles on optimal electrode configurations for an auditory cortex stimulation. Approach. In order to quantify the uncertainty of the optimal electrode configurations, multi-variate generalized polynomial chaos expansions of the model solutions are used based on uncertain conductivity profiles of the compartments skin, skull, gray matter, and white matter. Stochastic measures, probability density functions, and sensitivity of the quantities of interest are investigated for each electrode and the current density at the target with the resulting stimulation protocols visualized on the head surface. Main results. We demonstrate that the optimized stimulation protocols are only comprised of a few active electrodes, with tolerable deviations in the stimulation amplitude of the anode. However, large deviations in the order of the uncertainty in the conductivity profiles could be noted in the stimulation protocol of the compensating cathodes. Regarding these main stimulation electrodes, the stimulation protocol was most sensitive to uncertainty in skull conductivity. Finally, the probability that the current density amplitude in the auditory cortex target region is supra-threshold was below 50%. Significance. The results suggest that an uncertain conductivity profile in computational models of tDCS can have a substantial influence on the prediction of optimal stimulation protocols for stimulation of the auditory cortex. The investigations carried out in this study present a possibility to predict the probability of providing a therapeutic effect with an optimized electrode system for future auditory clinical and experimental procedures of tDCS applications.

Dedicated dental volumetric and total body multislice computed tomography: a comparison of image quality and radiation dose

NASA Astrophysics Data System (ADS)

Strocchi, Sabina; Colli, Vittoria; Novario, Raffaele; Carrafiello, Gianpaolo; Giorgianni, Andrea; Macchi, Aldo; Fugazzola, Carlo; Conte, Leopoldo

2007-03-01

Aim of this work is to compare the performances of a Xoran Technologies i-CAT Cone Beam CT for dental applications with those of a standard total body multislice CT (Toshiba Aquilion 64 multislice) used for dental examinations. Image quality and doses to patients have been compared for the three main i-CAT protocols, the Toshiba standard protocol and a Toshiba modified protocol. Images of two phantoms have been acquired: a standard CT quality control phantom and an Alderson Rando ® anthropomorphic phantom. Image noise, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR) and geometric accuracy have been considered. Clinical image quality was assessed. Effective dose and doses to main head and neck organs were evaluated by means of thermo-luminescent dosimeters (TLD-100) placed in the anthropomorphic phantom. A Quality Index (QI), defined as the ratio of squared CNR to effective dose, has been evaluated. The evaluated effective doses range from 0.06 mSv (i-CAT 10 s protocol) to 2.37 mSv (Toshiba standard protocol). The Toshiba modified protocol (halved tube current, higher pitch value) imparts lower effective dose (0.99 mSv). The conventional CT device provides lower image noise and better SNR, but clinical effectiveness similar to that of dedicated dental CT (comparable CNR and clinical judgment). Consequently, QI values are much higher for this second CT scanner. No geometric distortion has been observed with both devices. As a conclusion, dental volumetric CT supplies adequate image quality to clinical purposes, at doses that are really lower than those imparted by a conventional CT device.

Methodology for quantitative rapid multi-tracer PET tumor characterizations.

PubMed

Kadrmas, Dan J; Hoffman, John M

2013-10-04

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted.

Methodology for Quantitative Rapid Multi-Tracer PET Tumor Characterizations

PubMed Central

Kadrmas, Dan J.; Hoffman, John M.

2013-01-01

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted. PMID:24312149

Evaluation of the articular cartilage of the knee joint: value of adding a T2 mapping sequence to a routine MR imaging protocol.

PubMed

Kijowski, Richard; Blankenbaker, Donna G; Munoz Del Rio, Alejandro; Baer, Geoffrey S; Graf, Ben K

2013-05-01

To determine whether the addition of a T2 mapping sequence to a routine magnetic resonance (MR) imaging protocol could improve diagnostic performance in the detection of surgically confirmed cartilage lesions within the knee joint at 3.0 T. This prospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The study group consisted of 150 patients (76 male and 74 female patients with an average age of 41.2 and 41.5 years, respectively) who underwent MR imaging and arthroscopy of the knee joint. MR imaging was performed at 3.0 T by using a routine protocol with the addition of a sagittal T2 mapping sequence. Images from all MR examinations were reviewed in consensus by two radiologists before surgery to determine the presence or absence of cartilage lesions on each articular surface, first by using the routine MR protocol alone and then by using the routine MR protocol with T2 maps. Each articular surface was then evaluated at arthroscopy. Generalized estimating equation models were used to compare the sensitivity and specificity of the routine MR imaging protocol with and without T2 maps in the detection of surgically confirmed cartilage lesions. The sensitivity and specificity in the detection of 351 cartilage lesions were 74.6% and 97.8%, respectively, for the routine MR protocol alone and 88.9% and 93.1% for the routine MR protocol with T2 maps. Differences in sensitivity and specificity were statistically significant (P < .001). The addition of T2 maps to the routine MR imaging protocol significantly improved the sensitivity in the detection of 24 areas of cartilage softening (from 4.2% to 62%, P < .001), 41 areas of cartilage fibrillation (from 20% to 66%, P < .001), and 96 superficial partial-thickness cartilage defects (from 71% to 88%, P = .004). The addition of a T2 mapping sequence to a routine MR protocol at 3.0 T improved sensitivity in the detection of cartilage lesions within the knee joint from 74.6% to 88.9%, with only a small reduction in specificity. The greatest improvement in sensitivity with use of the T2 maps was in the identification of early cartilage degeneration. © RSNA, 2013.

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

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

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

Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation

NASA Astrophysics Data System (ADS)

Wang, Zhaohui; Ha, Seunghan; Kim, Kang

2012-02-01

A new design of light illumination scheme for deep tissue photoacoustic (PA) imaging, a light catcher, is proposed and evaluated by in silico simulation. Finite element (FE)-based numerical simulation model was developed for photoacoustic (PA) imaging in soft tissues. In this in silico simulation using a commercially available FE simulation package (COMSOL MultiphysicsTM, COMSOL Inc., USA), a short-pulsed laser point source (pulse length of 5 ns) was placed in water on the tissue surface. Overall, four sets of simulation models were integrated together to describe the physical principles of PA imaging. Light energy transmission through background tissues from the laser source to the target tissue or contrast agent was described by diffusion equation. The absorption of light energy and its conversion to heat by target tissue or contrast agent was modeled using bio-heat equation. The heat then causes the stress and strain change, and the resulting displacement of the target surface produces acoustic pressure. The created wide-band acoustic pressure will propagate through background tissues to the ultrasound detector, which is governed by acoustic wave equation. Both optical and acoustical parameters in soft tissues such as scattering, absorption, and attenuation are incorporated in tissue models. PA imaging performance with different design parameters of the laser source and energy delivery scheme was investigated. The laser light illumination into the deep tissues can be significantly improved by up to 134.8% increase of fluence rate by introducing a designed compact light catcher with highly reflecting inner surface surrounding the light source. The optimized parameters through this simulation will guide the design of PA system for deep tissue imaging, and help to form the base protocols of experimental evaluations in vitro and in vivo.

Optimizing CT technique to reduce radiation dose: effect of changes in kVp, iterative reconstruction, and noise index on dose and noise in a human cadaver.

PubMed

Chang, Kevin J; Collins, Scott; Li, Baojun; Mayo-Smith, William W

2017-06-01

For assessment of the effect of varying the peak kilovoltage (kVp), the adaptive statistical iterative reconstruction technique (ASiR), and automatic dose modulation on radiation dose and image noise in a human cadaver, a cadaver torso underwent CT scanning at 80, 100, 120 and 140 kVp, each at ASiR settings of 0, 30 and 50 %, and noise indices (NIs) of 5.5, 11 and 22. The volume CT dose index (CTDI vol ), image noise, and attenuation values of liver and fat were analyzed for 20 data sets. Size-specific dose estimates (SSDEs) and liver-to-fat contrast-to-noise ratios (CNRs) were calculated. Values for different combinations of kVp, ASiR, and NI were compared. The CTDI vol varied by a power of 2 with kVp values between 80 and 140 without ASiR. Increasing ASiR levels allowed a larger decrease in CTDI vol and SSDE at higher kVp than at lower kVp while image noise was held constant. In addition, CTDI vol and SSDE decreased with increasing NI at each kVp, but the decrease was greater at higher kVp than at lower kVp. Image noise increased with decreasing kVp despite a fixed NI; however, this noise could be offset with the use of ASiR. The CT number of the liver remained unchanged whereas that of fat decreased as the kVp decreased. Image noise and dose vary in a complicated manner when the kVp, ASiR, and NI are varied in a human cadaver. Optimization of CT protocols will require balancing of the effects of each of these parameters to maximize image quality while minimizing dose.

Optimal imaging and analysis of human vaginal coating by drug delivery gels

PubMed Central

Henderson, Marcus H; Couchman, Grace M; Walmer, David K; Peters, Jennifer J; Owen, Derek H; Brown, Matthew A; Lavine, Michael L; Katz, David F

2007-01-01

Objective We used a new optical imaging technique to compare human intravaginal coating distributions of Conceptrol® and Advantage™. These gels are surrogates for future microbicidal gels, differing in molecular structures and biophysical properties. Methods For each protocol, a 3-mL gel bolus was inserted to the posterior fornix while the woman was in the supine position. She then either: (1) remained supine (10 min); or (2) sat up (1 min), stood up (1 min), sat down (1 min), and returned to supine for a net elapsed time of 10 min. The imaging device is sized/shaped like a phallus, and measurements while the device was inserted provide data that simulate peri-intromission coating. Results Coating by Advantage™ was more extensive and uniform than coating by Conceptrol®, with smaller bare spots of uncoated epithelium. Change in posture tended to increase extent and uniformity of coating, details differing between gels. Conclusions Results are consistent with predictions of mechanistic coating theory, using gel rheological data as inputs. PMID:17241845

A Platform to Monitor Tumor Cellular and Vascular Response to Radiation Therapy by Optical Coherence Tomography and Fluorescence Microscopy in vivo

NASA Astrophysics Data System (ADS)

Leung, Michael Ka Kit

Radiotherapy plays a significant role in cancer treatment, and is thought to be curative by mainly killing tumor cells through damage to their genetic material. However, recent findings indicate that the tumor's vascular blood supply is also a major determinant of radiation response. The goals of this thesis are to: (1) develop an experimental platform for small animals to deliver ionizing radiation and perform high-resolution optical imaging to treatment targets, and (2) use this toolkit to longitudinally monitor the response of tumors and the associated vasculature. The thesis has achieved: (1) customization of a novel micro-irradiator for mice, (2) technical development of an improved optical coherence tomography imaging system, (3) comprehensive experimental protocol and imaging optimization for optical microscopy in a specialized animal model, and (4) completion of a feasibility study to demonstrate the capabilities of the experimental platform in monitoring the response of tumor and vasculature to radiotherapy.

A Hitchhiker's Guide to Functional Magnetic Resonance Imaging

PubMed Central

Soares, José M.; Magalhães, Ricardo; Moreira, Pedro S.; Sousa, Alexandre; Ganz, Edward; Sampaio, Adriana; Alves, Victor; Marques, Paulo; Sousa, Nuno

2016-01-01

Functional Magnetic Resonance Imaging (fMRI) studies have become increasingly popular both with clinicians and researchers as they are capable of providing unique insights into brain functions. However, multiple technical considerations (ranging from specifics of paradigm design to imaging artifacts, complex protocol definition, and multitude of processing and methods of analysis, as well as intrinsic methodological limitations) must be considered and addressed in order to optimize fMRI analysis and to arrive at the most accurate and grounded interpretation of the data. In practice, the researcher/clinician must choose, from many available options, the most suitable software tool for each stage of the fMRI analysis pipeline. Herein we provide a straightforward guide designed to address, for each of the major stages, the techniques, and tools involved in the process. We have developed this guide both to help those new to the technique to overcome the most critical difficulties in its use, as well as to serve as a resource for the neuroimaging community. PMID:27891073

Synthetic methodology for asymmetric ferrocene derived bio-conjugate systems via solid phase resin-based methodology.

PubMed

Scarborough, J Hunter; Gonzalez, Paulina; Rodich, Sean; Green, Kayla N

2015-03-12

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of "point of care" techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician's office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface.

Smart detection of microRNAs through fluorescence enhancement on a photonic crystal.

PubMed

Pasquardini, L; Potrich, C; Vaghi, V; Lunelli, L; Frascella, F; Descrovi, E; Pirri, C F; Pederzolli, C

2016-04-01

The detection of low abundant biomarkers, such as circulating microRNAs, demands innovative detection methods with increased resolution, sensitivity and specificity. Here, a biofunctional surface was implemented for the selective capture of microRNAs, which were detected through fluorescence enhancement directly on a photonic crystal. To set up the optimal biofunctional surface, epoxy-coated commercially available microscope slides were spotted with specific anti-microRNA probes. The optimal concentration of probe as well as of passivating agent were selected and employed for titrating the microRNA hybridization. Cross-hybridization of different microRNAs was also tested, resulting negligible. Once optimized, the protocol was adapted to the photonic crystal surface, where fluorescent synthetic miR-16 was hybridized and imaged with a dedicated equipment. The photonic crystal consists of a dielectric multilayer patterned with a grating structure. In this way, it is possible to take advantage from both a resonant excitation of fluorophores and an angularly redirection of the emitted radiation. As a result, a significant fluorescence enhancement due to the resonant structure is collected from the patterned photonic crystal with respect to the outer non-structured surface. The dedicated read-out system is compact and based on a wide-field imaging detection, with little or no optical alignment issues, which makes this approach particularly interesting for further development such as for example in microarray-type bioassays. Copyright © 2016 Elsevier B.V. All rights reserved.

A Cadaveric Analysis of the Optimal Radiographic Angle for Evaluating Trochlear Depth.

PubMed

Weinberg, Douglas Stanley; Gilmore, Allison; Guraya, Sahejmeet S; Wang, David M; Liu, Raymond W

2017-02-01

Disorders of the patellofemoral joint are common. Diagnosis and management often involves the use tangential imaging of the patella and trochlear grove, with the sunrise projection being the most common. However, imaging protocols vary between institutions, and limited data exist to determine which radiographic projections provide optimal visualization of the trochlear groove at its deepest point. Plain radiographs of 48 cadaveric femora were taken at various beam-femur angles and the maximum trochlear depth was measured; a tilt-board apparatus was used to elevate the femur in 5-degree increments between 40 and 75 degrees. A corollary experiment was undertaken to investigate beam-femur angles osteologically: digital representations of each bone were created with a MicroScribe digitizer, and trochlear depth was measured on all specimens at beam-femur angles from 0 to 75 degrees. The results of the radiographic and digitizer experiments showed that the maximum trochlear grove depth occurred at a beam-femur angle of 50 degrees. These results suggest that the optimal beam-femur angle for visualizing maximum trochlear depth is 50 degrees. This is significantly lower than the beam-femur angle of 90 degrees typically used in the sunrise projection. Clinicians evaluating trochlear depth on sunrise projections may be underestimating maximal depth and evaluating a nonarticulating portion of the femur. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Chelator-Free 64Cu-Integrated Gold Nanomaterials for Positron Emission Tomography Imaging Guided Photothermal Cancer Therapy

PubMed Central

2015-01-01

Using positron emission tomography (PET) imaging to monitor and quantitatively analyze the delivery and localization of Au nanomaterials (NMs), a widely used photothermal agent, is essential to optimize therapeutic protocols to achieve individualized medicine and avoid side effects. Coupling radiometals to Au NMs via a chelator faces the challenges of possible detachment of the radiometals as well as surface property changes of the NMs. In this study, we reported a simple and general chelator-free 64Cu radiolabeling method by chemically reducing 64Cu on the surface of polyethylene glycol (PEG)-stabilized Au NMs regardless of their shape and size. Our 64Cu-integrated NMs are proved to be radiochemically stable and can provide an accurate and sensitive localization of NMs through noninvasive PET imaging. We further integrated 64Cu onto arginine-glycine-aspartic acid (RGD) peptide modified Au nanorods (NRs) for tumor theranostic application. These NRs showed high tumor targeting ability in a U87MG glioblastoma xenograft model and were successfully used for PET image-guided photothermal therapy. PMID:25019252

MRI of perfluorocarbon emulsion kinetics in rodent mammary tumours

NASA Astrophysics Data System (ADS)

Fan, Xiaobing; River, Jonathan N.; Muresan, Adrian S.; Popescu, Carmen; Zamora, Marta; Culp, Rita M.; Karczmar, Gregory S.

2006-01-01

Perfluorocarbon (PFC) emulsions can be imaged directly by fluorine-19 MRI. We developed an optimized protocol for preparing PFC droplets of uniform size, evaluated use of the resulting droplets as blood pool contrast agents, studied their uptake by tumours and determined the spatial resolution with which they can be imaged at 4.7 T. Perfluorocarbon droplets of three different average sizes (324, 293 and 225 nm) were prepared using a microemulsifier. Images of PFC droplets with good signal-to-noise ratio were acquired with 625 µm in-plane resolution, 3 mm slice thickness and acquisition time of ~4.5 min per image. Kinetics of washout were determined using a simple mathematical model. The maximum uptake of the PFC droplets was three times greater at the tumour rim than in muscle, but the washout rate was two to three times slower in the tumour. The results are consistent with leakage of the droplets into the tumour extravascular space due to the hyper-permeability of tumour capillaries. PFC droplets may allow practical and quantitative measurements of blood volume and capillary permeability in tumours with reasonable spatial resolution.

Advances in Imaging and Management Trends of Traumatic Aortic Injuries

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

Nagpal, Prashant, E-mail: drprashantnagpal@gmail.com, E-mail: Prashant-nagpal@uiowa.edu; Mullan, Brian F.; Sen, Indrani

Acute traumatic aortic injury (ATAI) is a life-threatening injury. CT is the imaging tool of choice, and the knowledge of direct and indirect signs of injury, grading system, and current management protocol helps the emergency radiologist to better identify and classify the injury and provide additional details that can impact management options. Newer dual-source CT technology with ultrafast acquisition speed has also influenced the appropriate protocol for imaging in patients with suspected ATAI. This review highlights the imaging protocol in patients with blunt trauma, CT appearance and grading systems of ATAI, management options, and the role of the multidisciplinary teammore » in the management of these patients. We also briefly review the current literature on the definition, treatment, and follow-up protocol in patients with minimal aortic injury.« less

Multimodal Image-Based Virtual Reality Presurgical Simulation and Evaluation for Trigeminal Neuralgia and Hemifacial Spasm.

PubMed

Yao, Shujing; Zhang, Jiashu; Zhao, Yining; Hou, Yuanzheng; Xu, Xinghua; Zhang, Zhizhong; Kikinis, Ron; Chen, Xiaolei

2018-05-01

To address the feasibility and predictive value of multimodal image-based virtual reality in detecting and assessing features of neurovascular confliction (NVC), particularly regarding the detection of offending vessels, degree of compression exerted on the nerve root, in patients who underwent microvascular decompression for nonlesional trigeminal neuralgia and hemifacial spasm (HFS). This prospective study includes 42 consecutive patients who underwent microvascular decompression for classic primary trigeminal neuralgia or HFS. All patients underwent preoperative 1.5-T magnetic resonance imaging (MRI) with T2-weighted three-dimensional (3D) sampling perfection with application-optimized contrasts by using different flip angle evolutions, 3D time-of-flight magnetic resonance angiography, and 3D T1-weighted gadolinium-enhanced sequences in combination, whereas 2 patients underwent extra experimental preoperative 7.0-T MRI scans with the same imaging protocol. Multimodal MRIs were then coregistered with open-source software 3D Slicer, followed by 3D image reconstruction to generate virtual reality (VR) images for detection of possible NVC in the cerebellopontine angle. Evaluations were performed by 2 reviewers and compared with the intraoperative findings. For detection of NVC, multimodal image-based VR sensitivity was 97.6% (40/41) and specificity was 100% (1/1). Compared with the intraoperative findings, the κ coefficients for predicting the offending vessel and the degree of compression were >0.75 (P < 0.001). The 7.0-T scans have a clearer view of vessels in the cerebellopontine angle, which may have significant impact on detection of small-caliber offending vessels with relatively slow flow speed in cases of HFS. Multimodal image-based VR using 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions in combination with 3D time-of-flight magnetic resonance angiography sequences proved to be reliable in detecting NVC and in predicting the degree of root compression. The VR image-based simulation correlated well with the real surgical view. Copyright © 2018 Elsevier Inc. All rights reserved.

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children.

PubMed

Kim, Hyun Gi; Lee, Ho-Joon; Lee, Seung-Koo; Kim, Hyun Ji; Kim, Myung-Joon

2017-09-01

To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for <3-year-old patients and applied 30% ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P < 0.001). Qualitative analysis showed higher gray-white matter differentiation and sharpness and preserved overall diagnostic quality in the images with ASIR-V. Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. • It is possible to reduce radiation dose and improve image quality with ASIR-V. • We improved noise and CNR and decreased radiation dose. • Sharpness improved with ASIR-V. • Total radiation dose was decreased by 12.8% to 34.0%.

Interoperative fundus image and report sharing in compliance with integrating the healthcare enterprise conformance and web access to digital imaging and communication in medicine persistent object protocol.

PubMed

Wu, Hui-Qun; Lv, Zheng-Min; Geng, Xing-Yun; Jiang, Kui; Tang, Le-Min; Zhou, Guo-Min; Dong, Jian-Cheng

2013-01-01

To address issues in interoperability between different fundus image systems, we proposed a web eye-picture archiving and communication system (PACS) framework in conformance with digital imaging and communication in medicine (DICOM) and health level 7 (HL7) protocol to realize fundus images and reports sharing and communication through internet. Firstly, a telemedicine-based eye care work flow was established based on integrating the healthcare enterprise (IHE) Eye Care technical framework. Then, a browser/server architecture eye-PACS system was established in conformance with the web access to DICOM persistent object (WADO) protocol, which contains three tiers. In any client system installed with web browser, clinicians could log in the eye-PACS to observe fundus images and reports. Multipurpose internet mail extensions (MIME) type of a structured report is saved as pdf/html with reference link to relevant fundus image using the WADO syntax could provide enough information for clinicians. Some functions provided by open-source Oviyam could be used to query, zoom, move, measure, view DICOM fundus images. Such web eye-PACS in compliance to WADO protocol could be used to store and communicate fundus images and reports, therefore is of great significance for teleophthalmology.

Imaging of Lipids and Metabolites Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

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

Lanekoff, Ingela; Laskin, Julia

In recent years, mass spectroscopy imaging (MSI) has emerged as a foundational technique in metabolomics and drug screening providing deeper understanding of complex mechanistic pathways within biochemical systems and biological organisms. We have been invited to contribute a chapter to a new Springer series volume, entitled “Mass Spectrometry Imaging of Small Molecules”. The volume is planned for the highly successful lab protocol series Methods in Molecular Biology, published by Humana Press, USA. The volume is aimed to equip readers with step-by-step mass spectrometric imaging protocols and bring rapidly maturing methods of MS imaging to life science researchers. The chapter willmore » provide a detailed protocol of ambient MSI by use of nanospray desorption electrospray ionization.« less

Optimizing MRI Logistics: Focused Process Improvements Can Increase Throughput in an Academic Radiology Department.

PubMed

O'Brien, Jeremy J; Stormann, Jeremy; Roche, Kelli; Cabral-Goncalves, Ines; Monks, Annamarie; Hallett, Donna; Mortele, Koenraad J

2017-02-01

The purpose of this study was to describe and evaluate the effect of focused process improvements on protocol selection and scheduling in the MRI division of a busy academic medical center, as measured by examination and room times, magnet fill rate, and potential revenue increases and cost savings to the department. Focused process improvements, led by a multidisciplinary team at a large academic medical center, were directed at streamlining MRI protocols and optimizing matching protocol ordering to scheduling while maintaining or improving image quality. Data were collected before (June 2013) and after (March 2015) implementation of focused process improvements and divided by subspecialty on type of examination, allotted examination time, actual examination time, and MRI parameters. Direct and indirect costs were compiled and analyzed in consultation with the business department. Data were compared with evaluated effects on selected outcome and efficiency measures, as well as revenue and cost considerations. Statistical analysis was performed using a t test. During the month of June 2013, 2145 MRI examinations were performed at our center; 2702 were performed in March 2015. Neuroradiology examinations were the most common (59% in June 2013, 56% in March 2015), followed by body examinations (25% and 27%). All protocols and parameters were analyzed and streamlined for each examination, with slice thickness, TR, and echo train length among the most adjusted parameters. Mean time per examination decreased from 43.4 minutes to 36.7 minutes, and mean room time per patient decreased from 46.3 to 43.6 minutes (p = 0.009). Potential revenue from increased throughput may yield up to $3 million yearly (at $800 net revenue per scan) or produce cost savings if the facility can reduce staffed scanner hours or the number of scanners in its fleet. Actual revenue and expense impacts depend on the facility's fixed and variable cost structure, payer contracts, MRI fleet composition, and unmet MRI demand. Focused process improvements in selecting MRI protocols and scheduling examinations significantly increased throughput in the MRI division, thereby increasing capacity and revenue. Shorter scan and department times may also improve patient experience.

A study of the dependence of protocol optimization on the left ventricular ejection fraction (LVEF) in coronary CT angiography (CCTA) examination

NASA Astrophysics Data System (ADS)

Yu, Dong-Su; Cho, Jae-Hwan; Park, Cheol-Soo; Yoo, Heung-Joon; Choi, Cheon-Woong; Kim, Dae-Hyun

2013-10-01

The purpose of this study is to obtain a good quality image and to minimize patient doses and re-examination rates through an optimization of the protocol for coronary computed tomography angiography (CCTA) examination based on a comparison and an analysis of the heart rates (HRs) of patients who had left ventricular ejection fraction (LVEF) values of less than 40% and the HRs of ordinary patients. This study targeted 16 patients who received thallium single-photon emission computed tomography (SPECT) or echocardiography simultaneously among the patients who took the CCTA examinations. Depending on the LVEF value (30 ˜ 39, 40 ˜ 49, 50 ˜ 59, and 60% or above), the patients were divided into groups of four based on HR (50 ˜ 59, 60 ˜ 69, 70 ˜ 79, and 80 or above). DynEva software was used to set the region of interest (ROI) on the ascending aorta and for a measurement of the threshold value. Comparisons and analyses were made based on the LVEF values and the HRs, after which the results were compared with the ones from the existing examination protocols and contrast medium protocols. According to the study results, the relation between the HR and the LVEF demonstrated that it took a long time to reach the true 100 hounsfield unit (HU) when the LVEF was 40% or below. Contrasting media showed significant differences, except in the case where the HR was 80 or above, and/or the LVEF was less than 40%. Moreover, for an LVEF of less than 40%, time differences were significant when contrasting media reached the true 100 HU to begin the scanning process. Therefore, it was possible to predict that the contrasting media were already being washed out from the left ventricle.

Development of a protocol to optimize electric power consumption and life cycle environmental impacts for operation of wastewater treatment plant.

PubMed

Piao, Wenhua; Kim, Changwon; Cho, Sunja; Kim, Hyosoo; Kim, Minsoo; Kim, Yejin

2016-12-01

In wastewater treatment plants (WWTPs), the portion of operating costs related to electric power consumption is increasing. If the electric power consumption decreased, however, it would be difficult to comply with the effluent water quality requirements. A protocol was proposed to minimize the environmental impacts as well as to optimize the electric power consumption under the conditions needed to meet the effluent water quality standards in this study. This protocol was comprised of six phases of procedure and was tested using operating data from S-WWTP to prove its applicability. The 11 major operating variables were categorized into three groups using principal component analysis and K-mean cluster analysis. Life cycle assessment (LCA) was conducted for each group to deduce the optimal operating conditions for each operating state. Then, employing mathematical modeling, six improvement plans to reduce electric power consumption were deduced. The electric power consumptions for suggested plans were estimated using an artificial neural network. This was followed by a second round of LCA conducted on the plans. As a result, a set of optimized improvement plans were derived for each group that were able to optimize the electric power consumption and life cycle environmental impact, at the same time. Based on these test results, the WWTP operating management protocol presented in this study is deemed able to suggest optimal operating conditions under which power consumption can be optimized with minimal life cycle environmental impact, while allowing the plant to meet water quality requirements.

Optimized protocol for quantitative multiple reaction monitoring-based proteomic analysis of formalin-fixed, paraffin embedded tissues

PubMed Central

Kennedy, Jacob J.; Whiteaker, Jeffrey R.; Schoenherr, Regine M.; Yan, Ping; Allison, Kimberly; Shipley, Melissa; Lerch, Melissa; Hoofnagle, Andrew N.; Baird, Geoffrey Stuart; Paulovich, Amanda G.

2016-01-01

Despite a clinical, economic, and regulatory imperative to develop companion diagnostics, precious few new biomarkers have been successfully translated into clinical use, due in part to inadequate protein assay technologies to support large-scale testing of hundreds of candidate biomarkers in formalin-fixed paraffin embedded (FFPE) tissues. While the feasibility of using targeted, multiple reaction monitoring-mass spectrometry (MRM-MS) for quantitative analyses of FFPE tissues has been demonstrated, protocols have not been systematically optimized for robust quantification across a large number of analytes, nor has the performance of peptide immuno-MRM been evaluated. To address this gap, we used a test battery approach coupled to MRM-MS with the addition of stable isotope labeled standard peptides (targeting 512 analytes) to quantitatively evaluate the performance of three extraction protocols in combination with three trypsin digestion protocols (i.e. 9 processes). A process based on RapiGest buffer extraction and urea-based digestion was identified to enable similar quantitation results from FFPE and frozen tissues. Using the optimized protocols for MRM-based analysis of FFPE tissues, median precision was 11.4% (across 249 analytes). There was excellent correlation between measurements made on matched FFPE and frozen tissues, both for direct MRM analysis (R2 = 0.94) and immuno-MRM (R2 = 0.89). The optimized process enables highly reproducible, multiplex, standardizable, quantitative MRM in archival tissue specimens. PMID:27462933

Optimising μCT imaging of the middle and inner cat ear.

PubMed

Seifert, H; Röher, U; Staszyk, C; Angrisani, N; Dziuba, D; Meyer-Lindenberg, A

2012-04-01

This study's aim was to determine the optimal scan parameters for imaging the middle and inner ear of the cat with micro-computertomography (μCT). Besides, the study set out to assess whether adequate image quality can be obtained to use μCT in diagnostics and research on cat ears. For optimisation, μCT imaging of two cat skull preparations was performed using 36 different scanning protocols. The μCT-scans were evaluated by four experienced experts with regard to the image quality and detail detectability. By compiling a ranking of the results, the best possible scan parameters could be determined. From a third cat's skull, a μCT-scan, using these optimised scan parameters, and a comparative clinical CT-scan were acquired. Afterwards, histological specimens of the ears were produced which were compared to the μCT-images. The comparison shows that the osseous structures are depicted in detail. Although soft tissues cannot be differentiated, the osseous structures serve as valuable spatial orientation of relevant nerves and muscles. Clinical CT can depict many anatomical structures which can also be seen on μCT-images, but these appear a lot less sharp and also less detailed than with μCT. © 2011 Blackwell Verlag GmbH.

GUI implementation of image encryption and decryption using Open CV-Python script on secured TFTP protocol

NASA Astrophysics Data System (ADS)

Reddy, K. Rasool; Rao, Ch. Madhava

2018-04-01

Currently safety is one of the primary concerns in the transmission of images due to increasing the use of images within the industrial applications. So it's necessary to secure the image facts from unauthorized individuals. There are various strategies are investigated to secure the facts. In that encryption is certainly one of maximum distinguished method. This paper gives a sophisticated Rijndael (AES) algorithm to shield the facts from unauthorized humans. Here Exponential Key Change (EKE) concept is also introduced to exchange the key between client and server. The things are exchange in a network among client and server through a simple protocol is known as Trivial File Transfer Protocol (TFTP). This protocol is used mainly in embedded servers to transfer the data and also provide protection to the data if protection capabilities are integrated. In this paper, implementing a GUI environment for image encryption and decryption. All these experiments carried out on Linux environment the usage of Open CV-Python script.

Value of 100 kVp scan with sinogram-affirmed iterative reconstruction algorithm on a single-source CT system during whole-body CT for radiation and contrast medium dose reduction: an intra-individual feasibility study.

PubMed

Nagayama, Y; Nakaura, T; Oda, S; Tsuji, A; Urata, J; Furusawa, M; Tanoue, S; Utsunomiya, D; Yamashita, Y

2018-02-01

To perform an intra-individual investigation of the usefulness of a contrast medium (CM) and radiation dose-reduction protocol using single-source computed tomography (CT) combined with 100 kVp and sinogram-affirmed iterative reconstruction (SAFIRE) for whole-body CT (WBCT; chest-abdomen-pelvis CT) in oncology patients. Forty-three oncology patients who had undergone WBCT under both 120 and 100 kVp protocols at different time points (mean interscan intervals: 98 days) were included retrospectively. The CM doses for the 120 and 100 kVp protocols were 600 and 480 mg iodine/kg, respectively; 120 kVp images were reconstructed with filtered back-projection (FBP), whereas 100 kVp images were reconstructed with FBP (100 kVp-F) and the SAFIRE (100 kVp-S). The size-specific dose estimate (SSDE), iodine load and image quality of each protocol were compared. The SSDE and iodine load of 100 kVp protocol were 34% and 21%, respectively, lower than of 120 kVp protocol (SSDE: 10.6±1.1 versus 16.1±1.8 mGy; iodine load: 24.8±4versus 31.5±5.5 g iodine, p<0.01). Contrast enhancement, objective image noise, contrast-to-noise-ratio, and visual score of 100 kVp-S were similar to or better than of 120 kVp protocol. Compared with the 120 kVp protocol, the combined use of 100 kVp and SAFIRE in WBCT for oncology assessment with an SSCT facilitated substantial reduction in the CM and radiation dose while maintaining image quality. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

CT myocardial perfusion imaging: current status and future perspectives.

PubMed

Yang, Dong Hyun; Kim, Young-Hak

2017-07-01

Computed tomography myocardial perfusion (CTP) combined with coronary computed tomography angiography (CCTA) may constitute a "1-stop shop" for the noninvasive diagnosis of hemodynamically significant coronary stenosis during a single CT examination. CTP shows high diagnostic performance and provides incremental value over CCTA for the detection of hemodynamically significant coronary stenosis in patients with a high Agatston calcium score or coronary artery stents. Future studies should determine the optimal protocol and clinical value of CTP for guiding revascularization strategy and prognostication. In this article, we review the current status and future perspectives of CTP, focusing on technical considerations, clinical applications, and future research topics.

Deterministic generation of remote entanglement with active quantum feedback

DOE PAGES

Martin, Leigh; Motzoi, Felix; Li, Hanhan; ...

2015-12-10

We develop and study protocols for deterministic remote entanglement generation using quantum feedback, without relying on an entangling Hamiltonian. In order to formulate the most effective experimentally feasible protocol, we introduce the notion of average-sense locally optimal feedback protocols, which do not require real-time quantum state estimation, a difficult component of real-time quantum feedback control. We use this notion of optimality to construct two protocols that can deterministically create maximal entanglement: a semiclassical feedback protocol for low-efficiency measurements and a quantum feedback protocol for high-efficiency measurements. The latter reduces to direct feedback in the continuous-time limit, whose dynamics can bemore » modeled by a Wiseman-Milburn feedback master equation, which yields an analytic solution in the limit of unit measurement efficiency. Our formalism can smoothly interpolate between continuous-time and discrete-time descriptions of feedback dynamics and we exploit this feature to derive a superior hybrid protocol for arbitrary nonunit measurement efficiency that switches between quantum and semiclassical protocols. Lastly, we show using simulations incorporating experimental imperfections that deterministic entanglement of remote superconducting qubits may be achieved with current technology using the continuous-time feedback protocol alone.« less

Comparison of breathing gated CT images generated using a 5DCT technique and a commercial clinical protocol in a porcine model

PubMed Central

O’Connell, Dylan P.; Thomas, David H.; Dou, Tai H.; Lamb, James M.; Feingold, Franklin; Low, Daniel A.; Fuld, Matthew K.; Sieren, Jered P.; Sloan, Chelsea M.; Shirk, Melissa A.; Hoffman, Eric A.; Hofmann, Christian

2015-01-01

Purpose: To demonstrate that a “5DCT” technique which utilizes fast helical acquisition yields the same respiratory-gated images as a commercial technique for regular, mechanically produced breathing cycles. Methods: Respiratory-gated images of an anesthetized, mechanically ventilated pig were generated using a Siemens low-pitch helical protocol and 5DCT for a range of breathing rates and amplitudes and with standard and low dose imaging protocols. 5DCT reconstructions were independently evaluated by measuring the distances between tissue positions predicted by a 5D motion model and those measured using deformable registration, as well by reconstructing the originally acquired scans. Discrepancies between the 5DCT and commercial reconstructions were measured using landmark correspondences. Results: The mean distance between model predicted tissue positions and deformably registered tissue positions over the nine datasets was 0.65 ± 0.28 mm. Reconstructions of the original scans were on average accurate to 0.78 ± 0.57 mm. Mean landmark displacement between the commercial and 5DCT images was 1.76 ± 1.25 mm while the maximum lung tissue motion over the breathing cycle had a mean value of 27.2 ± 4.6 mm. An image composed of the average of 30 deformably registered images acquired with a low dose protocol had 6 HU image noise (single standard deviation) in the heart versus 31 HU for the commercial images. Conclusions: An end to end evaluation of the 5DCT technique was conducted through landmark based comparison to breathing gated images acquired with a commercial protocol under highly regular ventilation. The techniques were found to agree to within 2 mm for most respiratory phases and most points in the lung. PMID:26133604

A Web-based telemedicine system for diabetic retinopathy screening using digital fundus photography.

PubMed

Wei, Jack C; Valentino, Daniel J; Bell, Douglas S; Baker, Richard S

2006-02-01

The purpose was to design and implement a Web-based telemedicine system for diabetic retinopathy screening using digital fundus cameras and to make the software publicly available through Open Source release. The process of retinal imaging and case reviewing was modeled to optimize workflow and implement use of computer system. The Web-based system was built on Java Servlet and Java Server Pages (JSP) technologies. Apache Tomcat was chosen as the JSP engine, while MySQL was used as the main database and Laboratory of Neuro Imaging (LONI) Image Storage Architecture, from the LONI-UCLA, as the platform for image storage. For security, all data transmissions were carried over encrypted Internet connections such as Secure Socket Layer (SSL) and HyperText Transfer Protocol over SSL (HTTPS). User logins were required and access to patient data was logged for auditing. The system was deployed at Hubert H. Humphrey Comprehensive Health Center and Martin Luther King/Drew Medical Center of Los Angeles County Department of Health Services. Within 4 months, 1500 images of more than 650 patients were taken at Humphrey's Eye Clinic and successfully transferred to King/Drew's Department of Ophthalmology. This study demonstrates an effective architecture for remote diabetic retinopathy screening.

Rationally optimized cryopreservation of multiple mouse embryonic stem cell lines: I--Comparative fundamental cryobiology of multiple mouse embryonic stem cell lines and the implications for embryonic stem cell cryopreservation protocols.

PubMed

Kashuba, Corinna M; Benson, James D; Critser, John K

2014-04-01

The post-thaw recovery of mouse embryonic stem cells (mESCs) is often assumed to be adequate with current methods. However as this publication will show, this recovery of viable cells actually varies significantly by genetic background. Therefore there is a need to improve the efficiency and reduce the variability of current mESC cryopreservation methods. To address this need, we employed the principles of fundamental cryobiology to improve the cryopreservation protocol of four mESC lines from different genetic backgrounds (BALB/c, CBA, FVB, and 129R1 mESCs) through a comparative study characterizing the membrane permeability characteristics and membrane integrity osmotic tolerance limits of each cell line. In the companion paper, these values were used to predict optimal cryoprotectants, cooling rates, warming rates, and plunge temperatures, and then these predicted optimal protocols were validated against standard freezing protocols. Copyright © 2014 Elsevier Inc. All rights reserved.

Compulsory Use of the Backboard is Associated with Increased Frequency of Thoracolumbar Imaging.

PubMed

Clemency, Brian M; Tanski, Christopher T; Gibson Chambers, Jennifer; O'Brien, Michael; Knapp, Andrew S; Clark, Alexander J; McGoff, Patrick; Innes, Johanna; Lindstrom, Heather A; Hostler, David

2018-02-15

Backboards have been shown to cause pain in uninjured patients. This may alter physical exam findings, leading emergency department (ED) providers to suspect a spinal injury when none exists resulting in additional imaging of the thoracolumbar spine. New York had previously employed a "Spinal Immobilization" protocol that included compulsory backboard application for all patients with suspected spinal injuries. In 2015, New York instituted a new "Spinal Motion Restriction" protocol that made backboard use optional for these patients. The objective of this study was to determine if this protocol change was associated with decreased backboard utilization and ED thoracolumbar spine imaging. This was a retrospective before-and-after chart review of subjects transported by a single emergency medical services (EMS) agency to one of four EDs for emergency calls dispatched as motor vehicle collisions (MVC). EMS and ED data were included for all calls within a 6-month interval before and after the protocol change. The protocol change was implemented in the second half of 2015. Subject demographics, backboard use, and spine imaging were reviewed for the intervals January-June 2015 and January-June 2016. There were 818 subjects in the before period and 796 subjects in the after period. Subjects were similar in terms of gender, age and type of MVC in both periods. A backboard was utilized for 440 (54%) subjects in the before period and 92 (12%) subjects in the after period (p < 0.001). ED thoracic spine imaging was performed on 285 (35%) subjects in the before period, and 235 (30%) subjects in the after period (p = 0.02). ED lumbar spine imaging was performed for 335 (41%) subjects in the before period, and 281 (35%) subjects in the after period (p = 0.02). A shift from a spinal immobilization protocol to a spinal motion restriction protocol was associated with a decrease in backboard utilization by EMS providers and a decrease in thoracolumbar spine imaging by ED providers.

Submaximal delayed-onset muscle soreness: correlations between MR imaging findings and clinical measures

NASA Technical Reports Server (NTRS)

Evans, G. F.; Haller, R. G.; Wyrick, P. S.; Parkey, R. W.; Fleckenstein, J. L.; Blomqvist, C. G. (Principal Investigator)

1998-01-01

PURPOSE: To assess correlations between muscle edema on magnetic resonance (MR) images and clinical indexes of muscle injury in delayed-onset muscle soreness (DOMS) produced by submaximal exercise protocols. MATERIALS AND METHODS: Sixteen subjects performed 36 elbow flexions ("biceps curls") at one of two submaximal workloads that emphasized eccentric contractions. Changes in MR imaging findings, plasma levels of creatine kinase, and pain scores were correlated. RESULTS: Both exercise protocols produced DOMS in all subjects. The best correlation was between change in creatine kinase level and volume of muscle edema on MR images, regardless of the workload. Correlations tended to be better with the easier exercise protocol. CONCLUSION: Whereas many previous studies of DOMS focused on intense exercise protocols to ensure positive results, the present investigation showed that submaximal workloads are adequate to produce DOMS and that correlations between conventionally measured indexes of injury may be enhanced at lighter exercise intensities.

CT and MR Protocol Standardization Across a Large Health System: Providing a Consistent Radiologist, Patient, and Referring Provider Experience.

PubMed

Sachs, Peter B; Hunt, Kelly; Mansoubi, Fabien; Borgstede, James

2017-02-01

Building and maintaining a comprehensive yet simple set of standardized protocols for a cross-sectional image can be a daunting task. A single department may have difficulty preventing "protocol creep," which almost inevitably occurs when an organized "playbook" of protocols does not exist and individual radiologists and technologists alter protocols at will and on a case-by-case basis. When multiple departments or groups function in a large health system, the lack of uniformity of protocols can increase exponentially. In 2012, the University of Colorado Hospital formed a large health system (UCHealth) and became a 5-hospital provider network. CT and MR imaging studies are conducted at multiple locations by different radiology groups. To facilitate consistency in ordering, acquisition, and appearance of a given study, regardless of location, we minimized the number of protocols across all scanners and sites of practice with a clinical indication-driven protocol selection and standardization process. Here we review the steps utilized to perform this process improvement task and insure its stability over time. Actions included creation of a standardized protocol template, which allowed for changes in electronic storage and management of protocols, designing a change request form, and formation of a governance structure. We utilized rapid improvement events (1 day for CT, 2 days for MR) and reduced 248 CT protocols into 97 standardized protocols and 168 MR protocols to 66. Additional steps are underway to further standardize output and reporting of imaging interpretation. This will result in an improved, consistent radiologist, patient, and provider experience across the system.

Shuffle Optimizer: A Program to Optimize DNA Shuffling for Protein Engineering.

PubMed

Milligan, John N; Garry, Daniel J

2017-01-01

DNA shuffling is a powerful tool to develop libraries of variants for protein engineering. Here, we present a protocol to use our freely available and easy-to-use computer program, Shuffle Optimizer. Shuffle Optimizer is written in the Python computer language and increases the nucleotide homology between two pieces of DNA desired to be shuffled together without changing the amino acid sequence. In addition we also include sections on optimal primer design for DNA shuffling and library construction, a small-volume ultrasonicator method to create sheared DNA, and finally a method to reassemble the sheared fragments and recover and clone the library. The Shuffle Optimizer program and these protocols will be useful to anyone desiring to perform any of the nucleotide homology-dependent shuffling methods.

Quality control for quantitative multicenter whole-body PET/MR studies: A NEMA image quality phantom study with three current PET/MR systems

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

Boellaard, Ronald, E-mail: r.boellaard@vumc.nl; European Association of Nuclear Medicine Research Ltd., Vienna 1060; European Association of Nuclear Medicine Physics Committee, Vienna 1060

2015-10-15

Purpose: Integrated positron emission tomography/magnetic resonance (PET/MR) systems derive the PET attenuation correction (AC) from dedicated MR sequences. While MR-AC performs reasonably well in clinical patient imaging, it may fail for phantom-based quality control (QC). The authors assess the applicability of different protocols for PET QC in multicenter PET/MR imaging. Methods: The National Electrical Manufacturers Association NU 2 2007 image quality phantom was imaged on three combined PET/MR systems: a Philips Ingenuity TF PET/MR, a Siemens Biograph mMR, and a GE SIGNA PET/MR (prototype) system. The phantom was filled according to the EANM FDG-PET/CT guideline 1.0 and scanned for 5more » min over 1 bed. Two MR-AC imaging protocols were tested: standard clinical procedures and a dedicated protocol for phantom tests. Depending on the system, the dedicated phantom protocol employs a two-class (water and air) segmentation of the MR data or a CT-based template. Differences in attenuation- and SUV recovery coefficients (RC) are reported. PET/CT-based simulations were performed to simulate the various artifacts seen in the AC maps (μ-map) and their impact on the accuracy of phantom-based QC. Results: Clinical MR-AC protocols caused substantial errors and artifacts in the AC maps, resulting in underestimations of the reconstructed PET activity of up to 27%, depending on the PET/MR system. Using dedicated phantom MR-AC protocols, PET bias was reduced to −8%. Mean and max SUV RC met EARL multicenter PET performance specifications for most contrast objects, but only when using the dedicated phantom protocol. Simulations confirmed the bias in experimental data to be caused by incorrect AC maps resulting from the use of clinical MR-AC protocols. Conclusions: Phantom-based quality control of PET/MR systems in a multicenter, multivendor setting may be performed with sufficient accuracy, but only when dedicated phantom acquisition and processing protocols are used for attenuation correction.« less

Improvement of electroporation to deliver plasmid DNA into dental follicle cells

PubMed Central

Yao, Shaomian; Rana, Samir; Liu, Dawen; Wise, Gary E.

2010-01-01

Electroporation DNA transfer is a simple and versatile approach to deliver genes. To develop an optimal electroporation protocol to deliver DNA into cells, we conducted square wave electroporation experiments with using rat dental follicle cells as follows: 1) the cells were electroporated at different electric field strengths with lac Z plasmid; 2) plasmid concentrations were tested to determine the optimal doses; 3) various concentrations of bovine serum albumin or fetal bovine serum were added to the pulsing buffer; and, 4) the pulsing durations were studied to determine the optimal duration. These experiments indicated that the optimal electroporation electric field strength was 375 V/cm, and that plasmid concentrations greater than 0.18 μg/μl were required to achieve high transfection efficiency. BSA or FBS in the pulsing buffer significantly improved cell survival and increased the number of transfected cells. The optimal pulsing duration was in the range of 45 to 120 milliseconds (ms) at 375 V/cm. Thus, an improved electroporation protocol was established by optimizing the above parameters. In turn, this electroporation protocol can be used to deliver DNA into dental follicle cells to study the roles of candidate genes in regulating tooth eruption. PMID:19830717

Abdominal applications of 3.0-T MR imaging: comparative review versus a 1.5-T system.

PubMed

Choi, Jin-Young; Kim, Myeong-Jin; Chung, Yong Eun; Kim, Ji Youn; Jones, Alun C; de Becker, Jan; van Cauteren, Marc

2008-01-01

With the development of dedicated receiver coils and increased gradient performance, 3.0-T magnetic resonance (MR) systems are gaining wider acceptance in clinical practice. The expected twofold increase in signal-to-noise ratio (SNR) compared with that of 1.5-T MR systems may help improve spatial resolution or increase temporal resolution when used with parallel acquisition techniques. Several issues must be considered when applying 3.0-T MR in the abdomen, including the alteration of the radiofrequency field and relaxation time, increase in energy deposition and susceptibility effects, and problems associated with motion artifacts. For the evaluation of liver lesions, higher SNR and greater resolution achieved with the 3.0-T system could translate into better detection of malignant lesions on T2-weighted images obtained with adjusted imaging parameters. For the evaluation of pancreatic and biliary diseases, high-resolution T2-weighted imaging using single-shot turbo spin-echo sequences is useful; improvement in SNR was noticeable on two-dimensional MR cholangiopancreatographic images. For the preoperative imaging of rectal cancer, a single-shot sequence is useful for dramatically decreasing imaging time while maintaining image quality. Substantial modification of examination protocols, with optimized imaging parameters and sequence designs along with ongoing development of hardware, could contribute to an increased role of the 3.0-T system for abdominal MR examinations.

Technical Note: Independent component analysis for quality assurance in functional MRI.

PubMed

Astrakas, Loukas G; Kallistis, Nikolaos S; Kalef-Ezra, John A

2016-02-01

Independent component analysis (ICA) is an established method of analyzing human functional MRI (fMRI) data. Here, an ICA-based fMRI quality control (QC) tool was developed and used. ICA-based fMRI QC tool to be used with a commercial phantom was developed. In an attempt to assess the performance of the tool relative to preexisting alternative tools, it was used seven weeks before and eight weeks after repair of a faulty gradient amplifier of a non-state-of-the-art MRI unit. More specifically, its performance was compared with the AAPM 100 acceptance testing and quality assurance protocol and two fMRI QC protocols, proposed by Freidman et al. ["Report on a multicenter fMRI quality assurance protocol," J. Magn. Reson. Imaging 23, 827-839 (2006)] and Stocker et al. ["Automated quality assurance routines for fMRI data applied to a multicenter study," Hum. Brain Mapp. 25, 237-246 (2005)], respectively. The easily developed and applied ICA-based QC protocol provided fMRI QC indices and maps equally sensitive to fMRI instabilities with the indices and maps of other established protocols. The ICA fMRI QC indices were highly correlated with indices of other fMRI QC protocols and in some cases theoretically related to them. Three or four independent components with slow varying time series are detected under normal conditions. ICA applied on phantom measurements is an easy and efficient tool for fMRI QC. Additionally, it can protect against misinterpretations of artifact components as human brain activations. Evaluating fMRI QC indices in the central region of a phantom is not always the optimal choice.

Evaluation of telomere length in human cardiac tissues using cardiac quantitative FISH.

PubMed

Sharifi-Sanjani, Maryam; Meeker, Alan K; Mourkioti, Foteini

2017-09-01

Telomere length has been correlated with various diseases, including cardiovascular disease and cancer. The use of currently available telomere-length measurement techniques is often restricted by the requirement of a large amount of cells (Southern-based techniques) or the lack of information on individual cells or telomeres (PCR-based methods). Although several methods have been used to measure telomere length in tissues as a whole, the assessment of cell-type-specific telomere length provides valuable information on individual cell types. The development of fluorescence in situ hybridization (FISH) technologies enables the quantification of telomeres in individual chromosomes, but the use of these methods is dependent on the availability of isolated cells, which prevents their use with fixed archival samples. Here we describe an optimized quantitative FISH (Q-FISH) protocol for measuring telomere length that bypasses the previous limitations by avoiding contributions from undesired cell types. We have used this protocol on small paraffin-embedded cardiac-tissue samples. This protocol describes step-by-step procedures for tissue preparation, permeabilization, cardiac-tissue pretreatment and hybridization with a Cy3-labeled telomeric repeat complementing (CCCTAA) 3 peptide nucleic acid (PNA) probe coupled with cardiac-specific antibody staining. We also describe how to quantify telomere length by means of the fluorescence intensity and area of each telomere within individual nuclei. This protocol provides comparative cell-type-specific telomere-length measurements in relatively small human cardiac samples and offers an attractive technique to test hypotheses implicating telomere length in various cardiac pathologies. The current protocol (from tissue collection to image procurement) takes ∼28 h along with three overnight incubations. We anticipate that the protocol could be easily adapted for use on different tissue types.

Development of a calibration protocol for quantitative imaging for molecular radiotherapy dosimetry

NASA Astrophysics Data System (ADS)

Wevrett, J.; Fenwick, A.; Scuffham, J.; Nisbet, A.

2017-11-01

Within the field of molecular radiotherapy, there is a significant need for standardisation in dosimetry, in both quantitative imaging and dosimetry calculations. Currently, there are a wide range of techniques used by different clinical centres and as a result there is no means to compare patient doses between centres. To help address this need, a 3 year project was funded by the European Metrology Research Programme, and a number of clinical centres were involved in the project. One of the required outcomes of the project was to develop a calibration protocol for three dimensional quantitative imaging of volumes of interest. Two radionuclides were selected as being of particular interest: iodine-131 (131I, used to treat thyroid disorders) and lutetium-177 (177Lu, used to treat neuroendocrine tumours). A small volume of activity within a scatter medium (water), representing a lesion within a patient body, was chosen as the calibration method. To ensure ease of use in clinical centres, an "off-the-shelf" solution was proposed - to avoid the need for in-house manufacturing. The BIODEX elliptical Jaszczak phantom and 16 ml fillable sphere were selected. The protocol was developed for use on SPECT/CT gamma cameras only, where the CT dataset would be used to correct the imaging data for attenuation of the emitted photons within the phantom. The protocol corrects for scatter of emitted photons using the triple energy window correction technique utilised by most clinical systems. A number of clinical systems were tested in the development of this protocol, covering the major manufacturers of gamma camera generally used in Europe. Initial imaging was performed with 131I and 177Lu at a number of clinical centres, but due to time constraints in the project, some acquisitions were performed with 177Lu only. The protocol is relatively simplistic, and does not account for the effects of dead-time in high activity patients, the presence of background activity surrounding volumes of interest or the partial volume effect of imaging lesions smaller than 16 ml. The development of this simple protocol demonstrates that it is possible to produce a standardised quantitative imaging protocol for molecular radiotherapy dosimetry. However, the protocol needs further development to expand it to incorporate other radionuclides, and to account for the effects that have been disregarded in this initial version.

Pediatric functional magnetic resonance neuroimaging: tactics for encouraging task compliance.

PubMed

Schlund, Michael W; Cataldo, Michael F; Siegle, Greg J; Ladouceur, Cecile D; Silk, Jennifer S; Forbes, Erika E; McFarland, Ashley; Iyengar, Satish; Dahl, Ronald E; Ryan, Neal D

2011-05-06

Neuroimaging technology has afforded advances in our understanding of normal and pathological brain function and development in children and adolescents. However, noncompliance involving the inability to remain in the magnetic resonance imaging (MRI) scanner to complete tasks is one common and significant problem. Task noncompliance is an especially significant problem in pediatric functional magnetic resonance imaging (fMRI) research because increases in noncompliance produces a greater risk that a study sample will not be representative of the study population. In this preliminary investigation, we describe the development and application of an approach for increasing the number of fMRI tasks children complete during neuroimaging. Twenty-eight healthy children ages 9-13 years participated. Generalization of the approach was examined in additional fMRI and event-related potential investigations with children at risk for depression, children with anxiety and children with depression (N=120). Essential features of the approach include a preference assessment for identifying multiple individualized rewards, increasing reinforcement rates during imaging by pairing tasks with chosen rewards and presenting a visual 'road map' listing tasks, rewards and current progress. Our results showing a higher percentage of fMRI task completion by healthy children provides proof of concept data for the recommended tactics. Additional support was provided by results showing our approach generalized to several additional fMRI and event-related potential investigations and clinical populations. We proposed that some forms of task noncompliance may emerge from less than optimal reward protocols. While our findings may not directly support the effectiveness of the multiple reward compliance protocol, increased attention to how rewards are selected and delivered may aid cooperation with completing fMRI tasks. The proposed approach contributes to the pediatric neuroimaging literature by providing a useful way to conceptualize and measure task noncompliance and by providing simple cost effective tactics for improving the effectiveness of common reward-based protocols.

Pediatric functional magnetic resonance neuroimaging: tactics for encouraging task compliance

PubMed Central

2011-01-01

Background Neuroimaging technology has afforded advances in our understanding of normal and pathological brain function and development in children and adolescents. However, noncompliance involving the inability to remain in the magnetic resonance imaging (MRI) scanner to complete tasks is one common and significant problem. Task noncompliance is an especially significant problem in pediatric functional magnetic resonance imaging (fMRI) research because increases in noncompliance produces a greater risk that a study sample will not be representative of the study population. Method In this preliminary investigation, we describe the development and application of an approach for increasing the number of fMRI tasks children complete during neuroimaging. Twenty-eight healthy children ages 9-13 years participated. Generalization of the approach was examined in additional fMRI and event-related potential investigations with children at risk for depression, children with anxiety and children with depression (N = 120). Essential features of the approach include a preference assessment for identifying multiple individualized rewards, increasing reinforcement rates during imaging by pairing tasks with chosen rewards and presenting a visual 'road map' listing tasks, rewards and current progress. Results Our results showing a higher percentage of fMRI task completion by healthy children provides proof of concept data for the recommended tactics. Additional support was provided by results showing our approach generalized to several additional fMRI and event-related potential investigations and clinical populations. Discussion We proposed that some forms of task noncompliance may emerge from less than optimal reward protocols. While our findings may not directly support the effectiveness of the multiple reward compliance protocol, increased attention to how rewards are selected and delivered may aid cooperation with completing fMRI tasks Conclusion The proposed approach contributes to the pediatric neuroimaging literature by providing a useful way to conceptualize and measure task noncompliance and by providing simple cost effective tactics for improving the effectiveness of common reward-based protocols. PMID:21548928

Preoperative simulation for the planning of microsurgical clipping of intracranial aneurysms.

PubMed

Marinho, Paulo; Vermandel, Maximilien; Bourgeois, Philippe; Lejeune, Jean-Paul; Mordon, Serge; Thines, Laurent

2014-12-01

The safety and success of intracranial aneurysm (IA) surgery could be improved through the dedicated application of simulation covering the procedure from the 3-dimensional (3D) description of the surgical scene to the visual representation of the clip application. We aimed in this study to validate the technical feasibility and clinical relevance of such a protocol. All patients preoperatively underwent 3D magnetic resonance imaging and 3D computed tomography angiography to build 3D reconstructions of the brain, cerebral arteries, and surrounding cranial bone. These 3D models were segmented and merged using Osirix, a DICOM image processing application. This provided the surgical scene that was subsequently imported into Blender, a modeling platform for 3D animation. Digitized clips and appliers could then be manipulated in the virtual operative environment, allowing the visual simulation of clipping. This simulation protocol was assessed in a series of 10 IAs by 2 neurosurgeons. The protocol was feasible in all patients. The visual similarity between the surgical scene and the operative view was excellent in 100% of the cases, and the identification of the vascular structures was accurate in 90% of the cases. The neurosurgeons found the simulation helpful for planning the surgical approach (ie, the bone flap, cisternal opening, and arterial tree exposure) in 100% of the cases. The correct number of final clip(s) needed was predicted from the simulation in 90% of the cases. The preoperatively expected characteristics of the optimal clip(s) (ie, their number, shape, size, and orientation) were validated during surgery in 80% of the cases. This study confirmed that visual simulation of IA clipping based on the processing of high-resolution 3D imaging can be effective. This is a new and important step toward the development of a more sophisticated integrated simulation platform dedicated to cerebrovascular surgery.

SU-E-J-07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes

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

Morris, B; Duggar, W; Stanford, J

Purpose: IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI-preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced. Methods: 32 and 16cm CTDI-phantoms were used as surrogates for adult andmore » child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta’s Chest-preset to establish a dose baseline. The child-phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN-preset (named Peds Abd-pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child-phantom (relative to the baseline), while providing clinically-usable image quality. Results: The baseline dose to the child-phantom from the Chest-preset was 310% that of the adult-phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest-preset to the HN-preset, while the Peds Abd-pelvis-preset similarly reduced the dose by an average of 92%. Conclusion: XVI-preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically-usable image quality. Using a modified imaging preset (Peds Abd-pelvis-preset) greatly reduced the dose to the child-phantom compared to the dose for the Chest-preset for both the child and adult-phantoms. This outcome provides support for the development of child-specific protocols for IGRT imaging in pediatric patients.« less

Individual Optimal Frequency in Whole-Body Vibration: Effect of Protocol, Joint Angle, and Fatiguing Exercise.

PubMed

Carlucci, Flaminia; Felici, Francesco; Piccinini, Alberto; Haxhi, Jonida; Sacchetti, Massimo

2016-12-01

Carlucci, F, Felici, F, Piccinini, A, Haxhi, J, and Sacchetti, M. Individual optimal frequency in whole-body vibration: effect of protocol, joint angle, and fatiguing exercise. J Strength Cond Res 30(12): 3503-3511, 2016-Recent studies have shown the importance of individualizing the vibration intervention to produce greater effects on the neuromuscular system in less time. The purpose of this study was to assess the individual optimal vibration frequency (OVF) corresponding to the highest muscle activation (RMSmax) during vibration at different frequencies, comparing different protocols. Twenty-nine university students underwent 3 continuous (C) and 2 random (R) different vibrating protocols, maintaining a squat position on a vibration platform. The C protocol lasted 50 seconds and involved the succession of ascending frequencies from 20 to 55 Hz, every 5 seconds. The same protocol was performed twice, having the knee angle at 120° (C) and 90° (C90), to assess the effect of joint angle and after a fatiguing squatting exercise (CF) to evaluate the influence of fatigue on OVF assessment. In the random protocols, vibration time was 20 seconds with a 2-minute (R2) and a 4-minute (R4) pauses between tested frequencies. Muscle activation and OVF values did not differ significantly in the C, R2, and R4 protocols. RMSmax was higher in C90 (p < 0.001) and in CF (p = 0.04) compared with the C protocol. Joint angle and fatiguing exercise had no effect on OVF. In conclusion, the shorter C protocol produced similar myoelectrical activity in the R2 and the R4 protocols, and therefore, it could be equally valid in identifying the OVF with considerable time efficiency. Knee joint angle and fatiguing exercise had an effect on surface electromyography response during vibration but did not affect OVF identification significantly.

HiCTMap: Detection and analysis of chromosome territory structure and position by high-throughput imaging.

PubMed

Jowhar, Ziad; Gudla, Prabhakar R; Shachar, Sigal; Wangsa, Darawalee; Russ, Jill L; Pegoraro, Gianluca; Ried, Thomas; Raznahan, Armin; Misteli, Tom

2018-06-01

The spatial organization of chromosomes in the nuclear space is an extensively studied field that relies on measurements of structural features and 3D positions of chromosomes with high precision and robustness. However, no tools are currently available to image and analyze chromosome territories in a high-throughput format. Here, we have developed High-throughput Chromosome Territory Mapping (HiCTMap), a method for the robust and rapid analysis of 2D and 3D chromosome territory positioning in mammalian cells. HiCTMap is a high-throughput imaging-based chromosome detection method which enables routine analysis of chromosome structure and nuclear position. Using an optimized FISH staining protocol in a 384-well plate format in conjunction with a bespoke automated image analysis workflow, HiCTMap faithfully detects chromosome territories and their position in 2D and 3D in a large population of cells per experimental condition. We apply this novel technique to visualize chromosomes 18, X, and Y in male and female primary human skin fibroblasts, and show accurate detection of the correct number of chromosomes in the respective genotypes. Given the ability to visualize and quantitatively analyze large numbers of nuclei, we use HiCTMap to measure chromosome territory area and volume with high precision and determine the radial position of chromosome territories using either centroid or equidistant-shell analysis. The HiCTMap protocol is also compatible with RNA FISH as demonstrated by simultaneous labeling of X chromosomes and Xist RNA in female cells. We suggest HiCTMap will be a useful tool for routine precision mapping of chromosome territories in a wide range of cell types and tissues. Published by Elsevier Inc.

Dual-energy CT and ceramic or titanium prostheses material reduce CT artifacts and provide superior image quality of total knee arthroplasty.

PubMed

Kasparek, Maximilian F; Töpker, Michael; Lazar, Mathias; Weber, Michael; Kasparek, Michael; Mang, Thomas; Apfaltrer, Paul; Kubista, Bernd; Windhager, Reinhard; Ringl, Helmut

2018-06-07

To evaluate the influence of different scan parameters for single-energy CT and dual-energy CT, as well as the impact of different material used in a TKA prosthesis on image quality and the extent of metal artifacts. Eight pairs of TKA prostheses from different vendors were examined in a phantom set-up. Each pair consisted of a conventional CoCr prosthesis and the corresponding anti-allergic prosthesis (full titanium, ceramic, or ceramic-coated) from the same vendor. Nine different (seven dual-energy CT and two single-energy CT) scan protocols with different characteristics were used to determine the most suitable CT protocol for TKA imaging. Quantitative image analysis included assessment of blooming artifacts (metal implants appear thicker on CT than they are, given as virtual growth in mm in this paper) and streak artifacts (thick dark lines around metal). Qualitative image analysis was used to investigate the bone-prosthesis interface. The full titanium prosthesis and full ceramic knee showed significantly fewer blooming artifacts compared to the standard CoCr prosthesis (mean virtual growth 0.6-2.2 mm compared to 2.9-4.6 mm, p < 0.001). Dual-energy CT protocols showed less blooming (range 3.3-3.8 mm) compared to single-energy protocols (4.6-5.5 mm). The full titanium and full ceramic prostheses showed significantly fewer streak artifacts (mean standard deviation 77-86 Hounsfield unit (HU)) compared to the standard CoCr prosthesis (277-334 HU, p < 0.001). All dual-energy CT protocols had fewer metal streak artifacts (215-296 HU compared to single-energy CT protocols (392-497 HU)). Full titanium and ceramic prostheses were ranked superior with regard to the image quality at the bone/prosthesis interface compared to a standard CoCr prosthesis, and all dual-energy CT protocols were ranked better than single-energy protocols. Dual-energy CT and ceramic or titanium prostheses reduce CT artifacts and provide superior image quality of total knee arthroplasty at the bone/prosthesis interface. These findings support the use of dual-energy CT as a solid imaging base for clinical decision-making and the use of full-titanium or ceramic prostheses to allow for better CT visualization of the bone-prosthesis interface.

Thermodynamic metrics and optimal paths.

PubMed

Sivak, David A; Crooks, Gavin E

2012-05-11

A fundamental problem in modern thermodynamics is how a molecular-scale machine performs useful work, while operating away from thermal equilibrium without excessive dissipation. To this end, we derive a friction tensor that induces a Riemannian manifold on the space of thermodynamic states. Within the linear-response regime, this metric structure controls the dissipation of finite-time transformations, and bestows optimal protocols with many useful properties. We discuss the connection to the existing thermodynamic length formalism, and demonstrate the utility of this metric by solving for optimal control parameter protocols in a simple nonequilibrium model.

[Neuroimaging follow-up of cerebral aneurysms treated with endovascular techniques].

PubMed

Delgado, F; Saiz, A; Hilario, A; Murias, E; San Román Manzanera, L; Lagares Gomez-Abascal, A; Gabarrós, A; González García, A

2014-01-01

There are no specific recommendations in clinical guidelines about the best time, imaging tests, or intervals for following up patients with intracranial aneurysms treated with endovascular techniques. We reviewed the literature, using the following keywords to search in the main medical databases: cerebral aneurysm, coils, endovascular procedure, and follow-up. Within the Cerebrovascular Disease Group of the Spanish Society of Neuroradiology, we aimed to propose recommendations and an orientative protocol based on the scientific evidence for using neuroimaging to monitor intracranial aneurysms that have been treated with endovascular techniques. We aimed to specify the most appropriate neuroimaging techniques, the interval, the time of follow-up, and the best approach to defining the imaging findings, with the ultimate goal of improving clinical outcomes while optimizing and rationalizing the use of available resources. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

Model-based Iterative Reconstruction: Effect on Patient Radiation Dose and Image Quality in Pediatric Body CT

PubMed Central

Dillman, Jonathan R.; Goodsitt, Mitchell M.; Christodoulou, Emmanuel G.; Keshavarzi, Nahid; Strouse, Peter J.

2014-01-01

Purpose To retrospectively compare image quality and radiation dose between a reduced-dose computed tomographic (CT) protocol that uses model-based iterative reconstruction (MBIR) and a standard-dose CT protocol that uses 30% adaptive statistical iterative reconstruction (ASIR) with filtered back projection. Materials and Methods Institutional review board approval was obtained. Clinical CT images of the chest, abdomen, and pelvis obtained with a reduced-dose protocol were identified. Images were reconstructed with two algorithms: MBIR and 100% ASIR. All subjects had undergone standard-dose CT within the prior year, and the images were reconstructed with 30% ASIR. Reduced- and standard-dose images were evaluated objectively and subjectively. Reduced-dose images were evaluated for lesion detectability. Spatial resolution was assessed in a phantom. Radiation dose was estimated by using volumetric CT dose index (CTDIvol) and calculated size-specific dose estimates (SSDE). A combination of descriptive statistics, analysis of variance, and t tests was used for statistical analysis. Results In the 25 patients who underwent the reduced-dose protocol, mean decrease in CTDIvol was 46% (range, 19%–65%) and mean decrease in SSDE was 44% (range, 19%–64%). Reduced-dose MBIR images had less noise (P > .004). Spatial resolution was superior for reduced-dose MBIR images. Reduced-dose MBIR images were equivalent to standard-dose images for lungs and soft tissues (P > .05) but were inferior for bones (P = .004). Reduced-dose 100% ASIR images were inferior for soft tissues (P < .002), lungs (P < .001), and bones (P < .001). By using the same reduced-dose acquisition, lesion detectability was better (38% [32 of 84 rated lesions]) or the same (62% [52 of 84 rated lesions]) with MBIR as compared with 100% ASIR. Conclusion CT performed with a reduced-dose protocol and MBIR is feasible in the pediatric population, and it maintains diagnostic quality. © RSNA, 2013 Online supplemental material is available for this article. PMID:24091359

Aiming for a shorter rheumatoid arthritis MRI protocol: can contrast-enhanced MRI replace T2 for the detection of bone marrow oedema?

PubMed

Stomp, Wouter; Krabben, Annemarie; van der Heijde, Désirée; Huizinga, Tom W J; Bloem, Johan L; van der Helm-van Mil, Annette H M; Reijnierse, Monique

2014-10-01

To determine whether T1 post-gadolinium chelate images (T1Gd) can replace T2-weighted images (T2) for evaluating bone marrow oedema (BME), thereby allowing a shorter magnetic resonance imaging (MRI) protocol in rheumatoid arthritis (RA). In 179 early arthritis patients and 43 advanced RA patients, wrist and metacarpophalangeal joints were examined on a 1.5-T extremity MRI system with a standard protocol (coronal T1, T2 fat-saturated and coronal and axial T1 fat-saturated after Gd). BME was scored according to OMERACT RAMRIS by two observers with and without T2 images available. Agreement was assessed using intraclass correlation coefficients (ICCs) for semi-quantitative scores and test characteristics with T2 images as reference. Agreement between scores based on T2 and T1Gd images was excellent ICC (0.80-0.99). At bone level, sensitivity and specificity of BME on T1Gd compared to T2 were high for both patient groups and both readers (all ≥80 %). T1Gd and T2 images are equally suitable for evaluating BME. Because contrast is usually administered to assess (teno)synovitis, a short MRI protocol of T1 and T1Gd is sufficient in RA. • Bone marrow oedema scores are equal on T2 and T1-Gd-chelate enhanced sequences. • Agreement between scores based on T2 and T1-Gd-chelate images was excellent. • Sensitivity and specificity for presence of bone marrow oedema were high. • A short protocol without T2 images suffices in rheumatoid arthritis patients.

Evaluating the effect of increased pitch, iterative reconstruction and dual source CT on dose reduction and image quality.

PubMed

Gariani, Joanna; Martin, Steve P; Botsikas, Diomidis; Becker, Christoph D; Montet, Xavier

2018-06-14

To compare radiation dose and image quality of thoracoabdominal scans obtained with a high-pitch protocol (pitch 3.2) and iterative reconstruction (Sinogram Affirmed Iterative Reconstruction) in comparison to standard pitch reconstructed with filtered back projection (FBP) using dual source CT. 114 CT scans (Somatom Definition Flash, Siemens Healthineers, Erlangen, Germany), 39 thoracic scans, 54 thoracoabdominal scans and 21 abdominal scans were performed. Analysis of three protocols was undertaken; pitch of 1 reconstructed with FBP, pitch of 3.2 reconstructed with SAFIRE, pitch of 3.2 with stellar detectors reconstructed with SAFIRE. Objective and subjective image analysis were performed. Dose differences of the protocols used were compared. Dose was reduced when comparing scans with a pitch of 1 reconstructed with FBP to high-pitch scans with a pitch of 3.2 reconstructed with SAFIRE with a reduction of volume CT dose index of 75% for thoracic scans, 64% for thoracoabdominal scans and 67% for abdominal scans. There was a further reduction after the implementation of stellar detectors reflected in a reduction of 36% of the dose-length product for thoracic scans. This was not at the detriment of image quality, contrast-to-noise ratio, signal-to-noise ratio and the qualitative image analysis revealed a superior image quality in the high-pitch protocols. The combination of a high pitch protocol with iterative reconstruction allows significant dose reduction in routine chest and abdominal scans whilst maintaining or improving diagnostic image quality, with a further reduction in thoracic scans with stellar detectors. Advances in knowledge: High pitch imaging with iterative reconstruction is a tool that can be used to reduce dose without sacrificing image quality.

Performance Analysis of TCP Enhancements in Satellite Data Networks

NASA Technical Reports Server (NTRS)

Broyles, Ren H.

1999-01-01

This research examines two proposed enhancements to the well-known Transport Control Protocol (TCP) in the presence of noisy communication links. The Multiple Pipes protocol is an application-level adaptation of the standard TCP protocol, where several TCP links cooperate to transfer data. The Space Communication Protocol Standard - Transport Protocol (SCPS-TP) modifies TCP to optimize performance in a satellite environment. While SCPS-TP has inherent advantages that allow it to deliver data more rapidly than Multiple Pipes, the protocol, when optimized for operation in a high-error environment, is not compatible with legacy TCP systems, and requires changes to the TCP specification. This investigation determines the level of improvement offered by SCPS-TP's Corruption Mode, which will help determine if migration to the protocol is appropriate in different environments. As the percentage of corrupted packets approaches 5 %, Multiple Pipes can take over five times longer than SCPS-TP to deliver data. At high error rates, SCPS-TP's advantage is primarily caused by Multiple Pipes' use of congestion control algorithms. The lack of congestion control, however, limits the systems in which SCPS-TP can be effectively used.

Relating quantum privacy and quantum coherence: an operational approach.

PubMed

Devetak, I; Winter, A

2004-08-20

Given many realizations of a state or a channel as a resource, two parties can generate a secret key as well as entanglement. We describe protocols to perform the secret key distillation (as it turns out, with optimal rate). Then we show how to achieve optimal entanglement generation rates by "coherent" implementation of a class of secret key agreement protocols, proving the long-conjectured "hashing inequality."

Rethinking Traffic Management: Design of Optimizable Networks

DTIC Science & Technology

2008-06-01

Though this paper used optimization theory to design and analyze DaVinci , op- timization theory is one of many possible tools to enable a grounded...dynamically allocate bandwidth shares. The distributed protocols can be implemented using DaVinci : Dynamically Adaptive VIrtual Networks for a Customized...Internet. In DaVinci , each virtual network runs traffic-management protocols optimized for a traffic class, and link bandwidth is dynamically allocated

A Family of Quantum Protocols

NASA Astrophysics Data System (ADS)

Devetak, Igor; Harrow, Aram W.; Winter, Andreas

2004-12-01

We introduce three new quantum protocols involving noisy quantum channels and entangled states, and relate them operationally and conceptually with four well-known old protocols. Two of the new protocols (the mother and father) can generate the other five “child” protocols by direct application of teleportation and superdense coding, and can be derived in turn by making the old protocols “coherent.” This gives very simple proofs for two famous old protocols (the hashing inequality and quantum channel capacity) and provides the basis for optimal trade-off curves in several quantum information processing tasks.

4D-Listmode-PET-CT and 4D-CT for optimizing PTV margins in gastric lymphoma : Determination of intra- and interfractional gastric motion.

PubMed

Reinartz, Gabriele; Haverkamp, Uwe; Wullenkord, Ramona; Lehrich, Philipp; Kriz, Jan; Büther, Florian; Schäfers, Klaus; Schäfers, Michael; Eich, Hans Theodor

2016-05-01

New imaging protocols for radiotherapy in localized gastric lymphoma were evaluated to optimize planning target volume (PTV) margin and determine intra-/interfractional variation of the stomach. Imaging of 6 patients was explored prospectively. Intensity-modulated radiotherapy (IMRT) planning was based on 4D/3D imaging of computed tomography (CT) and positron-emission tomography (PET)-CT. Static and motion gross tumor volume (sGTV and mGTV, respectively) were distinguished by defining GTV (empty stomach), clinical target volume (CTV = GTV + 5 mm margin), PTV (GTV + 10/15/20/25 mm margins)  plus paraaortic lymph nodes and proximal duodenum. Overlap of 4D-Listmode-PET-based mCTV with 3D-CT-based PTV (increasing margins) and V95/D95 of mCTV were evaluated. Gastric shifts were determined using online cone-beam CT. Dose contribution to organs at risk was assessed. The 4D data demonstrate considerable intra-/interfractional variation of the stomach, especially along the vertical axis. Conventional 3D-CT planning utilizing advancing PTV margins of 10/15/20/25 mm resulted in rising dose coverage of mCTV (4D-Listmode-PET-Summation-CT) and rising D95 and V95 of mCTV. A PTV margin of 15 mm was adequate in 3 of 6 patients, a PTV margin of 20 mm was adequate in 4 of 6 patients, and a PTV margin of 25 mm was adequate in 5 of 6 patients. IMRT planning based on 4D-PET-CT/4D-CT together with online cone-beam CT is advisable to individualize the PTV margin and optimize target coverage in gastric lymphoma.