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iterative model reconstruction

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https://www.readbyqxmd.com/read/28338471/generalized-psf-modelling-for-optimized-quantitation-in-pet-imaging
#1
Saeed Ashrafinia, Hassan Mohy-Ud-Din, Nicolas Karakatsanis, Abhinav Jha, Michael Casey, Dan Kadrmas, Arman Rahmim
Point-Spread Function (PSF) modelling offers the capability to account for resolution degrading phenomena within the PET reconstruction framework. PSF modelling improves resolution and enhances contrast, but at the same time significantly alters image noise properties and induces edge overshoot effect. Thus, studying the effect of PSF modelling on quantitation task performance can be very important. Frameworks explored in the past involve a dichotomy of PSF vs. no-PSF modelling. By contrast, the present work focuses on quantitative performance evaluation of standard uptake value (SUV) PET images, while incorporating a wide spectrum of PSF models, including those that under- and over-estimate the true PSF, for the potential of enhanced quantitation of standardized uptake values (SUVs)...
March 24, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28333040/rigid-motion-correction-of-dual-opposed-planar-projections-in-single-photon-imaging
#2
Georgios I Angelis, William Ryder, John Gillam, Frederic Boisson, Andre Kyme, Roger Fulton, Steven Meikle, Peter Kench
Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomography problem, except that we wish to estimate the 2D planar projections rather than the 3D volume, where the angular sampling in all three axes depends on the rotational motion of the animal. In this study, we hypothesise that the motion corrected planar projections estimated by reconstructing an estimate of the 3D volume using an iterative motion compensating reconstruction algorithm and integrating it along the projection path, will closely match the true, motion-less, planar distribution regardless of the object motion...
March 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28314613/improved-image-quality-with-simultaneously-reduced-radiation-exposure-knowledge-based-iterative-model-reconstruction-algorithms-for-coronary-ct-angiography-in-a-clinical-setting
#3
Florian André, Philipp Fortner, Mani Vembar, Dirk Mueller, Wolfram Stiller, Sebastian J Buss, Hans-Ulrich Kauczor, Hugo A Katus, Grigorios Korosoglou
BACKGROUND: The aim of this study was to assess the potential for radiation dose reduction using knowledge-based iterative model reconstruction (K-IMR) algorithms in combination with ultra-low dose body mass index (BMI)-adapted protocols in coronary CT angiography (coronary CTA). METHODS: Forty patients undergoing clinically indicated coronary CTA were randomly assigned to two groups with BMI-adapted (I: <25.0 kg/m(2), II: <28.0 kg/m(2), III: <30.0 kg/m(2), IV: ≥30...
February 23, 2017: Journal of Cardiovascular Computed Tomography
https://www.readbyqxmd.com/read/28302073/image-quality-improvement-using-model-based-iterative-reconstruction-in-low-dose-chest-ct-for-children-with-necrotizing-pneumonia
#4
Jihang Sun, Tong Yu, Jinrong Liu, Xiaomin Duan, Di Hu, Yong Liu, Yun Peng
BACKGROUND: Model-based iterative reconstruction (MBIR) is a promising reconstruction method which could improve CT image quality with low radiation dose. The purpose of this study was to demonstrate the advantage of using MBIR for noise reduction and image quality improvement in low dose chest CT for children with necrotizing pneumonia, over the adaptive statistical iterative reconstruction (ASIR) and conventional filtered back-projection (FBP) technique. METHODS: Twenty-six children with necrotizing pneumonia (aged 2 months to 11 years) who underwent standard of care low dose CT scans were included...
March 16, 2017: BMC Medical Imaging
https://www.readbyqxmd.com/read/28297460/a-noise-power-spectrum-study-of-a-new-model-based-iterative-reconstruction-system-veo-3-0
#5
Guang Li, Xinming Liu, Cristina T Dodge, Corey T Jensen, X John Rong
The purpose of this study was to evaluate performance of the third generation of model-based iterative reconstruction (MBIR) system, Veo 3.0, based on noise power spectrum (NPS) analysis with various clinical presets over a wide range of clinically applicable dose levels. A CatPhan 600 surrounded by an oval, fat-equivalent ring to mimic patient size/shape was scanned 10 times at each of six dose levels on a GE HD 750 scanner. NPS analysis was performed on images reconstructed with various Veo 3.0 preset combinations for comparisons of those images reconstructed using Veo 2...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297293/dose-reduction-in-ct-urography-and-vasculature-phantom-studies-using-model-based-iterative-reconstruction
#6
Leland Page, Wei Wei, Vikas Kundra, X John Rong
To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scanner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvol) of 24 mGy...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28295418/technical-note-on-the-accuracy-of-parametric-two-parameter-cross-section-models-in-dual-energy-ct-applications
#7
Dong Han, Mariela A Porras-Chaverri, Joseph A O'Sullivan, David G Politte, Jeffrey F Williamson
PURPOSE: To evaluate and compare the theoretically achievable accuracy of two families of two-parameter photon cross-section models: basis vector model (BVM) and modified parametric fit model (mPFM). METHOD: The modified PFM assumes that photoelectric absorption and scattering cross sections can be accurately represented by power functions in effective atomic number and / or energy plus the Klein-Nishina cross section, along with empirical corrections that enforce exact prediction of elemental cross sections...
March 15, 2017: Medical Physics
https://www.readbyqxmd.com/read/28290345/first-experiences-with-model-based-iterative-reconstructions-influence-on-quantitative-plaque-volume-and-intensity-measurements-in-coronary-computed-tomography-angiography
#8
H Precht, P H Kitslaar, A Broersen, O Gerke, J Dijkstra, J Thygesen, K Egstrup, J Lambrechtsen
PURPOSE: Investigate the influence of adaptive statistical iterative reconstruction (ASIR) and the model-based IR (Veo) reconstruction algorithm in coronary computed tomography angiography (CCTA) images on quantitative measurements in coronary arteries for plaque volumes and intensities. METHODS: Three patients had three independent dose reduced CCTA performed and reconstructed with 30% ASIR (CTDIvol at 6.7 mGy), 60% ASIR (CTDIvol 4.3 mGy) and Veo (CTDIvol at 1...
February 2017: Radiography
https://www.readbyqxmd.com/read/28289943/intra-patient-comparison-of-reduced-dose-model-based-iterative-reconstruction-with-standard-dose-adaptive-statistical-iterative-reconstruction-in-the-ct-diagnosis-and-follow-up-of-urolithiasis
#9
Sean Tenant, Chun Lap Pang, Prageeth Dissanayake, Varut Vardhanabhuti, Colin Stuckey, Catherine Gutteridge, Christopher Hyde, Carl Roobottom
OBJECTIVES: To evaluate the accuracy of reduced-dose CT scans reconstructed using a new generation of model-based iterative reconstruction (MBIR) in the imaging of urinary tract stone disease, compared with a standard-dose CT using 30% adaptive statistical iterative reconstruction. METHODS: This single-institution prospective study recruited 125 patients presenting either with acute renal colic or for follow-up of known urinary tract stones. They underwent two immediately consecutive scans, one at standard dose settings and one at the lowest dose (highest noise index) the scanner would allow...
March 13, 2017: European Radiology
https://www.readbyqxmd.com/read/28289906/pediatric-chest-ct-at-chest-radiograph-doses-when-is-the-ultralow-dose-chest-ct-clinically-appropriate
#10
Javier E Villanueva-Meyer, David M Naeger, Jesse L Courtier, Michael D Hope, Jack W Lambert, John D MacKenzie, Andrew S Phelps
PURPOSE: Computed tomography (CT) use in emergency departments represents a significant contribution to pediatric patients' exposure to ionizing radiation. Here, we evaluate whether ultralow-dose chest CT can be diagnostically adequate for other diagnoses and whether model-based iterative reconstruction (MBIR) can improve diagnostic adequacy compared to adaptive statistical iterative reconstruction (ASIR) at ultralow doses. METHODS: Twenty children underwent chest CTs: 10 standard-dose reconstructed with ASIR and 10 ultralow-dose reconstructed with ASIR and MBIR...
March 14, 2017: Emergency Radiology
https://www.readbyqxmd.com/read/28287962/pet-image-reconstruction-and-deformable-motion-correction-using-unorganized-point-clouds
#11
Ivan Klyuzhin, Vesna Sossi
Quantitative PET imaging often requires correcting the image data for deformable motion. With cyclic motion, this is traditionally achieved by separating the coincidence data into a relatively small number of gates, and incorporating the inter-gate image transformation matrices into the reconstruction algorithm. In the presence of non-cyclic deformable motion, this approach may be impractical due to a large number of required gates. In this work, we propose an alternative approach to iterative image reconstruction with correction for deformable motion, wherein unorganized point clouds are used to model the imaged objects in the image space, and motion is corrected for explicitly by introducing a time-dependency into the point coordinates...
March 2, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28282862/an-assessment-of-iterative-reconstruction-methods-for-sparse-ultrasound-imaging
#12
Solivan A Valente, Marcelo V W Zibetti, Daniel R Pipa, Joaquim M Maia, Fabio K Schneider
Ultrasonic image reconstruction using inverse problems has recently appeared as an alternative to enhance ultrasound imaging over beamforming methods. This approach depends on the accuracy of the acquisition model used to represent transducers, reflectivity, and medium physics. Iterative methods, well known in general sparse signal reconstruction, are also suited for imaging. In this paper, a discrete acquisition model is assessed by solving a linear system of equations by an ℓ 1 -regularized least-squares minimization, where the solution sparsity may be adjusted as desired...
March 8, 2017: Sensors
https://www.readbyqxmd.com/read/28282642/shape-aware-surface-reconstruction-from-sparse-3d-point-clouds
#13
Florian Bernard, Luis Salamanca, Johan Thunberg, Alexander Tack, Dennis Jentsch, Hans Lamecker, Stefan Zachow, Frank Hertel, Jorge Goncalves, Peter Gemmar
The reconstruction of an object's shape or surface from a set of 3D points plays an important role in medical image analysis, e.g. in anatomy reconstruction from tomographic measurements or in the process of aligning intra-operative navigation and preoperative planning data. In such scenarios, one usually has to deal with sparse data, which significantly aggravates the problem of reconstruction. However, medical applications often provide contextual information about the 3D point data that allow to incorporate prior knowledge about the shape that is to be reconstructed...
February 14, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28275901/diagnosis-of-small-posterior-fossa-stroke-on-brain-ct-effect-of-iterative-reconstruction-designed-for-brain-ct-on-detection-performance
#14
Taihei Inoue, Takeshi Nakaura, Morikatsu Yoshida, Koichi Yokoyama, Kenichiro Hirata, Masafumi Kidoh, Seitaro Oda, Daisuke Utsunomiya, Kazunori Harada, Yasuyuki Yamashita
OBJECTIVES: In this study, we aimed to determine whether iterative model reconstruction designed for brain CT (IMR-neuro) would improve the accuracy of posterior fossa stroke diagnosis on brain CT. METHODS: We enrolled 37 patients with ischaemic stroke in the posterior fossa and 37 patients without stroke (controls). Using axial images reconstructed using filtered back-projection (FBP) and IMR-neuro, we compared the CT numbers in infarcted areas, image noise in the pons, and contrast-to-noise ratios (CNRs) of infarcted and non-infarcted areas on scans subjected to IMR-neuro and FBP...
March 8, 2017: European Radiology
https://www.readbyqxmd.com/read/28270290/application-of-low-tube-voltage-70-kv-and-advanced-modeled-iterative-reconstruction-in-the-third-generation-dual-source-ct-to-ct-colonography
#15
Jingjuan Liu, Weidong Pan, Huadan Xue, Bin Li, Xuan Wang, Hao Sun, Yun Wang, Wei Liu, Zhengyu Jin
Objective To explore the feasibility of reducing radiation dose of CT colonography (CTC) while preserving image quality using the third-generation dual-source CT at 70 kV tube voltage with advanced modeled iterative reconstruction (ADMIRE). Methods This prospective study consecutively included 53 patients. All patients underwent CTC at 120 kV in supine position with filtered back projection reconstruction and at 70 kV in prone position with ADMIRE with the same scan range. Radiation dose and image quality were compared between these two protocols...
February 20, 2017: Zhongguo Yi Xue Ke Xue Yuan Xue Bao. Acta Academiae Medicinae Sinicae
https://www.readbyqxmd.com/read/28270277/application-of-third-generation-dual-source-ct-for-ultra-high-resolution-temporal-bone-imaging-using-automated-tube-voltage-adaptation-in-children-with-hearing-impairment
#16
Yuanli Zhu, Yu Chen, Xinmiao Fan, Huadan Xue, Xiaowei Chen, Man Wang, Yun Wang, Zhuhua Zhang, Zhengyu Jin
Objective To evaluate the radiation dose and image quality of the third-generation dual-source CT using automated tube voltage adaptation (CARE kV) in temporal bone scanning in pediatric patients with hearing impairment. Methods Totally 27 children with hearing impairment less than 18 years old were randomly divided into two groups:Group A (n=14),examined with CARE kV (reference with 100 kV and 214 mA)and sinogram-affirmed iterative reconstruction;and Group B (n=13),examined with CARE kV (reference with 100 kV and 171 mA)and advanced modeled iterative reconstruction...
February 20, 2017: Zhongguo Yi Xue Ke Xue Yuan Xue Bao. Acta Academiae Medicinae Sinicae
https://www.readbyqxmd.com/read/28270276/third-generation-dual-source-ct-for-head-and-neck-ct-angiography-with-70-kv-tube-voltage-and-20-25-ml-contrast-medium-in-patients-with-body-weight-lower-than-75-kg
#17
Yu Chen, Yuanli Zhu, Huadan Xue, Yun Wang, Yumei Li, Zhuhua Zhang, Zhengyu Jin
Objective To investigate the image quality of head and neck CT angiography (CTA)using the third-generation dual-source CT combined with 70 kV tube voltage and 20-25 ml contrast medium (CM),and evaluate the effects of venous artifacts arising from the CM on the ipsilateral side of injection. Methods Totally 40 consecutive patients with suspected vascular diseases and body weight lower than 75 kg prospectively underwent head and neck CTA examination using the third-generation dual-source CT. CTA was performed with a third-generation dual-source CT system...
February 20, 2017: Zhongguo Yi Xue Ke Xue Yuan Xue Bao. Acta Academiae Medicinae Sinicae
https://www.readbyqxmd.com/read/28269599/simultaneous-reconstruction-and-segmentation-with-the-mumford-shah-functional-for-electron-tomography
#18
Li Shen, Eric Todd Quinto, Shiqiang Wang, Ming Jiang
Electron micrography (EM) is an important method for determining the three-dimensional (3D) structure of macromolecular complexes and biological specimens. But there are several limitations such as poor signal-to-noise, limitation on range of tilt angles and sub-region subject to electron exposure, unintentional movements of the specimen, with EM systems that make the reconstruction procedure a severely ill-posed problem. A different choice of reconstruction method may lead to different results and create different additional artifacts in reconstructed images...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269176/multivariate-autoregressive-model-constrained-by-anatomical-connectivity-to-reconstruct-focal-sources
#19
Brahim Belaoucha, Mouloud Kachouane, Theodore Papadopoulo
In this paper, we present a framework to reconstruct spatially localized sources from Magnetoencephalography (MEG)/Electroencephalography (EEG) using spatiotemporal constraint. The source dynamics are represented by a Multivariate Autoregressive (MAR) model whose matrix elements are constrained by the anatomical connectivity obtained from diffusion Magnetic Resonance Imaging (dMRI). The framework assumes that the whole brain dynamic follows a constant MAR model in a time window of interest. The source activations and the MAR model parameters are estimated iteratively...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28267541/free-breathing-high-pitch-80kvp-dual-source-computed-tomography-of-the-pediatric-chest-image-quality-presence-of-motion-artifacts-and-radiation-dose
#20
Boris Bodelle, Constanze Fischbach, Christian Booz, Ibrahim Yel, Claudia Frellesen, Martin Beeres, Thomas J Vogl, Jan-Erik Scholtz
OBJECTIVES: To investigate image quality, presence of motion artifacts and effects on radiation dose of 80kVp high-pitch dual-source CT (DSCT) in combination with an advanced modeled iterative reconstruction algorithm (ADMIRE) of the pediatric chest compared to single-source CT (SSCT). MATERIALS AND METHODS: The study was approved by the institutional review board. Eighty-seven consecutive pediatric patients (mean age 9.1±4.9years) received either free-breathing high-pitch (pitch 3...
April 2017: European Journal of Radiology
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