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iterative model reconstruction

Bertram J Wilm, Christoph Barmet, Simon Gross, Lars Kasper, S Johanna Vannesjo, Max Haeberlin, Benjamin E Dietrich, David O Brunner, Thomas Schmid, Klaas P Pruessmann
PURPOSE: The purpose of this work was to improve the quality of single-shot spiral MRI and demonstrate its application for diffusion-weighted imaging. METHODS: Image formation is based on an expanded encoding model that accounts for dynamic magnetic fields up to third order in space, nonuniform static B0 , and coil sensitivity encoding. The encoding model is determined by B0 mapping, sensitivity mapping, and concurrent field monitoring. Reconstruction is performed by iterative inversion of the expanded signal equations...
October 21, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
T J Tan, Kenneth K Lau, Dana Jackson, Nicholas Ardley, Adina Borasu
The purpose of this study was to assess the efficacy of model-based iterative reconstruction (MBIR), statistical iterative reconstruction (SIR), and filtered back projection (FBP) image reconstruction algorithms in the delineation of ureters and overall image quality on non-enhanced computed tomography of the renal tracts (NECT-KUB). This was a prospective study of 40 adult patients who underwent NECT-KUB for investigation of ureteric colic. Images were reconstructed using FBP, SIR, and MBIR techniques and individually and randomly assessed by two blinded radiologists...
October 21, 2016: Emergency Radiology
Michael Messerli, Fabian Rengier, Lotus Desbiolles, Niklas F Ehl, Ralf W Bauer, Sebastian Leschka, Hatem Alkadhi, Simon Wildermuth, Claas P Nähle
RATIONALE AND OBJECTIVES: To evaluate the influence of advanced modeled iterative reconstruction (ADMIRE) on the coronary artery calcium (CAC) scores by computed tomography (CT). MATERIALS AND METHODS: Sixty patients underwent CAC imaging with dual-source 192-slice CT. Agatston, volume and mass score were calculated from filtered back projection (FBP) and iterative reconstructions with different levels of ADMIRE. Friedman test and Wilcoxon rank sum test were used for multiple comparisons of CAC values and the difference ratio among different ADMIRE groups using FBP as reference...
October 11, 2016: Academic Radiology
Kevin P Murphy, Patrick D McLaughlin, Maria Twomey, Vincent E Chan, Fiachra Moloney, Adrian J Fung, Faimee E Chan, Tafline Kao, Siobhan B O'Neill, Benjamin Watson, Owen J O'Connor, Michael M Maher
INTRODUCTION: 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. METHODS: 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)...
October 13, 2016: Journal of Medical Imaging and Radiation Oncology
Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher
AIM: To assess the effect of neutral (NC) and positive (PC) oral contrast use on patient dose in low-dose abdominal computed tomography (CT). METHODS: Low-dose clinically indicated CTs were performed on 79 Crohn's patients (35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index (BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded...
September 28, 2016: World Journal of Radiology
Christian Schou Oxvig, Thomas Arildsen, Torben Larsen
The use of compressed sensing in atomic force microscopy (AFM) can potentially speed-up image acquisition, lower probe-specimen interaction, or enable super resolution imaging. The idea in compressed sensing for AFM is to spatially undersample the specimen, i.e. only acquire a small fraction of the full image of it, and then use advanced computational techniques to reconstruct the remaining part of the image whenever this is possible. Our initial experiments have shown that it is possible to leverage inherent structure in acquired AFM images to improve image reconstruction...
September 21, 2016: Ultramicroscopy
Justin Solomon, Ehsan Samei
The purpose of this study was to compare computed tomography (CT) low-contrast detectability from human readers with observer model-based surrogates of image quality. A phantom with a range of low-contrast signals (five contrasts, three sizes) was imaged on a state-of-the-art CT scanner (Siemens' force). Images were reconstructed using filtered back projection and advanced modeled iterative reconstruction and were assessed by 11 readers using a two alternative forced choice method. Concurrently, contrast-to-noise ratio (CNR), area-weighted CNR (CNRA), and observer model-based metrics were estimated, including nonprewhitening (NPW) matched filter, NPW with eye filter (NPWE), NPW with internal noise, NPW with an eye filter and internal noise (NPWEi), channelized Hotelling observer (CHO), and CHO with internal noise (CHOi)...
July 2016: Journal of Medical Imaging
Daniel P Redmond, Yeong Shiong Chiew, Vincent Major, J Geoffrey Chase
Monitoring of respiratory mechanics is required for guiding patient-specific mechanical ventilation settings in critical care. Many models of respiratory mechanics perform poorly in the presence of variable patient effort. Typical modelling approaches either attempt to mitigate the effect of the patient effort on the airway pressure waveforms, or attempt to capture the size and shape of the patient effort. This work analyses a range of methods to identify respiratory mechanics in volume controlled ventilation modes when there is patient effort...
September 23, 2016: Computer Methods and Programs in Biomedicine
André Ritter, Gisela Anton, Thomas Weber
A maximum-likelihood reconstruction technique for X-ray Talbot-Lau tomography is presented. This technique allows the iterative simultaneous reconstruction of discrete distributions of absorption coefficient, refractive index and a dark-field scattering coefficient. This technique avoids prior phase retrieval in the tomographic projection images and thus in principle allows reconstruction from tomographic data with less than three phase steps per projection. A numerical phantom is defined which is used to evaluate convergence of the technique with regard to photon statistics and with regard to the number of projection angles and phase steps used...
2016: PloS One
F Nouizi, H Erkol, A Luk, M Marks, M B Unlu, G Gulsen
We previously introduced photo-magnetic imaging (PMI), an imaging technique that illuminates the medium under investigation with near-infrared light and measures the induced temperature increase using magnetic resonance thermometry (MRT). Using a multiphysics solver combining photon migration and heat diffusion, PMI models the spatiotemporal distribution of temperature variation and recovers high resolution optical absorption images using these temperature maps. In this paper, we present a new fast non-iterative reconstruction algorithm for PMI...
October 3, 2016: Physics in Medicine and Biology
Qian Cao, Wojciech Zbijewski, Alejandro Sisniega, John Yorkston, Jeffrey H Siewerdsen, J Webster Stayman
Application of model-based iterative reconstruction (MBIR) to high resolution cone-beam CT (CBCT) is computationally challenging because of the very fine discretization (voxel size  <100 µm) of the reconstructed volume. Moreover, standard MBIR techniques require that the complete transaxial support for the acquired projections is reconstructed, thus precluding acceleration by restricting the reconstruction to a region-of-interest. To reduce the computational burden of high resolution MBIR, we propose a multiresolution penalized-weighted least squares (PWLS) algorithm, where the volume is parameterized as a union of fine and coarse voxel grids as well as selective binning of detector pixels...
October 21, 2016: Physics in Medicine and Biology
Andrew B Rosenkrantz, Ankur M Doshi, Luke A Ginocchio, Yindalon Aphinyanaphongs
RATIONALE AND OBJECTIVES: This study aimed to assess the performance of a text classification machine-learning model in predicting highly cited articles within the recent radiological literature and to identify the model's most influential article features. MATERIALS AND METHODS: We downloaded from PubMed the title, abstract, and medical subject heading terms for 10,065 articles published in 25 general radiology journals in 2012 and 2013. Three machine-learning models were applied to predict the top 10% of included articles in terms of the number of citations to the article in 2014 (reflecting the 2-year time window in conventional impact factor calculations)...
September 27, 2016: Academic Radiology
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...
2016: Journal of Applied Clinical Medical Physics
Tingting Li, Yonggao Zhang, Yadong Wang, Jianbo Gao, Yan Jiang
The aim of the study was to investigate the image quality of low-dose CT images with different reconstruction algorithms including filtered back projection (FBP), hybrid iterative reconstruction (HIR), and iterative model reconstruction (IMR) algorithms by comparison of routine dose images with FBP reconstruction, in patients with malignant obstructive tracheobronchial diseases.In total, 60 patients (59 ± 9.3 years, 37 males) with airway stent who are randomly assigned into 2 groups (routine-dose [RD] and low-dose [LD] group, 30 for each) underwent chest CT on a 256-slice CT (RD-group 120 kV, 250 mAs, LD-group 120 kV, 120 mAs)...
September 2016: Medicine (Baltimore)
Cheng Hui Yang, Tung-Hsin Wu, Chung-Jung Lin, Yi-You Chiou, Ying-Chou Chen, Ming-Huei Sheu, Wan-Yuo Guo, Chen Fen Chiu
PURPOSE: To evaluate the image quality and diagnostic confidence of reduced-dose computed tomography (CT) of the lumbar spine (L-spine) reconstructed with knowledge-based iterative model reconstruction (IMR). MATERIALS AND METHODS: Prospectively, group A consisted of 55 patients imaged with standard acquisition reconstructed with filtered back-projection. Group B consisted of 58 patients imaged with half tube current, reconstructed with hybrid iterative reconstruction (iDose(4)) in Group B1 and knowledge-based IMR in Group B2...
October 2016: European Journal of Radiology
Yuji Iyama, Takeshi Nakaura, Masafumi Kidoh, Seitaro Oda, Daisuke Utsunomiya, Naritsugu Sakaino, Shinichi Tokuyasu, Hirokazu Osakabe, Kazunori Harada, Yasuyuki Yamashita
RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the noise and image quality of images reconstructed with a knowledge-based iterative model reconstruction (knowledge-based IMR) in ultra-low dose cardiac computed tomography (CT). MATERIALS AND METHODS: We performed submillisievert radiation dose coronary CT angiography on 43 patients. We also performed a phantom study to evaluate the influence of object size with the automatic exposure control phantom...
September 21, 2016: Academic Radiology
Katharina Martini, Borna K Barth, Kai Higashigaito, Stephan Baumueller, Hatem Alkadhi, Thomas Frauenfelder
To determine the lowest CT radiation dose-level at maintained image-quality and high sensitivity for detection of pulmonary-nodules in obesity. Single-energy CT with tin-filtration was performed in a chest-phantom with solid pulmonary-nodules simulating over-weight and obesity. CTDIvol of the standard-protocol was 0.41 mGy, subsequent scans were obtained at 1/2 and 1/4 dose-levels. Images were reconstructed using FBP and advanced-modeled iterative reconstruction (ADMIRE). Noise, image-quality, and sensitivity for nodule-detection were assessed...
August 2, 2016: Current Problems in Diagnostic Radiology
P Fischer, A Jardani, A Soueid Ahmed, M Abbas, X Wang, H Jourde, N Lecoq
Large-scale inversion methods have been recently developed and permitted now to considerably reduce the computation time and memory needed for inversions of models with a large amount of parameters and data. In this work, we have applied a deterministic geostatistical inversion algorithm to a hydraulic tomography investigation conducted in an experimental field site situated within an alluvial aquifer in Southern France. This application aims to achieve a 2-D large-scale modeling of the spatial transmissivity distribution of the site...
September 19, 2016: Ground Water
Zsuzsanna Deák, Friedrich Maertz, Felix Meurer, Susan Notohamiprodjo, Fabian Mueck, Lucas L Geyer, Maximilian F Reiser, Stefan Wirth
OBJECTIVE: The aim of this study was to define optimal tube potential for soft tissue and vessel visualization in dose-reduced chest CT protocols using model-based iterative algorithm in average and overweight patients. METHODS: Thirty-six patients receiving chest CT according to 3 protocols (120 kVp/noise index [NI], 60; 100 kVp/NI, 65; 80 kVp/NI, 70) were included in this prospective study, approved by the ethics committee. Patients' physical parameters and dose descriptors were recorded...
September 16, 2016: Journal of Computer Assisted Tomography
Heloise Barras, Vincent Dunet, Anne-Lise Hachulla, Jochen Grimm, Catherine Beigelman-Aubry
BACKGROUND: Model-based iterative reconstruction (MBIR) reduces image noise and improves image quality (IQ) but its influence on post-processing tools including maximal intensity projection (MIP) and minimal intensity projection (mIP) remains unknown. PURPOSE: To evaluate the influence on IQ of MBIR on native, mIP, MIP axial and coronal reformats of reduced dose computed tomography (RD-CT) chest acquisition. MATERIAL AND METHODS: Raw data of 50 patients, who underwent a standard dose CT (SD-CT) and a follow-up RD-CT with a CT dose index (CTDI) of 2-3 mGy, were reconstructed by MBIR and FBP...
August 2016: Acta Radiologica Open
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