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iterative reconstruction

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https://www.readbyqxmd.com/read/28937493/adaptive-statistical-iterative-reconstruction-v-versus-adaptive-statistical-iterative-reconstruction-impact-on-dose-reduction-and-image-quality-in-body-computed-tomography
#1
Marco Gatti, Filippo Marchisio, Marco Fronda, Osvaldo Rampado, Riccardo Faletti, Laura Bergamasco, Roberto Ropolo, Paolo Fonio
OBJECTIVE: The aim of this study was to evaluate the impact on dose reduction and image quality of the new iterative reconstruction technique: adaptive statistical iterative reconstruction (ASIR-V). METHODS: Fifty consecutive oncologic patients acted as case controls undergoing during their follow-up a computed tomography scan both with ASIR and ASIR-V. Each study was analyzed in a double-blinded fashion by 2 radiologists. Both quantitative and qualitative analyses of image quality were conducted...
September 20, 2017: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/28937486/iterative-metallic-artifact-reduction-for-in-plane-gonadal-shielding-during-computed-tomographic-venography-of-young-males
#2
Jin Woo Choi, Sang Yub Lee, Jong Hyo Kim, Hyeongmin Jin, Jaewon Lee, Young Hun Choi, Hyeon-Kyeong Lee, Jae Hyung Park
OBJECTIVE: The purpose of this study was to evaluate a gonadal shield (GS) and iterative metallic artifact reduction (IMAR) during computed tomography scans, regarding the image quality and radiation dose. METHODS: A phantom was imaged with and without a GS. Prospectively enrolled, young male patients underwent lower extremity computed tomography venography (precontrast imaging without the GS and postcontrast imaging with the GS). Radiation dose was measured each time, and the GS-applied images were reconstructed by weighted filtered back projection and IMAR...
September 20, 2017: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/28936988/reducing-radiation-exposure-with-iterative-reconstruction-an-inter-and-intra-scanner-analysis
#3
Aaron Rohr, Jo Wick, Jacqueline Hill, Carissa Walter, Neville Irani, Shaun Best, Kirk Miller, Ryan Ash
Our purpose in this study was to compare delivered radiation exposure via Computed Tomography Dose Index Volume (CTDIvol) and Dose Length Production (DLP) measurements from computed tomography (CT) examinations performed on scanners with and without image-quality enhancing iterative reconstruction (IR) software. A retrospective analysis was conducted on randomly selected chest, abdomen, and/or pelvis CT examinations from three different scanners from January 1, 2013 to December 31, 2013. CTDIvol and DLP measurements were obtained from two CT scanners with and one CT scanner without IR software...
September 22, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/28936780/ct-based-spect-attenuation-correction-and-assessment-of-infarct-size-results-from-a-cardiac-phantom-study
#4
Alexander Stephan Kroiss, Stephan Gerhard Nekolla, Georg Dobrozemsky, Thomas Grubinger, Barry Lynn Shulkin, Markus Schwaiger
RATIONALE: Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model. METHODS: A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used...
September 21, 2017: Annals of Nuclear Medicine
https://www.readbyqxmd.com/read/28934809/ct-and-mri-techniques-for-imaging-around-orthopedic-hardware
#5
Thuy Duong Do, Reto Sutter, Stephan Skornitzke, Marc-André Weber
Orthopedic hardware impairs image quality in cross-sectional imaging. With an increasing number of orthopedic implants in an aging population, the need to mitigate metal artifacts in computed tomography and magnetic resonance imaging is becoming increasingly relevant. This review provides an overview of the major artifacts in CT and MRI and state-of-the-art solutions to improve image quality. All steps of image acquisition from device selection, scan preparations and parameters to image post-processing influence the magnitude of metal artifacts...
September 21, 2017: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/28933350/locally-linear-constraint-based-optimization-model-for-material-decomposition
#6
Qian Wang, Yining Zhu, Hengyong Yu
Dual spectral computed tomography (DSCT) has a superior material distinguishability than the conventional single spectral computed tomography (SSCT). However, the decomposition process is an illposed problem, which is sensitive to noise. Thus, the decomposed image quality is degraded, and the corresponding signal-to-noise ratio (SNR) is much lower than that of directly reconstructed image of SSCT. In this work, we establish a locally linear relationship between the decomposed results of DSCT and SSCT. Based on this constraint, we propose an optimization model for DSCT and develop an iterative method with image guided filtering...
September 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28932962/reduction-of-artifacts-caused-by-orthopedic-hardware-in-the-spine-in-spectral-detector-ct-examinations-using-virtual-monoenergetic-image-reconstructions-and-metal-artifact-reduction-algorithms
#7
Nils Große Hokamp, V Neuhaus, N Abdullayev, K Laukamp, S Lennartz, A Mpotsaris, J Borggrefe
OBJECTIVE: Aim of this study was to assess the artifact reduction in patients with orthopedic hardware in the spine as provided by (1) metal-artifact-reduction algorithms (O-MAR) and (2) virtual monoenergetic images (MonoE) as provided by spectral detector CT (SDCT) compared to conventional iterative reconstruction (CI). METHODS: In all, 28 consecutive patients with orthopedic hardware in the spine who underwent SDCT-examinations were included. CI, O-MAR and MonoE (40-200 keV) images were reconstructed...
September 21, 2017: Skeletal Radiology
https://www.readbyqxmd.com/read/28932758/iterative-image-processing-for-early-diagnostic-of-beta-amyloid-plaque-deposition-in-pre-clinical-alzheimer-s-disease-studies
#8
Nikolai V Slavine, Padmakar V Kulkarni, Roderick W McColl
PURPOSE: To test and evaluate an efficient iterative image processing strategy to improve the quality of sub-optimal pre-clinical PET images. A novel iterative resolution subsets-based method to reduce noise and enhance resolution (RSEMD) has been demonstrated on examples of PET imaging studies of Alzheimer's disease (AD) plaques deposition in mice brains. MATERIALS AND METHODS: The RSEMD method was applied to imaging studies of non-invasive detection of beta-amyloid plaque in transgenic mouse models of AD...
August 2017: Journal of Applied Bioinformatics & Computational Biology
https://www.readbyqxmd.com/read/28927642/iterative-approach-for-3d-reconstruction-of-the-femur-from-un-calibrated-2d-radiographic-images
#9
Kibeom Youn, Moon Soek Park, Jehee Lee
Three-dimensional reconstruction of the femur is important for surgical planning in patients with cerebral palsy. This study aimed to reconstruct the three-dimensional femur shape from un-calibrated bi-planar radiographic images using self-calibration to allow for low-dose preoperative planning. The existing self-calibration techniques require anatomical landmarks that are clearly visible on bi-planar images, which are not available on the femur. In our newly developed method, the self-calibration is performed so that the contour of the statistical shape matches the image contour while the statistical shape is concomitantly optimized...
September 15, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28924196/rapid-alignment-of-nanotomography-data-using-joint-iterative-reconstruction-and-reprojection
#10
Doğa Gürsoy, Young P Hong, Kuan He, Karl Hujsak, Seunghwan Yoo, Si Chen, Yue Li, Mingyuan Ge, Lisa M Miller, Yong S Chu, Vincent De Andrade, Kai He, Oliver Cossairt, Aggelos K Katsaggelos, Chris Jacobsen
As x-ray and electron tomography is pushed further into the nanoscale, the limitations of rotation stages become more apparent, leading to challenges in the alignment of the acquired projection images. Here we present an approach for rapid post-acquisition alignment of these projections to obtain high quality three-dimensional images. Our approach is based on a joint estimation of alignment errors, and the object, using an iterative refinement procedure. With simulated data where we know the alignment error of each projection image, our approach shows a residual alignment error that is a factor of a thousand smaller, and it reaches the same error level in the reconstructed image in less than half the number of iterations...
September 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28922116/iterative-low-dose-ct-reconstruction-with-priors-trained-by-artificial-neural-network
#11
Dufan Wu, Kyungsang Kim, Georges El Fakhri, Quanzheng Li
Dose reduction in computed tomography (CT) is essential for decreasing radiation risk in clinical applications. Iterative reconstruction algorithms are one of the most promising way to compensate for the increased noise due to reduction of photon flux. Most iterative reconstruction algorithms incorporate manually designed prior functions of the reconstructed image to suppress noises while maintaining structures of the image. These priors basically rely on smoothness constraints and cannot exploit more complex features of the image...
September 15, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28920914/robust-visual-tracking-via-online-discriminative-and-low-rank-dictionary-learning
#12
Tao Zhou, Fanghui Liu, Harish Bhaskar, Jie Yang
In this paper, we propose a novel and robust tracking framework based on online discriminative and low-rank dictionary learning. The primary aim of this paper is to obtain compact and low-rank dictionaries that can provide good discriminative representations of both target and background. We accomplish this by exploiting the recovery ability of low-rank matrices. That is if we assume that the data from the same class are linearly correlated, then the corresponding basis vectors learned from the training set of each class shall render the dictionary to become approximately low-rank...
September 12, 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28920898/hybrid-pre-log-and-post-log-image-reconstruction-for-computed-tomography
#13
Guobao Wang, Jian Zhou, Zhou Yu, Wenli Wang, Jinyi Qi
Tomographic image reconstruction for low-dose CT is increasingly challenging as dose continues to reduce in clinical applications. Pre-log domain methods and post-log domain methods have been proposed individually and each method has its own disadvantage. While having the potential to improve image quality for low-dose data by using an accurate imaging model, pre-log domain methods suffer slow convergence in practice due to the nonlinear transformation from the image to measurements. In contrast, post-log domain methods have fast convergence speed but the resulting image quality is suboptimal for low-count CT data because the log transformation is extremely unreliable for low-count measurements and undefined for negative values...
September 13, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28917520/short-term-complications-in-intra-and-extra-articular-anterior-cruciate-ligament-reconstruction-comparison-with-the-literature-on-isolated-intra-articular-reconstruction-a-multicenter-study-by-the-french-society-of-arthroscopy
#14
J C Panisset, R Pailhé, B Schlaterrer, L Sigwalt, B Sonnery-Cottet, C Lutz, S Lustig, C Batailler, S Bertiaux, F P Ehkirch, P Colombet, C Steltzlen, M L Louis, P D'ingrado, F Dalmay, P Imbert, D Saragaglia
INTRODUCTION: Lateral tenodesis (LT) is performed to limit the risk of iterative tear following anterior cruciate ligament (ACL) reconstruction in at-risk patients. By adding an extra procedure to isolated ACL graft, LT reconstruction increases operating time and may complicate postoperative course. The objective of the present study was to evaluate the rate of early complications. The study hypothesis was that associating ALL reconstruction to ACL reconstruction does not increase the complications rate found with isolated ACL reconstruction...
September 13, 2017: Orthopaedics & Traumatology, Surgery & Research: OTSR
https://www.readbyqxmd.com/read/28911333/profiling-bacterial-communities-by-minion-sequencing-of-ribosomal-operons
#15
Lee J Kerkhof, Kevin P Dillon, Max M Häggblom, Lora R McGuinness
BACKGROUND: An approach utilizing the long-read capability of the Oxford Nanopore MinION to rapidly sequence bacterial ribosomal operons of complex natural communities was developed. Microbial fingerprinting employs domain-specific forward primers (16S rRNA subunit), reverse primers (23S rRNA subunit), and a high-fidelity Taq polymerase with proofreading capabilities. Amplicons contained both ribosomal subunits for broad-based phylogenetic assignment (~ 3900 bp of sequence), plus the intergenic spacer (ITS) region (~ 300 bp) for potential strain-specific identification...
September 15, 2017: Microbiome
https://www.readbyqxmd.com/read/28910696/tissue-microstructure-estimation-using-a-deep-network-inspired-by-a-dictionary-based-framework
#16
Chuyang Ye
Diffusion magnetic resonance imaging (dMRI) captures the anisotropic pattern of water displacement in the neuronal tissue and allows noninvasive investigation of the complex tissue microstructure. A number of biophysical models have been proposed to relate the tissue organization with the observed diffusion signals, so that the tissue microstructure can be inferred. The Neurite Orientation Dispersion and Density Imaging (NODDI) model has been a popular choice and has been widely used for many neuroscientific studies...
September 6, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28902765/low-dose-90y-pet-ct-imaging-optimized-for-lesion-detectability-and-quantitative-accuracy-a-phantom-study-to-assess-the-feasibility-of-pretherapy-imaging-to-plan-the-therapeutic-dose
#17
Maryam Khazaee, Alireza Kamali-Asl, Parham Geramifar, Arman Rahmim
OBJECTIVE: The overall aim of this work is to optimize the reconstruction parameters for low-dose yttrium-90 (Y) PET/computed tomography (CT) imaging, and to determine Y minimum detectable activity, in an endeavor to investigate the feasibility of performing low-dose Y imaging in-vivo to plan the therapeutic dose in radioembolization. MATERIALS AND METHODS: This study was carried out using a Siemens Biograph 6 True Point PET/CT scanner. A Jaszczak phantom containing five hot syringes was imaged serially over 15 days...
September 11, 2017: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/28901617/dual-rotation-c-arm-cone-beam-computed-tomography-to-increase-low-contrast-detection
#18
Aymeric Reshef, Cyril Riddell, Yves Trousset, Saïd Ladjal, Isabelle Bloch
PURPOSE: This paper investigates the capabilities of a dual-rotation C-arm cone-beam computed tomography (CBCT) framework to improve non-contrast-enhanced low-contrast detection for full volume or volume-of-interest (VOI) brain imaging. METHOD: The idea is to associate two C-arm short-scan rotational acquisitions (spins): one over the full detector field of view (FOV) at low dose, and one collimated to deliver a higher dose to the central densest parts of the head...
September 2017: Medical Physics
https://www.readbyqxmd.com/read/28901616/regularization-of-nonlinear-decomposition-of-spectral-x-ray-projection-images
#19
Nicolas Ducros, Juan Felipe Perez-Juste Abascal, Bruno Sixou, Simon Rit, Françoise Peyrin
PURPOSE: Exploiting the x-ray measurements obtained in different energy bins, spectral computed tomography (CT) has the ability to recover the 3-D description of a patient in a material basis. This may be achieved solving two subproblems, namely the material decomposition and the tomographic reconstruction problems. In this work, we address the material decomposition of spectral x-ray projection images, which is a nonlinear ill-posed problem. METHODS: Our main contribution is to introduce a material-dependent spatial regularization in the projection domain...
September 2017: Medical Physics
https://www.readbyqxmd.com/read/28901614/investigating-simulation-based-metrics-for-characterizing-linear-iterative-reconstruction-in-digital-breast-tomosynthesis
#20
Sean D Rose, Adrian A Sanchez, Emil Y Sidky, Xiaochuan Pan
PURPOSE: Simulation-based image quality metrics are adapted and investigated for characterizing the parameter dependences of linear iterative image reconstruction for DBT. METHODS: Three metrics based on a 2D DBT simulation are investigated: (1) a root-mean-square-error (RMSE) between the test phantom and reconstructed image, (2) a gradient RMSE where the comparison is made after taking a spatial gradient of both image and phantom, and (3) a region-of-interest (ROI) Hotelling observer (HO) for signal-known-exactly/background-known-exactly (SKE/BKE) and signal-known-exactly/background-known-statistically (SKE/BKS) detection tasks...
September 2017: Medical Physics
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