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iterative reconstruction

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https://www.readbyqxmd.com/read/29792729/90-kvp-low-tube-voltage-ct-pulmonary-angiography-in-combination-with-advanced-modelled-iterative-reconstruction-algorithm-effects-on-radiation-dose-image-quality-and-diagnostic-accuracy-for-the-detection-of-pulmonary-embolism
#1
Doris Leithner, Tatjana Gruber-Rouh, Martin Beeres, Julian L Wichmann, Scherwin Mahmoudi, Simon S Martin, Lukas Lenga, Moritz H Albrecht, Christian Booz, Thomas J Vogl, Jan-Erik Scholtz
OBJECTIVE: To evaluate low-tube-voltage 90-kVp computed tomography pulmonary angiography (CTPA) with advanced modelled iterative reconstruction algorithm (Admire) compared to 120-kVp equivalent dual-energy acquisition with regards to radiation exposure, image quality, and diagnostic accuracy for pulmonary embolism (PE) assessment. METHODS: CTPA studies of 40 patients with suspected PE (56.7 ± 16.3 years) performed on a third-generation 192-slice dual-source CT scanner were retrospectively included...
May 24, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29791412/shock-wave-imaging-by-density-recovery-from-intensity-measurements
#2
Biswajit Medhi, Gopalakrishna M Hegde, Kalidevapura Jagannath Reddy, Debasish Roy, Ram Mohan Vasu
A method for quantitative estimation of density variation in high-speed flow, which uses light as an interrogating tool, is described. The wavefront distortion of the interrogating beam induced by the compressible flow field is estimated quantitatively, in which the density gradient of the flow field is seen as refractive-index gradient by the probing beam. The distorted wavefront is measured quantitatively by using the cross-sectional intensities of the distorted wavefront along the optical axis. Iterative algorithms are developed using both deterministic (Gauss-Newton) and stochastic (ensemble Kalman filter) update strategies to recover unknown parameters such as the phase of the wavefront or the refractive index distribution in the flow directly from the measured intensities...
May 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29791199/localization-of-the-inferior-alveolar-canal-using-ultralow-dose-ct-with-iterative-reconstruction-techniques
#3
Asma'a Abdulrahman Al-Ekrish, Wafa Alfaleh, Romed Hörmann, Ameera Alabdulwahid, Wolfgang Puelacher, Gerlig Widmann
OBJECTIVES: To compare subjective and objective localization of the inferior alveolar canal (IAC) on multidetector computed tomography (MDCT) images obtained by ultralow doses in combination with the reconstruction techniques of filtered backprojection (FBP), Adaptive Statistical Iterative Reconstruction (ASIR), or Model Based Iterative Reconstruction (MBIR) as compared to standard dose MDCT and FBP. METHODS: Three cadavers were imaged with a reference standard dose MDCT examination (CTDIvol: 29...
May 23, 2018: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/29778722/phylogenomics-resolves-evolutionary-relationships-and-provides-insights-into-floral-evolution-in-the-tribe-shoreeae-dipterocarpaceae
#4
Jacqueline Heckenhauer, Rosabelle Samuel, Peter S Ashton, Kamariah Abu Salim, Ovidiu Paun
A supra-annual, community-level synchronous flowering prevails in several parts of the tropical forests of Southeast Asia and its evolution has been hypothesized to be linked to pollinator shifts. The aseasonal Southeast Asian lowland rainforests are dominated by Dipterocarpaceae, which exhibit great floral diversity, a range of pollination syndromes and include species with annual and supra-annual gregarious flowering. Phylogenetic relationships within this family are still unclear, especially in the tribe Shoreeae...
May 17, 2018: Molecular Phylogenetics and Evolution
https://www.readbyqxmd.com/read/29776077/reconstructing-free-energy-landscapes-for-nonequilibrium-periodic-potentials
#5
N J López-Alamilla, Michael W Jack, K J Challis
We present a method for reconstructing the free-energy landscape of overdamped Brownian motion on a tilted periodic potential. Our approach exploits the periodicity of the system by using the k-space form of the Smoluchowski equation and we employ an iterative approach to determine the nonequilibrium tilt. We reconstruct landscapes for a number of example potentials to show the applicability of the method to both deep and shallow wells and near-to- and far-from-equilibrium regimes. The method converges logarithmically with the number of Fourier terms in the potential...
March 2018: Physical Review. E
https://www.readbyqxmd.com/read/29769576/motion-compensated-micro-ct-reconstruction-for-in-situ-analysis-of-dynamic-processes
#6
Thomas De Schryver, Manuel Dierick, Marjolein Heyndrickx, Jeroen Van Stappen, Marijn A Boone, Luc Van Hoorebeke, Matthieu N Boone
This work presents a framework to exploit the synergy between Digital Volume Correlation (DVC) and iterative CT reconstruction to enhance the quality of high-resolution dynamic X-ray CT (4D-µCT) and obtain quantitative results from the acquired dataset in the form of 3D strain maps which can be directly correlated to the material properties. Furthermore, we show that the developed framework is capable of strongly reducing motion artifacts even in a dataset containing a single 360° rotation.
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29769130/diagnostic-accuracy-of-low-dose-dual-source-cardiac-computed-tomography-as-compared-to-surgery-in-univentricular-heart-patients
#7
Narumol Chaosuwannakit, Pattarapong Makarawate
BACKGROUND: To evaluate the ability of low radiation dose dual-source computed tomography (DSCT) to depict the features of morphological univentricular heart and to define accuracy by comparing findings with surgery. METHODS: Low radiation dose dual-source cardiac computed tomography (CCT) of 33 cases of functional univentricular heart preliminary diagnosis by echocardiography compared with the results of surgery were retrospectively analyzed (aged 1 day to 4 years, median 5 months)...
May 16, 2018: Journal of Cardiothoracic Surgery
https://www.readbyqxmd.com/read/29768380/tradeoff-between-noise-reduction-and-inartificial-visualization-in-a-model-based-iterative-reconstruction-algorithm-on-coronary-computed-tomography-angiography
#8
Kenichiro Hirata, Daisuke Utsunomiya, Masafumi Kidoh, Yoshinori Funama, Seitaro Oda, Hideaki Yuki, Yasunori Nagayama, Yuji Iyama, Takeshi Nakaura, Daisuke Sakabe, Kenichi Tsujita, Yasuyuki Yamashita
We aimed to evaluate the image quality performance of coronary CT angiography (CTA) under the different settings of forward-projected model-based iterative reconstruction solutions (FIRST).Thirty patients undergoing coronary CTA were included. Each image was reconstructed using filtered back projection (FBP), adaptive iterative dose reduction 3D (AIDR-3D), and 2 model-based iterative reconstructions including FIRST-body and FIRST-cardiac sharp (CS). CT number and noise were measured in the coronary vessels and plaque...
May 2018: Medicine (Baltimore)
https://www.readbyqxmd.com/read/29764362/gpu-accelerated-iterative-reconstruction-for-limited-data-tomography-in-cbct-systems
#9
Claudia de Molina, Estefania Serrano, Javier Garcia-Blas, Jesus Carretero, Manuel Desco, Monica Abella
BACKGROUND: Standard cone-beam computed tomography (CBCT) involves the acquisition of at least 360 projections rotating through 360 degrees. Nevertheless, there are cases in which only a few projections can be taken in a limited angular span, such as during surgery, where rotation of the source-detector pair is limited to less than 180 degrees. Reconstruction of limited data with the conventional method proposed by Feldkamp, Davis and Kress (FDK) results in severe artifacts. Iterative methods may compensate for the lack of data by including additional prior information, although they imply a high computational burden and memory consumption...
May 15, 2018: BMC Bioinformatics
https://www.readbyqxmd.com/read/29763672/using-3d-spatial-correlations-to-improve-the-noise-robustness-of-multi-component-analysis-of-3d-multi-echo-quantitative-t2-relaxometry-data
#10
Dushyant Kumar, Hari Hariharan, Tobias D Faizy, Patrick Borchert, Susanne Siemonsen, Jens Fiehler, Ravinder Reddy, Jan Sedlacik
PURPOSE: We present a computationally feasible and iterative multi-voxel spatially regularized algorithm for myelin water fraction (MWF) reconstruction. This method utilizes 3D spatial correlations present in anatomical/pathological tissues and underlying B1+ -inhomogeneity or flip angle inhomogeneity to enhance the noise robustness of the reconstruction while intrinsically accounting for stimulated echo contributions using T2-distribution data alone. METHODS: Simulated data and in vivo data acquired using 3D non-selective multi-echo spin echo (3DNS-MESE) were used to compare the reconstruction quality of the proposed approach against those of the popular algorithm (the method by Prasloski et al...
May 12, 2018: NeuroImage
https://www.readbyqxmd.com/read/29763453/anisotropic-conductivity-tensor-imaging-for-transcranial-direct-current-stimulation-tdcs-using-magnetic-resonance-diffusion-tensor-imaging-mr-dti
#11
Mun Bae Lee, Hyung Joong Kim, Eung Je Woo, Oh In Kwon
Transcranial direct current stimulation (tDCS) is a widely used non-invasive brain stimulation technique by applying low-frequency weak direct current via electrodes attached on the head. The tDCS using a fixed current between 1 and 2 mA has relied on computational modelings to achieve optimal stimulation effects. Recently, by measuring the tDCS current induced magnetic field using an MRI scanner, the internal current pathway has been successfully recovered. However, up to now, there is no technique to visualize electrical properties including the electrical anisotropic conductivity, effective extracellular ion-concentration, and electric field using only the tDCS current in-vivo...
2018: PloS One
https://www.readbyqxmd.com/read/29762055/evaluating-the-effect-of-increased-pitch-iterative-reconstruction-and-dual-source-ct-on-dose-reduction-and-image-quality
#12
Joanna Gariani, Steve P Martin, Diomidis Botsikas, Christoph D Becker, Xavier Montet
OBJECTIVE: to compare radiation dose and image quality of thoraco-abdominal scans obtained with a high-pitch protocol (pitch 3.2) and iterative reconstruction (SAFIRE) in comparison to standard pitch reconstructed with FBP using dual-source CT. METHODS: 114 CT scans (Somatom Definition Flash, Siemens), 39 thoracic scans, 54 thoraco-abdominal scans and 21 abdominal scans were performed. Analysis of three protocols was undertaken; pitch of 1 reconstructed with FBP, pitch of 3...
May 15, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29757473/iterative-inversion-of-deformation-vector-fields-with-feedback-control
#13
Abhishek Kumar Dubey, Alexandros-Stavros Iliopoulos, Xiaobai Sun, Fang-Fang Yin, Lei Ren
PURPOSE: Often, the inverse deformation vector field (DVF) is needed together with the corresponding forward DVF in 4D reconstruction and dose calculation, adaptive radiation therapy, and simultaneous deformable registration. This study aims at improving both accuracy and efficiency of iterative algorithms for DVF inversion, and advancing our understanding of divergence and latency conditions. METHOD: We introduce a framework of fixed-point iteration algorithms with active feedback control for DVF inversion...
May 14, 2018: Medical Physics
https://www.readbyqxmd.com/read/29753661/lower-extremity-ct-angiography-at-80-kvp-using-iterative-model-reconstruction
#14
B Liu, S Gao, Z Chang, C Wang, Z Liu, J Zheng
PURPOSE: To evaluate the use of 80 kVp and iterative model reconstruction (IMR) in lower extremity computed tomography angiography (CTA). MATERIALS AND METHODS: Sixty patients were randomly assigned to Group A or Group B (both n=30) to further undergo CTA. Group A received Protocol 1 (P1) with 120 kVp, 180mAs, and 100mL of contrast agent with filtered back-projection (FBP). Group B received Protocol 2 (P2) and Protocol 3 (P3) with 80 kVp, 140mAs and 75mL of contrast agent with hybrid iterative reconstruction (P2) and IMR (P3)...
May 9, 2018: Diagnostic and Interventional Imaging
https://www.readbyqxmd.com/read/29742139/a-novel-soft-tissue-prediction-methodology-for-orthognathic-surgery-based-on-probabilistic-finite-element-modelling
#15
Paul G M Knoops, Alessandro Borghi, Federica Ruggiero, Giovanni Badiali, Alberto Bianchi, Claudio Marchetti, Naiara Rodriguez-Florez, Richard W F Breakey, Owase Jeelani, David J Dunaway, Silvia Schievano
Repositioning of the maxilla in orthognathic surgery is carried out for functional and aesthetic purposes. Pre-surgical planning tools can predict 3D facial appearance by computing the response of the soft tissue to the changes to the underlying skeleton. The clinical use of commercial prediction software remains controversial, likely due to the deterministic nature of these computational predictions. A novel probabilistic finite element model (FEM) for the prediction of postoperative facial soft tissues is proposed in this paper...
2018: PloS One
https://www.readbyqxmd.com/read/29738510/robust-adaptive-beamforming-with-sensor-position-errors-using-weighted-subspace-fitting-based-covariance-matrix-reconstruction
#16
Peng Chen, Yixin Yang, Yong Wang, Yuanliang Ma
When sensor position errors exist, the performance of recently proposed interference-plus-noise covariance matrix (INCM)-based adaptive beamformers may be severely degraded. In this paper, we propose a weighted subspace fitting-based INCM reconstruction algorithm to overcome sensor displacement for linear arrays. By estimating the rough signal directions, we construct a novel possible mismatched steering vector (SV) set. We analyze the proximity of the signal subspace from the sample covariance matrix (SCM) and the space spanned by the possible mismatched SV set...
May 8, 2018: Sensors
https://www.readbyqxmd.com/read/29737620/few-view-ct-reconstruction-with-group-sparsity-regularization
#17
Peng Bao, Jiliu Zhou, Yi Zhang
Classical total variation (TV) based iterative reconstruction algorithms is effective for the reconstruction of piecewise smooth image, but it causes over-smoothing effect for textured regions in the reconstructed image. To address this problem, this work presents a novel computed tomography (CT) reconstruction method for the few-view problem called the group-sparsity regularization-based simultaneous algebraic reconstruction technique (GSR-SART). Group-based sparse representation, which utilizes the concept of a group as the basic unit of sparse representation instead of a patch, is introduced as the image domain prior regularization term to eliminate the over-smoothing effect...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29737491/computed-tomography-imaging-with-the-adaptive-statistical-iterative-reconstruction-asir-algorithm-dependence-of-image-quality-on-the-blending-level-of-reconstruction
#18
Patrizio Barca, Marco Giannelli, Maria Evelina Fantacci, Davide Caramella
Computed tomography (CT) is a useful and widely employed imaging technique, which represents the largest source of population exposure to ionizing radiation in industrialized countries. Adaptive Statistical Iterative Reconstruction (ASIR) is an iterative reconstruction algorithm with the potential to allow reduction of radiation exposure while preserving diagnostic information. The aim of this phantom study was to assess the performance of ASIR, in terms of a number of image quality indices, when different reconstruction blending levels are employed...
May 8, 2018: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/29735355/association-of-focal-radiation-dose-adjusted-on-cross-sections-with-subsolid-nodule-visibility-and-quantification-on-computed-tomography-images-using-aidr-3d-comparison-among-scanning-at-84-42-and-7-mas
#19
Yukihiro Nagatani, Hiroshi Moriya, Satoshi Noma, Shigetaka Sato, Shinsuke Tsukagoshi, Tsuneo Yamashiro, Mitsuhiro Koyama, Noriyuki Tomiyama, Yoshiharu Ono, Sadayuki Murayama, Kiyoshi Murata
RATIONALE AND OBJECTIVES: The objectives of this study were to compare the visibility and quantification of subsolid nodules (SSNs) on computed tomography (CT) using adaptive iterative dose reduction using three-dimensional processing between 7 and 42 mAs and to assess the association of size-specific dose estimate (SSDE) with relative measured value change between 7 and 84 mAs (RMVC7-84 ) and relative measured value change between 42 and 84 mAs (RMVC42-84 ). MATERIALS AND METHODS: As a Japanese multicenter research project (Area-detector Computed Tomography for the Investigation of Thoracic Diseases [ACTIve] study), 50 subjects underwent chest CT with 120 kV, 0...
May 4, 2018: Academic Radiology
https://www.readbyqxmd.com/read/29732610/image-reconstruction-algorithm-for-motion-insensitive-mr-fingerprinting-mrf-morf
#20
Bhairav Bipin Mehta, Dan Ma, Eric Yann Pierre, Yun Jiang, Simone Coppo, Mark Alan Griswold
PURPOSE: The purpose of this study is to increase the robustness of MR fingerprinting (MRF) toward subject motion. METHODS: A novel reconstruction algorithm, MOtion insensitive MRF (MORF), was developed, which uses an iterative reconstruction based retrospective motion correction approach. Each iteration loops through the following steps: pattern recognition, metric based identification of motion corrupted frames, registration based motion estimation, and motion compensated data consistency verification...
May 6, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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