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https://www.readbyqxmd.com/read/29148430/low-dose-4d-cardiac-imaging-in-small-animals-using-dual-source-micro-ct
#1
Matthew Holbrook, Darin P Clark, Cristian T Badea
Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome these challenges, we propose and compare improvements on two strategies for cardiac gating in dual-source, preclinical micro-CT: fast prospective gating (PG) and uncorrelated retrospective gating (RG)...
November 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29147735/reduction-of-metallic-artifacts-of-the-post-treatment-intracranial-aneurysms-effects-of-single-energy-metal-artifact-reduction-algorithm
#2
Yu-Ning Pan, Ge Chen, Ai-Jing Li, Zhao-Qian Chen, Xiang Gao, Yi Huang, Bradley Mattson, Shan Li
PURPOSE: This study evaluated the quality of computed tomography (CT) and CT angiography images generated using the single-energy metal artifact reduction (SEMAR) algorithm during perfusion examination in patients who had undergone reconstruction with neurosurgical clipping or endovascular coiling for treatment of aneurysms. METHODS: A total of 55 patients with implanted intracranial clips or coils (24 men and 31 women; mean age 60.15 ± 15.86 years) underwent perfusion studies evaluated by CT and CT angiography with a 320-row CT scanner...
November 16, 2017: Clinical Neuroradiology
https://www.readbyqxmd.com/read/29140117/comparison-of-radiation-dose-and-image-quality-of-abdominopelvic-ct-using-iterative-aidr-3d-and-conventional-reconstructions
#3
Caroline Duarte de Mello-Amoedo, Aparecido Nakano Martins, Adriano Tachibana, Daniella Ferraro Pinho, Ronaldo Hueb Baroni
OBJECTIVE: The purpose of this study is to compare radiation dose and image quality of abdominopelvic CT studies reconstructed with iterative and conventional techniques. MATERIALS AND METHODS: This retrospective study enrolled 99 patients who underwent abdominopelvic CT examinations with the portal venous phase images reconstructed with both filtered back projection and Adaptive Iterative Dose Reduction 3D (AIDR 3D) at different time points. Subjective assessment of image quality was performed by two radiologists who scored axial images for overall quality, sharpness, noise, and acceptability in a blinded fashion...
November 15, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/29134188/simulation-study-of-quantitative-precision-of-the-pet-x-dedicated-breast-pet-scanner
#4
Chengeng Zeng, Paul E Kinahan, Hua Qian, Robert L Harrison, Kyle M Champley, Lawrence R MacDonald
The goal for positron emission tomography (PET)/X is measuring changes in radiotracer uptake for early assessment of response to breast cancer therapy. Upper bounds for detecting such changes were investigated using simulation and two image reconstruction algorithms customized to the PET/X rectangular geometry. Analytical reconstruction was used to study spatial resolution, comparing results with the distance of the closest approach (DCA) resolution surrogate that is independent of the reconstruction method...
October 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/29131203/computer-generated-hologram-using-binary-phase-with-an-aperture
#5
Wen Chen
Computer-generated holograms (CGHs) have attracted more and more attention in some application fields, such as 3D displays, optical security, and beam shaping. In this paper, a strategy is presented for optical information verification based on CGH using binary phase (1 bit) with an aperture. The input is encoded into the cascaded phase-only masks based on CGH via iterative phase retrieval, and one extracted phase mask is binarized in which one part is selected according to an aperture and further embedded into a random binary-phase host mask...
November 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29130074/does-noise-weighting-matter-in-ct-iterative-reconstruction
#6
Gengsheng L Zeng, Wenli Wang
This paper uses a computer simulation to investigate whether a more accurate noise model always results in less noisy images in CT iterative reconstruction. We start with a hypothetic non-realistic noise model for the CT measurements, by assuming that the attenuation coefficient is energy independent and there is no scattering. A variance formula for this model is derived and presented. Based on this model, computer simulations are conducted with 12 different ad hoc noise weighting methods, and their results are compared...
January 2017: IEEE transactions on radiation and plasma medical sciences
https://www.readbyqxmd.com/read/29125634/phase-retrieval-based-on-coded-splitting-modulation
#7
Y Yao, X He, C Liu, Jianqiang Zhu
A new coded splitting imaging technique is proposed to reconstruct the complex amplitude of a light field iteratively using a single-shot measurement. In this technique, a specially designed coded splitting plate is adopted to diffract the illuminating beam into multiple beams of different orders and code their wavefronts independently and differently. From the diffraction pattern array recorded on the detector plane, both the modulus and phase distributions of the illuminating beam can be reconstructed iteratively using known transmission functions of different orders of the coded splitting plate...
November 10, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/29120665/screening-for-lung-cancer-using-sub-millisievert-chest-ct-with-iterative-reconstruction-algorithm-image-quality-and-nodule-detectability
#8
Zhang Miao, Qi Weiwei, Sun Ye, Jiang Yan, Liu Xiaoyi, Nan Hong
OBJECTIVE: To investigate the image quality and nodules detectability using ultra-low dose (ULD) protocol with iterative model reconstruction (IMR) algorithm when compared to routine low dose (LD) chest CT in lung cancer screening. METHODS: Chest CT scans were acquired using a 256-slice scanner for 300 subjects. The scan protocol for ULD group was 120kVp/17mAs while the LD group was 120kVp/30mAs. All images were reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and IMR algorithms...
November 9, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/29119106/iterative-schemes-to-solve-low-dimensional-calibration-equations-in-parallel-mr-image-reconstruction-with-grappa
#9
Omair Inam, Mahmood Qureshi, Shahzad A Malik, Hammad Omer
GRAPPA (Generalized Autocalibrating Partially Parallel Acquisition) is a widely used parallel MRI reconstruction technique. The processing of data from multichannel receiver coils may increase the storage and computational requirements of GRAPPA reconstruction. Random projection on GRAPPA (RP-GRAPPA) uses random projection (RP) method to overcome the computational overheads of solving large linear equations in the calibration phase of GRAPPA, saving reconstruction time. However, RP-GRAPPA compromises the reconstruction accuracy in case of large reductions in the dimensions of calibration equations...
2017: BioMed Research International
https://www.readbyqxmd.com/read/29116101/on-chip-microscopy-using-random-phase-mask-scheme
#10
Anwar Hussain, Yicheng Li, Diyi Liu, Cuifang Kuang, Xu Liu
In this study, a simple and novel phase-retrieval scheme is implemented using multi-angle illumination to enhance the resolution of lensless microscopy. A random-phase mask (from 0 to 2π) precedes the sample to encode the information at the sensor plane. The sample is illuminated with multiple angles that are symmetrical along the optical axis of the system. The system is initially calibrated while recording the images without any sample at the corresponding multi angles. The two types of image are mutually subtracted, and the resultant images are summed at the sensor plane and backpropagated to the sample plane...
November 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29114620/reducing-radiation-dose-and-enhancing-imaging-quality-of-4dct-for-radiation-therapy-using-iterative-reconstruction-algorithms
#11
George Noid, An Tai, Guang-Pei Chen, Jared Robbins, X Allen Li
Purpose: Four-dimensional computed tomography (CT) images are typically used to quantify the necessary internal target volumes for thoracic and abdominal tumors. However, 4-dimensional CT is typically associated with excessive imaging dose to patients and the situation is exacerbated when using repeat 4-dimensional CT imaging on a weekly or daily basis throughout fractionated therapy. The aim of this work is to evaluate an iterative reconstruction (IR) algorithm that helps reduce the imaging dose to the patient while maintaining imaging quality as quantified by point spread function and contrast-to-noise ratios (CNRs)...
July 2017: Advances in Radiation Oncology
https://www.readbyqxmd.com/read/29110049/diagnostic-accuracy-of-low-dose-versus-ultra-low-dose-ct-for-lumbar-disc-disease-and-facet-joint-osteoarthritis-in-patients-with-low-back-pain-with-mri-correlation
#12
Sun Hwa Lee, Seong Jong Yun, Hyeon Hwan Jo, Dong Hyeon Kim, Jae Gwang Song, Yong Sung Park
OBJECTIVE: To compare the image quality, radiation dose, and diagnostic performance between low-dose (LD) and ultra-low-dose (ULD) lumbar-spine (L-spine) CT with iterative reconstruction (IR) for patients with chronic low back pain (LBP). METHODS: In total, 260 patients with chronic LBP who underwent L-spine CT between November 2015 and September 2016 were prospectively enrolled. Of these, 143 underwent LD-CT with IR and 117 underwent ULD-CT with IR. The patients were divided according to their body mass index (BMI) into BMI1 (<22...
November 6, 2017: Skeletal Radiology
https://www.readbyqxmd.com/read/29105487/high-pitch-dual-source-paranasal-sinus-ct-in-agitated-patients-with-maxillofacial-trauma-analysis-of-image-quality-motion-artifacts-and-dose-aspects
#13
Claudia Frellesen, Julian L Wichmann, Patricia Tischendorf, Jan-Erik Scholtz, Martin Beeres, Thomas J Vogl, Ralf W Bauer
Background Image quality benefits from high-pitch scanning in agitated patients by reducing acquisition time. Purpose To compare image quality and exposure parameters in patients with maxillofacial trauma on second- and third-generation dual-source computed tomography (DSCT). Material and Methods Four groups were compared. Group 1 was examined on second-generation DSCT (120 kV/50 mAs, pitch 3.0). The other three groups were examined on third-generation DSCT. Group 2 was scanned with 120 kV/50 mAs, pitch 2...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/29102769/a-scale-space-curvature-matching-algorithm-for-the-reconstruction-of-complex-proximal-humeral-fractures
#14
Lazaros Vlachopoulos, Gábor Székely, Christian Gerber, Philipp Fürnstahl
The optimal surgical treatment of complex fractures of the proximal humerus is controversial. It is proven that best results are obtained if an anatomical reduction of the fragments is achieved and, therefore, computer-assisted methods have been proposed for the reconstruction of the fractures. However, complex fractures of the proximal humerus are commonly accompanied with a relevant displacement of the fragments and, therefore, algorithms relying on the initial position of the fragments might fail. The state-of-the-art algorithm for complex fractures of the proximal humerus requires the acquisition of a CT scan of the (healthy) contralateral anatomy as a reconstruction template to address the displacement of the fragments...
October 27, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/29100255/multidetector-computed-tomography-angiography-md-cta-of-coronary-artery-bypass-grafts-update-2017
#15
Florian Jungmann, Tilman Emrich, Peter Mildenberger, Anna Lena Emrich, Christoph Düber, K F Kreitner
Background Coronary artery bypass grafting (CABG) is still an important therapeutic approach in the treatment especially of advanced coronary artery disease. In this study, we elucidate the current role of multidetector computed tomography angiography (MD-CTA) in imaging patients after CABG surgery. Method This study is based on recent reports in the literature (2007 - 2016) on imaging of CABG using 64-slice MD-CT scanners and beyond. We included 13 reports that compared ECG-gated MD-CTA with conventional invasive coronary angiography (ICA) as the reference standard for the assessment of graft patency and for the detection of > 50 % stenoses...
November 3, 2017: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/29099867/evaluating-causes-of-error-in-landmark-based-data-collection-using-scanners
#16
Brian M Shearer, Siobhán B Cooke, Lauren B Halenar, Samantha L Reber, Jeannette E Plummer, Eric Delson, Melissa Tallman
In this study, we assess the precision, accuracy, and repeatability of craniodental landmarks (Types I, II, and III, plus curves of semilandmarks) on a single macaque cranium digitally reconstructed with three different surface scanners and a microCT scanner. Nine researchers with varying degrees of osteological and geometric morphometric knowledge landmarked ten iterations of each scan (40 total) to test the effects of scan quality, researcher experience, and landmark type on levels of intra- and interobserver error...
2017: PloS One
https://www.readbyqxmd.com/read/29096395/automatic-correction-of-nonlinear-damping-effects-in-haadf-stem-tomography-for-nanomaterials-of-discrete-compositions
#17
Zhichao Zhong, Richard Aveyard, Bernd Rieger, Sara Bals, Willem Jan Palenstijn, K Joost Batenburg
HAADF-STEM tomography is a common technique for characterizing the three-dimensional morphology of nanomaterials. In conventional tomographic reconstruction algorithms, the image intensity is assumed to be a linear projection of a physical property of the specimen. However, this assumption of linearity is not completely valid due to the nonlinear damping of signal intensities. The nonlinear damping effects increase w.r.t the specimen thickness and lead to so-called "cupping artifacts", due to a mismatch with the linear model used in the reconstruction algorithm...
October 30, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29092410/extended-dynamic-mode-decomposition-with-dictionary-learning-a-data-driven-adaptive-spectral-decomposition-of-the-koopman-operator
#18
Qianxiao Li, Felix Dietrich, Erik M Bollt, Ioannis G Kevrekidis
Numerical approximation methods for the Koopman operator have advanced considerably in the last few years. In particular, data-driven approaches such as dynamic mode decomposition (DMD)(51) and its generalization, the extended-DMD (EDMD), are becoming increasingly popular in practical applications. The EDMD improves upon the classical DMD by the inclusion of a flexible choice of dictionary of observables which spans a finite dimensional subspace on which the Koopman operator can be approximated. This enhances the accuracy of the solution reconstruction and broadens the applicability of the Koopman formalism...
October 2017: Chaos
https://www.readbyqxmd.com/read/29091626/dynamic-projection-theory-for-fringe-projection-profilometry
#19
Hong Sheng, Jing Xu, Song Zhang
Fringe projection profilometry (FPP) has been widely used for three-dimensional reconstruction, surface measurement, and reverse engineering. However, FPP is prone to overexposure if objects have a wide range of reflectance. In this paper, we propose a dynamic projection theory based on FPP to rapidly measure the overexposed region with an attempt to conquer this challenge. This theory modifies the projected fringe image to the next better measurement based on the feedback provided by the previously captured image intensity...
October 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29082094/self-prior-strategy-for-organ-reconstruction-in-fluorescence-molecular-tomography
#20
Yuan Zhou, Maomao Chen, Han Su, Jianwen Luo
The purpose of this study is to propose a strategy for organ reconstruction in fluorescence molecular tomography (FMT) without prior information from other imaging modalities, and to overcome the high cost and ionizing radiation caused by the traditional structural prior strategy. The proposed strategy is designed as an iterative architecture to solve the inverse problem of FMT. In each iteration, a short time Fourier transform (STFT) based algorithm is used to extract the self-prior information in the space-frequency energy spectrum with the assumption that the regions with higher fluorescence concentration have larger energy intensity, then the cost function of the inverse problem is modified by the self-prior information, and lastly an iterative Laplacian regularization algorithm is conducted to solve the updated inverse problem and obtains the reconstruction results...
October 1, 2017: Biomedical Optics Express
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