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Image Reconstruction

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https://www.readbyqxmd.com/read/28644802/fully-non-linear-sp3-approximation-based-fluorescence-optical-tomography
#1
Naren Naik, Nishigandha Patil, Yamini Yadav, Jerry Eriksson, Asima Pradhan
In fluorescence optical tomography, many works in literature focus on the linear reconstruction problem to obtain the fluorescent yield or the linearized reconstruction problem to obtain the absorption coefficient. The nonlinear reconstruction problem, to reconstruct the fluorophore absorption coefficient, is of interest in imaging studies as it presents the possibility of better reconstructions owing to a more appropriate model. Accurate and computationally efficient forward models are also critical in the reconstruction process...
June 21, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28644800/online-combination-of-epid-cherenkov-imaging-for-3d-dosimetry-in-a-liquid-phantom
#2
Petr Bruza, Jacqueline M Andreozzi, David J Gladstone, Lesley A Jarvis, Joerg Rottmann, Brian W Pogue
Online acquisition of Cherenkov and portal imaging data was combined with a reconstruction scheme called EC3D, providing a full 3D dosimetry of megavoltage X-ray beams in a water tank. The methodology was demonstrated and quantified in a single static beam. Furthermore, the dynamics and visualization of the 3D dose reconstruction were demonstrated with a volumetric modulated arc therapy (VMAT) plan for TG-119 C-Shape geometry. The developed algorithm combines depth dose information, provided by Cherenkov images, with the lateral dose distribution, provided by the electronic portal imaging device (EPID)...
June 20, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28644799/hybrid-cs-dmri-periodic-time-variant-subsampling-and-omnidirectional-total-variation-based-reconstruction
#3
Yipeng Liu, Shan Wu, Xiaolin Huang, Bing Chen, Ce Zhu
Compressive sensing (CS) has been used to accelerate dynamic magnetic resonance imaging (DMRI). Currently, the online CS-DMRI is faster, whereas the offline CS-DMRI provides higher accuracy for image reconstruction. To achieve good image reconstruction performance in terms of both speed and accuracy, we propose a hybrid CS-DMRI method using periodic timevariant subsampling for different frames. In each period, there is one reference frame that is sampled at a higher subsampling ratio. The two nearby reference frames with good reconstruction quality can be used to provide rough predictions of the other frames between them...
June 20, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28644152/incorporating-hypr-de-noising-within-iterative-pet-reconstruction-hypr-osem
#4
Ju-Chieh Kevin Cheng, Julian C Matthews, Vesna Sossi, Jose Anton-Rodriguez, Andre Salomon, Ronald Boellaard
HighlY constrained back-PRojection (HYPR) is a post-processing de-noising technique originally developed for time-resolved Magnetic Resonance Imaging. It has been recently applied to dynamic imaging for Positron Emission Tomography (PET) and shown promising results. In this work, we have developed an iterative reconstruction algorithm (HYPR-OSEM) which improves the signal-to-noise ratio (SNR) in static imaging (i.e. single frame reconstruction) by incorporating HYPR de-noising directly within the ordered subsets expectation maximization (OSEM) algorithm...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28643891/direct-comparison-of-high-temporal-resolution-cine-mri-with-doppler-ultrasound-for-assessment-of-diastolic-dysfunction-in-mice
#5
Thomas A Roberts, Anthony N Price, Laurence H Jackson, Valerie Taylor, Anna L David, Mark F Lythgoe, Daniel J Stuckey
Diastolic dysfunction is a sensitive early indicator of heart failure and can provide additional data to conventional measures of systolic function. Transmitral Doppler ultrasound, which measures the one-dimensional flow of blood through the mitral valve, is currently the preferred method for the measurement of diastolic function, but the measurement of the left ventricular volume changes using high-temporal-resolution cinematic magnetic resonance imaging (CINE MRI) is an alternative approach which is emerging as a potentially more robust and user-independent technique...
June 23, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28643694/simultaneous-maximum-a-i-posteriori-i-longitudinal-pet-image-reconstruction
#6
Sam Ellis, Andrew J Reader
Positron emission tomography (PET) is frequently used to monitor functional changes that occur over extended time scales, for example in longitudinal oncology PET protocols that include routine clinical follow-up scans to assess the efficacy of a course of treatment. In these contexts PET datasets are currently reconstructed into images using single-dataset reconstruction methods. Inspired by recently proposed joint PET-MR reconstruction methods, we propose to reconstruct longitudinal datasets simultaneously by using a joint penalty term in order to exploit the high degree of similarity between longitudinal images...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28643383/multiecho-pseudo-golden-angle-stack-of-stars-thermometry-with-high-spatial-and-temporal-resolution-using-k-space-weighted-image-contrast
#7
Bryant T Svedin, Allison Payne, Bradley D Bolster, Dennis L Parker
PURPOSE: Implement and evaluate a 3D MRI method to measure temperature changes with high spatial and temporal resolution and large field of view. METHODS: A multiecho pseudo-golden angle stack-of-stars (SOS) sequence with k-space weighted image contrast (KWIC) reconstruction was implemented to simultaneously measure multiple quantities, including temperature, initial signal magnitude M(0), transverse relaxation time ( T2*), and water/fat images. Respiration artifacts were corrected using self-navigation...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643094/accuracy-and-reading-time-for-six-strategies-using-digital-breast-tomosynthesis-in-women-with-mammographically-negative-dense-breasts
#8
Alberto Stefano Tagliafico, Massimo Calabrese, Bianca Bignotti, Alessio Signori, Erica Fisci, Federica Rossi, Francesca Valdora, Nehmat Houssami
OBJECTIVE: To compare six strategies using digital breast tomosynthesis in women with mammographically negative dense breasts. MATERIALS AND METHODS: This is a substudy of the 'ASTOUND' trial. 163 women who underwent tomosynthesis with synthetically reconstructed projection images (S-2D) inclusive of 13 (7.9%) cases diagnosed with breast cancer at histopathology after surgery were evaluated. Accuracy measures and screen-reading time of six reading strategies were assessed: (A) Single reading of S-2D alone, (B) single reading of tomosynthesis alone, (C) single reading of joint interpretation of tomosynthesis + S-2D, (D) double-reading of S-2D alone, (E) double reading of tomosynthesis alone, (F) double reading of joint interpretation of tomosynthesis + S-2D...
June 22, 2017: European Radiology
https://www.readbyqxmd.com/read/28642661/customized-guide-for-femoral-component-positioning-in-hip-resurfacing-arthroplasty
#9
Chaturong Pornrattanamaneewong, Rapeepat Narkbunnam, Keerati Chareancholvanich
OBJECTIVE: To prove the accuracy of a customized guide developed according to our method. METHODS: This customized guide was developed from a three-dimensional model of proximal femur reconstructed using computed tomography data. Based on the new technique, the position of the guide pin insertion was selected and adjusted using the reference of the anatomical femoral neck axis. The customized guide consists of a hemispheric covering designed to fit the posterior part of the femoral neck...
March 2017: Acta Ortopedica Brasileira
https://www.readbyqxmd.com/read/28642647/comparison-between-rendering-3d-ct-and-transparent-3d-ct-in-acl-tunnel-positioning
#10
Marcos Amstalden Barros, Tiago Lazzaretti Fernandes, Dimitris Dimitriou, André Pedrinelli, Arnaldo José Hernandez
OBJECTIVE: To compare the transparent 3D computed tomography (CT) image protocol against conventional 3D-CT image-rendering protocol to assess femoral tunnel position in anatomic anterior cruciate ligament (ACL) reconstructions . METHODS: Eight knee CT scans from cadavers were analyzed by image rendering 3D-CT protocol, using Rhinoceros((r)) software. The central point of the ACL tunnel was set using the sagittal plane. Same CT scans were analyzed using transparent 3D-CT measurement protocol with OsiriX((r)) software...
January 2017: Acta Ortopedica Brasileira
https://www.readbyqxmd.com/read/28641952/the-effect-of-tissue-segmented-attenuation-maps-on-pet-quantification-with-a-special-focus-on-large-arteries
#11
A Mota-Cobian, J C Alonso-Farto, L Fernández-Friera, J Sánchez-González, B López-Melgar, L J Jiménez-Borreguero, V Fuster, J Ruiz-Cabello, S España
OBJECTIVES: Accuracy on quantitative PET image analysis relies on the correct application of attenuation correction which is one of the major challenges for PET/MRI that remains to be solved. The purpose of this study is to evaluate the effect of MRI-based attenuation maps and the use of flexible coils on the quantitative accuracy of PET images with a special focus on large arteries. MATERIALS AND METHODS: PET/CT data from eight oncologic patients was used. PET data was reconstructed using attenuation maps with different level of detail emulating several approaches available on current PET/MRI scanners...
June 19, 2017: Revista Española de Medicina Nuclear e Imagen Molecular
https://www.readbyqxmd.com/read/28641254/sparse-image-reconstruction-on-the-sphere-analysis-and-synthesis
#12
Christopher G R Wallis, Yves Wiaux, Jason D McEwen
We develop techniques to solve ill-posed inverse problems on the sphere by sparse regularisation, exploiting sparsity in both axisymmetric and directional scale-discretised wavelet space. Denoising, inpainting, and deconvolution problems, and combinations thereof, are considered as examples. Inverse problems are solved in both the analysis and synthesis settings, with a number of different sampling schemes. The most effective approach is that with the most restricted solution-space, which depends on the interplay between the adopted sampling scheme, the selection of the analysis/synthesis problem, and any weighting of the ℓ1 norm appearing in the regularisation problem...
June 16, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28641250/deep-convolutional-neural-network-for-inverse-problems-in-imaging
#13
Kyong Hwan Jin, Michael T McCann, Emmanuel Froustey, Michael Unser
In this paper, we propose a novel deep convolutional neural network (CNN)-based algorithm for solving ill-posed inverse problems. Regularized iterative algorithms have emerged as the standard approach to ill-posed inverse problems in the past few decades. These methods produce excellent results, but can be challenging to deploy in practice due to factors including the high computational cost of the forward and adjoint operators and the difficulty of hyper parameter selection. The starting point of our work is the observation that unrolled iterative methods have the form of a CNN (filtering followed by point-wise nonlinearity) when the normal operator ( H*H where H* is the adjoint of the forward imaging operator, H ) of the forward model is a convolution...
June 15, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28641249/eit-imaging-regularization-based-on-spectral-graph-wavelets
#14
Bo Gong, Benjamin Schullcke, Sabine Krueger-Ziolek, Marko Vauhkonen, Gerhard Wolf, Ullrich Mueller-Lisse, Knut Moeller
The objective of Electrical Impedance Tomographic reconstruction is to identify the distribution of tissue conductivity from electrical boundary conditions. This is an ill-posed inverse problem usually solved under the finite element method framework. In previous studies, standard sparse regularization was used for difference EIT to achieve a sparse solution. However, regarding element-wise sparsity, standard sparse regularization interferes with the smoothness of conductivity distribution between neighboring elements and is sensitive to noise...
June 16, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28640827/the-application-of-multi-baseline-digital-close-range-photogrammetry-in-three-dimensional-imaging-and-measurement-of-dental-casts
#15
Xiaoming Fu, Chun Peng, Zan Li, Shan Liu, Minmin Tan, Jinlin Song
OBJECTIVE: To explore a new technique for reconstructing and measuring three-dimensional (3D) models of orthodontic plaster casts using multi-baseline digital close-range photogrammetry (MBDCRP) with a single-lens reflex camera. STUDY DESIGN: Thirty sets of orthodontic plaster casts that do not exhibit severe horizontal overlap (>2 mm) between any two teeth were recorded by a single-lens reflex camera with 72 pictures taken in different directions. The 3D models of these casts were reconstructed and measured using the open source software MeshLab...
2017: PloS One
https://www.readbyqxmd.com/read/28640235/stereo-vision-based-high-dynamic-range-imaging-using-differently-exposed-image-pair
#16
Won-Jae Park, Seo-Won Ji, Seok-Jae Kang, Seung-Won Jung, Sung-Jea Ko
In this paper, a high dynamic range (HDR) imaging method based on the stereo vision system is presented. The proposed method uses differently exposed low dynamic range (LDR) images captured from a stereo camera. The stereo LDR images are first converted to initial stereo HDR images using the inverse camera response function estimated from the LDR images. However, due to the limited dynamic range of the stereo LDR camera, the radiance values in under/over-exposed regions of the initial main-view (MV) HDR image can be lost...
June 22, 2017: Sensors
https://www.readbyqxmd.com/read/28640114/injury-of-the-dentato-rubro-thalamic-tract-in-patients-with-cerebellar-infarct-case-report
#17
Sung Ho Jang, Hyeok Gyu Kwon
RATIONALE: Several studies using diffusion tensor tractography (DTT) have reported on injury in the dentato-rubro-thalamic tract (DRTT) in patients with brain injury. However, there is no study of injury in the DRTT following cerebellar infarct. We report on patients with injury in the DRTT following cerebellar infarct, demonstrated on DTT. PATIENT CONCERNS: Three patients with cerebellar infarct were enrolled in this study. Diffusion tensor imaging data were acquired at 3 weeks (patient 1) and 2 weeks (patients 2 and 3) after onset and the DRTT was reconstructed...
June 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28640112/cement-leakage-in-osteoporotic-vertebral-compression-fractures-with-cortical-defect-using-high-viscosity-bone-cement-during-unilateral-percutaneous-kyphoplasty-surgery
#18
Tie Liu, Zhe Li, Qingjun Su, Yong Hai
The purpose of this study was to investigate cement leakage (CL) in osteoporotic vertebral compression fractures (OVCFs) with cortical defect using high-viscosity bone cement during unilateral percutaneous kyphoplasty (PKP) surgery.This study included a series of 77 patients (23 males, 54 females) with single level osteoporotic vertebral body fracture (OVCF) who underwent unilateral PKP in our hospital. Preoperative x-ray, computed tomography (CT) scan, and 3-dimensional reconstructions were studied. During the PKP procedure, needle was carefully put to avoid too near to the cortical defect according to CT image...
June 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28639870/advanced-imaging-techniques-in-the-knee-benefits-and-limitations-of-new-rapid-acquisition-strategies-for-routine-knee-mri
#19
Elisabeth R Garwood, Michael P Recht, Lawrence M White
OBJECTIVE: The purpose of this article is to review current and emerging techniques and strategies that can be used to accelerate acquisition times in routine knee MRI. CONCLUSION: Specific techniques reviewed include 3D fast spin-echo imaging as well as new approaches to rapid image acquisition techniques (parallel imaging, compressed sensing, simultaneous multislice, and neural network reconstruction techniques) and their potential application to knee MRI.
June 22, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28639852/osteochondritis-dissecans-etiology-pathology-and-imaging-with-a-special-focus-on-the-knee-joint
#20
Juergen Bruns, Mathias Werner, Christian Habermann
This article is a review of the current understanding of the etiology, pathogenesis, and how to diagnose and treat knee osteochondritis dissecans (OCD) followed by an analysis of and outcomes of the treatments available. OCD is seen in children and adolescents with open growth plates (juvenile OCD) and adults with closed growth plates (adult OCD). The etiology of OCD lesions remains unclear and is characterized by an aseptic necrosis in the subchondral bone area. Mechanical factors seem to play an important role...
June 1, 2017: Cartilage
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