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https://www.readbyqxmd.com/read/28092528/low-rank-and-adaptive-sparse-signal-lassi-models-for-highly-accelerated-dynamic-imaging
#1
Saiprasad Ravishankar, Brian Moore, Raj Nadakuditi, Jeffrey Fessler
Sparsity-based approaches have been popular in many applications in image processing and imaging. Compressed sensing exploits the sparsity of images in a transform domain or dictionary to improve image recovery from undersampled measurements. In the context of inverse problems in dynamic imaging, recent research has demonstrated the promise of sparsity and low-rank techniques. For example, the patches of the underlying data are modeled as sparse in an adaptive dictionary domain, and the resulting image and dictionary estimation from undersampled measurements is called dictionary-blind compressed sensing, or the dynamic image sequence is modeled as a sum of low-rank and sparse (in some transform domain) components (L+S model) that are estimated from limited measurements...
January 10, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28092414/dce-mri-of-the-prostate-using-shutter-speed-vs-tofts-model-for-tumor-characterization-and-assessment-of-aggressiveness
#2
Stefanie J Hectors, Cecilia Besa, Mathilde Wagner, Guido H Jajamovich, George K Haines, Sara Lewis, Ashutosh Tewari, Ardeshir Rastinehad, Wei Huang, Bachir Taouli
PURPOSE: To quantify Tofts model (TM) and shutter-speed model (SSM) perfusion parameters in prostate cancer (PCa) and noncancerous peripheral zone (PZ) and to compare the diagnostic performance of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to Prostate Imaging and Reporting and Data System (PI-RADS) classification for the assessment of PCa aggressiveness. MATERIALS AND METHODS: Fifty PCa patients (mean age 60 years old) who underwent MRI at 3...
January 16, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28092203/machine-learning-of-three-dimensional-right-ventricular-motion-enables-outcome-prediction-in-pulmonary-hypertension-a-cardiac-mr-imaging-study
#3
Timothy J W Dawes, Antonio de Marvao, Wenzhe Shi, Tristan Fletcher, Geoffrey M J Watson, John Wharton, Christopher J Rhodes, Luke S G E Howard, J Simon R Gibbs, Daniel Rueckert, Stuart A Cook, Martin R Wilkins, Declan P O'Regan
Purpose To determine if patient survival and mechanisms of right ventricular failure in pulmonary hypertension could be predicted by using supervised machine learning of three-dimensional patterns of systolic cardiac motion. Materials and Methods The study was approved by a research ethics committee, and participants gave written informed consent. Two hundred fifty-six patients (143 women; mean age ± standard deviation, 63 years ± 17) with newly diagnosed pulmonary hypertension underwent cardiac magnetic resonance (MR) imaging, right-sided heart catheterization, and 6-minute walk testing with a median follow-up of 4...
January 16, 2017: Radiology
https://www.readbyqxmd.com/read/28091591/intraarterial-route-increases-the-risk-of-cerebral-lesions-after-mesenchymal-cell-administration-in-animal-model-of-ischemia
#4
Bárbara Argibay, Jesse Trekker, Uwe Himmelreich, Andrés Beiras, Antonio Topete, Pablo Taboada, María Pérez-Mato, Alba Vieites-Prado, Ramón Iglesias-Rey, José Rivas, Anna M Planas, Tomás Sobrino, José Castillo, Francisco Campos
Mesenchymal stem cells (MSCs) are a promising clinical therapy for ischemic stroke. However, critical parameters, such as the most effective administration route, remain unclear. Intravenous (i.v.) and intraarterial (i.a.) delivery routes have yielded varied outcomes across studies, potentially due to the unknown MSCs distribution. We investigated whether MSCs reached the brain following i.a. or i.v. administration after transient cerebral ischemia in rats, and evaluated the therapeutic effects of both routes...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28090793/development-and-validation-of-a-predictor-of-insufficient-enhancement-during-the-hepatobiliary-phase-of-gd-eob-dtpa-enhanced-magnetic-resonance-imaging
#5
Enming Cui, Wansheng Long, Liangping Luo, Maoqing Hu, Liebin Huang, Xiangmeng Chen
Background Insufficient enhancement of liver parenchyma negatively affects diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Currently, there is no reliable method for predicting insufficient enhancement during the hepatobiliary phase (HBP) in Gd-EOB-DTPA-enhanced MRI. Purpose To develop a predictor for insufficient enhancement of liver parenchyma during HBP in Gd-EOB-DTPA-enhanced MRI. Material and Methods In order to formulate a HBP enhancement test (HBP-ET), clinical factors associated with relative enhancement ratio (RER) of liver parenchyma were retrospectively determined from the datasets of 156 patients (Development group) who underwent Gd-EOB-DTPA-enhanced MRI between November 2012 and May 2015...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/28090746/development-of-an-in-vivo-visual-robot-system-with-a-magnetic-anchoring-mechanism-and-a-lens-cleaning-mechanism-for-laparoendoscopic-single-site-surgery-less
#6
Haibo Feng, Dinghui Dong, Tengfei Ma, Jinlei Zhuang, Yili Fu, Yi Lv, Liyi Li
BACKGROUND: Surgical robot systems which can significantly improve surgical procedures have been widely used in laparoendoscopic single-site surgery (LESS). For a relative complex surgical procedure, the development of an in vivo visual robot system for LESS can effectively improve the visualization for surgical robot systems. METHODS: In this work, an in vivo visual robot system with a new mechanism for LESS was investigated. A finite element method (FEM) analysis was carried out to ensure the safety of the in vivo visual robot during the movement, which was the most important concern for surgical purposes...
January 16, 2017: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
https://www.readbyqxmd.com/read/28090735/high-throughput-protein-targeted-biomolecular-detection-using-frequency-domain-faraday-rotation-spectroscopy
#7
Richard J Murdock, Shawn A Putnam, Soumen Das, Ankur Gupta, Elyse D Z Chase, Sudipta Seal
A clinically relevant magneto-optical technique (fd-FRS, frequency-domain Faraday rotation spectroscopy) for characterizing proteins using antibody-functionalized magnetic nanoparticles (MNPs) is demonstrated. This technique distinguishes between the Faraday rotation of the solvent, iron oxide core, and functionalization layers of polyethylene glycol polymers (spacer) and model antibody-antigen complexes (anti-BSA/BSA, bovine serum albumin). A detection sensitivity of ≈10 pg mL(-1) and broad detection range of 10 pg mL(-1) ≲ cBSA ≲ 100 µg mL(-1) are observed...
January 16, 2017: Small
https://www.readbyqxmd.com/read/28090665/can-patel-s-%C3%AF-accurately-estimate-directionality-of-connections-in-brain-networks-from-fmri
#8
Yunzhi Wang, Olivier David, Xiaoping Hu, Gopikrishna Deshpande
PURPOSE: Investigating directional interactions between brain regions plays a critical role in fully understanding brain function. Consequently, multiple methods have been developed for noninvasively inferring directional connectivity in human brain networks using functional MRI (fMRI). Recent simulations by Smith et al showed that Patel's τ, a method based on higher-order statistics, was the best approach for inferring directional interactions from fMRI. Because simulations make restrictive assumptions about reality, we set out to verify this finding using experimental fMRI data obtained from a three-region network in a rat model with electrophysiological validation...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090658/analysis-of-the-effects-of-noise-dwi-sampling-and-value-of-assumed-parameters-in-diffusion-mri-models
#9
Elizabeth B Hutchinson, Alexandru V Avram, M Okan Irfanoglu, C Guan Koay, Alan S Barnett, Michal E Komlosh, Evren Özarslan, Susan C Schwerin, Sharon L Juliano, Carlo Pierpaoli
PURPOSE: This study was a systematic evaluation across different and prominent diffusion MRI models to better understand the ways in which scalar metrics are influenced by experimental factors, including experimental design (diffusion-weighted imaging [DWI] sampling) and noise. METHODS: Four diffusion MRI models-diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), mean apparent propagator MRI (MAP-MRI), and neurite orientation dispersion and density imaging (NODDI)-were evaluated by comparing maps and histogram values of the scalar metrics generated using DWI datasets obtained in fixed mouse brain with different noise levels and DWI sampling complexity...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090633/magnetic-field-effects-on-particle-beams-and-their-implications-for-dose-calculation-in-mr-guided-particle-therapy
#10
Hermann Fuchs, Philipp Moser, Martin Gröschl, Dietmar Georg
PURPOSE: To investigate and model effects of magnetic fields on proton and carbonion beams for dose calculation. METHODS: In a first step Monte Carlo simulations using Gate 7.1/Geant4.10.0.p03 were performed for proton and carbon ion beams in magnetic fields ranging from 0 to 3 T. Initial particle energies ranged from 60-250 MeV (protons) and 120-400 MeV/u (carbon ions), respectively. The resulting dose distributions were analyzed focusing on beam deflection, dose deformation as well as the impact of material het- erogeneities...
January 16, 2017: Medical Physics
https://www.readbyqxmd.com/read/28090452/classifying-thoracolumbar-fractures-role-of-quantitative-imaging
#11
REVIEW
Fernando Ruiz Santiago, Pablo Tomás Muñoz, Elena Moya Sánchez, Marta Revelles Paniza, Alberto Martínez Martínez, Antonio Luis Pérez Abela
This article describes different types of vertebral fractures that affect the thoracolumbar spine and the most relevant contributions of the different classification systems to vertebral fracture management. The vertebral fractures types are based on the three columns model of Denis that includes compression, burst, flexion-distraction and fracture-dislocation types. The most recent classifications systems of these types of fractures are reviewed, including the Thoracolumbar Injury Classification and Severity score (TLICS) and the Arbeitsgemeinschaft für Osteosynthesefragen Spine Thoracolumbar Injury Classification and Severity score (AOSpine-TLICS)...
December 2016: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28090450/quantitative-magnetic-resonance-imaging-of-the-lumbar-intervertebral-discs
#12
REVIEW
Dosik Hwang, Sewon Kim, Nirusha A Abeydeera, Sheronda Statum, Koichi Masuda, Christine B Chung, Palanan Siriwanarangsun, Won C Bae
Human lumbar spine is composed of multiple tissue components that serve to provide structural stability and proper nutrition. Conventional magnetic resonance (MR) imaging techniques have been useful for evaluation of IVD, but inadequate at imaging the discovertebral junction and ligamentous tissues due primarily to their short T2 nature. Ultrashort time to echo (UTE) MR techniques acquire sufficient MR signal from these short T2 tissues, thereby allowing direct and quantitative evaluation. This article discusses the anatomy of the lumbar spine, MR techniques available for morphologic and quantitative MR evaluation of long and short T2 tissues of the lumbar spine, considerations for T2 relaxation modeling and fitting, and existing and new techniques for spine image post-processing, focusing on segmentation...
December 2016: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28090443/topographical-and-depth-dependent-glycosaminoglycan-concentration-in-canine-medial-tibial-cartilage-3-weeks-after-anterior-cruciate-ligament-transection-surgery-a-microscopic-imaging-study
#13
Daniel Mittelstaedt, David Kahn, Yang Xia
BACKGROUND: Medical imaging has become an invaluable tool to diagnose damage to cartilage. Depletion of glycosaminoglycans (GAG) has been shown to be one of the early signs of cartilage degradation. In order to investigate the topographical changes in GAG concentration caused by the anterior cruciate ligament transection (ACLT) surgery in a canine model, microscopic magnetic resonance imaging (µMRI) and microscopic computed tomography (µCT) were used to measure the GAG concentration with correlation from a biochemical assay, inductively coupled plasma optical emission spectroscopy (ICP-OES), to understand where the topographical and depth-dependent changes in the GAG concentration occur...
December 2016: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28090442/can-mri-accurately-detect-pilon-articular-malreduction-a-quantitative-comparison-between-ct-and-3t-mri-bone-models
#14
Shairah Radzi, Constantin Edmond Dlaska, Gary Cowin, Mark Robinson, Jit Pratap, Michael Andreas Schuetz, Sanjay Mishra, Beat Schmutz
BACKGROUND: Pilon fracture reduction is a challenging surgery. Radiographs are commonly used to assess the quality of reduction, but are limited in revealing the remaining bone incongruities. The study aimed to develop a method in quantifying articular malreductions using 3D computed tomography (CT) and magnetic resonance imaging (MRI) models. METHODS: CT and MRI data were acquired using three pairs of human cadaveric ankle specimens. Common tibial pilon fractures were simulated by performing osteotomies to the ankle specimens...
December 2016: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28089709/objective-assessment-of-dietary-patterns-by-use-of-metabolic-phenotyping-a-randomised-controlled-crossover-trial
#15
Isabel Garcia-Perez, Joram M Posma, Rachel Gibson, Edward S Chambers, Tue H Hansen, Henrik Vestergaard, Torben Hansen, Manfred Beckmann, Oluf Pedersen, Paul Elliott, Jeremiah Stamler, Jeremy K Nicholson, John Draper, John C Mathers, Elaine Holmes, Gary Frost
BACKGROUND: Accurate monitoring of changes in dietary patterns in response to food policy implementation is challenging. Metabolic profiling allows simultaneous measurement of hundreds of metabolites in urine, the concentrations of which can be affected by food intake. We hypothesised that metabolic profiles of urine samples developed under controlled feeding conditions reflect dietary intake and can be used to model and classify dietary patterns of free-living populations. METHODS: In this randomised, controlled, crossover trial, we recruited healthy volunteers (aged 21-65 years, BMI 20-35 kg/m(2)) from a database of a clinical research unit in the UK...
January 12, 2017: Lancet Diabetes & Endocrinology
https://www.readbyqxmd.com/read/28089570/use-of-augmented-reality-in-laparoscopic-gynecology-to-visualize-myomas
#16
Nicolas Bourdel, Toby Collins, Daniel Pizarro, Clement Debize, Anne-Sophie Grémeau, Adrien Bartoli, Michel Canis
OBJECTIVE: To report the use of augmented reality (AR) in gynecology. DESIGN: AR is a surgical guidance technology that enables important hidden surface structures to be visualized in endoscopic images. AR has been used for other organs, but never in gynecology and never with a very mobile organ like the uterus. We have developed a new AR approach specifically for uterine surgery and demonstrated its use for myomectomy. SETTING: Tertiary university hospital...
January 12, 2017: Fertility and Sterility
https://www.readbyqxmd.com/read/28089452/co-folding-of-a-flif-flig-split-domain-forms-the-basis-of-the-ms-c-ring-interface-within-the-bacterial-flagellar-motor
#17
Michael J Lynch, Robert Levenson, Eun A Kim, Ria Sircar, David F Blair, Frederick W Dahlquist, Brian R Crane
The interface between the membrane (MS) and cytoplasmic (C) rings of the bacterial flagellar motor couples torque generation to rotation within the membrane. The structure of the C-terminal helices of the integral membrane protein FliF (FliFC) bound to the N terminal domain of the switch complex protein FliG (FliGN) reveals that FliGN folds around FliFC to produce a topology that closely resembles both the middle and C-terminal domains of FliG. The interface is consistent with solution-state nuclear magnetic resonance, small-angle X-ray scattering, in vivo interaction studies, and cellular motility assays...
December 31, 2016: Structure
https://www.readbyqxmd.com/read/28089450/a-structural-model-for-vinculin-insertion-into-pip2-containing-membranes-and-the-effect-of-insertion-on-vinculin-activation-and-localization
#18
Peter M Thompson, Srinivas Ramachandran, Lindsay B Case, Caitlin E Tolbert, Arpit Tandon, Mihir Pershad, Nikolay V Dokholyan, Clare M Waterman, Sharon L Campbell
Vinculin, a scaffolding protein that localizes to focal adhesions (FAs) and adherens junctions, links the actin cytoskeleton to the adhesive super-structure. While vinculin binds to a number of cytoskeletal proteins, it can also associate with phosphatidylinositol 4,5-bisphosphate (PIP2) to drive membrane association. To generate a structural model for PIP2-dependent interaction of vinculin with the lipid bilayer, we conducted lipid-association, nuclear magnetic resonance, and computational modeling experiments...
December 31, 2016: Structure
https://www.readbyqxmd.com/read/28089160/investigation-of-hexavalent-chromium-sorption-in-serpentine-sediments
#19
Thanasis Mpouras, Maria Chrysochoou, Dimitris Dermatas
In this study the removal of hexavalent chromium (Cr(6+)) by serpentine sediments was investigated in order to delineate Cr(6+) sorption behavior in aquifers with ultramafic geologic background. Batch experiments were conducted in order to determine the influence of several parameters on Cr(6+) removal, including the pH of the sediment solution, mineralogy, sediment's particle size and Cr(6+) initial concentration. The results showed that Cr(6+) removal was due to both adsorption and reduction phenomena. Reduction was attributed to the presence of a magnetic fraction in the sediment, mostly related to magnetite, which contributed almost 50% of the total removal in the pH range 3-7...
January 5, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/28088837/disease-severity-classification-using-quantitative-magnetic-resonance-imaging-data-of-cartilage-in-femoroacetabular-impingement
#20
Lisa L Henn, John Hughes, Eleena Iisakka, Jutta Ellermann, Shabnam Mortazavi, Connor Ziegler, Mikko J Nissi, Patrick Morgan
Femoroacetabular impingement (FAI) is a condition in which subtle deformities of the femoral head and acetabulum (hip socket) result in pathological abutment during hip motion. FAI is a common cause of hip pain and can lead to acetabular cartilage damage and osteoarthritis. For some patients with FAI, surgical intervention is indicated, and it can improve quality of life and potentially delay the onset of osteoarthritis. For other patients, however, surgery is contraindicated because significant cartilage damage has already occurred...
January 15, 2017: Statistics in Medicine
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