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MRI theory and use

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https://www.readbyqxmd.com/read/27906119/degrading-traumatic-memories-with-eye-movements-a-pilot-functional-mri-study-in-ptsd
#1
Kathleen Thomaes, Iris M Engelhard, Marit Sijbrandij, Danielle C Cath, Odile A Van den Heuvel
BACKGROUND: Eye movement desensitization and reprocessing (EMDR) is an effective treatment for posttraumatic stress disorder (PTSD). During EMDR, the patient recalls traumatic memories while making eye movements (EMs). Making EMs during recall is associated with decreased vividness and emotionality of traumatic memories, but the underlying mechanism has been unclear. Recent studies support a "working-memory" (WM) theory, which states that the two tasks (recall and EMs) compete for limited capacity of WM resources...
2016: European Journal of Psychotraumatology
https://www.readbyqxmd.com/read/27891090/disrupted-nodal-and-hub-organization-account-for-brain-network-abnormalities-in-parkinson-s-disease
#2
Yuko Koshimori, Sang-Soo Cho, Marion Criaud, Leigh Christopher, Mark Jacobs, Christine Ghadery, Sarah Coakeley, Madeleine Harris, Romina Mizrahi, Clement Hamani, Anthony E Lang, Sylvain Houle, Antonio P Strafella
The recent application of graph theory to brain networks promises to shed light on complex diseases such as Parkinson's disease (PD). This study aimed to investigate functional changes in sensorimotor and cognitive networks in Parkinsonian patients, with a focus on inter- and intra-connectivity organization in the disease-associated nodal and hub regions using the graph theoretical analyses. Resting-state functional MRI data of a total of 65 participants, including 23 healthy controls (HCs) and 42 patients, were investigated in 120 nodes for local efficiency, betweenness centrality, and degree...
2016: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/27885945/clinical-imaging-and-immunohistochemical-characteristics-of-focal-cortical-dysplasia-type-ii-extratemporal-epilepsies-in-children-analyses-of-an-institutional-case-series
#3
Friederike Knerlich-Lukoschus, Mary B Connolly, Glenda Hendson, Paul Steinbok, Christopher Dunham
OBJECTIVE Focal cortical dysplasia (FCD) Type II is divided into 2 subgroups based on the absence (IIA) or presence (IIB) of balloon cells. In particular, extratemporal FCD Type IIA and IIB is not completely understood in terms of clinical, imaging, biological, and neuropathological differences. The aim of the authors was to analyze distinctions between these 2 formal entities and address clinical, MRI, and immunohistochemical features of extratemporal epilepsies in children. METHODS Cases formerly classified as Palmini FCD Type II nontemporal epilepsies were identified through the prospectively maintained epilepsy database at the British Columbia Children's Hospital in Vancouver, Canada...
November 25, 2016: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/27831865/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#4
Amir Kiperwas, Daniel Rosenfeld, Yonina C Eldar
We present an algorithm for resampling a function from its values on a non-Cartesian grid onto a Cartesian grid. This problem arises in many applications such as MRI, CT, radio astronomy and geophysics. Our algorithm, termed SParse Uniform ReSampling (SPURS), employs methods from modern sampling theory to achieve a small approximation error while maintaining low computational cost. The given non-Cartesian samples are projected onto a selected intermediate subspace, spanned by integer translations of a compactly supported kernel function...
November 1, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27807409/structural-magnetic-resonance-imaging-can-identify-trigeminal-system-abnormalities-in-classical-trigeminal-neuralgia
#5
REVIEW
Danielle D DeSouza, Mojgan Hodaie, Karen D Davis
Classical trigeminal neuralgia (TN) is a chronic pain disorder that has been described as one of the most severe pains one can suffer. The most prevalent theory of TN etiology is that the trigeminal nerve is compressed at the root entry zone (REZ) by blood vessels. However, there is significant evidence showing a lack of neurovascular compression (NVC) for many cases of classical TN. Furthermore, a considerable number of patients who are asymptomatic have MR evidence of NVC. Since there is no validated animal model that reproduces the clinical features of TN, our understanding of TN pathology mainly comes from biopsy studies that have limitations...
2016: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/27785843/comparison-of-a-non-stationary-voxelation-corrected-cluster-size-test-with-tfce-for-group-level-mri-inference
#6
Huanjie Li, Lisa D Nickerson, Thomas E Nichols, Jia-Hong Gao
Two powerful methods for statistical inference on MRI brain images have been proposed recently, a non-stationary voxelation-corrected cluster-size test (CST) based on random field theory and threshold-free cluster enhancement (TFCE) based on calculating the level of local support for a cluster, then using permutation testing for inference. Unlike other statistical approaches, these two methods do not rest on the assumptions of a uniform and high degree of spatial smoothness of the statistic image. Thus, they are strongly recommended for group-level fMRI analysis compared to other statistical methods...
October 27, 2016: Human Brain Mapping
https://www.readbyqxmd.com/read/27782870/factors-associated-with-the-decision-of-the-rheumatologist-to-order-sacroiliac-joints-magnetic-resonance-imaging-si-mri-or-hla-b27-testing-in-the-diagnostic-work-up-of-patients-with-spondyloarthritis-in-clinical-practice
#7
Wilson Bautista-Molano, Robert B M Landewé, Cesar Serna, Rafael Valle-Oñate, Désirée van der Heijde
OBJECTIVES: To evaluate the patients' characteristics associated with the clinical decision to request SI-MRI and/or HLA-B27 in patients with SpA in daily practice. METHODS: Patients referred to a rheumatology outpatient-clinic in a national referral-centre were selected. Patients with a clinical diagnosis of SpA according to the rheumatologist were included. SI-MRI and HLA-B27 was available for patients in whom the rheumatologists had ordered these tests. Characteristics associated with ordering SI-MRI or HLA-B27 were identified with univariable analyses...
October 26, 2016: Clinical and Experimental Rheumatology
https://www.readbyqxmd.com/read/27779779/direct-sar-mapping-by-thermoacoustic-imaging-a-feasibility-study
#8
Simone A Winkler, Paul A Picot, Michael M Thornton, Brian K Rutt
PURPOSE: To develop a new method capable of directly measuring specific absorption rate (SAR) deposited in tissue using the thermoacoustic signal induced by short radiofrequency (RF) pulse excitation. THEORY: A detailed model based on the thermoacoustic wave generation and propagation is presented. METHODS: We propose a new concept for direct measurement of SAR, to be used as a safety assessment/monitoring tool for MRI. The concept involves the use of short bursts of RF energy and the measurement of the resulting thermoacoustic excitation pattern by an array of ultrasound transducers, followed by image reconstruction to yield the 3D SAR distribution...
October 25, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27775513/smoothing-splines-on-unit-ball-domains-with-application-to-corneal-topography
#9
Ram Iyer, Farzana Nasrin, Elton See, Steven Mathews
Optical coherence tomography (OCT) is a non-invasive imaging technique used to study and understand internal structures of biological tissues such as the anterior chamber of the human eye. An interesting problem is the reconstruction of the shape of the biological tissue from OCT images, that is not only a good fit of the data but also respects the smoothness properties observed in the images. A similar problem arises in Magnetic Resonance Imaging (MRI). We cast the problem as a penalized weighted least squares regression with a penalty on the magnitude of the second derivative (Laplacian) of the surface...
October 19, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27761675/a-greedy-algorithm-for-brain-mri-s-registration
#10
Clément Chesseboeuf
This document presents a non-rigid registration algorithm for the use of brain magnetic resonance (MR) images comparison. More precisely, we want to compare pre-operative and post-operative MR images in order to assess the deformation due to a surgical removal. The proposed algorithm has been studied in Chesseboeuf et al. ((Non-rigid registration of magnetic resonance imaging of brain. IEEE, 385-390. doi: 10.1109/IPTA.2015.7367172 , 2015), following ideas of Trouvé (An infinite dimensional group approach for physics based models in patterns recognition...
October 19, 2016: Acta Biotheoretica
https://www.readbyqxmd.com/read/27757819/brain-network-connectivity-in-women-exposed-to-intimate-partner-violence-a-graph-theory-analysis-study
#11
Annerine Roos, Jean-Paul Fouche, Dan J Stein
Evidence suggests that women who suffer from intimate partner violence (IPV) and posttraumatic stress disorder (PTSD) have structural and functional alterations in specific brain regions. Yet, little is known about how brain connectivity may be altered in individuals with IPV, but without PTSD. Women exposed to IPV (n = 18) and healthy controls (n = 18) underwent structural brain imaging using a Siemens 3T MRI. Global and regional brain network connectivity measures were determined, using graph theory analyses...
October 18, 2016: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/27746390/3d-mr-image-denoising-using-rough-set-and-kernel-pca-method
#12
Ashish Phophalia, Suman K Mitra
In this paper, we have presented a two stage method, using kernel principal component analysis (KPCA) and rough set theory (RST), for denoising volumetric MRI data. A rough set theory (RST) based clustering technique has been used for voxel based processing. The method groups similar voxels (3D cubes) using class and edge information derived from noisy input. Each clusters thus formed now represented via basis vector. These vectors now projected into kernel space and PCA is performed in the feature space. This work is motivated by idea that under Rician noise MRI data may be non-linear and kernel mapping will help to define linear separator between these clusters/basis vectors thus used for image denoising...
October 13, 2016: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/27746386/multisite-reliability-of-mr-based-functional-connectivity
#13
Stephanie Noble, Dustin Scheinost, Emily S Finn, Xilin Shen, Xenophon Papademetris, Sarah C McEwen, Carrie E Bearden, Jean Addington, Bradley Goodyear, Kristin S Cadenhead, Heline Mirzakhanian, Barbara A Cornblatt, Doreen M Olvet, Daniel H Mathalon, Thomas H McGlashan, Diana O Perkins, Aysenil Belger, Larry J Seidman, Heidi Thermenos, Ming T Tsuang, Theo G M van Erp, Elaine F Walker, Stephan Hamann, Scott W Woods, Tyrone D Cannon, R Todd Constable
Recent years have witnessed an increasing number of multisite MRI functional connectivity (fcMRI) studies. While multisite studies provide an efficient way to accelerate data collection and increase sample sizes, especially for rare clinical populations, any effects of site or MRI scanner could ultimately limit power and weaken results. Little data exists on the stability of functional connectivity measurements across sites and sessions. In this study, we assess the influence of site and session on resting state functional connectivity measurements in a healthy cohort of traveling subjects (8 subjects scanned twice at each of 8 sites) scanned as part of the North American Prodrome Longitudinal Study (NAPLS)...
October 13, 2016: NeuroImage
https://www.readbyqxmd.com/read/27734306/functional-connectivity-abnormalities-and-associated-cognitive-deficits-in-fetal-alcohol-spectrum-disorders-fasd
#14
Jeffrey R Wozniak, Bryon A Mueller, Sarah N Mattson, Claire D Coles, Julie A Kable, Kenneth L Jones, Christopher J Boys, Kelvin O Lim, Edward P Riley, Elizabeth R Sowell
: Consistent with well-documented structural and microstructural abnormalities in prenatal alcohol exposure (PAE), recent studies suggest that functional connectivity (FC) may also be disrupted. We evaluated whole-brain FC in a large multi-site sample, examined its cognitive correlates, and explored its potential to objectively identify neurodevelopmental abnormality in individuals without definitive dysmorphic features. Included were 75 children with PAE and 68 controls from four sites...
October 12, 2016: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/27729289/association-of-baseline-knee-sagittal-dynamic-joint-stiffness-during-gait-and-2-year-patellofemoral-cartilage-damage-worsening-in-knee-osteoarthritis
#15
Alison H Chang, Joan S Chmiel, Orit Almagor, Ali Guermazi, Pottumarthi V Prasad, Kirsten C Moisio, Laura Belisle, Yunhui Zhang, Karen Hayes, Leena Sharma
OBJECTIVE: Knee sagittal dynamic joint stiffness (DJS) describes the biomechanical interaction between change in external knee flexion moment and flexion angular excursion during gait. In theory, greater DJS may particularly stress the patellofemoral (PF) compartment and thereby contribute to PF osteoarthritis (OA) worsening. We hypothesized that greater baseline knee sagittal DJS is associated with PF cartilage damage worsening 2 years later. METHODS: Participants all had OA in at least one knee...
October 8, 2016: Osteoarthritis and Cartilage
https://www.readbyqxmd.com/read/27695193/how-age-of-acquisition-influences-brain-architecture-in-bilinguals
#16
Miao Wei, Anand A Joshi, Mingxia Zhang, Leilei Mei, Franklin R Manis, Qinghua He, Rachel L Beattie, Gui Xue, David W Shattuck, Richard M Leahy, Feng Xue, Suzanne M Houston, Chuansheng Chen, Qi Dong, Zhong-Lin Lu
In the present study, we explored how Age of Acquisition (AoA) of L2 affected brain structures in bilingual individuals. Thirty-six native English speakers who were bilingual were scanned with high resolution MRI. After MRI signal intensity inhomogeneity correction, we applied both voxel-based morphometry (VBM) and surface-based morphometry (SBM) approaches to the data. VBM analysis was performed using FSL's standard VBM processing pipeline. For the SBM analysis, we utilized a semi-automated sulci delineation procedure, registered the brains to an atlas, and extracted measures of twenty four pre-selected regions of interest...
November 2015: Journal of Neurolinguistics
https://www.readbyqxmd.com/read/27659824/advanced-mr-imaging-in-hemispheric-low-grade-gliomas-before-surgery-the-indications-and-limits-in-the-pediatric-age
#17
Simona Gaudino, Rosellina Russo, Tommaso Verdolotti, Massimo Caulo, Cesare Colosimo
INTRODUCTION: Advanced magnetic resonance imaging (MRI) techniques is an umbrella term that includes diffusion (DWI) and diffusion tensor (DTI), perfusion (PWI), spectroscopy (MRS), and functional (fMRI) imaging. These advanced modalities have improved the imaging of brain tumors and provided valuable additional information for treatment planning. Despite abundant literature on advanced MRI techniques in adult brain tumors, few reports exist for pediatric brain ones, potentially because of technical challenges...
October 2016: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27636845/the-effects-of-an-apoe-promoter-polymorphism-on-human-white-matter-connectivity-during-non-demented-aging
#18
Peifen Chang, Xin Li, Chao Ma, Sisi Zhang, Zhen Liu, Kewei Chen, Lin Ai, Jingling Chang, Zhanjun Zhang
Polymorphisms of the apolipoprotein E (APOE) promoter rs405509 are related to Alzheimer's disease (AD). The T/T allele of rs405509 decreases the transcription of the APOE gene and leads to impairments in a specific brain structural network in aged individuals; thus, it is an important risk factor for AD. However, it remains unknown whether rs405509 affects white matter networks during aging. Here, we investigated the effect of the rs405509 genotype (T/T versus G-allele) on age-related brain white matter structural networks via construction of the graph theory-based structural connectome using diffusion MRI data in a large cohort...
September 13, 2016: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/27627444/noninvasive-mri-based-liver-iron-quantification-methodic-approaches-practical-applicability-and-significance
#19
A P Wunderlich, H Cario, M S Juchems, M Beer, S A Schmidt
Due to the dependence of transverse relaxation times T2 and T2* on tissue iron content, MRI offers different options for the determination of iron concentration. These are the time-consuming spin-echo sequence as well as the gradient-echo sequence. For the latter, several data analysis approaches have been proposed, with different requirements for acquisition and post-processing: the mathematically challenging R2* analysis and the signal-intensity ratio method with its high demand on the signal homogeneity of MR images...
September 14, 2016: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/27611013/new-insights-about-time-varying-diffusivity-and-its-estimation-from-diffusion-mri
#20
Lipeng Ning, Kawin Setsompop, Carl-Fredrik Westin, Yogesh Rathi
PURPOSE: Characterizing the relation between the applied gradient sequences and the measured diffusion MRI signal is important for estimating the time-dependent diffusivity, which provides important information about the microscopic tissue structure. THEORY AND METHODS: In this article, we extend the classical theory of Stepišnik for measuring time-dependent diffusivity under the Gaussian phase approximation. In particular, we derive three novel expressions which represent the diffusion MRI signal in terms of the mean-squared displacement, the instantaneous diffusivity, and the velocity autocorrelation function...
September 9, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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