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MRI theory and use

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
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
Ashish Phophalia, Suman K Mitra
In this paper, we have presented a two stage method, using Kernel Principal Componenet 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 cluster thus formed now represented via basis vector. These vectors now projected into to kernel space and PCA is performed in the feature space...
October 13, 2016: Magnetic Resonance Imaging
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 are an efficient way to speed up 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
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
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
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
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
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
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
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
Zhe Charles Zhou, Andrew P Salzwedel, Susanne Radtke-Schuller, Yuhui Li, Kristin K Sellers, John H Gilmore, Yen-Yu Ian Shih, Flavio Fröhlich, Wei Gao
Resting state functional magnetic resonance imaging (rsfMRI) has emerged as a versatile tool for non-invasive measurement of functional connectivity patterns in the brain. RsfMRI brain dynamics in rodents, non-human primates, and humans share similar properties; however, little is known about the resting state functional connectivity patterns in the ferret, an animal model with high potential for developmental and cognitive translational study. To address this knowledge-gap, we performed rsfMRI on anesthetized ferrets using a 9...
September 2, 2016: NeuroImage
Armando De Virgilio, Marco de Vincentiis, Maurizio Inghilleri, Giovanni Fabrini, Michela Conte, Andrea Gallo, Maria Ida Rizzo, Antonio Greco
Hypertrophic pachymeningitis (HP) is a rare disorder that causes thickening of the dura mater. Inflammatory lesions may be located in the cerebral or spinal dura mater or, less frequently, in both locations simultaneously. Numerous clinico-pathological entities cause thickening of the pachymeninges. Indeed, HP is a potential manifestation of many different diseases, but the diagnosis often remains uncertain. Cases in which the pachymeningitis has no known aetiology are termed "idiopathic" HP (IHP). Recently, it has been suggested that IgG4-related disease represents a subset of cases previously diagnosed as idiopathic hypertrophic pachymeningitis...
September 3, 2016: Immunologic Research
Xiaojia Liu, Fuqing Zhou, Xiang Li, Wenshu Qian, Jiaolong Cui, Iris Y Zhou, Keith D K Luk, Ed X Wu, Yong Hu
Resting state functional magnetic resonance imaging (rsfMRI) has been extensively applied to investigate the organization of functional networks in the brain. As an essential part of the central nervous system (CNS), the spinal cord has not been well explored about its intrinsic functional network. In this study, we aim to thoroughly investigate the characteristics of the intrinsic functional network in the spinal cord using rsfMRI. Functional connectivity and graph theory analysis were employed to evaluate the organization of the functional network, including its topology and network communication properties...
November 12, 2016: Neuroscience
Chandler Sours, Prashant Raghavan, W Alex Foxworthy, M Alex Meredith, Dina El Metwally, Jiachen Zhuo, John H Gilmore, Alexandre E Medina, Rao P Gullapalli
How the newborn brain adapts to its new multisensory environment has been a subject of debate. Although an early theory proposed that the brain acquires multisensory features as a result of postnatal experience, recent studies have demonstrated that the neonatal brain is already capable of processing multisensory information. For multisensory processing to be functional, it is a prerequisite that multisensory convergence among neural connections occur. However, multisensory connectivity has not been examined in human neonates nor are its location(s) or afferent sources understood...
August 31, 2016: Brain Imaging and Behavior
Young Han Lee, Jaemoon Yang, Ha-Kyu Jeong, Jin-Suck Suh
PURPOSE: Biochemical imaging of glycosaminoglycan chemical exchange saturation transfer (gagCEST) could predict the depletion of glycosaminoglycans (GAG) in early osteoarthritis. The purpose of this study was to evaluate the relationship between the magnetization transfer ratio asymmetry (MTRasym) of gagCEST images and visual analog scale (VAS) pain scores in the knee joint. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board...
August 28, 2016: Magnetic Resonance Imaging
Benjamin L Schwartz, Ziying Yin, Richard L Magin
Cylindrical homogenous phantoms for magnetic resonance (MR) elastography in biomedical research provide one way to validate an imaging systems performance, but the simplified geometry and boundary conditions can cloak complexity arising at tissue interfaces. In an effort to develop a more realistic gel tissue phantom for MRE, we have constructed a heterogenous gel phantom (a sphere centrally embedded in a cylinder). The actuation comes from the phantom container, with the mechanical waves propagating toward the center, focusing the energy and thus allowing for the visualization of high-frequency waves that would otherwise be damped...
September 21, 2016: Physics in Medicine and Biology
Nikodem Kuźnik, Mateusz Michał Tomczyk
Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e...
2016: Beilstein Journal of Nanotechnology
Jelle Veraart, Dmitry S Novikov, Daan Christiaens, Benjamin Ades-Aron, Jan Sijbers, Els Fieremans
We introduce and evaluate a post-processing technique for fast denoising diffusion-weighted MR images. By exploiting the intrinsic redundancy in diffusion MRI using universal properties of the eigenspectrum of random covariance matrices, we remove noise-only principal components, thereby enabling signal-to-noise ratio enhancements, yielding parameter maps of improved quality for visual, quantitative, and statistical interpretation. By studying statistics of residuals, we demonstrate that the technique suppresses local signal fluctuations that solely originate from thermal noise rather than from other sources such as anatomical detail...
August 11, 2016: NeuroImage
Ilya Kuprov
This paper presents an overview of the Fokker-Planck formalism for non-biological magnetic resonance simulations, describes its existing applications and proposes some novel ones. The most attractive feature of Fokker-Planck theory compared to the commonly used Liouville - von Neumann equation is that, for all relevant types of spatial dynamics (spinning, diffusion, stationary flow, etc.), the corresponding Fokker-Planck Hamiltonian is time-independent. Many difficult NMR, EPR and MRI simulation problems (multiple rotation NMR, ultrafast NMR, gradient-based zero-quantum filters, diffusion and flow NMR, off-resonance soft microwave pulses in EPR, spin-spin coupling effects in MRI, etc...
September 2016: Journal of Magnetic Resonance
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