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MRI theory and use

Elizabeth A Shay, Quanjing Chen, Frank E Garcea, Bradford Z Mahon
Multivoxel pattern analysis (MVPA) over functional MRI data can distinguish neural representational states that do not differ in their overall amplitude of BOLD contrast. Here we used MVPA to test whether simple intransitive actions can be distinguished in primary motor cortex. Participants rotated and flexed each of their extremities (hands and feet) during fMRI scanning. The primary motor cortex for the hand/wrist was functionally defined in each hemisphere in each subject. Within those subject-specific ROIs, we found that the average amplitude of BOLD contrast for two different movements of the contralateral hand (rotation, flexion) were higher than for the ipsilateral hand, as well as movements by both feet; however, there was no difference in amplitude between the two different types of movements for the contralateral hand...
March 16, 2018: Cognitive Neuroscience
Fatma Gargouri, Fathi Kallel, Sebastien Delphine, Ahmed Ben Hamida, Stéphane Lehéricy, Romain Valabregue
Resting state functional MRI (rs-fMRI) is an imaging technique that allows the spontaneous activity of the brain to be measured. Measures of functional connectivity highly depend on the quality of the BOLD signal data processing. In this study, our aim was to study the influence of preprocessing steps and their order of application on small-world topology and their efficiency in resting state fMRI data analysis using graph theory. We applied the most standard preprocessing steps: slice-timing, realign, smoothing, filtering, and the tCompCor method...
2018: Frontiers in Computational Neuroscience
Christopher G Watson, Christian Stopp, Jane W Newburger, Michael J Rivkin
Objective: Adolescents with d-transposition of the great arteries (d-TGA) who had the arterial switch operation in infancy have been found to have structural brain differences compared to healthy controls. We used cortical thickness measurements obtained from structural brain MRI to determine group differences in global brain organization using a graph theoretical approach. Methods: Ninety-two d-TGA subjects and 49 controls were scanned using one of two identical 1...
February 2018: Brain and Behavior
Ka-Loh Li, Daniel Lewis, Alan Jackson, Sha Zhao, Xiaoping Zhu
BACKGROUND: Previous studies have measured cerebral blood flow (CBF) with DSC-MRI using an "early time points" (ET) method based on microsphere theory. PURPOSE: To develop and assess a new ET method for absolute CBF estimation using low-dose high-temporal (LDHT) T1W-DCE-MRI. STUDY TYPE: Retrospective cohort study. SUBJECTS: Seven patients with sporadic vestibular schwannoma (VS) who underwent test-retest imaging; one patient with glioblastoma multiforme (GBM) imaged pretreatment; and 12 neurofibromatosis type 2 (NF2) patients undergoing bevacizumab treatment, imaged pre- and 90 days posttreatment...
February 23, 2018: Journal of Magnetic Resonance Imaging: JMRI
W H van Harten, N Goedbloed, A H Boekhout, S Heintzbergen
BACKGROUND: In general, patients with a cancer suspicion visit the hospital multiple times before diagnosis is completed. Using various "operations management" techniques a few fast track diagnostic services were implemented in the Netherlands Cancer Institute (NKI) in 2006. Growing patient numbers and increasing process complexity, led to diminished service levels. To decrease the amount of patient visits and to extend these services beyond the (obvious) breast cancer services, fast track diagnostics is now implemented for all 18 cancer types that present with a frequency of minimally one per week...
February 7, 2018: BMC Health Services Research
D Koh, J Felder, N J Shah
MRI volume coils can be represented by equivalent lumped element circuits and for a variety of these circuit configurations analytical design equations have been presented. The unification of several volume coil topologies results in a two-dimensional gridded equivalent lumped element circuit which compromises the birdcage resonator, its multiple endring derivative but also novel structures like the capacitive coupled ring resonator. The theory section analyzes a general two-dimensional circuit by noting that its current distribution can be decomposed into a longitudinal and an azimuthal dependency...
January 25, 2018: Journal of Magnetic Resonance
Jean-Pierre Korb
The nuclear magnetic relaxation dispersion (NMRD) technique consists of measurement of the magnetic-field dependence of the longitudinal nuclear-spin-lattice relaxation rate 1/T1. Usually, the acquisition of the NMRD profiles is made using a fast field cycling (FFC) NMR technique that varies the magnetic field and explores a very large range of Larmor frequencies (10 kHz < ω0/(2π) <40 MHz). This allows extensive explorations of the fluctuations to which nuclear spin relaxation is sensitive...
February 2018: Progress in Nuclear Magnetic Resonance Spectroscopy
Cui Yuan, Hongru Zhu, Zhengjia Ren, Minlan Yuan, Meng Gao, Yan Zhang, Yuchen Li, Yajing Meng, Qiyong Gong, Su Lui, Changjian Qiu, Wei Zhang
BACKGROUND: Neuroimaging findings suggest that social anxiety disorder (SAD) may be correlated with changes in regional- or network-level brain function. However, few studies have explored alterations in intrinsic resting cerebral function in patients with SAD at both the regional and network levels, particularly focusing on the theory of mind (ToM)-related regions. This study was performed to investigate changes in neural activity and functional connectivity (FC) in ToM-related regions during the resting state in SAD patients and to determine how these alterations are correlated with the clinical symptoms of SAD...
December 22, 2017: Comprehensive Psychiatry
K M Park, B I Lee, K J Shin, S Y Ha, J Park, T H Kim, C W Mun, S E Kim
OBJECTIVE: Increasing evidence has suggested that epilepsy is a network disease. Graph theory is a mathematical tool that allows for the analysis and quantification of the brain network. We aimed to evaluate the influences of duration of epilepsy on the topological organization of brain network in focal epilepsy patients with normal MRI using the graph theoretical analysis based on diffusion tenor imaging. METHODS: We prospectively enrolled 66 patients with focal epilepsy (18/66 patients were newly diagnosed) and 84 healthy subjects...
January 17, 2018: Acta Neurologica Scandinavica
Jiehui Jiang, Hucheng Zhou, Huoqiang Duan, Xin Liu, Chuantao Zuo, Zhemin Huang, Zhihua Yu, Zhuangzhi Yan
Mapping the human brain is one of the great scientific challenges of the 21st century. Brain network analysis is an effective technique based on graph theory that is widely used to investigate network patterns in the human brain. Currently, mapping an individual brain network using a single image has been a hotspot in the field of brain science; techniques, such as the Kullback-Leibler (KL) method, have applications in structural Magnetic Resonance (MR) imaging. However, maintaining an image's intensity, shape, texture and gradient information during feature extraction is very challenging...
December 2017: Heliyon
Paul Kokeny, Yu-Chung N Cheng, He Xie
Modeling MRI signal behaviors in the presence of discrete magnetic particles is important, as magnetic particles appear in nanoparticle labeled cells, contrast agents, and other biological forms of iron. Currently, many models that take into account the discrete particle nature in a system have been used to predict magnitude signal decays in the form of R2* or R2' from one single voxel. Little work has been done for predicting phase signals. In addition, most calculations of phase signals rely on the assumption that a system containing discrete particles behaves as a continuous medium...
December 26, 2017: Magnetic Resonance Imaging
Said Sönmez, Bayram Şahin, Beldan Polat, Şenol Çomoğlu, Kadir Serkan Orhan
Spontaneous cerebrospinal fluid (CSF) otorrhea frequently occurs without temporal bone trauma, fracture, surgery, or any identifiable causes. It is usually associated with tegmen tympani defects of the temporal bone in adults. The congenital origin theory and the arachnoid granulation theory have been accepted to explain the tegmen tympani defect. Magnetic resonance imaging (MRI) and computed tomography (CT) are used to show the defects, brain tissue, and the meninges. We recently encountered three cases of spontaneous CSF otorrhea with a defect on the tegmental plate of the temporal bone...
December 14, 2017: Journal of International Advanced Otology
J E Reynolds, J Billington, S Kerrigan, J Williams, C Elliott, A M Winsor, L Codd, M Bynevelt, M K Licari
BACKGROUND: It has been hypothesised that abnormal functioning of the mirror neuron system (MNS) may lead to deficits in imitation and the internal representation of movement, potentially contributing to the motor impairments associated with developmental coordination disorder (DCD). AIMS: Using fMRI, this study examined brain activation patterns in children with and without DCD on a finger adduction/abduction task during four MNS activation states: observation; motor imagery; execution; and imitation...
December 20, 2017: Research in Developmental Disabilities
Hiroko Furuhashi, Toru Chikui, Daisuke Inadomi, Tomoko Shiraishi, Kazunori Yoshiura
OBJECTIVE: Though the motions of structures outside the mouth in trumpet performance have been reported, the dynamics of intraoral structures remain unelucidated. This study explored the tongue's movement in trumpet playing using cine magnetic resonance imaging (cine MRI) and demonstrated the effects of intraoral anatomical structures on changes in pitch and dynamics. METHODS: Cine MRI was applied to 18 trumpet players, who were divided into two groups (7 beginner, 11 advanced) based on their ability to play a certain high note...
December 2017: Medical Problems of Performing Artists
Jeroen J N van Schie, Cristina Lavini, Lucas J van Vliet, Frans M Vos
BACKGROUND: The arterial input function (AIF) represents the time-dependent arterial contrast agent (CA) concentration that is used in pharmacokinetic modeling. PURPOSE: To develop a novel method for estimating the AIF from dynamic contrast-enhanced (DCE-) MRI data, while compensating for flow enhancement. STUDY TYPE: Signal simulation and phantom measurements. PHANTOM MODEL: Time-intensity curves (TICs) were simulated for different numbers of excitation pulses modeling flow effects...
November 28, 2017: Journal of Magnetic Resonance Imaging: JMRI
Vincent Gras, Franck Mauconduit, Alexandre Vignaud, Alexis Amadon, Denis Le Bihan, Tony Stöcker, Nicolas Boulant
PURPOSE: T2 -weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra-high-field because of the errors accumulated by the imperfections of the train of refocusing pulses. As parallel transmission (pTx) has proved particularly useful to counteract RF heterogeneities, universal pulses were recently demonstrated to save precious time and computational efforts by skipping B1 calibration and online RF pulse tailoring. Here, we report a universal RF pulse design for non-selective refocusing pulses to mitigate the RF inhomogeneity problem at 7T in turbo spin-echo sequences with variable flip angles...
November 29, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Frank Jonker, Cees Jonker, Laura Bronzwaer, Erik Scherder
OBJECTIVE: Amygdalohippocampectomy (AHE) is the resective surgery for medically intractable mesial temporal lobe epilepsy. To date no study has investigated a wide range of neuropsychiatric symptoms in right AHE outpatients. PATIENTS AND METHODS: Three patients with right AHE participated in this study. The control group are patients with cognitive complaints with no history of epilepsy or neurological impairment and no structural abnormalities on the MRI/CT. We expected no difference in verbal memory compared to the controls...
January 2018: Clinical Neurology and Neurosurgery
Jeffrey N Browndyke, Miles Berger, Patrick J Smith, Todd B Harshbarger, Zachary A Monge, Viral Panchal, Tiffany L Bisanar, Donald D Glower, John H Alexander, Roberto Cabeza, Kathleen Welsh-Bohmer, Mark F Newman, Joseph P Mathew
OBJECTIVES: Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls. EXPERIMENTAL DESIGN: Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals...
February 2018: Human Brain Mapping
Yan Tang, Xue Xiao, Hua Xie, Chang-Min Wan, Li Meng, Zhen-Hua Liu, Wei-Hua Liao, Bei-Sha Tang, Ji-Feng Guo
Familial Parkinson's disease (PD) is often caused by mutation of a certain gene, while sporadic PD is associated with variants of genes which can influence the susceptibility to PD. The goal of this study was to investigate the difference between the two forms of PD in terms of brain abnormalities using resting-state functional MRI and graph theory. Thirty-one familial PD patients and 36 sporadic PD patients underwent resting-state functional MRI scanning. Frequency-dependent functional connectivity was calculated for each subject using wavelet-based correlations of BOLD signal over 246 brain regions from Brainnetome Atlas...
2017: Frontiers in Neuroanatomy
Justin A M J Van Leeuwen, Finnur Snorrason, Stephan M Röhrl
Background and purpose - Although the use of patient-specific positioning guides (PSPGs) in total knee replacement (TKR) in theory is promising, the technique has not yet proven its superior- ity compared with the conventional method. We compared radio- logical alignment and clinical outcome between TKR performed with the use of PSPGs and the conventional operation method. Patients and methods - 3 hospitals participated in a prospec- tive trial. 109 patients were randomized to either the conventional method or to the use of PSPGs...
November 22, 2017: Acta Orthopaedica
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