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MRI theory and use

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https://www.readbyqxmd.com/read/29741663/statistical-model-of-dynamic-markers-of-the-alzheimer-s-pathological-cascade
#1
Steve Balsis, Lisa Geraci, Jared Benge, Deborah A Lowe, Tabina K Choudhury, Robert Tirso, Rachelle S Doody
Objectives: Alzheimer's disease (AD) is a progressive disease reflected in markers across assessment modalities, including neuroimaging, cognitive testing, and evaluation of adaptive function. Identifying a single continuum of decline across assessment modalities in a single sample is statistically challenging because of the multivariate nature of the data. To address this challenge, we implemented advanced statistical analyses designed specifically to model complex data across a single continuum...
May 5, 2018: Journals of Gerontology. Series B, Psychological Sciences and Social Sciences
https://www.readbyqxmd.com/read/29740301/impaired-prefrontal-amygdala-pathway-self-reported-emotion-and-erection-in-psychogenic-erectile-dysfunction-patients-with-normal-nocturnal-erection
#2
Jianhuai Chen, Yun Chen, Qingqiang Gao, Guotao Chen, Yutian Dai, Zhijian Yao, Qing Lu
Background: Neuroimaging studies have demonstrated that the prefrontal cortex and amygdala play an important role in sexual arousal (SA). However, little is known about the interactions between the prefrontal and cortex amygdala, which mediate the cognitive regulation of emotion and SA. Objective: We seek to determine whether nocturnal erection of psychogenic erectile dysfunction (pED) patients are normal and whether there are changes of topological organization in the prefrontal-amygdala pathway of brain network in pED...
2018: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/29730541/stroke-causes-a-transient-imbalance-of-interhemispheric-information-flow-in-eeg-during-non-rem-sleep
#3
Frederic Zubler, Andrea Seiler, Thomas Horvath, Corinne Roth, Silvia Miano, Christian Rummel, Heidemarie Gast, Lino Nobili, Kaspar A Schindler, Claudio L Bassetti
OBJECTIVE: Large-scale connectivity, especially interhemispheric connections, plays a crucial role for recovery after stroke. Here we used methods from information theory to characterize interhemispheric information flow in wake- and sleep-EEG after cerebral ischemia. METHODS: 34 patients with unilateral ischemic stroke were included. Symbolic Transfer Entropy (STE) was applied between bipolar EEG signals on the left and the right cerebral hemisphere during polysomnographic recordings in the acute phase and 3 months after stroke...
April 17, 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/29730491/default-mode-network-abnormalities-in-posttraumatic-stress-disorder-a-novel-network-restricted-topology-approach
#4
Teddy J Akiki, Christopher L Averill, Kristen M Wrocklage, J Cobb Scott, Lynnette A Averill, Brian Schweinsburg, Aaron Alexander-Bloch, Brenda Martini, Steven M Southwick, John H Krystal, Chadi G Abdallah
Disruption in the default mode network (DMN) has been implicated in numerous neuropsychiatric disorders, including posttraumatic stress disorder (PTSD). However, studies have largely been limited to seed-based methods and involved inconsistent definitions of the DMN. Recent advances in neuroimaging and graph theory now permit the systematic exploration of intrinsic brain networks. In this study, we used resting-state functional magnetic resonance imaging (fMRI), diffusion MRI, and graph theoretical analyses to systematically examine the DMN connectivity and its relationship with PTSD symptom severity in a cohort of 65 combat-exposed US Veterans...
May 3, 2018: NeuroImage
https://www.readbyqxmd.com/read/29728936/a-simple-measure-of-cognitive-reserve-is-relevant-for-cognitive-performance-in-ms-patients
#5
Marida Della Corte, Gabriella Santangelo, Alvino Bisecco, Rosaria Sacco, Mattia Siciliano, Alessandro d'Ambrosio, Renato Docimo, Teresa Cuomo, Luigi Lavorgna, Simona Bonavita, Gioacchino Tedeschi, Antonio Gallo
Cognitive reserve (CR) contributes to preserve cognition despite brain damage. This theory has been applied to multiple sclerosis (MS) to explain the partial relationship between cognition and MRI markers of brain pathology. Our aim was to determine the relationship between two measures of CR and cognition in MS. One hundred and forty-seven MS patients were enrolled. Cognition was assessed using the Rao's Brief Repeatable Battery and the Stroop Test. CR was measured as the vocabulary subtest of the WAIS-R score (VOC) and the number of years of formal education (EDU)...
May 4, 2018: Neurological Sciences
https://www.readbyqxmd.com/read/29722629/cognitive-function-disease-burden-and-the-structural-connectome-in-systemic-lupus-erythematosus
#6
S J Wiseman, M E Bastin, E N Amft, J F F Belch, S H Ralston, J M Wardlaw
Objective To investigate brain structural connectivity in relation to cognitive abilities and systemic damage in systemic lupus erythematosus (SLE). Methods Structural and diffusion MRI data were acquired from 47 patients with SLE. Brains were segmented into 85 cortical and subcortical regions and combined with whole brain tractography to generate structural connectomes using graph theory. Global cognitive abilities were assessed using a composite variable g, derived from the first principal component of three common clinical screening tests of neurological function...
January 1, 2018: Lupus
https://www.readbyqxmd.com/read/29713112/bayesian-modeling-of-nmr-data-quantifying-longitudinal-relaxation-in-vivo-and-in-vitro-with-a-tissue-water-relaxation-mimic-crosslinked-bovine-serum-albumin
#7
Kelsey Meinerz, Scott C Beeman, Chong Duan, G Larry Bretthorst, Joel R Garbow, Joseph J H Ackerman
Recently, a number of MRI protocols have been reported that seek to exploit the effect of dissolved oxygen (O2 , paramagnetic) on the longitudinal 1 H relaxation of tissue water, thus providing image contrast related to tissue oxygen content. However, tissue water relaxation is dependent on a number of mechanisms, and this raises the issue of how best to model the relaxation data. This problem, the model selection problem, occurs in many branches of science and is optimally addressed by Bayesian probability theory...
January 2018: Applied Magnetic Resonance
https://www.readbyqxmd.com/read/29697054/incorporating-drug-delivery-into-an-imaging-driven-mechanics-coupled-reaction-diffusion-model-for-predicting-the-response-of-breast-cancer-to-neoadjuvant-chemotherapy-theory-and-preliminary-clinical-results
#8
Angela M Jarrett, David A Hormuth Ii, Stephanie L Barnes, Xinzeng Feng, Wei Huang, Thomas E Yankeelov
Clinical methods for assessing tumor response to therapy are largely rudimentary, monitoring only temporal changes in tumor size. Our goal is to predict the response of breast tumors to therapy using a mathematical model that utilizes magnetic resonance imaging (MRI) data obtained non-invasively from individual patients. We extended a previously established, mechanically coupled, reaction-diffusion model for predicting tumor response initialized with patient-specific diffusion weighted MRI (DW-MRI) data by including the effects of chemotherapy drug delivery, which is estimated using dynamic contrast-enhanced (DCE-) MRI data...
April 26, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29682499/paracest-agents-encapsulated-in-reverse-nano-assembled-capsules-racs-how-slow-molecular-tumbling-can-quench-cest-contrast
#9
Annah Farashishiko, Jacqueline R Slack, Mauro Botta, Mark Woods
Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule...
2018: Frontiers in Chemistry
https://www.readbyqxmd.com/read/29673867/structural-differences-in-hippocampal-and-entorhinal-gray-matter-volume-support-individual-differences-in-first-person-navigational-ability
#10
Katherine R Sherrill, Elizabeth R Chrastil, Irem Aselcioglu, Michael E Hasselmo, Chantal E Stern
The ability to update position and orientation to reach a goal is crucial to spatial navigation and individuals vary considerably in this ability. The current structural MRI study used voxel-based morphometry (VBM) analysis to relate individual differences in human brain morphology to performance in an active navigation task that relied on updating position and orientation in a landmark-free environment. Goal-directed navigation took place from either a first person perspective, similar to a person walking through the landmark-free environment, or Survey perspective, a bird's eye view...
April 16, 2018: Neuroscience
https://www.readbyqxmd.com/read/29657915/macromolecular-crowding-may-significantly-affect-the-performance-of-an-mri-contrast-agent-a-1-h-nmr-spectroscopy-microimaging-and-fast-field-cycling-nmr-relaxometry-study
#11
Ren-Hao Cheng, Jie-Min Chen, Yu-Wen Chen, Honghao Cai, Xiaohong Cui, Dennis W Hwang, Zhong Chen, Shangwu Ding
Contrast enhancement agents are often employed in magnetic resonance imaging (MRI) for clinical diagnosis and biomedical research. However, the current theory on MRI contrast generation does not consider the ubiquitous presence of macromolecular crowders in biological systems, which poses the risk of inaccurate data interpretation and misdiagnosis. To address this issue, herein the macromolecular crowding effects on MRI contrast agent are investigated with the 1 H relaxation rate of water in aqueous solutions of Dotarem with different concentrations of macromolecules...
April 2018: ChemistryOpen
https://www.readbyqxmd.com/read/29618992/fronto-temporal-connectivity-predicts-ect-outcome-in-major-depression
#12
Amber M Leaver, Benjamin Wade, Megha Vasavada, Gerhard Hellemann, Shantanu H Joshi, Randall Espinoza, Katherine L Narr
Background: Electroconvulsive therapy (ECT) is arguably the most effective available treatment for severe depression. Recent studies have used MRI data to predict clinical outcome to ECT and other antidepressant therapies. One challenge facing such studies is selecting from among the many available metrics, which characterize complementary and sometimes non-overlapping aspects of brain function and connectomics. Here, we assessed the ability of aggregated, functional MRI metrics of basal brain activity and connectivity to predict antidepressant response to ECT using machine learning...
2018: Frontiers in Psychiatry
https://www.readbyqxmd.com/read/29610569/respiratory-motion-correction-for-compressively-sampled-free-breathing-cardiac-mri-using-smooth-l-1-norm-approximation
#13
Muhammad Bilal, Jawad Ali Shah, Ijaz M Qureshi, Kushsairy Kadir
Transformed domain sparsity of Magnetic Resonance Imaging (MRI) has recently been used to reduce the acquisition time in conjunction with compressed sensing (CS) theory. Respiratory motion during MR scan results in strong blurring and ghosting artifacts in recovered MR images. To improve the quality of the recovered images, motion needs to be estimated and corrected. In this article, a two-step approach is proposed for the recovery of cardiac MR images in the presence of free breathing motion. In the first step, compressively sampled MR images are recovered by solving an optimization problem using gradient descent algorithm...
2018: International Journal of Biomedical Imaging
https://www.readbyqxmd.com/read/29568689/both-activated-and-less-activated-regions-identified-by-functional-mri-reconfigure-to-support-task-executions
#14
Nianming Zuo, Zhengyi Yang, Yong Liu, Jin Li, Tianzi Jiang
Introduction: Functional magnetic resonance imaging (fMRI) has become very important for noninvasively characterizing BOLD signal fluctuations, which reflect the changes in neuronal firings in the brain. Unlike the activation detection strategy utilized with fMRI, which only emphasizes the synchronicity between the functional nodes (activated regions) and the task design, brain connectivity and network theory are able to decipher the interactive structure across the entire brain. However, little is known about whether and how the activated/less-activated interactions are associated with the functional changes that occur when the brain changes from the resting state to a task state...
January 2018: Brain and Behavior
https://www.readbyqxmd.com/read/29544397/decoding-intransitive-actions-in-primary-motor-cortex-using-fmri-toward-a-componential-theory-of-action-primitives-in-motor-cortex
#15
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...
April 9, 2018: Cognitive Neuroscience
https://www.readbyqxmd.com/read/29497372/the-influence-of-preprocessing-steps-on-graph-theory-measures-derived-from-resting-state-fmri
#16
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
https://www.readbyqxmd.com/read/29484251/graph-theory-analysis-of-cortical-thickness-networks-in-adolescents-with-d-transposition-of-the-great-arteries
#17
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
https://www.readbyqxmd.com/read/29473980/low-dose-t1w-dce-mri-for-early-time-points-perfusion-measurement-in-patients-with-intracranial-tumors-a-pilot-study-applying-the-microsphere-model-to-measure-absolute-cerebral-blood-flow
#18
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
https://www.readbyqxmd.com/read/29415717/implementing-large-scale-fast-track-diagnostics-in-a-comprehensive-cancer-center-pre-and-post-measurement-data
#19
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
https://www.readbyqxmd.com/read/29414062/a-novel-analytical-description-of-periodic-volume-coil-geometries-in-mri
#20
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...
March 2018: Journal of Magnetic Resonance
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