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MRI theory and use

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https://www.readbyqxmd.com/read/29344935/progressive-topological-disorganization-of-brain-network-in-focal-epilepsy
#1
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
https://www.readbyqxmd.com/read/29322101/a-novel-individual-level-morphological-brain-networks-constructing-method-and-its-evaluation-in-pet-and-mr-images
#2
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
https://www.readbyqxmd.com/read/29288036/a-study-of-mri-gradient-echo-signals-from-discrete-magnetic-particles-with-considerations-of-several-parameters-in-simulations
#3
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
https://www.readbyqxmd.com/read/29283104/repair-of-tegmen-tympani-defect-presenting-with-spontaneous-cerebrospinal-fluid-otorrhea-using-the-middle-cranial-fossa-approach
#4
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
https://www.readbyqxmd.com/read/29274848/mirror-neuron-system-activation-in-children-with-developmental-coordination-disorder-a-replication-functional-mri-study
#5
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
https://www.readbyqxmd.com/read/29231953/fundamental-tongue-motions-for-trumpet-playing-a-study-using-cine-magnetic-resonance-imaging-cine-mri
#6
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
https://www.readbyqxmd.com/read/29193415/estimating-the-arterial-input-function-from-dynamic-contrast-enhanced-mri-data-with-compensation-for-flow-enhancement-i-theory-method-and-phantom-experiments
#7
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
https://www.readbyqxmd.com/read/29193250/design-of-universal-parallel-transmit-refocusing-kt-point-pulses-and-application-to-3d-t2-weighted-imaging-at-7t
#8
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
https://www.readbyqxmd.com/read/29175724/a-right-amygdalohippocampectomy-a-diagnostic-challenge
#9
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...
November 21, 2017: Clinical Neurology and Neurosurgery
https://www.readbyqxmd.com/read/29164774/task-related-changes-in-degree-centrality-and-local-coherence-of-the-posterior-cingulate-cortex-after-major-cardiac-surgery-in-older-adults
#10
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...
November 21, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29163072/altered-functional-brain-connectomes-between-sporadic-and-familial-parkinson-s-patients
#11
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
https://www.readbyqxmd.com/read/29161930/no-radiological-and-clinical-advantages-with-patient-specific-positioning-guides-in-total-knee-replacement
#12
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
https://www.readbyqxmd.com/read/29154463/establishing-upper-limits-on-neuronal-activity-evoked-ph-changes-with-apt-cest-mri-at-7-t
#13
Vitaliy Khlebnikov, Jeroen C W Siero, Alex A Bhogal, Peter R Luijten, Dennis W J Klomp, Hans Hoogduin
PURPOSE: To detect neuronal activity-evoked pH changes by amide proton transfer-chemical exchange saturation transfer (APT-CEST) MRI at 7 T. METHODS: Three healthy subjects participated in the study. A low-power 3-dimensional APT-CEST sequence was optimized through the Bloch-McConnell equations. pH sensitivity of the sequence was estimated both in phantoms and in vivo. The feasibility of pH-functional MRI was tested in Bloch-McConnell-simulated data using the optimized sequence...
November 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29139161/cognitive-abilities-brain-white-matter-hyperintensity-volume-and-structural-network-connectivity-in-older-age
#14
Stewart J Wiseman, Tom Booth, Stuart J Ritchie, Simon R Cox, Susana Muñoz Maniega, Maria Del C Valdés Hernández, David Alexander Dickie, Natalie A Royle, John M Starr, Ian J Deary, Joanna M Wardlaw, Mark E Bastin
OBJECTIVE: To assess brain structural connectivity in relation to cognitive abilities in healthy ageing, and the mediating effects of white matter hyper-intensity (WMH) volume. METHODS: MRI data were analysed in 558 members of the Lothian Birth Cohort 1936. Brains were segmented into 85 regions and combined with tractography to generate structural connectomes. WMH volume was quantified. Relationships between whole-brain connectivity, assessed using graph theory metrics, and four major domains of cognitive ability (visuospatial reasoning, verbal memory, information processing speed and crystallized ability) were investigated, as was the mediating effects of WMH volume on these relationships...
November 14, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29104148/laminar-fmri-and-computational-theories-of-brain-function
#15
REVIEW
K E Stephan, F H Petzschner, L Kasper, J Bayer, K V Wellstein, G Stefanics, K P Pruessmann, J Heinzle
Recently developed methods for functional MRI at the resolution of cortical layers (laminar fMRI) offer a novel window into neurophysiological mechanisms of cortical activity. Beyond physiology, laminar fMRI also offers an unprecedented opportunity to test influential theories of brain function. Specifically, hierarchical Bayesian theories of brain function, such as predictive coding, assign specific computational roles to different cortical layers. Combined with computational models, laminar fMRI offers a unique opportunity to test these proposals noninvasively in humans...
November 2, 2017: NeuroImage
https://www.readbyqxmd.com/read/29094378/modeling-rater-diagnostic-skills-in-binary-classification-processes
#16
Xiaoyan Lin, Hua Chen, Don Edwards, Kerrie P Nelson
Many disease diagnoses involve subjective judgments by qualified raters. For example, through the inspection of a mammogram, MRI, or ultrasound image, the clinician himself becomes part of the measuring instrument. To reduce diagnostic errors and improve the quality of diagnoses, it is necessary to assess raters' diagnostic skills and to improve their skills over time. This paper focuses on a subjective binary classification process, proposing a hierarchical model linking data on rater opinions with patient true disease-development outcomes...
November 2, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/29084064/new-insights-into-cerebral-small-vessel-disease-and-vascular-cognitive-impairment-from-mri
#17
Eric E Smith, Andrew E Beaudin
PURPOSE OF REVIEW: We review recent MRI research that addresses two important challenges in cerebral small vessel disease (SVD) research: early diagnosis, and linking SVD with cognitive impairment. First, we review studies of MRI measurements of blood flow and blood-brain barrier integrity. Second, we review MRI studies identifying neuroimaging correlates of SVD-related cognitive dysfunction, focusing on brain connectivity and white matter microarchitecture. This research is placed in context through discussion of recent recommendations for management of incidentally discovered SVD, and neuroimaging biomarker use in clinical trials...
February 2018: Current Opinion in Neurology
https://www.readbyqxmd.com/read/29081852/the-aetiology-of-the-non-ossifying-fibroma-of-the-distal-femur-and-its-relationship-to-the-surrounding-soft-tissues
#18
A Goldin, D A Muzykewicz, J Dwek, S J Mubarak
PURPOSE: We aim to retrospectively evaluate patients with non-ossifying fibroma (NOF) of the distal femur by radiographs, CT and MRI, and to provide a theory describing the reasoning for the distal femur NOF's location and aetiology. METHODS: Charts of patients with NOFs between 2003 and 2014 were retrospectively reviewed. Inclusion criteria encompassed a diagnosis of NOF of the distal femur by imaging, and histologically, if available. Radiographs, CT and MRI were used to characterise the relationship of the NOF lesions with the surrounding soft tissues...
October 1, 2017: Journal of Children's Orthopaedics
https://www.readbyqxmd.com/read/29077570/determination-of-mean-ionization-potential-using-magnetic-resonance-imaging-for-the-reduction-of-proton-beam-range-uncertainties-theory-and-application
#19
Atchar Sudhyadhom
The accurate determination of mean ionization potential (I m) has the potential to reduce range uncertainty based margins and therefore allow for more focal treatments in proton radiotherapy. Many methods have been proposed to reduce uncertainty in I m and stopping power ratios (SPR), each with varying degrees of accuracy and issues. In this work, we present a simple parameterized model to determine I m in human biological tissue, allowing for the computation of patient-specific I m at the voxel level using magnetic resonance imaging (MRI)...
October 27, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29034164/aberrant-brain-functional-connectivity-in-newborns-with-congenital-heart-disease-before-cardiac-surgery
#20
Josepheen De Asis-Cruz, Mary T Donofrio, Gilbert Vezina, Catherine Limperopoulos
Newborns with congenital heart disease (CHD) requiring open heart surgery are at increased risk for neurodevelopmental disabilities. Recent quantitative MRI studies have reported disrupted growth, microstructure, and metabolism in fetuses and newborns with complex CHD. To date, no study has examined whether functional brain connectivity is altered in this high-risk population after birth, before surgery. Our objective was to compare whole-brain functional connectivity of resting state networks in healthy, term newborns (n = 82) and in term neonates with CHD before surgery (n = 30) using graph theory and network-based statistics...
2018: NeuroImage: Clinical
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