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Abnormal Corpus Callosum Integrity in Bipolar Disorder: A Diffusion Tensor Imaging Study

WANG, Fei; KALMAR, Jessica H.; EDMISTON, Erin; CHEPENIK, Lara G.; BHAGWAGAR, Zubin; SPENCER, Linda; PITTMAN, Brian; JACKOWSKI, Marcel; PAPACLEMETRIS, Xenophon; CONSTABLE, R. Todd; BLUMBERG, Hilary P.
Fonte: ELSEVIER SCIENCE INC Publicador: ELSEVIER SCIENCE INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
96.17%
Objective: Abnormalities in the anterior interhemispheric connections provided by the corpus callosum (CC) have long been implicated in bipolar disorder (BID). In this study, we used complementary diffusion tensor imaging methods to study the structural integrity of the CC and localization of potential abnormalities in BD. Methods: Subjects included 33 participants with BID and 40 healthy comparison participants. Fractional anisotropy (FA) measures were compared between groups with region of interest (ROD methods to investigate the anterior, middle, and posterior CC and voxel-based methods to further localize abnormalities. Results: In ROI-based analyses, FA was significantly decreased in the anterior and middle CC in the BID group (p <.05). Voxel-based analyses similarly localized group differences to the genu, rostral body, and anterior midbody of CC (p <.05, corrected). Conclusion: The findings demonstrate abnormalities in the structural integrity of the anterior CC in BID that might contribute to altered interhemispheric connectivity in this disorder.; National Institute of Mental Health (NIH); National Institute of Mental Health (NIH)[R01MH69747]; National Institute of Mental Health (NIH); National Institute of Mental Health (NIH)[R01MH070902]; National Institute of Mental Health (NIH); National Institute of Mental Health (NIH)[T32MH14276]; National Institute of Mental Health (NIH); National Institute of Mental Health (NIH)[R01 EB006494]; National Institute of Mental Health (NIH)[K23MH077914]; National Institute of Mental Health (NIH); The Department of Veterans Affairs Career Development; The Department of Veterans Affairs Career Development; Merit Review; Merit Review; Research Enhancement Award Program (REAP); Research Enhancement Award Program (REAP); Attias Family Foundation; Attias Family Foundation; Marcia Simon Kaplan; Marcia Simon Kaplan; Klingenstein Foundation; Klingenstein Foundation; Alational Institutes; Alational Institutes; Health (NIH)/National Center for Research Resources/Clinical and Translational Science Awards; Health (NIH)/National Center for Research Resources/Clinical and Translational Science Awards[UL1RR024139-01]; NIH/National Institute of Biomedical Imaging and Bioengineering[R01 EB006494]; NIH/National Institute of Biomedical Imaging and Bioengineering

Imagem por tensores de difusão em crianças com leucomalácia periventricular; Diffusion tensor imaging in children with periventricular leukomalacia

Nagae, Lidia Mayumi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/06/2009 PT
Relevância na Pesquisa
96.17%
A avaliação através de imagem por ressonância magnética (RM) com utilização de sequências convencionais demonstra evidência de lesões destrutivas ou malformativas do sistema nervoso central em 70-90% das crianças com paralisia cerebral (PC), embora sua capacidade para identificação de tratos específicos da substância branca seja limitada. A grande variabilidade das lesões da substância branca na PC, já demonstrada por estudos post-mortem, é tida como uma das razões pelas quais as respostas a tratamento se mostrem tão variadas. Nossa hipótese é de que a técnica de imagem por tensores de difusão (TD) seja uma técnica apropriada para caracterização in vivo de lesões em tratos específicos da substância branca em crianças com PC associada à leucomalácia periventricular (LMP). Neste estudo, 24 crianças com PC associada à LMP e 35 controles normais foram avaliados pela técnica. Foram estabelecidos critérios para identificação de 26 tratos da substância branca com base nos mapas de cores bidimensionais gerados utilizando-se TD. Um sistema de escore qualitativo foi criado, com base na inspeção visual dos tratos em comparação com controles pareados por idade, para graduar a gravidade das anormalidades...

Imagens de tensor de difusão em idosos deprimidos: um estudo baseado na análise estatística do voxel; Diffusion tensor images in elderly depressed: a voxelwise statistical analysis study

Bezerra, Diana Moitinho
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/09/2011 PT
Relevância na Pesquisa
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Introdução: Os transtornos depressivos constituem um problema de saúde pública na terceira idade, e estima-se que a depressão será uma das três principais causas de sobrecarga de doença no mundo nas próximas decadas. Métodos de neuroimagem têm sido amplamente utilizados em estudos de depressão em idosos, pois são técnicas não invasivas que permitem a detecção de alterações cerebrais estruturais e funcionais. Fração de Anisotropia (FA) e Difusividade Média (MD) são índices indiretos da integridade micro-estrutural da substância branca, mensurados através de imagens de tensor de difusão (DTI). A maioria dos estudos a respeito de depressão e neuroimagem tem focado apenas em possíveis diferenças em regiões de interesse (ROI) previamente determinadas. Pesquisas sobre depressão em idosos e as alterações estruturais por tensor de difusão em todo o cérebro são escassos. O objetivo deste estudo foi investigar a existência de alterações nos parâmetros de FA ou MD em todo o cérebro, sem uma região de interesse previamente definida, comparando idosos deprimidos a idosos sem depressão. Métodos: Exames de imagem cerebral por ressonância magnética foram obtidos de 47 idosos deprimidos (idade média=70...

Avaliação de substância branca através de imagem por tensor de difusão em crianças  em risco e portadoras de transtorno bipolar; Evaluation of white matter using diffusion tensor imaging in children at-risk and with bipolar disorder

Teixeira, Ana Maria Aristimunho
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/09/2012 PT
Relevância na Pesquisa
86.31%
O Transtorno de Humor Bipolar (THB) acomete até 3% dos adultos e os filhos desses pacientes constituem uma população em risco para o desenvolvimento de transtornos psiquiátricos. No entanto, faltam marcadores que permitam a identificação precoce dos indivíduos que apresentam maior vulnerabilidade para o desenvolvimento de psicopatologia. Estudos preliminares com Ressonância Magnética (RM) indicaram que alterações em substância branca estariam presentes não apenas em pacientes em episódio de alteração de humor, mas também em pacientes eutímicos e em seus familiares saudáveis, sugerindo que tais alterações poderiam constituir um endofenótipo potencial deste transtorno. A Imagem por Tensor de Difusão (Diffusion Tensor Magnetic Resonance Imaging - DT-MRI) é uma aquisição de RM que permite análise mais completa e detalhada das características da substância branca cerebral que a RM tradicional. A investigação de alterações na estrutura cerebral, particularmente de substância branca, de jovens portadores de THB não medicados e familiares saudáveis criteriosamente avaliados pode ajudar a elucidar a neurobiologia subjacente ao THB e, conseqüentemente, a identificar marcadores de vulnerabilidade ao transtorno. Objetivo: Avaliar se havia alterações em substância branca em crianças e adolescentes com THB e crianças e adolescentes filhos saudáveis de portadores de transtorno do humor bipolar quando comparados a controles saudáveis...

Avaliação por imagem por tensor de difusão do corpo caloso em pacientes com epilepsia mesial temporal e esclerose hipocampal; Diffusion tensor imaging of the CC of patients with mesial temporal epilepsy and hippocampal sclerosis

Lyra, Katarina Paz de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/06/2015 PT
Relevância na Pesquisa
96.32%
INTRODUÇÃO: Epilepsia do lobo temporal mesial (ELTM) por esclerose hipocampal (EH) é a forma de epilepsia focal mais comum na idade adulta e a causa mais frequente de refratariedade ao tratamento clínico. Apesar de se tratar de uma patologia da substância cinzenta, alguns estudos, por meio da imagem por tensor de difusão (diffusion tensor imaging-DTI), têm demonstrado alteração da substância branca temporal e extratemporal nestes pacientes. O corpo caloso (CC) é a maior comissura cerebral conectando áreas corticais homólogas de ambos os hemisférios cerebrais e tem sido implicado na propagação da atividade epiléptica. O objetivo principal do presente estudo foi avaliar possíveis alterações no CC de pacientes com ELTM-EH pela técnica de DTI e verificar se essas dependem da lateralidade da EH e da concordância entre os exames de ressonância magnética (RM) e os exames de vídeo-eletroencefalograma (EEG). Como objetivo secundário, também avaliou-se se estas alterações se correlacionavam com alguma variável clínica ou com as medidas volumétricas do CC. MÉTODOS: 42 pacientes com ELTM-EH (idades: 20-54 anos) e 30 voluntários saudáveis como grupo controle (idades: 18-53 anos) realizaram exame de RM de crânio...

Imagem por tensor de difusão da substância branca aparentemente normal no comprometimento cognitivo leve e na doença de Alzheimer; Diffusion tensor imaging of normal-appearing white matter in mild cognitive impairment and early Alzheimer disease

Sergilaine Pereira Martins
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/06/2014 PT
Relevância na Pesquisa
96.18%
A ressonância magnética por tensor de difusão (DTI) proporciona aumento da sensibilidade para estudar a alterações na microestrutura da substância branca aparentemente normal (SBAN) in vivo e é especialmente indicada para estudar doenças que apresentam lesão axonal e desmielinização. No presente estudo, sugerimos a hipótese de que a neurodegeneração produz alterações microestruturais na SBAN de indivíduos com DA e CCL, especialmente em regiões específicas do cérebro. Foram estudados 71 participantes (21 com DA leve, 25 com CCL e 25 controles normais-CN) que foram recrutados de serviço médico neurológico em Campinas. Os indivíduos foram avaliados por um protocolo de avaliação clínica padronizada que incluiu: escala de depressão geriátrica (GDS), questionário de atividades funcionais (FAQ - Pfeffer), mini exame do estado mental (MEEM), teste de aprendizado auditivo-verbal de REY (RAVLT), testes de memória prospectiva (MP) (consulta e pertence) (subtestes do Teste de Memória Comportamental Rivermead), teste de fluência verbal (FV) (animais e FAS), teste desenho do relógio (TDR) e teste de nomeação de Boston (TNB). As imagens de RNM foram adquiridas usando um scanner MRT 1.5. A anisotropia fracionada (FA) e as difusividades axial (DAx) e radial (DRa) foram analisadas em regiões de interesse (ROI) alocados nos lobos frontal...

Diffusion tensor imaging of the spinal cord: a review

Vedantam,Aditya; Jirjis,Michael; Eckhardt,Gerald; Sharma,Abhishiek; Schmit,Brian D.; Wang,Marjorie C.; Ulmer,John L.; Kurpad,Shekar
Fonte: Sociedade Brasileira de Coluna Publicador: Sociedade Brasileira de Coluna
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
96.15%
Diffusion tensor imaging (DTI) is a magnetic resonance technique capable of measuring the magnitude and direction of water molecule diffusion in various tissues. The use of DTI is being expanded to evaluate a variety of spinal cord disorders both for prognostication and to guide therapy. The purpose of this article is to review the literature on spinal cord DTI in both animal models and humans in different neurosurgical conditions. DTI of the spinal cord shows promise in traumatic spinal cord injury, cervical spondylotic myelopathy, and intramedullary tumors. However, scanning protocols and image processing need to be refined and standardized.

White matter correlates of cognitive domains in normal aging with diffusion tensor imaging

Sasson, Efrat; Doniger, Glen M.; Pasternak, Ofer; Tarrasch, Ricardo; Assaf, Yaniv
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
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The ability to perform complex as well as simple cognitive tasks engages a network of brain regions that is mediated by the white matter fiber bundles connecting them. Different cognitive tasks employ distinctive white matter fiber bundles. The temporal lobe and its projections subserve a variety of key functions known to deteriorate during aging. In a cohort of 52 healthy subjects (ages 25–82 years), we performed voxel-wise regression analysis correlating performance in higher-order cognitive domains (executive function, information processing speed, and memory) with white matter integrity, as measured by diffusion tensor imaging (DTI) fiber tracking in the temporal lobe projections [uncinate fasciculus (UF), fornix, cingulum, inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF)]. The fiber tracts were spatially registered and statistical parametric maps were produced to spatially localize the significant correlations. Results showed that performance in the executive function domain is correlated with DTI parameters in the left SLF and right UF; performance in the information processing speed domain is correlated with fractional anisotropy (FA) in the left cingulum, left fornix, right and left ILF and SLF; and the memory domain shows significant correlations with DTI parameters in the right fornix...

Dual-Phase Cardiac Diffusion Tensor Imaging with Strain Correction

Stoeck, Christian T.; Kalinowska, Aleksandra; von Deuster, Constantin; Harmer, Jack; Chan, Rachel W.; Niemann, Markus; Manka, Robert; Atkinson, David; Sosnovik, David E.; Mekkaoui, Choukri; Kozerke, Sebastian
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
96.22%
Purpose In this work we present a dual-phase diffusion tensor imaging (DTI) technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging. Methods: In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference. Results: The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001) upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°...

Probing dynamic myocardial microstructure with cardiac magnetic resonance diffusion tensor imaging

Axel, Leon; Wedeen, Van J; Ennis, Daniel B
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Outros
EN_US
Relevância na Pesquisa
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This article is an invited editorial comment on the paper entitled “In vivo cardiovascular magnetic resonance diffusion tensor imaging shows evidence of abnormal myocardial laminar orientations and mobility in hypertrophic cardiomyopathy” by Ferreira et al., and published as Journal of Cardiovascular Magnetic Resonance 2014; 16:87.

Towards optimal human magnetic resonance diffusion tensor imaging (DTI) protocols with wild bootstrap analysis

Zhu, Tong (1974 - ); Zhong, Jianhui
Fonte: University of Rochester. Publicador: University of Rochester.
Tipo: Tese de Doutorado Formato: Number of Pages:xxviii, 197 leaves.; Illustrations:ill. (some col.)
ENG
Relevância na Pesquisa
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Thesis (Ph. D.)--University of Rochester. Dept. of Biomedical Engineering, 2009.; Diffusion Tensor Imaging (DTI) depicts tissue morphology via unique patterns of random molecular motions of water inside tissues. DTI-derived parameters have been explored as surrogate biomarkers in a variety of neurological and clinical applications to non-invasively infer underlying anatomical architectures as well as their alterations due to pathological processes of diseases. However, when the DTI technique is applied, imprecision due to measurement uncertainties decreases the sensitivity and the specificity of these DTI-derived parameters as surrogate biomarkers for various applications. The main goal of this dissertation is to apply an optimized wild bootstrap analysis, which is a nonparametric and empirical statistical method, to estimate measurement uncertainties of DTI-derived parameters within each voxel of DTI data of human brain. In contrast to previous analytical approaches, this method does not impose any assumptions about underlying noise distributions and is therefore capable of depicting variations in acquired DTI data containing sources of complex uncertainties in real DTI acquisitions. In this study, evidence collected from real human DTI data of a group of 13 volunteers with an optimized wild bootstrap analysis provides...

Fiber Pathways for Language in the Developing Brain: A Diffusion Tensor Imaging (DTI) Study

Broce, Iris J
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
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The present study characterized two fiber pathways important for language, the superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) and the frontal aslant tract (FAT), and related these tracts to speech, language, and literacy skill in children five to eight years old. We used Diffusion Tensor Imaging (DTI) to characterize the fiber pathways and administered several language assessments. The FAT was identified for the first time in children. Results showed no age-related change in integrity of the FAT, but did show age-related change in the left (but not right) SLF/AF. Moreover, only the integrity of the right FAT was related to phonology but not audiovisual speech perception, articulation, language, or literacy. Both the left and right SLF/AF related to language measures, specifically receptive and expressive language, and language content. These findings are important for understanding the neurobiology of language in the developing brain, and can be incorporated within contemporary dorsal-ventral-motor models for language.

Diffusion tensor imaging (DTI) findings following pediatric non-penetrating TBI: a meta-analysis

Roberts, R.M.; Mathias, J.L.; Rose, S.E.
Fonte: Routledge Publicador: Routledge
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
96.18%
This study meta-analyzed research examining Diffusion Tensor Imaging following pediatric non-penetrating traumatic brain injury to identify the location and extent of white matter changes. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) data from 20 studies were analyzed. FA increased and ADC decreased in most white matter tracts in the short-term (moderate-to-large effects), and FA decreased and ADC increased in the medium- to long-term (moderate-to-very-large effects). Whole brain (short-term), cerebellum and corpus callosum (medium- to long-term) FA values have diagnostic potential, but the impact of age/developmental stage and injury severity on FA/ADC, and the predictive value, is unclear.; R. M. Roberts and J. L. Mathias, S. E. Rose

Visualisierung des motorischen Systems bei Patienten mit Hirntumoren durch kombinierte funktionelle Kernspinresonanz- und Diffusions-Tensor-Bildgebung; Combined diffusion tensor imaging and functional MRI for visualizing the motor system in patients with cerebral tumors

Kunath, Frank
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
96.25%
Einleitung Raumforderungen der Zentralregion stellen für die neurochirurgische Behandlung eine besondere Herausforderung dar. Magnetresonanz- tomographische (MRT) Bildgebungsmodalitäten haben das Potential, als nicht-invasive Hirnkartierungsmethoden zur präoperative Planung und operativen Risikoverminderung beizutragen. Dabei bietet die funktionelle Magnetresonanztomographie (fMRT) wichtige Informationen über die kortikale Funktion, während die Diffusions-Tensor-Magnetresonanztomographie (DTI) die subkortikale Faserbahnarchitektur darstellt. Eine systematische Kombination dieser beiden kernspintomographischen Modalitäten für die neurochirurgische Operationsplanung bei Patienten mit Raumforderungen der Zentralregion steht aus. Methodik Durchführung und Visualisierung von strukturellen, funktionellen und diffusionsgewichteten MRT-Aufnahmen bei Probanden und neurochirurgischen Patienten mit kortikalen und subkortikalen Raumforderungen der Zentralregion. Akquirierung von fMRT-Daten mit motorischen Paradigmen zur Darstellung des primären, motorischen Kortex und von DTI-Daten zur Traktographie des motorischen Faserbahnsystems (Pyramidenbahn). Durchführung einer klassischen Traktographie mittels, vom Untersucher vordefinierter...

A hitchhiker's guide to diffusion tensor imaging

Soares, José Miguel; Marques, Paulo César Gonçalves; Alves, Victor; Sousa, Nuno
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em /03/2013 ENG
Relevância na Pesquisa
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Diffusion Tensor Imaging (DTI) studies are increasingly popular among clinicians and researchers as they provide unique insights into brain network connectivity. However, in order to optimize the use of DTI, several technical and methodological aspects must be factored in. These include decisions on: acquisition protocol, artifact handling, data quality control, reconstruction algorithm, and visualization approaches, and quantitative analysis methodology. Furthermore, the researcher and/or clinician also needs to take into account and decide on the most suited software tool(s) for each stage of the DTI analysis pipeline. Herein, we provide a straightforward hitchhiker's guide, covering all of the workflow's major stages. Ultimately, this guide will help newcomers navigate the most critical roadblocks in the analysis and further encourage the use of DTI.; The work was supported by SwitchBox-FP7-HEALTH-2010-grant 259772-2. The authors acknowledge Nadine Santos for her help in editing the manuscript.

Use of diffusion tensor imaging to assess the impact of normobaric hyperoxia within at-risk pericontusional tissue after traumatic brain injury

Veenith, Tonny V.; Carter, Eleanor L.; Grossac, Julia; Newcombe, Virginia F.; Outtrim, Joanne G.; Nallapareddy, Sridhar; Lupson, Victoria; Correia, Marta M.; Mada, Marius M.; Williams, Guy B.; Menon, David K.; Coles, Jonathan P.
Fonte: NPG Publicador: NPG
Tipo: Article; published version
Relevância na Pesquisa
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This is the final published version of the article. It was originally published by NPG in Journal of Cerebral Blood Flow & Metabolism here: http://www.nature.com/jcbfm/journal/vaop/ncurrent/full/jcbfm2014123a.html.; Ischemia and metabolic dysfunction remain important causes of neuronal loss after head injury, and we have shown that normobaric hyperoxia may rescue such metabolic compromise. This study examines the impact of hyperoxia within injured brain using diffusion tensor imaging (DTI). Fourteen patients underwent DTI at baseline and after 1 hour of 80% oxygen. Using the apparent diffusion coefficient (ADC) we assessed the impact of hyperoxia within contusions and a 1 cm border zone of normal appearing pericontusion, and within a rim of perilesional reduced ADC consistent with cytotoxic edema and metabolic compromise. Seven healthy volunteers underwent imaging at 21%, 60%, and 100% oxygen. In volunteers there was no ADC change with hyperoxia, and contusion and pericontusion ADC values were higher than volunteers (P<0.01). There was no ADC change after hyperoxia within contusion, but an increase within pericontusion (P<0.05). We identified a rim of perilesional cytotoxic edema in 13 patients, and hyperoxia resulted in an ADC increase towards normal (P = 0.02). We demonstrate that hyperoxia may result in benefit within the perilesional rim of cytotoxic edema. Future studies should address whether a longer period of hyperoxia has a favorable impact on the evolution of tissue injury.; RCUK...

Use of diffusion tensor imaging to assess the impact of normobaric hyperoxia within at-risk pericontusional tissue following traumatic brain injury

Veenith, T. V.; Carter, E. L.; Grossac, J.; Newcombe, V. F.; Outtrim, J. G.; Nallapareddy, Sridhar; Lupson, Victoria; Correia, M. M.; Mada, Marius M.; Williams, Guy B.; Menon, David K.; Coles, J. P.
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Article; accepted version
EN
Relevância na Pesquisa
96.18%
This is the final published version, which can also be viewed on the publisher's website at: http://www.nature.com/jcbfm/journal/vaop/ncurrent/full/jcbfm2014123a.html; Ischaemia and metabolic dysfunction remain important causes of neuronal loss following head injury, and we have shown that normobaric hyperoxia may rescue such metabolic compromise. This study examines the impact of hyperoxia within injured brain using diffusion tensor imaging (DTI). Fourteen patients underwent DTI at baseline and following one hour of 80% oxygen. Using the apparent diffusion coefficient (ADC) we assessed the impact of hyperoxia within contusions and a 1 cm border zone of normal appearing pericontusion, and within a rim of perilesional reduced ADC consistent with cytotoxic oedema and metabolic compromise. Seven healthy volunteers underwent imaging at 21%, 60% and 100% oxygen. In volunteers there was no ADC change with hyperoxia, and contusion and pericontusion ADC values were higher than volunteers (p < 0.01). There was no ADC change following hyperoxia within contusion, but an increase within pericontusion (p < 0.05). We identified a rim of perilesional cytotoxic oedema in 13 patients, and hyperoxia resulted in an ADC increase towards normal (p = 0.02). We demonstrate that hyperoxia may result in benefit within the perilesional rim of cytotoxic oedema. Future studies should address whether a longer period of hyperoxia has a favourable impact on the evolution of tissue injury.; Dr TV Veenith was supported by clinical research training fellowship from National institute of Academic Anaesthesia and Raymond Beverly Sackler studentship. VFJN is supported by an NIHR academic clinical fellowship. JPC was supported by Wellcome trust project grant. DKM is supported by an NIHR Senior Investigator Award. This work was supported by a Medical Research Council (UK) Program Grant (Acute brain injury: heterogeneity of mechanisms...

Diffusion Tensor Imaging Biomarkers of Brain Development and Disease

Calabrese, Evan Darcy Cozzens
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014
Relevância na Pesquisa
86.31%

Understanding the structure of the brain has been a major goal of neuroscience research over the past century, driven in part by the understanding that brain structure closely follows function. Normative brain maps, or atlases, can be used to understand normal brain structure, and to identify structural differences resulting from disease. Recently, diffusion tensor magnetic resonance imaging has emerged as a powerful tool for brain atlasing; however, its utility is hindered by image resolution and signal limitations. These limitations can be overcome by imaging fixed ex-vivo specimens stained with MRI contrast agents, a technique known as diffusion tensor magnetic resonance histology (DT-MRH). DT-MRH represents a unique, quantitative tool for mapping the brain with unprecedented structural detail. This technique has engendered a new generation of 3D, digital brain atlases, capable of representing complex dynamic processes such as neurodevelopment. This dissertation explores the use of DT-MRH for quantitative brain atlasing in an animal model and initial work in the human brain.

Chapter 1 describes the advantages of the DT-MRH technique, and the motivations for generating a quantitative atlas of rat postnatal neurodevelopment. The second chapter covers optimization of the DT-MRH hardware and pulse sequence design for imaging the developing rat brain. Chapter 3 details the acquisition and curation of rat neurodevelopmental atlas data. Chapter 4 describes the creation and implementation of an ontology-based segmentation scheme for tracking changes in the developing brain. Chapters 5 and 6 pertain to analyses of volumetric changes and diffusion tensor parameter changes throughout rat postnatal neurodevelopment...

Diffusion Tensor Imaging of Myelin Water

Avram, Alexandru Vlad
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
Relevância na Pesquisa
96.27%

In recent years, the emergence of diffusion tensor imaging (DTI) has provided a unique means via water diffusional characteristics to investigate the white matter integrity in the human brain, and its impact on neuronal functions. However, since the characterization of white matter integrity using DTI often lacks tissue specificity, most research studies report changes in anisotropy that are not explicitly correlated with particular cellular origins. To improve the utility of DTI in translational neuroimaging, it is critical to develop DTI acquisition techniques that are quantitative and tissue specific.

There are, nevertheless, existing methods for tissue specificity. For example, myelin water images can be generated using multiple echo time (TE) or magnetization transfer techniques. These techniques can detect changes in the concentration of myelin associated markers, but not in their spatial organization. Most white matter pathologies however start with early microstructural changes in the myelin sheaths during which the tissue contents remain similar and are thus not differentiable on a conventional MR image. Thus, the ability to construct a diffusion tensor that is myelin specific can have an immediate impact on our better understanding myelin physiology and pathophysiology during brain development.

Unfortunately...

Improved delineation of short cortical association fibers and gray/white matter boundary using whole-brain three-dimensional diffusion tensor imaging at submillimeter spatial resolution.

Song, AW; Chang, HC; Petty, C; Guidon, A; Chen, NK
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Artigo de Revista Científica Formato: 636 - 640
Publicado em /11/2014 ENG
Relevância na Pesquisa
96.24%
Recent emergence of human connectome imaging has led to a high demand on angular and spatial resolutions for diffusion magnetic resonance imaging (MRI). While there have been significant growths in high angular resolution diffusion imaging, the improvement in spatial resolution is still limited due to a number of technical challenges, such as the low signal-to-noise ratio and high motion artifacts. As a result, the benefit of a high spatial resolution in the whole-brain connectome imaging has not been fully evaluated in vivo. In this brief report, the impact of spatial resolution was assessed in a newly acquired whole-brain three-dimensional diffusion tensor imaging data set with an isotropic spatial resolution of 0.85 mm. It was found that the delineation of short cortical association fibers is drastically improved as well as the definition of fiber pathway endings into the gray/white matter boundary-both of which will help construct a more accurate structural map of the human brain connectome.