Diffusion-tensor imaging at 3 T

TY - JOUR

T1 - Diffusion-tensor imaging at 3 T

T2 - detection of white matter alterations in neurological patients on the basis of normal values

AU - Deppe, Michael

AU - Duning, Thomas

AU - Mohammadi, Siawoosh

AU - Schwindt, Wolfram

AU - Kugel, Harald

AU - Knecht, Stefan

AU - Ringelstein, E Bernd

PY - 2007/6/1

Y1 - 2007/6/1

N2 - OBJECTIVE: Fractional anisotropy (FA) is a powerful measure to study the integrity of the cerebral white matter in vivo. However, because clinical FA assessments are frequently based on single slice evaluations, intra- and interindividual comparisons are highly dependent on image alignment. We attempted to develop an observer-independent, fully automated technique for quantitative FA assessment.MATERIALS AND METHODS: We employed whole brain diffusion tensor imaging at 3 T with an echo planar imaging sequence (isotropic spatial resolution 1.8 mm) on 4 patients (2x Alzheimer disease, 1x microangiopathy, 1x paraneoplastic disease) and 2 normal control groups (group "young," age 19-32 years; group "old," age 59-69 years). The images were spatially normalized to the standard brain template of the Montreal Neurologic Institute. We introduced a fractional anisotropy index (FAI) as a single measure for the mean tissue anisotropy in certain brain regions of interest. The regions of interest were defined by masks in relation to the Montreal Neurologic Institute coordinate space. We varied the spatial extent of the masks. Confidence intervals of the FAIs for both control groups were calculated.RESULTS: We found the resulting FAIs to be highly robust against considerable mask variations (product-moment correlation: r > 0.97). The FAIs of the 4 patients presented with neurologic conditions associated with white matter alterations significantly fell outside the confidence intervals for normal FA.CONCLUSION: FAIs based on mean fractional anisotropy values obtained from isotropic whole-head high-field diffusion tensor imaging by fully automated algorithms represent a robust and observer-independent measure for the comparative assessment of white matter integrity, ideally suited for further statistical treatments.

AB - OBJECTIVE: Fractional anisotropy (FA) is a powerful measure to study the integrity of the cerebral white matter in vivo. However, because clinical FA assessments are frequently based on single slice evaluations, intra- and interindividual comparisons are highly dependent on image alignment. We attempted to develop an observer-independent, fully automated technique for quantitative FA assessment.MATERIALS AND METHODS: We employed whole brain diffusion tensor imaging at 3 T with an echo planar imaging sequence (isotropic spatial resolution 1.8 mm) on 4 patients (2x Alzheimer disease, 1x microangiopathy, 1x paraneoplastic disease) and 2 normal control groups (group "young," age 19-32 years; group "old," age 59-69 years). The images were spatially normalized to the standard brain template of the Montreal Neurologic Institute. We introduced a fractional anisotropy index (FAI) as a single measure for the mean tissue anisotropy in certain brain regions of interest. The regions of interest were defined by masks in relation to the Montreal Neurologic Institute coordinate space. We varied the spatial extent of the masks. Confidence intervals of the FAIs for both control groups were calculated.RESULTS: We found the resulting FAIs to be highly robust against considerable mask variations (product-moment correlation: r > 0.97). The FAIs of the 4 patients presented with neurologic conditions associated with white matter alterations significantly fell outside the confidence intervals for normal FA.CONCLUSION: FAIs based on mean fractional anisotropy values obtained from isotropic whole-head high-field diffusion tensor imaging by fully automated algorithms represent a robust and observer-independent measure for the comparative assessment of white matter integrity, ideally suited for further statistical treatments.

KW - Adult

KW - Aged

KW - Aged, 80 and over

KW - Algorithms

KW - Alzheimer Disease

KW - Anisotropy

KW - Brain Mapping

KW - Cerebrovascular Disorders

KW - Diffusion Magnetic Resonance Imaging

KW - Echo-Planar Imaging

KW - Female

KW - Humans

KW - Male

KW - Microcirculation

KW - Middle Aged

KW - Paraneoplastic Syndromes, Nervous System

KW - Reference Values

U2 - 10.1097/01.rli.0000261935.41188.39

DO - 10.1097/01.rli.0000261935.41188.39

M3 - SCORING: Journal article

C2 - 17507803

VL - 42

SP - 338

EP - 345

JO - INVEST RADIOL

JF - INVEST RADIOL

SN - 0020-9996

IS - 6

ER -