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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Regionally-specific diffusion tensor imaging in mild cognitive impairment and Alzheimer's disease
M M Mielke1, N A Kozauer, K C G Chan
1Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA. mmielke1@jhmi.edu
Neuroimage
|May 22, 2009
Summary
Diffusion tensor imaging reveals decreased fractional anisotropy (FA) in specific brain fiber tracts in Alzheimer's disease (AD) patients compared to normal controls and mild cognitive impairment. This FA measure remains stable over short periods.
Area of Science:
- Neuroimaging
- Neurology
- Biomedical Engineering
Background:
- Diffusion tensor imaging (DTI) has identified cross-sectional differences in brain fiber tracts between normal controls (NC), mild cognitive impairment (MCI), and Alzheimer's disease (AD) patients.
- Longitudinal assessment of these DTI-derived measures is needed to understand disease progression.
Purpose of the Study:
- To investigate longitudinal changes in fractional anisotropy (FA) within specific brain regions in individuals across the spectrum of cognitive function, from NC to mild AD.
- To assess the stability of FA measures over a 3-month period in these groups.
Main Methods:
- Seventy-five participants (25 NC, 25 MCI, 25 mild AD) underwent DTI and clinical evaluations at baseline and 3 months.
- Fractional anisotropy (FA) was analyzed in regions of interest including the fornix, cingulum bundle, splenium, and cerebral peduncles.
- Generalized estimating equations (GEE) were used for cross-sectional and longitudinal analyses of FA and clinical data.
Main Results:
- Alzheimer's disease (AD) patients exhibited lower FA than normal controls (NC) in the fornix and anterior cingulum bundle at both baseline and 3 months.
- AD patients showed lower FA compared to mild cognitive impairment (MCI) in the fornix, anterior cingulum bundle, and splenium.
- Lower FA in the fornix and anterior cingulum correlated with poorer cognitive performance across all participants.
Conclusions:
- Fractional anisotropy (FA) is decreased in specific fiber tracts in individuals with cognitive decline, indicating its utility in differentiating between normal cognition, MCI, and AD.
- FA measures in these key brain regions are stable over short (3-month) periods in clinically stable individuals.
- The fornix, a critical hippocampal outflow tract, may serve as a significant imaging biomarker for Alzheimer's disease progression.
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