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Ultrastructural hippocampal and white matter alterations in mild cognitive impairment: a diffusion tensor imaging
Andreas Fellgiebel1, Paulo Wille, Matthias J Müller
1Department of Psychiatry, University of Mainz, Mainz, Germany. fellgiebel@psychiatrie.klinik.uni-mainz.de
Dementia and Geriatric Cognitive Disorders
|April 17, 2004
Summary
Diffusion tensor imaging reveals brain tissue alterations in mild cognitive impairment (MCI) patients, particularly in the hippocampus. This technique helps quantify MCI pathology and distinguish it from normal aging.
Area of Science:
- Neuroimaging
- Neurology
- Medical Physics
Background:
- Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia, often preceding Alzheimer's disease (AD).
- White matter pathology in AD is known, but its presence and extent in MCI as a predictor of progression to AD remain unclear.
- Diffusion tensor imaging (DTI) is a sensitive MRI technique for assessing the ultrastructural integrity of white matter tracts.
Purpose of the Study:
- To investigate white matter alterations in MCI patients using DTI.
- To compare DTI findings in MCI patients with those in AD patients and healthy controls.
- To evaluate DTI's potential as a tool for quantifying MCI pathology and predicting AD progression.
Main Methods:
- Prospective study involving 14 MCI patients, 19 AD patients, and 10 healthy controls.
- Acquisition of conventional and diffusion tensor MRI scans.
- Measurement of mean diffusivity (MD) and fractional anisotropy (FA) in various brain regions, including white matter tracts and the hippocampus.
Main Results:
- MCI patients exhibited higher MD values in the left centrum semiovale, left and right temporal regions, and left hippocampus compared to controls.
- AD patients showed increased MD in several regions, including the left centrum semiovale, left and right parietal, left and right temporal, and left hippocampus.
- Decreased FA was observed in the left temporal area and left hippocampus in AD patients compared to controls; no significant FA differences were found between MCI and controls.
- No significant differences in FA and MD values were detected between MCI and AD patients.
- Elevated MD values in MCI patients were found in regions characteristic of early AD changes, with a sensitivity of 71.4% and specificity of 80% for distinguishing MCI from controls.
Conclusions:
- DTI detects significant white matter alterations in MCI patients, particularly elevated mean diffusivity in the hippocampus.
- These findings suggest that DTI can validate the MCI concept and quantify in vivo pathology.
- Diffusion tensor MRI shows promise as a tool for identifying MCI and potentially predicting its progression to Alzheimer's disease.