Affiliations: Department of Neurology, Medical University of Graz, Graz, Austria
Correspondence:
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Correspondence to: Dr. Reinhold Schmidt, Department of Neurology, Medical University Graz, Division of Neurogeriatrics, Auenbruggerplatz 22, 8036 Graz, Austria. Tel.: +43 316 385 83397; Fax: +43 316 385 14178; E-mail: reinhold.schmidt@medunigraz.at.
Abstract: Magnetization-transfer imaging (MTI), a magnetic resonance imaging acquisition protocol, can detect microstructural brain tissue changes by assessing the magnetization exchange between tissue water and protons bound to macromolecules. This short literature review summarizes results of previous MTI studies in normal aging, cerebral small vessel disease, and Alzheimer's disease (AD). During normal aging, the magnetization transfer ratio (MTR), a measure for the magnitude of magnetization transfer between macromolecular and water protons, declines in normal appearing brain tissue and associations between lower MTR and executive dysfunction have been described. In AD, MTR changes follow a disease-specific temporo-parietal pattern, independent of cortical atrophy. The differential diagnostic contribution beyond atrophy seems to be modest and the independent effect of MTR alterations as predictors of conversion from mild cognitive impairment to AD needs to be explored. MTR correlates well with global cognitive measures like the Mini-Mental State Examination, and MTR decreases rapidly over time in AD. Longitudinal studies are needed to determine the clinical relevance of global and regional MTI measures in normal aging and neurodegenerative disease. Moreover, correlative MTI-histopathologic postmortem studies are warranted to determine the full spectrum of tissue destruction underlying MTR lowering apart from demyelination.
Keywords: Aging, Alzheimer's disease, dementia, magnetic resonance imaging, magnetization transfer contrast imaging, mild cognitive impairment, vascular dementia
