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Cognitive ageing and white matter integrity: a diffusion tensor and magnetisation transfer MRI study

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Original languageEnglish
Title of host publicationProceedings of the ISMRM, 13th Scientific Meeting Exhibition, Miami, USA
Publication statusPublished - 2005

Abstract

Retaining the integrity of the brain’s white matter might be important for successful cognitive ageing [1]. There are associations between the number of white matter lesions (e.g. Fazekas scores) and cognitive test scores [2]. Diffusion tensor MRI (DT-MRI) can provide more sensitive indicators of the state of cerebral white matter. Mean diffusivity () and fractional anisotropy (FA) are found to correlate significantly with cognitive ability in old age, especially with tests of executive function [3]. On the other hand, one study suggested that DT- MRI parameters correlate with life-long cognitive traits rather than cognitive ability in old age specifically [4]. Here we test the hypothesis that white matter integrity as measured by DT-MRI and magnetisation transfer MRI (MT-MRI) is related to cognitive ability in youth and old age [5]. In MT-MRI, a saturation pulse is used to selectively saturate the bound proton pool, giving rise to contrast that reflects differences in the resonant properties of free and bound protons. The magnetisation transfer ratio (MTR) , which expresses the magnitude of this effect, therefore reflects the amount and nature of macromolecular structures in a given brain volume, and can indicate white matter structural damage resulting from myelin loss. DT-MRI and MT-MRI are therefore complementary imaging modalities in that they provide measures of white matter tract integrity.

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