Diffusion tensor imaging in mild cognitive impairment and Alzheimer's disease: a review

Purpose of review To provide a comprehensive review of diffusion tensor imaging in evaluating microstructural changes in the spectrum of cognitive decline from ageing to Alzheimer's disease, in particular focusing on mild cognitive impairment. Recent findings Mild cognitive impairment represents a transition phase between normal ageing and early Alzheimer's disease. Diffusion tensor imaging has emerged as a useful imaging modality that provides information about the structural integrity of tissue. In healthy ageing, diffusion tensor imaging abnormalities occur in the frontal regions, specifically the frontal white matter, anterior cingulum and the genu of the corpus callosum. Some studies report an anterior-posterior gradient change with greater abnormalities in the genu than the splenium of the corpus callosum and in the frontal than parietal white matter. In Alzheimer's disease, diffusion tensor imaging abnormalities are concentrated in the posterior regions: the parahippocampal gyrus, temporal white matter, splenium of corpus callosum and posterior cingulum. In mild cognitive impairment, changes seem to parallel those in Alzheimer's disease, with similar posterior regions showing abnormalities. Summary Due to the similarities in diffusion tensor imaging findings in both mild cognitive impairment and Alzheimer's disease, it is likely that diffusion tensor imaging has the potential to emerge as a useful clinical tool for early detection and monitoring of disease progression and treatment response in mild cognitive impairment/Alzheimer's disease patients.