Diffusion tensor imaging for Alzheimer's disease: A review of concepts and potential clinical applicability

Abstract

In view of the urgent need to identify an early and specific biomarker for Alzheimer’s disease (AD), a PubMed database search was performed using the terms “Alzheimer disease” and “Diffusion Magnetic Resonance Imaging” to enable review of Diffusion tensor imaging (DTI) concepts and its potential clinical role in AD evaluation. Detailed analysis of selected abstracts showed that the main DTI measures, fractional anisotropy and apparent diffusion coefficient, indicators of fiber tract integrity, provide a direct assessment of WM fibers and may be used as a new biomarker for AD. These findings were found to correlate with cognitive assessments, rates of AD progression and were also able to differentiate among groups including mild cognitive impairment, AD, and other dementias. Despite several consistent DTI findings in AD patients, there is still a lack of knowledge and studies on the DTI field. DTI is not yet ready for clinical use, and requires extensive further research in order to achieve this goal.

Changes of Myelin Organization in Patients with Alzheimer’s Disease Shown by q-Space Myelin Map Imaging

“…Further, diffusion tensor imaging and magnetic transfer imaging (MTI) studies can quantify white matter microstructural changes which are believed to reflect mostly ischemic demyelination, axonal loss, and gliosis. Investigations using diffusion tensor imaging showed AD-related changes in temporal areas, parietal areas, frontal areas, the corpus callosum, cingulate gyrus/cingulate fiber tracts, uncinate fasciculus, inferior longitudinal fasciculus/superior longitudinal fasciculus fiber pathways, hippocampus, thalamus, basal ganglia, and internal capsule (for a review, see [12]). A study using MTI revealed a decrease in the bilateral magnetization transfer ratio of AD patients in the temporal, cingulate, parietal, and prefrontal white matter regions, and these results indicated a widespread decrease of white matter myelination in AD [13].…”

Assessment of regional MR diffusion changes in dementia with Lewy bodies and Alzheimer's disease

“…There have been a number of diffusion imaging studies in AD (Vasconcelos et al ., 2009), the majority of which have compared AD and similar aged controls or with subjects with mild cognitive impairment. The most consistent findings are that posterior brain regions seem to be more affected than anterior regions during the early stages of AD, then, as the disease progresses, the limbic and frontal structures also become involved followed lastly by the primary sensorimotor regions, which have been shown to correlate with the clinical manifestations of the disease (Medina and Gaviria, 2008).…”

Alterations and Associations Between Magnetic Susceptibility of the Basal Ganglia and Diffusion Properties in Alzheimer’s Disease

“…Our findings are consistent with the findings of previous studies; both found that the FA values of patients with AD are reduced ( Naggara et al, 2006 ; Ukmar et al, 2008 ; Liu et al, 2011 ; Brueggen et al, 2019 ). Past studies have also shown that cognitive function is associated with diffusion indexes ( Vasconcelos et al, 2009 ; Ling et al, 2011 ; Mayo et al, 2019 ), suggesting that white matter damage adversely affects cognitive function. FA reflects the dispersion direction of the white matter, the regular and organized white matter has higher FA values, and if the structure of the white matter becomes disordered, FA values will decrease.…”