Microstructural changes in the white matter tracts of the brain due to mild cognitive impairment

Background Mild cognitive impairment (MCI) is an early stage of memory loss or cognitive decline and progresses to Alzheimer’s disease at a rate of about 15% per year. It is important to study the effects of MCI on the brain. Here we present a novel along‐tract analysis of microstructural brain metrics computed from diffusion MRI. We extract, map, and visualize the profile of microstructural abnormalities on 3D models of fiber tracts, yielding fine‐scale maps of the effects of MCI. Methods We analyzed multi‐shell diffusion‐weighted MRI data with 127 volumes from 131 ADNI3 participants (age: 55‐91years, 74F,57M). Participants included 44 with MCI and 87 cognitively normal controls (CN). Pre‐processed using the ADNI3 dMRI protocol. We applied multi‐shell‐multi‐tissue CSD and a probabilistic particle‐filtering‐tracking to generate whole‐brain tractograms. We applied DIPY’s BUAN tractometry pipeline to extract 30 white matter tracts from all subjects and evaluate the effects of MCI on 4 DTI measures (FA, MD, RD, and AD) along the length of the tracts. BUAN applies Linear‐Mixed‐Models with DTI measures set as the response variable, group mean modeled as fixed effects term, and subject‐specific mean as random effects term. Results We report significant group differences between MCI and CN in 6 bundles with p‐values