Generalized <i>q</i>‐sampling imaging‐based fiber tracking measures of white matter tracts in cognitive impairment

Background Diffusion magnetic resonance imaging (dMRI) is a non-invasive technique for exploring white matter fiber organization of the brain. As traditional diffusion tensor (DTI) methods may provide inaccurate descriptions local crossing and diverging fibers, we examined generalized q-sampling (GQI), novel method providing better directional quantitative information using dMRI data from community-dwelling older adults. Method We baseline 227 adults aged 71±8 on average Wake Forest Alzheimer’s Disease Research Center’s Clinical Core, who had year-1 follow-up global Dementia Rating (CDR) score 0 (indicates normal cognitive function) 0.5 (akin to MCI). The primary outcome measure was migration status determined by CDR increase/decrease between (mean difference = 13.9 months), shown in Figure. performed atlas-based tracking analysis GQ DSI Studio generate normalized anisotropy (NQA), DTI fractional (DTI_FA) restricted (RDI) measures several AD-related (WM) tracts: Corpus Callosum (CC), Fornix, Cingulum bundle/Parahippocampal tracts (see Table 2: CFP; CP; CPP), Uncinate Fasciculus (UF), Superior Longitudinal (SLF) Inferior Fronto-Occipital (IFOF). multinomial logistic regression (MLR) models adjusted age, sex, education, as standardized GQI-based indices sNQA, sRDI, sDTI_FA predictors. Result 1 lists demographics biomarker characteristics groups. MLR results 2 show significant associations 4 (Reversion) reference (stability cognition). Decrease sNQA bilateral CP right Fornix significantly associated with higher odds Reversion relative reference. Increase left IFOF reversion sRDI CFP, CPP, UF Conclusion In early trajectories impairment, RDI be sensitive marker WM tracts. Future work will validate these markers other groups (negative MCI stability).