Visualizing Microstructural Changes in Aging and Cognitive Decline through SANDI Analysis in Ultra-High Gradient Diffusion Imaging

Motivation: Aging and cognitive dysfunction contribute to neurodegeneration, as seen at the macroscopic level in clinical MRI. Higher gradients and sensitivity in diffusion imaging could allow for earlier detection of neurodegeneration on microstructure. Goal(s): This study investigates microstructural alterations associated with aging and cognitive decline through ultra-high gradient dMRI and the SANDI model. Approach: Imaging data was collected in 10 older adults with ranging cognitive scores and 25 younger and middle-aged adults. SANDI microstructure parameters were studied in relation to cognitive scores using ROI analysis. Results: Soma signal fraction appears decreased in older adults, and negatively associated with age and level of cognitive impairment. Impact: This study employs ultra-high gradient diffusion MRI to probe changes in neurite density and soma fraction from aging and cognitive impairment. This approach can elucidate early damage at the microstructural level from aging and neurodegenerative diseases.