Prevalence of MR-visible perivascular spaces increases with age in rhesus macaques.

Motivation: Aging macaques share many features with humans including cognitive impairment, gray matter atrophy, and increased white matter diffusivity, but MR-visible Perivascular Spaces (PVS) are unexplored. Goal(s): Quantify the number and volume of MR-Visible PVS in the white matter of a large population of macaques ranging from early adulthood to advanced old age. Approach: MR-visible PVS were identified using semi-automated strategies applied to high-resolution (0.5mm isotropic) T2-weighted MRI data. Results: We found significant correlations between age and the number of PVS identified, as well as volume. Post-mortem histological characterization from one case study advances our understanding of this radiological finding. Impact: This is the first study to report MR-visible PVS in rhesus macaques, providing a model for investigating underlying mechanisms and potential therapeutic strategies.