490 Characterizing water transfer rate in the young and elderly using diffusion prepared and multi-echo arterial spin labeling MRI

Objectives/Goals: Our study’s overarching goal is to characterize the relationship between water transfer rate (Kw) across the blood–brain barrier (BBB) as measured by diffusion prepared (DP) and multi-echo (ME) ASL in two cohorts that have been shown to have regionally different water transfer rates due to underlying changes in BBB physiology. Methods/Study Population: Ten young, healthy participants (aged 21–30 years, 4f) and 12 elderly participants (aged 66–84 years, 8f) underwent MRI scans on a 3T Siemens Prisma scanner. Structural scans, along with DP and ME ASL, were acquired from each of the participants. The order of the DP and ME ASL sequences was reversed in half the participants to account for ordinal bias. FreeSurfer was used to segment the structural image into respective gray matter, white matter, and deep cortical gray regions to perform region of interest (ROI) analysis. Results/Anticipated Results: We are still in the project’s analysis phase. The anticipated result is that we will see different water transfer rate (Kw) patterns between the old and young groups and between the two sequence groups. Discussion/Significance of Impact: The significance of the results is that we can answer two questions: 1) if there are any differences between water transfer rates in the two age groups and 2) whether there are any variations in performance differences between the sequences.