Quantitative T2 of Long Post-Labeling-Delay (PLD) ASL Signal as a Reporter of Extravascular Microenvironment

Motivation: Quantitative T2 values of ASL spins may then inform their local microenvironment. Goal(s): In this study, we aim to conduct a technical development to demonstrate the feasibility of measuring ASL T2 at long post-labeling-delay (PLD), at a time when the spins have fully exited the vasculature. Approach: A protocol comprised of Pseudo-Continuous Arterial Spin Labeling (PCASL) module followed by optimized background suppression pulses and 2D multiple-spin-echo (MSE) EPI readout was used to collect T2-weighted images at different post labeling delay (PLD). Results: We estimated T2 of ASL difference signals at long PLDs and also find age related changes in T2 values. Impact: Our result suggests that ASL spins may be used as a reporting probe to assessment the microvascular environment of the brain in health and diseases.