Aging Effect on Cerebral Microvascular Volumetric Pulsatility Revealed by High-Resolution 4D CBV and ASL MRI at 7T

Motivation: Microvascular pulsation is crucial for glymphatic system and may influence neuronal activity. It remains challenging to measure microvascular pulsatility using noninvasive imaging technology. Goal(s): This study aims to develop a new method to quantify cerebral microvascular volumetric pulsatility index (mvPI) and investigate its changes with age. Approach: Using 7T high-resolution 4D-VASO and ASL MRI, we measured mvPI across cortical-laminae and white matter. Results: mvPI was highest in CSF at the cortical surface, which decreased towards the cortical layers as well as in larger arteries. In the deep WM, a significantly increased mvPI was observed in older compared to younger. Impact: Our method offers the first in vivo measurement of microvascular volumetric pulsatility in human brain which has implications for cerebral microvascular health and its relationship research with glymphatic system, aging and neurodegenerative diseases.