Arterial Spin Labeling fMRI in White Matter at 7 Tesla

To date, the White Matter (WM) tracts functionality is never directly assessed using fMRI, but only inferred indirectly via healthy/impaired cortical connectivity. In this study, we use Arterial Spin Labeling (ASL), a non-invasive, quantitative, reproducible fMRI technique, to investigate WM Cerebral Blood Flow (CBF) dynamics at high field. We first show that WM CBF can be measured using standard 2D-EPI-PASL at 7T; and quantify CBF changes in GM and WM during finger-tapping. While the BOLD signal was only found elevated in GM, a net CBF increase was observed in GM and contralateral (but not ipsilateral) WM during the task (+77/25%).