Simultaneous 4D CSF flowmetry and BOLD fMRI using EPTI for investigation of neural activity evoked CSF flow responses

Motivation: To investigate brain-wide CSF flow dynamics and how neural activity drives it. Goal(s): Develop a novel tool to simultaneously map CSF flow and T2*-BOLD fMRI with high sensitivity/specificity and effectively measure neural-activity-evoked CSF flow. Approach: Single-shot PGSE-EPTI is developed with high sensitivity to slow flow to acquire distortion-free phase-contrast flow velocity and directions, while simultaneously obtaining clean T2*-BOLD, T2, S0 contrasts with improved specificity. Results: Using the EPTI CSF flowmetry technique, brain-wide CSF dynamics were measured with high spatiotemporal details, and visual-task-evoked CSF flow responses were observed in both ventricles (global-response) and visual cortex subarachnoid space (local-response), synchronized with the simultaneously-acquired T2*-BOLD-fMRI signal. Impact: We developed a novel EPTI CSF-flowmetry technique to simultaneously map whole-brain CSF flow and T2*-BOLD-fMRI with high sensitivity/specificity for investigation of neural-activity-driven CSF flow. It successfully measured both global and local visual-task-evoked CSF flow responses in ventricles and visual-cortex subarachnoid-space.