Dynamic measurement of concurrent BOLD and brain tissue displacement quantification in vivo at 7T using motion-encoded stimulated-echo EPI

Motivation: Understanding the spatiotemporal relationships between blood volume changes, tissue displacement, and CSF flow is important for elucidating brain waste clearance mechanisms, and measuring these compartments concurrently would enable effective analysis. Goal(s): To demonstrate the feasibility of leveraging both magnitude-valued and phase-valued data to measure BOLD fMRI and tissue motion simultaneously. Approach: We apply a combination of computer simulations and in vivo imaging with visual stimulation using the Displacement Encoding with Stimulated Echoes (DENSE) pulse sequence. Results: DENSE magnitude-valued data show significant response to visual stimulation in the visual cortex, while the phase-valued data show typical cardiac-gated motion in both cortex and brainstem. Impact: BOLD fMRI can be acquired simultaneously with brain tissue displacement quantification using the DENSE pulse sequence, enabling future spatiotemporal analyses of concurrent blood volume changes, tissue displacement, and CSF flow for understanding waste clearance mechanisms.