Alteration of Water Exchange Rates Following Focused ultrasound-Mediated BBB Opening in the Dorsal Striatum: A Diffusion-Prepared pCASL Study

Motivation: Focused ultrasound (FUS) enables temporary blood-brain barrier (BBB) opening, supporting targeted drug delivery and brain modulation. Safer, contrast-free imaging methods are needed to confirm BBB opening without gadolinium-based agents, which carry health risks. Goal(s): This study investigates water as an endogenous tracer to confirm FUS-induced BBB opening, minimizing the need for contrast agents. Approach: We assessed changes in water permeability using a diffusion-prepared arterial spin labeling (DP-pCASL) MRI technique in non-human primates, comparing perfusion and water exchange rates before and after FUS-induced BBB opening. Results: FUS-induced BBB opening significantly reduced water exchange rates, supporting DP-pCASL as a non-contrast method for detection. Impact: This study evaluated a non-contrast MRI method to assess focused ultrasound-induced BBB opening, providing a safer alternative to gadolinium-based agents for monitoring BBB permeability changes and supporting clinical advances in FUS-mediated drug delivery and neuromodulation.