Motivation: Sleep affects vascular health and brain waste clearance. Sleep disorders, including obstructive sleep apnoea (OSA), are associated with higher small vessel disease (SVD) burden increasing stroke/dementia risk. OSA treatment relies on continuous positive airway pressure (CPAP). Goal(s): We aimed to assess the effect of CPAP on MRI-based blood pulsatility index (PI) measures and associations with SVD burden. Approach: We assessed arterial/venous PI using phase-contrast MRI in patients with moderate/severe OSA before and after 4 months CPAP. Results: Arterial PI tended lower post-CPAP, consistent with better vascular health. Post-CPAP patients with higher venous PI had less severe basal ganglia perivascular space burden. Impact: Few studies have investigated MRI-based blood pulsatility index (PI) in obstructive sleep apnoea (OSA). We found effective treatment may improve brain vascular health, altering blood PI. Higher venous PI post-treatment may link to brain waste clearance, but requires further study.
