Longitudinal effects of CPAP therapy on MRI-Perivascular spaces in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is a disorder marked by repeated episodes of airway collapse during sleep, leading to hypoxaemia and sympathoexcitation. Its impact on brain fluid transport remains unclear. We investigated MRI-visible perivascular spaces (PVS) in healthy controls (n=20; 5 females, mean{+/-}SD age = 52.1{+/-}9.9 years) and OSA patients (n=20; 3 females, mean{+/-}SD age = 54.6{+/-}9.6 years) before and after continuous positive airway pressure (CPAP) therapy in a longitudinal case-control study. MRI-PVS were automatically quantified using a deep learning model called the nnU-Net. At baseline, OSA patients had significantly greater whole-brain PVS volumes and cluster counts than controls (volume: exp({beta})=1.65, 95%CI [1.07, 2.51], p=0.01; cluster counts: exp({beta})=1.51, 95%CI [1.1, 2.04], p=0.01). However, after 12 months of CPAP, these differences were no longer significant (volume: exp({beta})=1.56, 95%CI [1.03, 2.39], p=0.054; cluster counts: exp({beta})=1.39, 95%CI [0.97, 1.92], p=0.072). Similarly, PVS metrics were significantly greater in OSA patients than controls at baseline in the frontal (volume: exp({beta})=1.66, 95%CI [1.02, 2.64], p=0.04; cluster counts: exp({beta})=1.46, 95%CI [1.02, 2.08], p=0.04) and temporal lobe (volume: exp({beta})=1.92, 95%CI [1.2, 3.03], p=0.01; cluster counts: exp({beta})=1.68, 95%CI [1.1, 2.55], p=0.02). After 12 months of CPAP, PVS metrics remained significantly higher in the OSA patients compared to controls in the frontal (volume: exp({beta})=1.68, 95%CI [0.94, 2.87], p=0.085; cluster counts: exp({beta})=1.4, 95%CI [0.92, 2.05], p=0.12) and temporal lobes (volume: exp({beta})=1.54, 95%CI [0.94, 2.38], p=0.085; cluster counts: exp({beta})=1.44, 95%CI [0.95, 2.12], p=0.089). These findings suggest that OSA is associated with PVS enlargement, which may be regionally reversible with CPAP treatment.