Perivascular space volume measurement at the inferior basal ganglia on cranial ultrasound in neonates: associations with germinal matrix hemorrhage and brain maturation

PURPOSE: The aim of this study was to assess the feasibility of cranial ultrasound (CUS)-based perivascular space (PVS) volume quantification in neonates, evaluate its relationship with magnetic resonance imaging (MRI)-based PVS volume measurements, explore associations with germinal matrix hemorrhage (GMH), and examine longitudinal changes with maturation. METHODS: This retrospective, single-center study included neonates who underwent CUS with PVS volume measurements at term-equivalent age (TEA) between November 2024 and March 2025. Neonates were grouped into those with GMH and controls. Group differences were analyzed and longitudinal changes of CUS-based PVS according to maturation were evaluated using generalized estimating equations in relation to corrected-gestational age (CGA). In neonates with both CUS and MRI at TEA, corresponding PVS volumes were compared using Spearman correlation and Bland-Altman analysis. RESULTS: A total of 89 neonates were included. Among 19 neonates with GMH (10 males, median [IQR], gestational age [GA]: 260 [247 to 269] days) and 70 controls (46 males, GA: 265 [254 to 274] days), those with GMH had larger CUS-based PVS volumes (0.052 [0.041 to 0.065] cm3 vs. 0.041 [0.030 to 0.054] cm3, P=0.024). Longitudinal analysis revealed increasing CUS-based PVS volume with CGA in both GMH (0.26 mm3/day, P=0.020) and control groups (0.17 mm3/day, P=0.026). CUS-based PVS volume correlated with MRI-based PVS volume (r=0.453, P=0.026) and showed good agreement on Bland-Altman analysis. CONCLUSION: CUS-based neonatal PVS volume quantification was feasible, correlated with MRI, reflected GMH-related changes, and increased with maturation. CUS-based PVS volume quantification has the potential to serve as a valuable marker of glymphatic function in neonates.