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.