Gestational Age‐Specific Reference Ranges for Multimodal Cranial Ultrasound Parameters of Brain Parenchyma in Neonates: A Retrospective Cross‐Sectional Study

ABSTRACT Background Cranial ultrasound (cUS) is the first‐line neonatal neuroimaging modality; however, quantitative gestational age (GA)‐specific reference ranges for multimodal brain parenchyma parameters remain undefined. Objective To establish GA‐stratified reference values for structural, hemodynamic, elastographic, volumetric, and microvascular cUS parameters in neonates without major cerebral or systemic abnormalities. Methods This retrospective cross‐sectional study enrolled 100 neonates without major cerebral or systemic abnormalities (GA 24–42 weeks) across four groups ( n = 25 each). Nine parameters were assessed within 24–72 h using an Aloka Symphony 70: lateral ventricle width, grayscale echogenicity in the periventricular white matter, middle cerebral artery (MCA) peak systolic velocity (PSV), resistive index (RI), and pulsatility index (PI), periventricular white matter and basal ganglia Young's modulus, ventricle‐to‐parenchyma volume ratio (VV/PV), and microvascular density (MVD). Results All nine parameters showed significant GA‐dependent variation ( p < 0.001). Strongest positive correlations with GA were observed for white matter stiffness ( r = 0.912) and MVD ( r = 0.896); strongest negative correlations for VV/PV ( r = −0.790) and RI ( r = −0.738). White matter stiffness increased from 2.89 to 7.96 kPa; MVD nearly tripled. Centile tables (P5–P95) were generated for all parameters. Conclusions This study provides the first comprehensive multimodal GA‐specific reference ranges for neonatal brain parenchyma, potentially facilitating early detection of maturational deviations in clinical neurosonography.