Utility of Cranial Ultrasound to Investigate Brain Injury in Hypoxic-Ischemic Encephalopathy

Background: With increasing availability of brain magnetic resonance imaging (MRI) in high-income countries, cranial ultrasound (cUS) is used less frequently to evaluate infants with hypoxic-ischemic encephalopathy (HIE). This study aimed to correlate findings of brain injury on early postnatal cUS with brain injury on neonatal brain MRI performed as part of routine clinical care for near-term and term infants with moderate to severe HIE.

Methods: This was a retrospective cohort study comparing early postnatal cUS and later neonatal brain MRI using scoring systems with prognostic validity to assess brain injury in near-term/term infants with moderate or severe HIE. Infants were born between 2010 and 2021 and were treated at a single tertiary neonatal intensive care unit.

Results: A total of 94 infants were included in this study. cUS was performed in the first five days after birth and brain MRI at a median of 6.7 days (interquartile range 5.4, 7.9). Findings of white matter injury on cUS <24 hours and gray matter injury on cUS >48 hours correlated with similar nature and severity of brain injury on brain MRI. Subgroup analyses of cUS performed <24 and >48 hours and contemporaneous brain MRI performed on days 3 to 5 provided stronger evidence for correlations of brain injury between neuroimaging modalities.

Conclusion: This study provides evidence for the correlation of findings of brain injury between cUS and brain MRI. Early postnatal cUS can provide information on potential findings on brain MRI and may help inform outcome of newborns in low-middle income countries and situations where MRI is not clinically possible.