Magnetic resonance imaging versus ultrasound at early post-term age in brain imaging of preterm infants

Objective: To compare the incidence of brain lesions detected on cranial ultrasonography (US) and magnetic resonance imaging (MRI) at early post-term age in a group of preterm infants. Subjects and methods: In this prospective study, entry criteria were very preterm infants with birth weight ≤1250 g or gestational age ≤30 weeks, or brain lesions on early US scan. 73 neonates were included in the study. All infants underwent sequential cranial US scans and an US and MRI scan at early post-term age. Results: Abnormal US and MR findings were detected in 53.4% and 84.9% of neonates respectively. US underestimated the diffuse white matter damage shown in 6.9% and on MRI in 26.4% of neonates, the increase of the subarachnoid space shown on US in 19.2% and on MRI in 43.1% of neonates and thinning of the corpus callosum detected on US in only 5.5% and on MRI in 27.4% of neonates. MRI was the only method to detect abnormalities in the posterior fossa, basal ganglia, cortex and the posterior limb of the internal capsule. US detected with high sensitivity the presence of cystic periventricular leukomalacia, ventricular enlargement, persistent germinal matrix/intraventricular hemorrhage and porencephalic cyst as a result of periventricular hemorrhagic infraction. Conclusion: MRI offers more complete visualization of brain lesions in preterm neonates and is more informative in regard to diagnosis. Follow up assessment of these neonates is needed to show the relationship to neurodevelopment outcome.