221 Neonatal Cranial Ultrasound Compared with Conventional MRI at School Age in Preterm Born Children, Related to Neurodevelopmental Outcome

Abstract

Background: Cranial ultrasound (US) is the method of first choice to detect brain injury in preterm born infants. Recently Magnetic Resonance Imaging (MRI) has become available. Correlation between US and MRI is excellent for haemorrhages but poor for subtle white matter injury.Aim: To compare neonatal cranial US with MRI at school age, both related to outcome.Patients and methods: 221 (78.1%) out of 283 eligible children (GA< 32 weeks (mean 29.4 wks) and/or BW < 1500 grams (mean 1197 gr)) had a neonatal cranial US and an MRI at school age. Neonatal US findings were classified into group 1 (normal US), group 2 (Intraventricular Haemorrhage (IVH) grade 1/2, periventricular leukomalacia (PVL) grade 1, germinal layer necrosis) and group 3 (IVH grade 3/4, cystic PVL grade 2/3, thalamic lesions, focal infarction). MRIs were classified into group 1 (normal MRI ), group 2 (mild gliosis i.e. less than 5 small (2mm) areas of hyperintensity, mild ventricular dilatation (VD), thinning of corpus callosum) and group 3 (extensive gliosis, marked VD, thalamic lesions, cerebellar or cortical atrophy). IQ was estimated by 5 subtests of the WISC-R and motor function was assessed with the Movement ABC.Results: Of the 96 children in US group 1: 45 (47%) were in MRI group 1, 50 (52%) in MRI group 2 and 1 (1%) was in MRI group 3. Of the 90 children with a mildly abnormal US (group 2): 40 (44%) were in MRI group 1, 46 (51%) in MRI group 2 and 4 (4%) in MRI group 3. Of the 35 children with severe US abnormalities (group 3): 2 (6%) had a normal MRI, 8 (23%) were in MRI group 2 and 25 (71%) had a severely abnormal MRI (group 3). The predictive value of a normal US for a normal or mildly abnormal MRI was 99% (95% CI: 94–100%). The predictive value of a severely abnormal US for a severely abnormal MRI was 71% (95% CI: 54–85%). Mean IQ in US group 1 was not different from mean IQ in US group 2 (p=0.34), but higher than in US group 3 (p=0.02). Mean IQ in MRI group 1 was higher than in MRI group 2 (p=0.026) and in MRI group 3 (p=0.0001). Median Movement ABC scores in US group 1 were similar compared with US group 2 (p=0.59) but better compared with US group 3 (p=0.0001). For MRI median Movement ABC scores were better in MRI group 1 compared with MRI group 2 and MRI group 3 (p=0.0001 each).Conclusions: A normal cranial US almost guaranteed a normal or mildly abnormal MRI. MRI subgroups differentiated better for neurodevelopmental outcome than US subgroups.