Radial structure in the preterm cortex; persistence of the preterm phenotype at term equivalent age?

Abstract

Preterm birth increases the risk of perinatal brain injury and is believed to initiate a cascade of processes causing white matter damage resulting in subsequent neurological deficit; neonatal magnetic resonance imaging provides a number of potential biomarkers of this deficit. In this work we unify measures of the cortical folding pattern and of white matter integrity to establish correlation between grey and white matter derived properties. Diffusion weighted MRI has revealed that the cortical grey matter in the extremely preterm period exhibits a strong transient radial organisation suggesting neuronal axons are orientated towards the underlying white matter. This effect is lost during cortical maturation and is considered no longer visible on MRI at term equivalent age. Here we show that, in a group of 19 infants, radial organisation in the cortical grey matter remains detectable at term-equivalent age and that there is a strong anterior-posterior asymmetry. A group of three infants with moderate or severe abnormal white matter abnormality have significantly higher cortical grey matter radial organisation (p < 0.02), higher grey matter FA (p < 0.01) and a lower measure of cortical complexity (p < 0.03) than infants with normal or mild abnormal white matter abnormality; all measures associated with the preterm phenotype before term equivalent age. The novel combination of state-of-the-art imaging techniques, analysing grey-matter based spatial characteristics, may provide insight into the mechanism of neurodevelopmental deficits seen in infants with abnormal MR imaging at term equivalent age.