Age-related grey matter changes in preterm infants: an MRI study

Grey matter (GM) maturation has not been previously studied in healthy preterm children. The purpose of this study was to evaluate the age dependency of GM development in 116 GM areas in preterm subjects. Sixty one preterm infants (corrected age: 13.7+/-9.92 months, gestational age: 33.4+/-1.9 weeks) with normal structural appearance on MRI were included in the study. Using a T1-weighted high resolution 3D spoiled gradient echo sequence, volumes of 116 GM areas were calculated after their segmentation using the Voxel Based Morphometry Toolboxes and the Individual Brain Atlas Statistical Parametric Mapping (IBASPM) software packages. Non linear regression analysis assessed age dependency of volume data for every GM area using the monoexponential function y=A-Bexp(-x/C). All supratentorial GM areas followed the monoexponential function model reasonably well. Cerebellar structures had a poor goodness of fit. Volume increase of the individual GM areas followed an inferior to superior and a posterior to anterior pattern. The putamen, thalamus, and caudate nucleus reached 99% of the final volume earlier than most cortical GM areas. The visual cortex and the postcentral and precentral cortices matured earlier than the parietal, frontal and temporal cortices. The fronto-occipital asymmetry or torque seen in adults was observed in the preterm infants; the left occipital areas reached maturation earlier than the right, while the right prefrontal and frontal areas matured earlier than the left. To conclude, GM development progresses in a region-specific manner coinciding with functional, phylogenetical and regional white matter (WM) maturation.