During the early postnatal period the cerebral cortex undergoes substantial reorganisation. Early changes in environmental factors (e.g. premature birth, socio-economic status) affect the reorganisation of the cerebral cortex.

In order to answer the question of how premature birth affects the cortex, we have analysed T1 MR images (n = 14) of prematurely born children (26–35 GW) at term equivalent age. Furthermore, in order to identify the factors affecting the maturation of the cerebral cortex at school age we have analysed T1 MR images of prematurely born children at school age (n = 42, 6.62 ± 0.48 years). While the segmentation of cerebral tissue in school age children was performed using the automatic method (CIVET), we have developed a new morphology-driven automatic segmentation method for the segmentation of cerebral tissue at term equivalent age. The grey and white matter surface meshes were extracted and regional volumes of the cortex and cortical thickness were estimated. Cortical metrics were calculated using the advanced MR image processing tools developed at MNI.

Mean cortical thickness, from term equivalent age to school age, showed a two-fold increase in prematurely born children. Regional variations of cortical thickness in prematurely born children at term equivalent age and school age indicated that the limbic cortex is the first to thicken while the frontal cortex lags behind. Parents’ socio-economic status showed positive correlation with mean cortical thickness at school age.

In conclusion, this is the first reported analysis of longitudinal changes of cortical thickness from term equivalent age to school age in prematurely born children.