Diffusion tensor imaging-based assessment of white matter tracts and visual-motor outcomes in very preterm neonates.

INTRODUCTION: The purpose of this study was to assess the impact of brain injury on white matter development and long-term outcomes in very preterm (VPT) neonates.

METHODS: Eighty-five VPT neonates (born <32/40 weeks gestational age (GA)) scanned within 2 weeks of birth were divided into three groups based on the presence of perinatal cerebral injury: (i) no injury, (ii) mild/moderate injury and (iii) severe injury. Diffusion tensor imaging (DTI) was acquired for each neonate and fractional anisotropy (FA), and diffusivity measures were calculated in the posterior limb of the internal capsule (PLIC) and optic radiation (OR). At 2 and 4 years of age, 41 and 44 children were assessed for motor and visual-motor abilities. Analyses determined the relation between GA and DTI measures, injury groups and DTI measures as well as developmental assessments.

RESULTS: GA was related to all DTI measures within the PLIC bilaterally, FA in the OR bilaterally and AD in the left OR. The severely injured group had significantly different DTI measures in the left PLIC compared to the other two groups, independent of lateralization of lesions. Group differences in the left OR were also found, due to higher incidence of the white matter injury in the left hemisphere. No differences were found between groups and outcome measures at 2 and 4 years, with the exception of destructive periventricular venous haemorrhagic infarction (PVHI).

CONCLUSIONS: DTI measures of the PLIC and OR were affected by injury in VPT neonates. These findings seen shortly after birth did not always translate into long-term motor and visual-motor impairments suggesting compensatory mechanisms.