Altered microstructure of white matter except the corpus callosum is independent of prematurity

Background: Diffusion tensor imaging (DTI) reflects the maturation of the brain microstructure. Although preterm infants are at significant risk for altered brain microstructure, it remains unclear whether this is affected by prematurity itself or other clinical factors. Objectives: To investigate DTI parameters in preterm infants at a term-equivalent age (TEA) compared with healthy term infants and to assess the associations between DTI parameters and clinical factors that may affect brain development. Methods: We studied 34 preterm infants without apparent brain lesions and 12 healthy term infants using tract-based spatial statistics. Region-of-interest analysis was performed in the posterior and anterior limbs of the internal capsule (PLIC and ALIC), corpus callosum (CC), optic radiation, and cerebral peduncle. Results: Preterm infants had significantly decreased fractional anisotropy (FA) in nearly the entire white matter (WM) compared with term infants (p < 0.01). Multiple regression analysis showed that FA in the PLIC, ALIC, optic radiation, and cerebral peduncle were positively associated with postmenstrual age (PMA) at imaging and that the apparent diffusion coefficient was negatively associated with PMA. Only FA in the CC was positively correlated with gestational age. Chronic lung disease (CLD) and postnatal infection were associated with decreased FA in the CC and PLIC, respectively. Conclusions: Preterm infants at TEA showed an altered microstructure of the WM compared with healthy term infants. The altered microstructure of the measured WM except the CC was independent of the degree of prematurity. Chronic lung disease and postnatal infection are related to localized WM alterations.