Mild brain lesions do not affect brain volumes in moderate-late preterm infants

It is unknown whether frequently occurring mild brain lesions affect brain volumes in moderate (MP²; 32⁺⁰-33⁺⁶ weeks' gestation) and late (LP³; 34⁺⁰-35⁺⁶ weeks' gestation) preterm infants. Therefore, we aimed to investigate the effect of mild brain lesions on brain volumes in moderate-late preterm (MLPT⁴) infants and to compare brain volumes between MP and LP infants.

From August 2017 to November 2019, eligible MLPT infants born at Isala Women and Children's Hospital were enrolled in a prospective cohort study (Brain Imaging in Moderate-late Preterm infants 'BIMP-study'). MRI was performed around term equivalent age (TEA⁵). MRI scans were assessed for (mild) brain lesions. T2-weighted images were used for automatic segmentation of eight brain structures. Linear regression analysis was performed to compare absolute and relative brain volumes between infants with and without mild brain lesions and between MP and LP infants.

36 MP and 68 LP infants were included. In infants with mild brain lesions, intracranial volume (B = 27.4 cm³, p = 0.02), cerebrospinal fluid (B = 8.78 cm³, p = 0.01) and cerebellar volumes (B = 1.70 cm³, p = 0.03) were significantly larger compared to infants without mild brain lesions. After correction for weight and postmenstrual age at MRI, these volumes were no longer significantly different. LP infants had larger brain volumes than MP infants, but differences were not significant. Relative brain volumes showed no significant differences in both analyses.

Neither having mild brain lesions, nor being born moderate prematurely affected brain volumes at TEA in MLPT infants.