Post-hemorrhagic ventricular dilatation affects white matter maturation in extremely preterm infants.

BACKGROUND: Data on microstructural white matter integrity in preterm infants with post-hemorrhagic ventricular dilatation (PHVD) using diffusion tensor imaging (DTI) are limited. Also, to date, no study has focused on the DTI changes in extremely preterm (EP) infants with PHVD. METHODS: A case-control study of EP infants <28 weeks' gestation with PHVD was conducted. Diffusivity and fractional anisotropy (FA) values of corticospinal tracts (CST) and corpus callosum (CC) were measured using DTI at term-equivalent age. Outcomes were assessed at 2-years-corrected age. RESULTS: Twenty-one infants with PHVD and 21 matched-controls were assessed. FA values in the CC were lower in infants with PHVD compared with controls (mean difference, 0.05 [95% confidence interval (CI), 0.02-0.08], p < 0.001). In infants with periventricular hemorrhagic infarction, FA values in the CC were lower than in controls (mean difference, 0.05 [95% CI, 0.02-0.09], p = 0.005). The composite cognitive and motor scores were associated with the FA value of the CC (coefficient 114, p = 0.01 and coefficient 147, p = 0.004; respectively). CONCLUSIONS: Extremely preterm infants with PHVD showed lower FA values in CC. A positive correlation was also shown between the composite cognitive and motor scores and FA value of the CC at 2-years-corrected age. IMPACT: Extremely preterm infants with post-hemorrhagic ventricular dilatation showed lower fractional anisotropy values in their corpus callosum compared with controls reflecting the impaired microstructure of these commissural nerve fibers that are adjacent to the dilated ventricles. Impaired microstructure of the corpus callosum was shown to be associated with cognitive and motor scores at 2-years-corrected age.

Cerebral Blood Flow Measured by Phase-Contrast Magnetic Resonance Angiography in Preterm and Term Neonates.

BACKGROUND: Preterm infants show a decreased tortuosity in all proximal segments of the cerebral vasculature at term-equivalent age (TEA). Recently MRI techniques were developed to measure cerebral blood flow (CBF) based on phase-contrast images. OBJECTIVES: We hypothesized that arterial CBF corrected for brain size differs between full-term and preterm infants at TEA. METHODS: 344 infants without major brain abnormalities had a cranial MRI for clinical reasons including phase-contrast magnetic resonance angiography (PC-MRA) around TEA (mean 41.1 ± SD 1.2 weeks). This cohort consisted of 172 preterm infants (gestational age at birth 24.1-31.9 weeks) and 172 term-born infants (gestational age at birth 37.0-42.6 weeks). The total CBF in milliliters/minute was calculated by adding the blood flow of the carotid and basilar arteries, and compared to age at scan, body weight, and several parameters of estimated brain size. RESULTS: After logarithmic transformation, total CBF was associated with body weight, estimated brain weight, head circumference, and 2D brain surface measurements at TEA. Total CBF was significantly (9-12%) higher in term compared to preterm infants after correction for 2D brain surface measurements, head circumference or postmenstrual age at MRI (p < 0.05). CONCLUSIONS: Total CBF as measured by PC-MRA was associated with body and (estimated) brain weight and 2D brain surface measurements and was higher in term compared to preterm born infants.