Role of Diffusion Tensor Imaging as an Independent Predictor of Cognitive and Language Development in Extremely Low-Birth-Weight Infants

BACKGROUND AND PURPOSE: Diffusion tensor imaging at term can predict later development of cerebral palsy. Less is known about its ability to independently predict cognitive and language development in extremely preterm infants. The goals of the study were to investigate the following: 1) whether regional DTI measures at term-equivalent age in extremely low-birth-weight infants (birth weight, ≤1000 g) are predictive of Bayley III developmental scores at 18- to 22-months' corrected age, and 2) to compare white matter microstructural development at term and neurodevelopmental outcomes of extremely low-birth-weight infants with healthy term controls.

MATERIALS AND METHODS: Fractional anisotropy and mean diffusivity in 7 vulnerable cerebral regions were measured in 42 extremely low-birth-weight and 16 term infants with high-quality DTI scans. The Bayley mental scale score (average of cognitive and language scale scores) was the primary outcome of interest with individual scores serving as secondary outcomes. Multiple linear regression modeling was used to identify the incremental ability of DTI measures to predict Bayley scores over known predictors.

RESULTS: Compared with healthy term infants, extremely low-birth-weight infants exhibited significantly higher mean diffusivity and lower fractional anisotropy in 6 of 7 regions. At 18- to 22-months' corrected age, 39 extremely low-birth-weight infants (93%) and 14 term infants (88%) had undergone neurodevelopmental assessments. Although not statistically significant, extremely low-birth-weight infants averaged 7–9 points lower on Bayley subtests than term controls. In multivariable analyses, centrum semiovale mean diffusivity was a significant predictor of mental and language scale scores, and subventricular zone fractional anisotropy was a significant predictor of cognitive scale scores. A 10% increase in centrum semiovale mean diffusivity was associated with a 4.6 (95% CI, 1.6–7.6) point lower mental scale score (adjusted R² = 0.341, P = .001).

CONCLUSIONS: In our extremely low-birth-weight cohort, DTI was an independent predictor of later cognitive and language development.