Diffusion tensor brain imaging findings at term-equivalent age may predict neurologic abnormalities in low birth weight preterm infants

Abstract

Background and purpose: Low birth weight preterm infants are at high risk of brain injury, particularly injury to the white matter. Diffusion tensor imaging is thought to be more sensitive than conventional MR imaging for detecting subtle white matter abnormalities. The objective of this study was to examine whether diffusion tensor imaging could detect abnormalities that may be associated with later neurologic abnormalities in infants with otherwise normal or minimally abnormal conventional MR imaging findings.

Methods: We prospectively studied 137 low birth weight (<1800 g) preterm infants. Neonatal conventional MR imaging and diffusion tensor imaging were performed near term-equivalent age before discharge, and neurologic development of the infants was later followed up at 18 to 24 months of age.

Results: Among the preterm infants who were fully studied, 63 underwent normal conventional MR imaging. Three of these infants developed cerebral palsy, and 10 others showed abnormal neurologic outcome. Diffusion tensor imaging results for these infants showed a significant reduction of fractional anisotropy in the posterior limb of the internal capsule in neurologically abnormal infants (including those with cerebral palsy) compared with control preterm infants with normal neurologic outcomes.

Conclusion: These results suggest that neonatal diffusion tensor imaging may allow earlier detection of specific anatomic findings of microstructural abnormalities in infants at risk for neurologic abnormalities and disability. The combination of conventional MR imaging and diffusion tensor imaging may increase the predictive value of neonatal MR imaging for later neurologic outcome abnormalities and may become the basis for future interventional clinical studies to improve outcomes.

Fig 1

Images show region of interest placement for the posterior limb of the internal capsule. B0, image without diffusion weighting; DWI, diffusion-weighted image; FA, fractional anisotropy image; ADC, apparent diffusion coefficient map.

Fig 2

Average FA histograms by clinical subgroup. N, normal neurologic outcome; AN abnormal neurologic outcome.

Fig 3

Average ADC histograms by clinical subgroup. N, normal neurologic outcome; AN abnormal neurologic outcome.