[Diffusion tensor imaging at term-equivalent age in extremely-low-birth-weight infants with periventricular leukomalacia].

It is important to predict the neurological prognoses of preterm infants as part of their normal follow-up. Previous reports have shown that conventional magnetic resonance imaging (MRI) and electroencephalography are useful in predicting neurological prognoses. Diffusion tensor imaging (DTI) is a relatively new method of evaluating the central nervous system (CNS) that can detect abnormalities quantitatively. We compared DTI at term-equivalent age in two extremely-low-birth-weight infants diagnosed with periventricular leukomalacia (PVL) with conventional MRI and DTI in three control extremely-low-birth-weight infants. DTI was analyzed using the free software, "Volume-one" and "dTVII SR." We compared the fractional anisotropy (FA) values at the corpus callosum, posterior limbs of the internal capsule, cerebral peduncle, and corticospinal tract using manual region of interest (ROI) analysis, and at the commissural fibers and corticospinal tract using tract-specific analysis. The FA values were lower in patients with PVL than in control infants at all measurement points, except the commissural fibers on tract-specific analysis. These measurement points showed no abnormality using conventional MRI. This suggests that DTI can detect CNS abnormalities that cannot be detected with conventional MRI. However, our sample size was very small and we examined only cases in which PVL was detected with conventional MRI. Further study is necessary to examine the correlation of DTI findings and neurological prognoses in infants who have no abnormality on conventional MRI.