[The relationship between the severity of periventricular leukomalacia and the fractional anisotropy values of diffusion tensor imaging].

OBJECTIVE: We performed diffusion tensor imaging (DTI) in children with periventricular leukomalacia (PVL) to quantify the relationship between the fractional anisotropy (FA) values of DTI and the severity of PVL.

METHODS: In this study, we performed DTI in 16 children (seven males, nine females) with PVL. To evaluate the FA values, we used region-of-interest (ROI) measurements and tractography-based measurements. We classified the patients into two groups based on the severity of the magnetic resonance imaging (MRI) findings: the mild group had white matter injury limited to a triangular zone around the lateral ventricle (n = 9) and the severe group had it extended forward (n = 7). Then, we performed ROI measurements for these two groups to evaluate the FA values. We also divided the patients into two groups based on their motor ability :those that could (n = 10) and could not (n = 6) stand. We used tractography-based measurements to evaluate the FA values. To reduce the bias caused by age, we divided the patients into two groups: those younger than 3 years and those 3 years of age and older. All data were analyzed using the Mann-Whitney U-test, and p < 0.05 was considered statistically significant.

RESULTS: In the ROI measurements, regardless of age, the severe group showed a more significant FA reduction in the white matter of the parietal and occipital lobes, including the middle/posterior part of the centrum ovale, superior longitudinal fasciculus, arcuate fascicullus, and thalamic radiation. In the tractography-based measurements, regardless of age, the measured FA values were significantly lower in the group that could not stand.

CONCLUSIONS: This study suggested that the measured FA values could be used to evaluate the severity of PVL quantitatively, and that DTI provides much more information for understanding the pathophysiology of PVL, as compared with conventional MRI.