Changes in Integrity of Normal-Appearing White Matter in Patients with Moyamoya Disease: A Diffusion Tensor Imaging Study

BACKGROUND AND PURPOSE: DTI is widely used for the evaluation of white matter integrity in various neurologic diseases. The purpose of this study was to investigate changes in white matter integrity by using DTI in NAWM of patients with MMD and to evaluate the correlation between diffusion and perfusion characteristics through an interhemispheric comparison.

MATERIALS AND METHODS: We retrospectively reviewed 20 primary MMD patients with asymmetric disease stage and 20 age-matched healthy controls. FA_CS and ADC_CS values of bilateral centrum semiovale were measured by using region of interest analysis. Mean FA_CS and ADC_CS were compared between patient and control groups by unpaired t test. Interhemispheric differences in FA_CS and ADC_CS were assessed and compared between the H-TTP_delayed and the H-TTP_shorter by using paired t test. AIs also were assessed to verify interhemispheric differences.

RESULTS: The patient group showed a significantly lower mean FA_CS and a higher mean ADC_CS value than the control group. In the patient group, the H-TTP_delayed had a significantly lower FA_CS and higher ADC_CS value than the H-TTP_shorter. Both AI_FA and AI_ADC were significantly higher in the patient compared with the control group.

CONCLUSIONS: DTI can describe subtle changes in white matter integrity in NAWM of patients with primary MMD that are not detected by conventional MR imaging. In addition, diffusion characteristics are well correlated with perfusion characteristics. We believe that DTI is a useful ancillary tool to evaluate patients with MMD.