"Brush Sign" on Susceptibility-Weighted MR Imaging Indicates the Severity of Moyamoya Disease

BACKGROUND AND PURPOSE: SW) is a high spatial resolution MR imaging technique showing magnetic inhomogeneity that could demonstrate increased oxygen extraction in focal cerebral ischemia. The aim of this study was to investigate the characteristics in the signal intensity of DMVs by using SW) and to determine whether this method could indicate the severity of the hemodynamics in MMD by evaluating the correlation between SW) stage and hemodynamics on SPECT. MATERIALS AND METHODS: Consecutive MMD patients were prospectively analyzed before treatment. Routine MR imaging including SWI was performed, and the number of the conspicuous DMVs draining into the subependymal veins was classified: stage 1, mild (<5); stage 2, moderate (5-10); and stage 3, severe (>10). The SW) stage was evaluated in correlation with clinical presentations, and CBF and CVR were quantified by using a SPECT iodine 123 N-isopropyl-p-iodoamphetamine split-dose method. RESULTS: Patients were 12 males and 21 females (range, 8-66 years), consisting of 4 asymptomatic patients, 13 patients with TIA, 9 patients with infarct, and 7 patients with hemorrhage. There was a significant difference in CVR among clinical presentations, though there was no difference in age, Suzuki stage, or CBF. Conversely, SW) stage was significantly higher in patients with TIA and infarct than asymptomatic patients (P < .01). Higher SWI stage significantly had lower CBF and CVR in the middle cerebral artery area (P < .05). CONCLUSIONS: SW) stage strongly correlates with ischemic presentations in MMD and also correlates with hemodynamics on SPECT, especially CVR. Increased conspicuity of DMVs, known as "brush sign", could predict the severity of MMD.