Abstract TP157: Clinical Significance of the Ivy Sign on FLAIR MRI in Moyamoya Disease

Background and purpose: Leptomeningeal collateral is well developed in patient with moyamoya disease, and it appears as high signal intensity (Ivy sign) on FLAIR images. Some studies reported correlations between Ivy sign and cerebral vascular reserve, but the clinical meaning of Ivy sign is still uncertain. Therefore, we aimed to investigate the clinical significance of Ivy sign in moyamoya disease. Methods: FLAIR images of 87 patients with moyamoya disease were reviewed by two neurologists blinded to any clinical information. In order to decide dominant hemisphere with Ivy sign, we divided cerebral hemisphere into 4 regions from anterior to posterior, and each region was scored (0-3 point) based on the prominence of Ivy sign. Clinical findings were obtained by retrospective chart reviews. Results: Ivy sign was observed in all moyamoya patients. The score of patients with nonspecific symptom was lower than the patients with complete stroke (4.88±2.85 vs 7.85±3.54, p=0.045). The score was lower in mild symptom group (nonspecific symptom or single event of TIA) than the severe symptom group (recurrent TIA or complete stroke) (6.38±0.90 vs 7.83±0.43, p=0.045). Dominant hemispheric Ivy sign (IDH) could be determined in 79 patients and 58 patients of them had lateralizing symptom. The side of IDH was significantly correlated with side of symptoms (p=0.002). Twenty-nine patients of 37 with right IDH (78.4%) had clinical symptom on the left side, and 13 out of 21 with left IDH (61.9%) was symptomatic on the right side. Ischemic or hemorrhagic lesions were detected on MRI in 50 patients and 10 patients of them had bilateral lesions of similar size. The side of IDH was correlated with the side of MRI lesion (p=0.036). Conclusions: Ivy sign was detected in all patients with moyamoya disease. Since the sign was highly correlated with clinical findings, more prominent sign may suggest more frequent and severe clinical events. Ivy sign can be utilized as a means of determining treatment option and predicting clinical outcome.