RT Journal Article SR Electronic T1 “Ivy Sign” on Fluid-Attenuated Inversion-Recovery Images in Childhood Moyamoya Disease JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 1836 OP 1838 VO 20 IS 10 A1 Masayuki Maeda A1 Chika Tsuchida YR 1999 UL http://www.ajnr.org/content/20/10/1836.abstract AB Summary: We report on MR studies of a 15-year-old girl with moyamoya disease in whom diffuse leptomeningeal enhancement (“ivy sign”) was revealed by fluid-attenuated inversion-recovery (FLAIR) and contrast-enhanced imaging. We speculate that the mechanism behind this enhancement is caused by a retrograde slow flow of engorged pial vasculature via leptomeningeal anastomosis. Nevertheless, it remains unknown whether the precise source of a high signal on FLAIR images is attributable to pial vessels themselves or congested thickening of the leptomeninges or both.