The Leptomeningeal “Ivy Sign” on Fluid-Attenuated Inversion Recovery MR Imaging in Moyamoya Disease: A Sign of Decreased Cerebral Vascular Reserve?

A 47-year-old woman with frequent transient left upper and lower motor weakness. Arrows indicate the ivy sign. The ivy sign score of the right side is 1 in the ACA and PCA regions, respectively, and 2 in the ant-MCA and post-MCA regions, respectively. No ivy sign is seen on the left side. The ivy sign score in individual hemispheres is 6 on the right side and zero on the left side.

The template of constant regions of interest for the 3D-SRT. A representative 6 sections of the template are shown: A, callosomarginal; B, precentral; C, central; D, parietal; E, angular; F, temporal; G, posterior cerebral; H, pericallosal; I, basal ganglia; J, thalamus; K, hippocampus; L, cerebellum. Adapted from Takeuchi R et al.¹¹

Bar graph shows the ivy sign score of each type of hemispheric symptom. The ivy sign scores show significant positive correlation with the grades of clinical types of hemispheric symptoms (P < .001).

Bar graph shows the ivy sign score according to 4 cortico-subcortical regions, each color indicating a different grade. Each color represents the percentage of the score in the hemisphere compared with all 96 hemispheres for each ivy sign score. The number along the each color represents the score.

A 47-year-old woman with minor CSs with left motor weakness and sensory disturbance. The type of hemisphere was CS on the right side and AS on the left side. A, Axial FLAIR image shows the ivy sign over the right hemisphere (arrows). The ivy sign score is 2 in the ACA, ant-MCA, and post-MCA regions, respectively, and zero in PCA region on the right side. There is no ivy sign on the left. The ivy sign score in the individual hemispheres is 6 on the right side and zero on the left side. B, In resting SPECT, CBF is reduced in the ACA, ant-MCA, and post-MCA regions on the right side (arrowheads). C, In ACZ-SPECT, CBF in the left hemisphere is markedly elevated, whereas in the right hemisphere it is not and shows relative depression in the ACA, ant-MCA, and post-MCA regions, which indicates the decreased CVR in the right side (arrowheads). The calculated CVR (%) is 13.7, 8.7, 12.4, and 57.4 from the ACA, ant-MCA, post-MCA, and PCA regions, respectively on the right, whereas it is 46.5, 51.3, 72.1, and 73.9, respectively, on the left. The CVR is relatively preserved in the right PCA region and in all 4 regions on the left side. Note that the areas with decreased CVR correspond to the regions with a prominent ivy sign on the FLAIR image (A). D, Axial FLAIR image obtained at 3 months after revascularization surgery, when her symptoms were alleviated, shows almost complete disappearance of the ivy sign, which was noted over the right hemisphere.