"Ivy sign" in childhood moyamoya disease: depiction on FLAIR and contrast-enhanced T1-weighted MR images.

PURPOSE: To compare contrast material-enhanced T1-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) images with or without gadolinium in depicting the leptomeningeal ivy sign in children with moyamoya disease.

MATERIALS AND METHODS: Twenty-nine sets of FLAIR and postcontrast T1-weighted MR images were available in 19 consecutive children with primary moyamoya disease confirmed with conventional and MR angiography. Contrast-enhanced FLAIR MR images also were available in 15 sets. Two pediatric radiologists reviewed FLAIR and postcontrast T1-weighted images in separate sessions for the leptomeningeal ivy sign and assigned a rating of "present," "absent," or "equivocal" by consensus. Unenhanced and contrast-enhanced FLAIR MR images were compared side by side to determine which better depicted leptomeningeal high signal intensities.

RESULTS: Postcontrast T1-weighted MR images revealed the leptomeningeal ivy sign in 40 hemispheres (frequency of visualization, 71% [40 of 56 hemispheres]), whereas unenhanced FLAIR MR images depicted it in 26 hemispheres (frequency of visualization, 46% [26 of 56 hemispheres]). An equivocal rating was given in 21 hemispheres versus in 11 on FLAIR and postcontrast T1-weighted images, respectively. FLAIR and postcontrast T1-weighted images agreed in 40 hemispheres. There was no case with a positive rating on FLAIR images when postcontrast T1-weighted images were negative. Unenhanced FLAIR MR imaging was superior to contrast-enhanced FLAIR imaging in seven hemispheres, whereas enhanced FLAIR was better in four of 28 hemispheres. In the remaining 17, findings with each sequence were similar.

CONCLUSION: Contrast-enhanced T1-weighted images are better than FLAIR images for depicting the leptomeningeal ivy sign in moyamoya disease.