IVY sign Moyamoya disease MRI

A 21 yo male with history of transient ischemic attacks.
Here is his MRI Axial FLAIR and Non contrast 3 D TOF MR Angiogram of Brain

MRI Axial FLAIR images of brain show serpigenous T2 hyperintensities along the cortical sulci overlying bilateral cerebral convexities in perisylvain regions and along inter hemispheric fissure – ‘IVY’ sign. The proposed mechanisms for this high signals attributed to sluggish flow in cortical branches of ACA and MCA or retrograde slow flow in engorged pial vasculature due to leptomeningeal anastomosis.

MR Angiogram of brain shows steno occlusive lesions of anterior circulation of Circle of Willis; Intra cranial portions of ICAs, ACAs and MCAs are involved with marked sparsity of cortical branches on either side. 

No recent infarct on diffusion.

Imaging wise bilateral intra cranial steno occlusive lesions with ivy sign, possibility of arteriopathy and moyamoya disease suggested and advised DSA for further evaluation.

"IVY" sign is also reported in Vasculitis : Post Tb Meningitis Vasculitis induced infarcts with "IVY"sign