fig 6.

A 50-year-old woman with moyamoya disease and history of transient ischemic attacks.

A and B, AP arteriogram of the right (A) and left (B) carotid artery reveals stenoses of distal carotid artery on both sides as well as high-grade stenoses of the A1 segment (arrow) and occlusion of left M1 segment. Collateral vessels of left M1 segment (arrowheads) cannot be seen by either MRA (C) or CTA (D).

C, MRA, oblique AP view, is impaired by poststenotic signal loss, belying an occlusion of the left A1 segment (broad arrow), as well as the right M1 segment (arrowheads). The postocclusive branches of the left MCA are filled by collateral vessels, and very low flow in these segments results in poor MRA signal. Thus, postocclusive segments of the MCA (left) cannot be seen clearly. Notice stenosis of supraclinoid segment of ICA (long arrow).

D, CTA, targeted-MIP AP view, correctly shows the right M1 segment as open and presents the clearest depiction of the left distal MCA branches (arrows).