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Fig 1. Representative MRA and angiographic images. Aggressive appearing lesions were those that demonstrated multiple short segment irregularity with alternating narrowing and dilation (beading) (white arrow) (A) or multiple longer segmental narrowing with normal intervening vessel (black arrowheads) (B). Aneurysms (not shown) were included in this definition. Benign appearing lesions (C) had smooth (white arrows), often solitary, tapered (white arrowhead) narrowing that could be concentric or eccentric. Incidental hypoplasia of the ipsilateral A1 is noted.
