Fig 6. Time-of-flight MRA maximum intensity projection (MIP) viewed from posteriorly. The posterior circulation has been removed. There is smooth, regular, concentric, distal left internal carotid and proximal prebifurcation M1 segment flow attenuation (white arrowhead) resulting in reduction in flow signal intensity from remaining MCA branches (white arrow). The A1 segment of the ACA is unaffected. The pattern of proximal involvement was seen in >80% and the "benign" morphology was seen in half of patients studied.