Figure 1. MRA shows a signal void within the left MCA followed by a normal signal in the distal end of segment M1 of MCA and normal M2 segment (left and right panels, shown by arrow). ICA is seen within normal limits with no evidence of stenosis. Significant collateral circulation is seen bilaterally.

ACA, anterior cerebral artery; BA, basilar artery; ICA, internal carotid artery; MCA, middle cerebral artery; M1, first segment of MCA; M2, second segment of MCA; M3, third segment of MCA; MRA, magnetic resonance angiography; PCA, posterior cerebral artery; VA, vertebral artery