FIG 1. Images of the replica of an anterior communicating artery aneurysm.

A, On an original axial image, transverse through the center of the aneurysm, an aneurysmal sac (left arrow) shows relatively low signal intensity compared with the A1 segments (arrowheads) of the anterior cerebral artery. This signal intensity is due to the relatively slow flow in the intracranial aneurysm. Stronger signal intensity (right arrow) at the left aspect of the replica is observed; this is due to stronger flow from the right A1 segment into the left aspect of the aneurysm.

B–D, Anteroposterior (B), inferosuperior (C), and left-to-right (D) projections of MIP MR angiograms show the anterior communicating artery aneurysm (arrow).