FIG 5. A, DSA of the left internal carotid artery performed at 12 months after treatment of a 3-mm aneurysm of the anterior communicating (arrow). The frontal head view shows no residual neck or aneurysm (class 1).

B, Contrast-enhanced MR angiograph with MIP reconstruction in the frontal plane shows a hypersignal (arrow) at the site of the anterior communicating artery misinterpreted as a residual neck (class 2).