Ruptured Cerebral Microaneurysm Diagnosed by 3-Dimensional Fast Spin-Echo T1 Imaging with Variable Flip Angles

Cerebral microaneurysms, which are 2 mm or small in size, are a rare cause of subarachnoid hemorrhage (SAH). The authors present 2 cases with ruptured microaneurysms, in which 3-dimensional (3D) fast spin-echo T1 imaging with variable flip angles (CUBE T1) using gadolinium-diethylenetriaminepentaacetic acid (Gd) enhancement was useful in diagnosing the microaneurysms as the source of bleeding. Case 1 was a 61-year-old woman who had an SAH localized to the left Sylvian fissure. A small bulge (1.4 mm) at the bifurcation of left middle cerebral artery (MCA), which was detected by 3D angiography, was well enhanced by CUBE T1 with Gd enhancement. The patient was successfully treated by trapping of the lower division of the left M2 segment with superficial temporal artery–M3 bypass. The intraoperative findings indicated that the microaneurysm at the bifurcation of the left MCA was the ruptured site. Case 2 was a 41-year-old man who had a diffuse SAH. A small bulge (1.5 mm) at the inferolateral wall of the left internal carotid artery (ICA), which was detected by 3D angiography, was well enhanced by CUBE T1 with Gd enhancement. The patient was treated by trapping of the left ICA with external carotid artery–saphenous vein graft–M2 bypass without complications. The intraoperative findings indicated that the microaneurysm at the inferolateral wall of the left ICA was the ruptured site. CUBE T1 with Gd enhancement was useful as an adjunctive tool for the diagnosis of ruptured cerebral microaneurysms. This sequence might enable neurosurgeons to perform curative surgery with certainty for ruptured microaneurysms.