[Diagnosis of unruptured cerebral aneurysms using magnetic resonance angiography and three dimensional computed tomographic angiography].

The purpose of this study is to confirm the use of magnetic resonance (MR) angiography and three-dimensional computed tomographic (3D CT) angiography, in the screening of unruptured cerebral aneurysms. Sixty-six unruptured cerebral aneurysms in forty-eight patients were examined by MR angiography, 3D CT angiography and digital subtraction angiography (DSA). All cases underwent surgery. Three out of sixty-six (4.5%) cerebral aneurysms detected by MR angiography and 3D CT angiography were false positive. The false aneurysms were located at the region of the internal carotid artery and the posterior communicating artery, and were under 2.0mm in size. The diagnosis of the infundibular dilatation at the junction of the internal carotid artery and the posterior communicating artery remained difficult. The true positive diagnosis of aneurysms using MR angiography or 3D CT angiography was 95.5%, in our hospital. All unruptured cerebral aneurysms over 2.0mm in size were detected correctly by using MR angiography and 3D CT angiography, as well as DSA. The inadequate diagnosis of aneurysms caused by MR angiography was due to the overlapping of vessels and the surrounding noise. Superselective maximum intensity projection (MIP) and interactive vascular imaging (IVI) were adopted for exact diagnosis. Furthermore, the three slab method of MR angiography was used for containing the limits between the vertebral artery and the distal anterior cerebral artery, and the triple method was able to decrease surrounding noise. Using MR angiography, we diagnosed and operated on about 100 cases of unruptured cerebral aneurysm in one year. Our conclusion is that we can diagnose any unruptured cerebral aneurysm, over 2.0mm in size, using MR angiography and 3D CT angiography.