Cerebral aneurysms: evaluation with three-dimensional CT angiography.

PURPOSE: To evaluate the usefulness of three-dimensional CT angiography (CTA), in which contrast material is used to create reformations of dynamic scans, in the diagnosis and the preoperative evaluation of cerebral aneurysms. METHODS: We used 3-D CTA to examine 65 patients with suspected or angiographically verified cerebral aneurysms. A blind study was performed to evaluate the diagnostic accuracy of 3-D CTA for cerebral aneurysms with the use of conventional angiography as the reference standard. RESULTS: In 50 patients, conventional angiography revealed 73 cerebral aneurysms ranging from 2 to 32 mm in maximum diameter. Three of the 73 cerebral aneurysms were located outside the imaging volume of 3-D CTA. The sensitivities of the two neuroradiologists for the remaining 70 aneurysms were 67% and 70%, respectively. Although 3-D CTA depicted cerebral aneurysms 5 mm or larger with good accuracy, it was less useful for the detection of smaller aneurysms. For the evaluation of giant aneurysms, this technique elucidated the relationships among the aneurysm, surrounding arteries, and neighboring bone structure. CONCLUSION: Three-dimensional CTA is useful for the diagnosis of cerebral aneurysms with diameters of 5 mm or more. This technique is especially useful in the preoperative evaluation of giant aneurysms.