Purpose: The value of CT angiography in the detection and evaluation of aneurysms was compared to digital subtraction angiography (DSA).
Material and methods: Seventeen patients with acute subarachnoid hemorrhage (SAH) or with known or suspected aneurysm were investigated by means of spiral CT angiography, which included 3D reconstruction. These findings were compared with those at DSA.
Results: In 16 patients, 20 aneurysms were found; the remaining patient had an ectatic vessel that simulated an aneurysm. Seventeen of the angiographically proved aneurysms were detected at CT angiography (sensitivity 85%). One further aneurysm was identified retrospectively as the result of greater experience in the method. All the aneurysms that escaped detection at CT were 3 mm in size. All the vessels of the circle of Willis, except for the posterior communicating artery, were properly evaluated at CT angiography. Difficulties were encountered in assessing the posterior communicating artery and the extradural segment of the internal carotid artery owing to their close spatial relationship to the bony structures of the skull base and the cavernous sinus.
Conclusion: CT angiography is a low-risk technique with a low level of invasiveness that is useful in following up known aneurysms. The 3D reconstruction yields further topographic information that helps in the planning of endovascular or surgical intervention. The facility for rotating the reconstructed vessels and displaying them from different angles is of particular value in cases difficult to assess at angiography.