Cerebral aneurysms: accuracy of 320-detector row nonsubtracted and subtracted volumetric CT angiography for diagnosis

To assess the accuracy of 320-detector row nonsubtracted and subtracted volumetric computed tomographic (CT) angiography for detection of cerebral aneurysms. After institutional review board approval and informed written consent were obtained, 282 consecutive patients suspected of having cerebral aneurysms underwent CT angiography with a 320-detector row volumetric CT scanner and three-dimensional (3D) rotational digital subtraction angiography (DSA). The sensitivity, specificity, and accuracy of nonsubtracted and subtracted volumetric CT angiography for depiction of aneurysms were analyzed, with 3D DSA as the reference standard. P values less than .05 were considered to indicate a significant difference. Among the 282 patients, 198 (70.2%) had 239 cerebral aneurysms that were detected on the basis of 3D DSA. Nonsubtracted volumetric CT angiography showed 231 of the 239 (96.7%) aneurysms. The primary reason for missed aneurysms was close proximity to bone tissue. Sensitivity, specificity, and accuracy of nonsubtracted volumetric CT angiography for depicting aneurysms were 96.7%, 100%, and 97.5%, respectively, on a per-aneurysm basis. Subtracted volumetric CT angiography showed 237 of 239 (99.2%) aneurysms. Sensitivity, specificity, and accuracy of subtracted volumetric CT angiography for depicting aneurysms were 99.2%, 100%, and 99.4%, respectively, on a per-aneurysm basis. There was no statistically significant difference in accuracy between subtracted volumetric CT angiography and 3D DSA (P = .500). However, nonsubtracted volumetric CT angiography was significantly less sensitive than 3D DSA and subtracted volumetric CT angiography (P = .031 and .008, respectively). Subtracted 320-detector row volumetric CT angiography provides excellent sensitivity for detection of cerebral aneurysms and should be the first-line imaging technique for the noninvasive evaluation of aneurysms. The accuracy of nonsubtracted volumetric CT angiography was lower than that for subtracted volumetric CT angiography, especially for aneurysms adjacent to bone tissue.