Intracranial aneurysms: CT angiography and MR angiography for detection - Prospective blinded comparison in a large patient cohort

PURPOSE: To compare computed tomographic (CT) angiography and magnetic reso nance (MR) angiography with intraarterial digital subtraction angiography ( DSA) in the detection of intracranial aneurysms. MATERIALS AND METHODS: One hundred forty-two patients underwent intraarteri al DSA to detect aneurysms. CT angiography, three-dimensional time-df-fligh t angiography, and intraarterial DSA were performed contemporaneously. Film hard-copy images and maximum intensity projection reconstructions of the C T angiograms and MR angiograms were reviewed at different times. RESULTS: The accuracy per patient for the best observer was 0.87 at CT angi og- and 0.85 at MR angiography. The accuracy per aneurysm for the best was 0.73 at CT angiography and 0.67 at MR angiography. Differences between read ers and modalities were not significant. Interobserver agreement was good: K value of 0.73 for CT angiography and of 0.74 for MR angiography. The sens itivity fbr detection of aneurysms smatter than 5 mm was 0.57 for Cf angiog raphy and 0.35 for MR angiography compared with 0.94 and 0.86, respectively , for of aneurysms 5 mm or larger. The accuracy of both CT angiography and angiography was lower for detection of internal carotid artery aneurysms co mpared with that at other sites. With low observer confidence, the likeliho od of correct interpretation was significantly poorer. CONCLUSION: CT angiography and MR angiography have limited sensitivity in t he detection of small aneurysms but good interobserver agreement. There is no significant difference in diagnostic performance between the noninvasive modalities.