Depiction of branch vessels arising from intracranial aneurysm sacs: Time-of-flight MR angiography versus CT angiography

BackgroundTo evaluate the sensitivity, specificity, and accuracy of time-of-flight MR angiography (MRA) compared with CT angiography (CTA) for detection of branch vessels arising from the intracranial aneurysm sac, using a 3-tesla MR scanner and an area detector CT scanner.MethodsFifty patients with an intracranial aneurysm (25 patients with a branch vessel arising from the sac and 25 patients without) underwent rotational intraarterial digital subtraction angiography (rotational DSA), MRA, and CTA. The following six image sets were assessed using a 3-point scale for the existence of a branch vessel: (1) volume rendering with MRA (MRA-VR); (2) CTA-VR; (3) source images with MRA; (4) source images with CTA; (5) VR and source images with MRA (‘MRA-VR + source images’); and (6) ‘CTA-VR + source images’. Each set comprised the data of all 50 patients. Three radiologists then performed consensus review and calculated the sensitivity, specificity, and accuracy for MRA and CTA; rotational DSA was considered as the gold standard.ResultsHigher accuracies were obtained in review using VR + source compared with both VR and source alone. In addition, higher accuracies were obtained in review using MRA compared with CTA. The highest accuracy of 0.96 was obtained for ‘MRA-VR + source images’; in contrast, accuracy on ‘CTA-VR + source images’ was 0.86.ConclusionsThe results show that 3-tesla MRA is an ideal non-invasive imaging examination for detection of a branch vessel arising from an intracranial aneurysm sac. Higher accuracy, especially sensitivity, with MRA compared with CTA was found in ICA, but accuracy with MRA was same as that with CTA in MCA.