Purpose: To determine the accuracy of multi-slice computed tomographic (CT) angiography in diagnosing total versus near occlusions of the internal carotid artery (ICA).
Methods and Materials: Fifty-seven ICA total or near occlusions identified by conventional angiography were studied with multi-slice CT angiography 1 to 3 days after conventional angiography. The CT angiography in diagnosing total versus near occlusions was analyzed by two radiologists independently. The results were compared with those of conventional angiography.
Results: Conventional angiography depicted 31 total occlusions, including 10 without a stump, 19 with a stump less than 2 cm, and 2 with a stump greater than 2 cm. Among them, 22 had downward extent of the intracranial ICA reconstitution flow at or above the carotid siphon, 8 at the carotid canal, and 1 at the distal cervical ICA. Conventional angiography also depicted 26 near occlusions, including 21 proximal-third high-grade stenoses, 1 middle-third high-grade stenosis, 2 distal high-grade stenoses, and 2 diffusely hypoplastic lumen along the cervical ICA. Multi-slice CT angiography correctly depicted all total and near occlusions with no inter-rater variance. In depicting the occlusive level, CT angiography correctly depicted the occlusive level and downward extent of the intracranial ICA reconstitution flow in all occlusions. In depicting the stenotic level of near occlusions, CT angiography correctly identified the level of high-grade stenosis in all near occlusions. CT angiography further subdivided the 21 near occlusions with a proximal-third stenosis into a focal (n = 19) and diffuse (n = 2) vascular involvements according to the vascular wall information shown on CT.
Conclusion: Multi-slice CT angiography had an excellent correlation (100%) with conventional angiography in diagnosing total versus near occlusion of the ICA. Multi-slice CT angiography may be considered as a substitute of conventional angiography in confirming the results of ultrosonography in diagnosing total versus near occlusions of the ICA.