Carotid arterial stenosis: Evaluation at CT angiography with the volume-rendering technique

PURPOSE: To determine whether computed tomographic (CT) angiography with th e volume-rendering technique (VRT) can be used to accurately quantify carot id arterial stenosis and to identify occlusions. MATERIALS AND METHODS: Spiral CT was performed in 23 patients who were refe rred for carotid stenosis evaluation. VRT im ages and shaded-surface displa y (SSD) images of 46 carotid arterial bifurcations were compared with findi ngs from digital subtraction angiography (DSA). RESULTS:Agreement on stenosis category between VRT CT angiography and DSA w as found in 39 (85%) of the 46 carotid arteries studied. VRT CT angiography was 92% (49 of 53) sensitive and 96% (82 of 85) specific for the detection of grade 2-3 stenoses (greater than or equal to 70% stenosis). Agreement o n stenosis category between SSD CT angiography and DSA was found in 38 (83% ) of the 46 carotid arteries studied. SSD CT angiography was 91% (48 of 53) sensitive and 93% (79 of 85) specific for the detection of grade 2-3 steno ses. Calcified stenoses were correctly graded at VRT CT angiography in 10 o f the 10 cages with heavy mural calcified plaques, while eight of the 10 st enoses were accurately quantified at SSD CT angiography. CONCLUSION: These results indicate that VRT CT angiography is as accurate a s SSD CT angiography in the evaluation of carotid arterial bifurcations.