Multidetector CTA in the Quantification of Internal Carotid Artery Stenosis: Value of Different Reformation Techniques and Axial Source Images Compared with Selective Carotid Arteriography

Purpose: To evaluate the role of 4 different reformation techniques and axial images from multidetector computed tomographic angiography (MDCTA) versus selective carotid arteriography (SCA) in patients with internal carotid artery (ICA) stenosis. Methods: Imaging studies from 50 patients (43 men; mean age 70.3±8.0 years, range 51– 85) with known cerebrovascular disease who underwent MDCTA and SCA in a single university hospital were retrospectively analyzed. Axial images, multiplanar reformation (MPR), curved planar reformation (CPR), volume rendering threshold (VRT), and virtual angioscopy (VA) images were reviewed by 2 independent observers who were blinded to the results of SCA, which served as the gold standard. The degree of stenosis was categorized as 0%–49%, 50%–69%, or 70%–99%; a stenosis >70% was considered as hemodynamically significant. Results: Thirty-four hemodynamically significant stenoses were identified on SCA. The agreement with SCA images was good for both observers using axial CT images (κ=0.89 for observer 1 and 0.88 for observer 2); corresponding results for MPR and CPR were κ=0.91 and 0.92 for observer 1 and 0.88 and 0.91 for observer 2, respectively. VRT (κ=0.72 for observer 1 and 0.66 for observer 2) and VA (κ=0.74 for observer 1 and 0.70 for observer 2) showed a slightly inferior correlation with SCA images. Sensitivities for reformations and axial CT images were 100% each; corresponding specificities ranged from 85% to 95%. Conclusion: Axial images as well as all 4 reformation techniques agreed well with SCA in the grading of ICA stenosis.