Abstract
BACKGROUND AND PURPOSE: Color duplex ultrasonography (CDU) is a standard method of noninvasive evaluation of internal carotid artery stenosis (ICAS). B-flow imaging (BFI), on the other hand, is a newer method. We investigated the accuracy of the two noninvasive tests—CDU and BFI—each separately and as a combination of the two tests by comparing with digital subtraction angiography as a reference standard.
METHODS: We performed CDU, BFI, and digital subtraction angiography on 95 consecutive patients with ICAS. Separate and combined test results of CDU and BFI were compared with digital subtraction angiography results.
RESULTS: For identifying 70% to 99% ICAS, as CDU criterion, the ratio of internal carotid artery to common carotid artery peak systolic velocity had the highest diagnostic accuracy (sensitivity, 94%; specificity, 96%). The sensitivity and specificity of BFI were 65% and 98%, respectively. With CDU and BFI, results were concordant in 144 (89%) cases for 70% to 99% ICAS. Sensitivity and specificity of combined CDU and BFI results for identification of ICAS were 95% and 99%, respectively. The misclassification rates of CDU and BFI were 4.7% and 8.1%, respectively. When combined test results were concordant, the misclassification rate decreased to 1.4%.
CONCLUSION: CDU showed a slightly better accuracy than did BFI in the diagnosis of carotid artery stenosis. Combined use of CDU and BFI is more accurate than use of either test alone.
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