• Vol. 36 No. 4, 247–252
  • 15 April 2007

Detection of Internal Carotid Artery Stenosis with Duplex Velocity Criteria Using Receiver Operating Characteristic Analysis

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ABSTRACT

Introduction: Duplex ultrasonography is an excellent non-invasive screening tool for carotid artery stenosis. The aim of this study was to evaluate optimal ultrasonographic criteria for determination of internal carotid artery stenosis with reference to digital subtraction angiography. Materials and Methods: From January 1995 to December 2003, 114 symptomatic patients underwent both duplex ultrasonography and angiography. Seven velocity criteria were compared with angiographic stenosis and receiver operating characteristic curves were used to determine the best cutoff for each criteria. Results: Internal carotid artery/common carotid artery systolic velocity ratios (PSV ICA/PSV CCA) and systolic internal carotid artery/diastolic common carotid artery ratios (PSV ICA/EDV CCA) were superior to other criteria for diagnosing internal carotid artery stenosis. For 50% stenosis, the best criterion of PSV ICA/PSV CCA was 1.5 [sensitivity 100%, specificity 85%, area under the curve (AUC) 99%], and the best criterion of PSV ICA/EDV CCA was 3.5 (sensitivity 100%, specificity 58%, AUC 99%). For 60% stenosis, the best criterion of PSV ICA/PSV CCA was 2.6 (sensitivity 100%, specificity 94%, AUC 99%), and the best criterion of PSV ICA/EDV CCA was 10.3 (sensitivity 100%, specificity 96%, AUC 99%). For 70% stenosis, the best criterion of PSV ICA/PSV CCA was 3.1 (sensitivity 100%, specificity 91%, AUC 99%), and the best criterion of PSV ICA/EDV CCA was 10.3 (sensitivity 100%, specificity 91%, AUC 99%). Conclusion: Our study showed that velocity ratios are superior to other criteria for detecting carotid stenosis. Each laboratory needs to validate its own results.


Carotid stenosis is a clear marker of increased stroke risk and is an important parameter in clinical risk stratification. Grading carotid stenosis has a direct impact on management decisions in view of the benefit provided by carotid endarterectomy in symptomatic patients with 70% to 99% stenosis.1 Patients in this group who underwent endarterectomy had significantly lower stroke risks compared to medically treated patients. Subgroups of patients with 50% to 69% stenosis may expect a smaller benefit from surgery: a larger number of patients must undergo surgery to prevent a stroke at 2 years compared to patients with ≥70% stenosis.1 The benefit of endarterectomy for asymptomatic patients with ≥60% stenosis has been demonstrated in the Asymptomatic Carotid Atherosclerosis Study.

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