INTRODUCTION. Carotid duplex, a non-Invasive, rapid, relatively inexpensive, readily available, and fairly accurate screening test is widely used in the evaluation of carotid artery stenosis. Although expensive, and associated with significant morbidity and mortality, angiography remains the gold standard for the diagnosis of extracranial occlusive disease.
OBJECTIVES. To validate the accuracy of carotid duplex scan in comparison to carotid angiography in detecting carotid artery stenosis (CAS) and to determine the cut-off value for duplex ultrasound criteria that will accurately predict the presence of significant CAS.
METHODS. Cross-sectional study of 53 patients (106 carotids) who underwent carotid duplex scanning and angiography between January 1996 to September 2000 at the Vascular and Catheterization Laboratories of St. Lukes Medical Center.
RESULTS. Correlation between duplex scan and carotid angiogram results is highly significant. Exact correlation was translated to 56 percent agreement and the overall test performance showed excellent results with sensitivity of 91 percent, specificity of 98 percent, and overall accuracy of 96 percent. The stenosis category that will accurately predict the presence of significant carotid artery stenosis was assigned at 60 percent stenosis.
CONCLUSION. The accuracy of carotid duplex is very impressive and is comparable with foreign studies. It is a practical screening test on which to base a physicians clinical decision particularly in the severe and totally occluded carotids. Patients with normal carotid duplex can be excluded to undergo further testing. In situations in which duplex scans reveal minimal and moderate stenosis, further diagnostic tests such as carotid angiography may be indicated depending on patients clinical presentation and physicians judgment.