The role of carotid duplex ultrasonography in the therapeutic algorithm of extracranial carotid disease

The current study was conceived to evaluate the feasibility of developing a diagnostic algorithm for carotid bifurcation disease predicated exclusively upon carotid duplex scanning in lieu of conventional angiography. Fifty-one patients were evaluated for carotid artery disease by a neurologist, neuroradiologist, vascular surgeon, and registered vascular technologist. Testing parameters included carotid color Doppler ultrasonography, angiography, and computerized axial tomography (CT) and/or magnetic resonance imaging (MRI) of the head. The accuracy of duplex scanning was based upon a comparison to reference standard selected carotid angiography. By defining an angiographically established stenosis of greater than 60% as a positive study, the results of the duplex examination in the 51 patients produced a sensitivity of 88.1%, specificity of 88.3%, and an overall accuracy of 88%. A review of the ultrasonographic studies that did not correlate with angiography showed that five patients (9.8%) would have had significantly different approaches to management had confirmatory angiography been omitted. Three of the four patients had preocclusive carotid stenosis on angiogram that was erroneously identified as total occlusion by color duplex scans. Angiography demonstrated an 80% carotid stenosis in a fourth patient with a false-negative duplex scan. The fifth patient with angiographic total occlusion of the internal carotid artery was adjudged to have an 80-90% stenosis by duplex scan. Although the color duplex evaluation of the extracranial circulation remains a highly sensitive screening modality, our data support the need for carotid angiography prior to developing a therapeutic algorithm for the successful management of extracranial vascular disease.