Color Duplex Scanning of the Extracranial Carotid Arteries

Abstract

A complete carotid duplex examination should include: the peak systolic and end diastolic velocities of common, internal, and external carotid arteries, right and left subclavian arteries, and vertebral arteries; the internal carotid to common carotid artery peak systolic velocities ratio; flow direction of the vertebral artery (antegrade, retrograde, or bidirectional); analysis of the Doppler spectral waveform of the examined vessels; and the presence or absence of plaque and description of its morphology. A carotid duplex ultrasound examination should be termed “inconclusive” if the findings are uncertain, and it cannot be ensured that the carotid artery does not have significant carotid artery disease. Calcification and shadowing, high bifurcation, short neck, or any other circumstances that prevent adequate interrogation of the carotid artery can result in an inconclusive examination. In this scenario, other diagnostic modalities must be recommended to delineate the proper pathology. The accuracy of duplex scanning in the examination of the carotid artery bifurcation has resulted in its use for detecting significant carotid stenosis in symptomatic patients, the evaluation of patients with neck bruits, postoperative imaging of endarterectomized vessels, and follow-up of asymptomatic patients to document progression of disease. Other clinical implications include carotid endarterectomy based on duplex ultrasound without angiography, intraoperative assessment of carotid endarterectomy, long-term follow-up after carotid endarterectomy, plaque morphology and outcome, and carotid duplex scanning following trauma.