Less than 60 degrees ( beyond 60degrees, error is exponentially increased) Ideally. Carotid duplex testing can be used for atherosclerotic disease screening, surveillance for disease progression or restenosis after intervention, and diagnosis of occlusive and nonatherosclerotic conditions involving the aortic arch branches, carotid, vertebral, or subclavian arteries.Ĭopyright © 2013 Elsevier Inc. SCANNING TECHNIQUE Always angle correct to the flow NOT the vessel wall. Appropriate test interpretation allows an initial clinical decision regarding medical treatment, intervention, or the need for additional cerebrovascular imaging.
In most normal circumstances, the vertebral artery is a lowresistance vessel. Carotid duplex ultrasound is the recommended diagnostic test for symptomatic and asymptomatic patients with known or suspected extracranial carotid artery occlusive disease. After insonation of the carotid bifurcation, the ultrasound beam is directed posteriorly and laterally between the vertebral foramina, with color and pulsed Doppler sonography to identify the vertebral artery. The interpretation criteria are based on carotid artery bifurcation imaging and pulsed Doppler velocity spectra analysis with measurements of peak systolic and end-diastolic velocity from the diseased ICA and peak systolic velocity ratio calculated from the nondiseased common carotid artery and the site of maximum ICA stenosis. In an effort to bring standardization to carotid duplex testing, the Intersocietal Accreditation Commission of vascular laboratories has recommended use of the Society of Radiologists in Ultrasound Consensus Conference criteria for ICA stenosis severity. The interpretation of carotid duplex testing is not standardized most vascular laboratories use either referenced or internally validated criteria for stenosis classification.
When compared with angiography, the sensitivity and specificity of predicting internal carotid artery (ICA) stenosis are both high (>90%), but vary with disease prevalence, stenosis severity categories, and the velocity spectra criteria used. Carotid duplex ultrasound is an accurate noninvasive technique to estimate the risk of atheroembolic stroke using extracranial carotid artery bifurcation-based imaging and velocimetry criteria.
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