However, symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful test in the evaluation of the extracranial vasculature in the setting of carotid stenosis, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [120]. The lack of need for IV contrast decreases the risk to the patient. However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high- grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. In the absence of suspected confounding factors that might result in Doppler error or active treatment plan, US imaging may be the only indicated examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the surveillance imaging of asymptomatic carotid stenosis.
Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful test in the evaluation of the extracranial vasculature in the setting of carotid stenosis, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [120]. The lack of need for IV contrast decreases the risk to the patient. However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high- grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. In the absence of suspected confounding factors that might result in Doppler error or active treatment plan, US imaging may be the only indicated examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the surveillance imaging of asymptomatic carotid stenosis.