From a management prospective, carotid stenosis is divided into 3 categories based on the degree of stenosis including mild (<50%), moderate (50%-69%), and severe (>70%) stenosis, with the latter 2 categories having a higher probability of hemodynamic significance subsequent ipsilateral stroke [121,122]. The risk for progression of carotid stenosis is poorly characterized. In small case-controlled studies, the risk of mild or moderate stenosis to progress is between 30% and 40% within the ensuing 3 years [123]. The type of surveillance imaging indicated is informed by the degree of stenosis and, thereby, concern of the hemodynamic significance of the stenosis. In most cases, surveillance imaging of asymptomatic carotid disease focuses on the area of stenosis guided by the character of the stenosis and presence of involvement of the other cerebrovascular territories. However, if hemodynamically significant stenosis is suspected, parenchymal imaging, physiologic imaging, and invasive imaging may be useful to guide management of asymptomatic carotid disease [112]. For symptomatic carotid disease, please see Variants 1 to 5 for indicated imaging procedures. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography accurately measures the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for surveillance imaging is obviated by the invasive nature of the examination and availability of both sensitive and specific noninvasive tests. Although cerebral angiography is not used as routine surveillance imaging for asymptomatic carotid disease, angiography can be useful in some cases of known, hemodynamically significant stenosis to determine appropriate treatment options.
Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. From a management prospective, carotid stenosis is divided into 3 categories based on the degree of stenosis including mild (<50%), moderate (50%-69%), and severe (>70%) stenosis, with the latter 2 categories having a higher probability of hemodynamic significance subsequent ipsilateral stroke [121,122]. The risk for progression of carotid stenosis is poorly characterized. In small case-controlled studies, the risk of mild or moderate stenosis to progress is between 30% and 40% within the ensuing 3 years [123]. The type of surveillance imaging indicated is informed by the degree of stenosis and, thereby, concern of the hemodynamic significance of the stenosis. In most cases, surveillance imaging of asymptomatic carotid disease focuses on the area of stenosis guided by the character of the stenosis and presence of involvement of the other cerebrovascular territories. However, if hemodynamically significant stenosis is suspected, parenchymal imaging, physiologic imaging, and invasive imaging may be useful to guide management of asymptomatic carotid disease [112]. For symptomatic carotid disease, please see Variants 1 to 5 for indicated imaging procedures. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography accurately measures the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for surveillance imaging is obviated by the invasive nature of the examination and availability of both sensitive and specific noninvasive tests. Although cerebral angiography is not used as routine surveillance imaging for asymptomatic carotid disease, angiography can be useful in some cases of known, hemodynamically significant stenosis to determine appropriate treatment options.