Efficacy is achieved only if surgical morbidity is sufficiently low.
Furthermore, endarterectomy is under study and may be considered in patients with hemodynamically significant asymptomatic atherosclerotic lesions at the origin of the internal carotid artery. Given the fact that safe, effective treatment is available, accurate diagnostic methods are necessary to evaluate structural lesions and flow at the bifurcation of the common carotid artery as well as along the course of the internal carotid artery in the intracranial branches. While conventional cerebral angiography is still the gold standard for diagnosis of cerebral vascular disease and assessment of collateral circulation, angiography has known risks. In fact, the patients at highest risk for stroke during angiography are those with atherosclerotic changes in the carotid vessels. Furthermore, the angiogram cannot be practically repeated in serial fashion.