ABSTRACT
To prevent cerebral ischemia, carotid endarterectomy (CEA) is the gold standard for the treatment of low-to-medium surgical risk patients with symptomatic as well as asymptomatic high-grade carotid artery stenoses. 1-3 For patients at high surgical risk, carotid artery stenting has been shown to be at least equivalent to surgery. 4 The selection criteria for a carotid procedure in a randomized trial as well as in daily practice are almost exclusively based on neurological symptoms and the degree of stenosis. For both symptomatic and asymptomatic patients, the risk of an ipsilateral stroke has been shown to be linearly related to the severity of stenosis, 5 although the risk for symptomatic patients is substantially higher. The annual incidence of stroke has been shown to be rather stable for carotid artery stenoses below 80%, ranging between 1 and 1.8%, but increases up to 3.4% for stenoses between 80 and 89% and even to 5.1% for lesions between 90 and 99%. 6,7
Although the severity of a carotid artery stenosis is a major determinant of the risk of stroke, many asymptomatic high-grade stenoses remain stable and never cause neurological symptoms, whereas others produce serious, potentially life-threatening events even at lower degrees of stenosis. 8 The majority of strokes are caused by embolization from the atherosclerotic plaque rather than from hypoperfusion as a consequence of the severity of
the stenosis. 9 Consequently, there has been extensive search to identify carotid artery lesion characteristics other than the degree of stenosis that may indicate a high risk of stroke. The vulnerability of a plaque is mainly dictated by its morphology, which is influenced by pathophysiologic mechanisms at the cellular and molecular levels. 10
Thus, in order to identify by imaging modalities patients with carotid artery lesions who are at a high risk for cerebrovascular events, it is necessary both to exactly determine the degree of stenosis and to evaluate plaque morphology in terms of plaque vulnerability.
