ULTRASONIC CAROTID-ARTERY PLAQUE STRUCTURE AND THE RISK OF CEREBRAL INFARCTION ON COMPUTED-TOMOGRAPHY

Purpose: The North American and the European Symptomatic Carotid Endar terectomy Trial investigators reported a conclusive benefit of carotid endarterectomy for patients with symptomatic 70% to 99% internal caro tid artery (ICA) stenosis. However, it has been suggested that plaque structure may be an even more important factor in producing stroke tha n the degree of stenosis. The aim of this study was to test the hypoth esis that the ultrasonic characteristics of carotid artery plaques wer e closely related to symptoms and to the prevalence of cerebral infarc ts on computed tomography (CT). Methods: One hundred five carotid arte ry plaques causing greater than 70% stenosis in the ICA in 83 consecut ive patients who underwent brain CT were characterized into four ultra sonic types: echolucent plaques, predominately echolucent plaques, pre dominately echogenic plaques, and echogenic plaques. Patients with per manent neurologic deficit were excluded. Results: There was a signific ant ipsilateral association between type 1 plaques and symptomatic hem ispheres (p < 0.002). Twenty-six of the 105 cerebral hemispheres asses sed by CT had infarcts, There was an increased incidence of brain infa rcts in type I plaques (37%) compared with 18% in types II, III, and I V combined (p < 0.02). Conclusion: Our results support the hypothesis that echolucent plaques; are more frequently associated with symptoms and cerebral infarctions and provide further evidence that these plaqu es are unstable and tend to embolize. Studies on the natural history o f asymptomatic carotid artery stenosis should investigate whether plaq ue characterization could identify a high-risk group.