ULTRASOUND FOR THE ASSESSMENT OF THE EMBOLIC RISK OF CAROTID PLAQUES

In a prospective study we compared duplex-ultrasound characteristics o f symptomatic internal carotid artery (ICA) stenoses with cranial comp uterized tomographic (CCT) findings in 82 patients suffering from comp leted or transient middle cerebral artery symptoms. The aim was to ass ess the pathogenic role of ICA. plaque morphology and the potential em bolic risk of ICA plaques. The degree of carotid stenosis was estimate d by spectral analysis of the pulsed Doppler signal. The CCT findings were classified as being either normal, lacunar lesions, hemodynamical ly induced low-perfusion infarctions, or territorial embolic infarctio ns. According to their ultrasonic features we characterized the ICA pl aque surface as smooth or irregular and their structure as homogeneous or heterogeneous. Plaques with an irregular surface and heterogeneous echogenicity dominated significantly in CCT-territorial infarctions ( p<0.01), whereas hemodynamically induced low-perfusion infarctions sho wed no relationship with any plaque characteristic. High degree ICA st enoses (> 50%) dominated in both territorial infarctions and low-perfu sion infarctions, as compared to ipsilateral normal CCT or lacunes (p< 0.05). Normal CCT and lacunar infarctions were associated with homogen eous and smooth plaques (both p<0.05). We conclude that > 50% ICA sten oses can cause both hemodynamically induced low-perfusion infarctions as well as thromboembolic territorial infarctions, whereas ulcerated a nd heterogeneous plaques constitute a high risk factor for arterio-art erial embolic stroke. Furthermore, carotid ultrasound may help to esti mate the clinical significance of carotid lesions.