engleski

Atherosclerotic plaque - morphology, dynamics, complications and symptoms

Atherosclerotic disease of large extracranial arteries accounts for about 30 percent of strokes according to the TOAST study. Artery to artery embolism is the leading pathomechanism of ischemic stroke in patients with extracranial carotid stenosis. CDFI is a routine sonographic method for the assessment of extracranial artery disease. CDFI displays vascular structures as well as the velocity and flow direction of red blood cells by mapping the Doppler frequency information. The most common site of lesion is the carotid bulbus posterolaterally. The surface of the plaque can be smooth, irregular or ulcerated. Echogenicity is an important factor, because it provides information on the probable histologic composition of the plaque. A fibrofatty plaque that contains a large amount of lipid material is the least echogenic plaque type and may be so faintly echogenic as to be difficult to identify by sonography. A plaque with a high collagen content (fibrous plaque) is moderately or strongly echogenic and the degree of echogenicity correlates with the amount of collagen within the plaque architecture. On the contrary, calcified plaques are highly echogenic. The stenosis percentage must be calculated as accurately as possible. The degree of stenosis indicates whether or not a patient is likely to benefit from carotid endarterectomy (CEA). Recently, a new Doppler method has been introduced, i.e. power Doppler imaging. Power Doppler provides better detection of high-grade stenosis than CDFI, closer to DSA, and provides superior visualization of plaque surface morphology than by CDFI or DSA. However, the main disadvantage of this technique is that it provides no hemodynamic information concerning the direction or velocity of blood flow.

atherosclerosis; plaque; ultrasonography

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