Ultrasound and lipoproteins as predictors of lipid-rich, rupture-prone plaques in the carotid artery

The aim of this review is to summarize present knowledge of the ultrasonic detection and determinants of carotid atherosclerosis with lipid-rich cores and to review the evidence that these measures of plaque type may predict cerebral events. With the use of high-resolution ultrasound B-mode imaging, carotid plaques evaluated as only weakly reflecting the ultrasound beam (e cholucent) have been associated with a higher risk of neurological events t han are plaques reflecting the ultrasound signal strongly (echorich). Histo logically, these echolucent plaques have a higher content of lipid and hemo rrhage than do echorich plaques, which contain more calcification and fibro us tissue. Findings in the coronary arteries indicate that a lipid-rich pla que with a thin, fibrous cap is more vulnerable, is more prone to rupture, and cause symptoms compared with fibrous plaques. A search for determinants in the blood for these vulnerable plaques suggests that low density lipopr otein (LDL) cholesterol is the best lipid predictor for the extent of ather osclerosis, whereas triglyceride-rich Lipoproteins in particular seem to pr edict an echolucent plaque. Lowering of LDL cholesterol and triglyceride-ri ch lipoproteins in plasma is associated with reduced progression of coronar y atherosclerosis and coronary events. LDL cholesterol reduction is also as sociated with a reduced stroke rate. These improvements in the prognosis ar e thought to be the result of a reduction in the lipid content of the plaqu es, making them more stable and resistant to rupture rather than an actual reduction in plaque volume and degree of stenosis. Ln conclusion, it appear s that ultrasound B-mode imaging as well as lipoproteins presumably may pre dict dangerous and rupture-prone, lipid-rich plaques in the carotid arterie s, thereby being potential diagnostic tools in the prevention of neurologic al events.