Background-Echo-lucency of carotid atherosclerotic plaques on computerized ultrasound B-mode images has been associated with a high incidence of brain infarcts as evaluated on CT scans. We tested the hypotheses that triglyceride-rich lipoproteins in the fasting and postprandial state predict carotid plaque echo-lucency and that echo-lucency predicts a high plaque lipid content. Methods and Results-The study included 137 patients with neurological symptoms and Ն50% stenosis of the relevant carotid artery. High-resolution B-mode ultrasound images of carotid plaques were computer processed to yield a measure of echogenicity (gray-scale level). Lipoproteins were measured before and hourly for 4 hours after a standardized fatty meal. A subgroup of 58 patients underwent endarterectomy. On linear regression analysis, echo-lucency (low gray-scale level) was associated with elevated levels of fasting and postprandial plasma triglycerides (Pϭ.0002 and Pϭ.002) [5][6][7] and stroke, 5,7 and even reduced total mortality. 5,6 The role of triglyceride-rich lipoproteins is much less clear. Nevertheless, elevated plasma triglyceride levels have repeatedly been associated with an increased incidence of myocardial infarction, 8 and three intervention trials have provided some evidence that a reduction in triglyceride-rich lipoproteins is associated with a reduction in the progression of coronary atherosclerosis 9 and the incidence of coronary events. -11In a recent study, we demonstrated that elevated plasma levels of triglyceride-rich lipoproteins in the fasting or postprandial state were associated with echo-lucent carotid artery plaques as evaluated subjectively by B-mode ultrasonography. 12Weak reflection of ultrasound from carotid atherosclerotic plaques, ie, echo-lucency, is also associated with a higher histological content of lipids, 13 as well as with increased risk of developing neurological symptoms.14 -17 It is therefore conceivable that elevated plasma levels of triglyceride-rich lipoproteins may be associated with atherosclerotic plaques, with lipid-rich cores particularly prone to rupture and causing neurological symptoms, and that such plaques can be diagnosed noninvasively and subjectively as echo-lucent plaques on B-mode ultrasonography.Recently, computerized assessment of plaque echogenicity (measured as gray-scale level) has been introduced as a more quantitative and objective method of ultrasonographic plaque characterization. 18 -20 With this improved method, a high fibrous tissue content was associated with a high gray-scale value (echo-rich plaque), whereas a high lipid and hemorrhage content was associated with a low gray scale value (echo-lucent plaque). 20 In addition, plaque echo-lucency was associated with a higher incidence of brain infarcts as assessed with CT scans. 18,19 In this study, we tested the hypotheses that (1) elevated plasma levels of triglyceride-rich lipoproteins in the fasting or postprandial state predict echo-lucency of carotid atherosclerotic plaques on computerized ultrasound B-...

The intensity of the reflected B-mode ultrasound signal appears related to the histological composition of the plaque. The association between intraplaque haemorrhage and a high lipid content may support the theory of the lipid-rich plaque being more prone to rupture.