Carotid plaque echogenicity and types of silent CT-brain infarcts - Is there an association in patients with asymptomatic carotid stenosis?

Background. The aim of this study was to identify the differences in echoge nicity and the degree of stenosis of asymptomatic carotid plaques associate d with different types of ipsilateral silent CT-brain infarcts. Methods. Some 273 asymptomatic carotid plaques (218 patients) causing 50 to 99% stenosis were studied with high-resolution ultrasound. B-mode images w ere digitised and normalised by assigning certain grey Values to blood and adventitia. The grey scale median (GSM) of the plaque in the normalised ima ge was used to quantify echogenicity Every patient had a CT-brain scan whic h an independent neuroradiologist read. The presence of 1) non-lacunar and 2) lacunar silent CT-brain infarcts ipsilateral to the carotid plaque was n oted. Results. The mean GSM of plaques associated with non-lacunar silent CT-brai n infarcts was 19.6, of plaques associated with lacunar infarcts was 35.5 a nd of those associated with no infarcts was 32 (p=0.008, ANOVA). The mean d egree of stenosis was 79%, 12% and 73% respectively (p=0.1, ANOVA). Plaque echogenicity (p=0.007) and not the degree of stenosis (p=0.07) predicted th e presence of non-lacunar silent CT-brain infarcts (logistic regression). Conclusions. Carotid bifurcation plaques, which are associated with non-lac unar silent CT-brain infarcts, are significantly more hypoechoic than those associated with lacunar or no infarcts. Plaques associated with lacunar si lent infarcts and no infarcts have the same echogenicity and degree of sten osis. These findings suggest an embologenic mechanism of non-lacunar silent CT-brain infarcts that may have prognostic implications in patients with a symptomatic carotid stenosis. Prospective studies of asymptomatic carotid s tenosis should assess the significance of 1) plaque echogenicity and 2) the presence of different types of silent CT-brain infarcts and atheroembolic stroke.