Carotid artery plaque composition relationship to clinical presentation and ultrasound b-mode imaging commentary

Abstract

[Extract] The selection of patients for carotid endarterectomy (CEA) has been the subject of endless debate since the procedure was introduced in the middle of the last Century. Approximately 16 years ago, a collaboration of European Vascular Specialists published a multi-centre study comparing ultrasound and histological characteristics of carotid atherosclerosis.1 At the time (and even today) it represented one of the biggest studies of its kind. The investigators recruited 270 patients scheduled for CEA from nine European centres. A detailed pre-operative carotid ultrasound was performed which included assessment of stenosis severity; plaque echogenicity (on a scale of 1–3); plaque composition (homogenous/heterogeneous) and plaque surface characteristics (regular/irregular). Endarterectomy samples were formalin fixed, wax embedded, sectioned and then examined with histological techniques. A number of microscopic features were examined in the plaque, most notably their "soft" constituents (lipid and haemorrhage) and calcification. There were two particularly notable findings from this work. First; the authors reported that patients with more recent symptoms had significantly greater amounts of soft constituents within their atherosclerotic plaque. This suggested that intraplaque haemorrhage, a large lipid core and/or a large necrotic core were important characteristics of unstable carotid atheroma. Second; the authors reported a significant association between plaque hypoechogenicity on ultrasound and a large amount of soft tissue on histology. This finding suggested that ultrasound could be used to detect unstable plaques.