Multidetector computed tomography (mdct): able to define the plaque composition as assessed by histology?

Background―Plaque morphology is an important predictor of stroke risk. Although plaque morphology is not used, so far, in the decision making of whether to perform carotid endoarterectomy (CEA) or not, having a non-invasive technique capable of diagnosing vulnerable plaque would be very useful in the recognition of patients at high risk of cerebrovascular disease. Aim ― To compare human carotid plaques composition obtained by means of histological analysis and MDCT. Methods ― 37 patients (22 male, 15 females; mean age: 70±7 years) undergoing CEA due to high grade carotid artery stenosis (82±9%) were evaluated with MDCT for non-invasive plaque morphology assessment prior to CEA. Plaques removed during surgery were divided into 5 mm pieces. The part corresponding to the point of maximum stenosis was formalin fixed and paraffin embebbed for histology. Sections were stained with Haematoxilin-Eosin and Masson-Trichrome to assess plaque morphology and composition (collagen, smooth muscle cell, lipids and calcium). Kappa statistics was used for the degree of agreement between the histological and MDTC images. Results―Images of histological sections were computer-reconstructed with Zeiss- Panorama software after being photographed under a microscope (90 frames for each section on average). The area occupied by collagen, smooth muscle cells, lipids, calcium and thrombus was then quantified (absolute amount, mm2, and percentage over the total area) using the Zeiss-Axiovision-measurement software. According to the composition thus obtained, plaques were classified into four classes: lipidic (10%), fibrotic (45%), mixed (35%), and calcific (10%). DSCT plaque analysis was performed on a image of the vessel area at the highest degree of stenosis. A good correlation between histology and MDCT was found (k=0.76). Conclusion―MDCT angiography of the carotid arteries is feasible and the evaluation of carotid plaque composition allows non-invasive assessment of different plaque components. This may have an impact on the non-invasive differentiation of vulnerable plaques.