Detection of vulnerable plaque in a murine model of atherosclerosis with optical coherence tomography

Objectives: The aim of this study was to evaluate the feasibility of optical coherence tomography (OCT) to identify the components of vulnerable plaques in a well-established murine model of human atherosclerosis. Background: Although the pathologic features that predict plaque rupture at autopsy are well known, the development of a technology to identify these high risk features in vivo is lacking. OCT uses reflected light to provide histology-like images of plaque with higher resolution than competing imaging modalities. Whether OCT can reliably identify the features of an atherosclerotic plaque that define it as vulnerable-thin fibrous cap, large lipid core, and high percent of lipid in the artery-requires further study. Methods: OCT images of the atherosclerotic innominate artery segments from the apolipoprotein E knockout (apoE ^-/-) mice were recorded and correlated with histology in both in vivo (n = 7) and well as in ex vivo experiments (n = 12). Results: Excellent correlation between the OCT and histology measurements for fibrous cap thickness, lipid core size, and percentage lipid content was found. The fibrous cap thicknesses examined span those of human fibrous caps known to rupture (<65 μm). Regions of greatest light reflection in OCT images were observed when calcium hydroxy-apatite was scattered in lipid, less in fibrous tissue, and least in lipid. Conclusions: These findings suggest that OCT holds promise for the identification of features defining vulnerable plaque including fibrous cap thickness, lipid core size, and the percentage of lipid content.