Atherosclerotic tissue characterization in vivo by optical coherence tomography attenuation imaging

Optical coherence tomography OCT is rap- idly becoming the method of choice for assessing arterial wall pathology in vivo. Atherosclerotic plaques can be di- agnosed with high accuracy, including measurement of the thickness of fibrous caps, enabling an assessment of the risk of rupture. While the OCT image presents mor- phological information in highly resolved detail, it relies on interpretation of the images by trained readers for the identification of vessel wall components and tissue type. We present a framework to enable systematic and auto- matic classification of atherosclerotic plaque constituents, based on the optical attenuation coefficient t of the tis- sue. OCT images of 65 coronary artery segments in vitro, obtained from 14 vessels harvested at autopsy, are ana- lyzed and correlated with histology. Vessel wall compo- nents can be distinguished based on their optical proper- ties: necrotic core and macrophage infiltration exhibit strong attenuation, t10 mm 1 , while calcific and fi- brous tissue have a lower t25mm 1 . The algorithm is successfully applied to OCT patient data, demonstrating that the analysis can be used in a clinical setting and assist diagnostics of vessel wall pathology. © 2010 Society of Photo-