Abstract 9479: Histopathological Validation of Optical Coherence Tomography Analysis for Lipid-Rich Plaque and Thin-Cap Fibroatheroma
Background: Optical coherence tomography (OCT) is a unique imaging modality capable of characterizing important morphological features of vulnerable plaque. However, the histopathological correlation data is limited. This study sought to assess agreement of lipid-rich plaques (LLP) between an OCT system and histology in coronary autopsy specimens
Methods: OCT examinations were performed in 52 coronary arteries from 19 autopsy hearts within 6 hours after death. LLP were selected for OCT versus histological comparisons. OCT images of LLP were signal-poor regions with diffuse borders >60° in circumferential extent with fibrous cap thickness <300µm. Thin-cap fibroatheroma (TCFA) was defined as LLP with cap thickness <65µm.
Results: OCT identified 211 focal plaques. Of those, 40 plaques (19%) were matched with the OCT criteria of LLP and 17 plaques (8%) with TCFA. OCT LLP highly associated with prevalence of large lipid deposition within plaques (85%). However, 41% of those plaques contained areas of extracellular lipid accumulation but no necrotic core and inflammatory cells, which are known as preatheroma (upper images in Figure). False-positive diagnoses of OCT for LLP often contained histological evidence of microcalcification deposition within smooth muscle cells (lower images in Figure), hemosiderin deposition, or organized thrombus. Although the sensitivity for detecting TCFA was 100%, it should be noted that the positive predictive value was only 59%. The positive predictive value of TCFA is increased if intravascular ultrasound is used in addition to OCT for detecting TCFA.
Conclusions: Atherosclerotic lesions are heterogeneous, and OCT light signals are attenuated not only by the lipid component but also by microcalcification and/or hemosiderin within plaques. OCT cannot detect the inflammatory status of atherosclerotic LLP. In this specific population, OCT has a limitation in detecting vulnerable plaques corresponding histological specimen.
- © 2011 by American Heart Association, Inc.