Abstract 17646: Diagnosis of Thin-cap Fibroatheroma and Superficial Foam Cells Accumulation by Measuring Attenuation Coefficients in Optical Coherence Tomography: A Histological Validation Study
Purpose: Intracoronary optical coherence tomography (OCT) has been purported to accurately detect lipid-rich plaque (LRP) in vivo. However, on AHA classification of atherosclerotic plaques, the initial (type I) lesion contains scattered lipidic macrophage foam cells, and the advanced (type V) lesion also contains lipidic necrotic core. This study evaluated whether OCT can distinguish these 2 different staged lesions by measuring attenuation coefficients.
Methods: OCT studies were conducted in fifty-six coronary arteries from 19 autopsy hearts within 6 hours after death. LRP were selected for OCT versus histological comparisons. OCT images of LRP were signal-poor regions with diffuse borders >60° in circumferential extent. Optical attenuation coefficients, which were calculated as distance from signal peak intensity to its half intensity, were measured for each plaque (Figure). The histological initial lesion was defined as plaque with intimal superficial foam cells accumulation without necrotic core. The histological advanced lesion was plaque with large necrotic cores containing numerous cholesterol clefts with overlying fibrous cap measuring <65μm (thin-cap fibroatheroma).
Results: A total of 92 LRPs were identified on OCT. Of those, 22 plaques were diagnosed as the initial lesion, and 10 as the advanced lesion on histological analysis. There was no significant difference in optical attenuation coefficients between two different staged lesions (13.7±7.0 versus 17.7±8.7, p=NS, Figure).
Conclusions: Our result suggests that OCT has a limitation in differentiating between initial lesions and advanced lesions of AHA atherosclerotic plaque classification. Lipidic tissue attenuates OCT signal drastically regardless of the type of lipidic component. OCT has a limitation in discriminating between advanced staged vulnerable atheromas and initial staged plaques with superficial foam cells accumulation.
- © 2013 by American Heart Association, Inc.