QUANTITATIVE ANALYSIS OF THE POLARIZATION CHARACTERISTICS OF ATHEROSCLEROTIC PLAQUES

摘要

In this study we demonstrate the capability of cross-polarization optical coherence tomography (CP OCT) to assess collagen and elastin fibers condition in atherosclerotic plaques basing on ratio of the OCT signal levels in cross- and со- polarizations. We consider the depolarization factor (DF) and the effective birefringence (Δn) as quantitative characteristics of CP OCT images. We revealed that calculation of both DF and Δn in the region of interest (fibrous cap) yields a statistically significant difference between stable and unstable plaques (0.46±0.21 vs 0.09±0.04 for IDF; (4.7±1.0)?10~(–4) vs (2.5±0.7)?10~(–4) for Δn; p<0.05). In parallel with CP OCT we used the nonlinear microscopy for analysis of thin cross-section of atherosclerotic plaque, revealing the different average isotropy index of collagen and elastin fibers for stable and unstable plaques (0.30 ± 0.10 vs 0.70 ± 0.08; р<0.001). The proposed approach for quantitative assessment of CP OCT images allows cross-scattering and birefringence characterization of stable and unstable atherosclerotic plaques.