Aim: To optimize conventional coronary optical coherence tomography (OCT) images using the attenuation-compensated technique to improve identification of plaques and the external elastic lamina (EEL) contour.
Methods and results: The attenuation-compensated technique was optimized via manipulating contrast exponent C, and compression exponent N, to achieve an optimal contrast and signal-to-noise ratio (SNR). This was applied to 60 human coronary lesions (38 native and 22 stented) ex vivo conventional coronary OCT images acquired from heart autopsies of 10 patients and matching histology was available as reference. Three independent reviewers assessed the conventional and attenuation-compensated OCT images blindly for plaque characteristics and EEL detection. Conventional OCT and compensated OCT assessment were compared against histology. Using an optimized algorithm, the attenuation-compensated OCT images had a 2-fold improvement in contrast between different tissues in both stented and non-stented epicardial coronaries (P < 0.05). Overall sensitivity and specificity for plaque classification increased from 84 to 89% and from 92 to 94%, respectively, with substantial agreement among the three reviewers (Fleiss' Kappa k, 0.72 and 0.71, respectively). Furthermore, operators were 2.5 times more likely to identify the EEL contour in the attenuation-compensated OCT images (k = 0.72) than in the conventional OCT images (k = 0.36).
Conclusion: The attenuation-compensated technique can be retrospectively applied to conventional OCT images and improves the detection of plaque characteristics and the EEL contour. This approach could complement conventional OCT imaging in the evaluation of plaque characteristics and quantify plaque burden in the clinical setting.
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