Evaluation of coronary arterial calcification - Ex-vivo assessment by optical frequency domain imaging.
The purpose of this study was to determine the diagnostic ability of optical frequency domain imaging (OFDI) to carry out quantitative and qualitative evaluation of coronary calcification in comparing with ex vivo human autopsy heart specimens. Analysis was carried out in 25 coronary artery specimen obtained from 16 cadavers that were imaged ex-vivo imaging by OFDI and intravascular ultrasound (IVUS). Of 235 cross-sections obtained for histologic evaluation, 149 were classified as showing calcified plaques, and in this group a comparison between histology versus co-registered images by OFDI and IVUS was performed. Maximum thickness of calcification measured by OFDI was well correlated with histology (rs = 0.70, p < 0.0001) whereas IVUS was not useful for quantitative analysis because of the presence of acoustic shadows occurring behind calcifications. Furthermore qualitative evaluation could be carried out using OFDI, for calcifications with vague or invisible outer borders by OFDI had lipid contents (lipid pool or histologic necrotic core) more frequently as compared to those with a clear outer border (79% vs. 24%, p < 0.0001). We also found that calcified nodules, a well-recognized thrombogenic substrate, demonstrated atypical appearance in OFDI, showing irregular surfaces with high attenuation. OFDI demonstrated a greater ability than IVUS to provide quantitative and qualitative evaluation of coronary arterial calcification. Precise recognition of calcified plaque morphology by OFDI may serve to determine the treatment strategy of patients having atherosclerotic coronary disease.