BACKGROUND: The histopathological validation of optical coherence tomography (OCT) in visualizing atherosclerotic plaques has been reported only in ex vivo studies. We sought to evaluate the accuracy of OCT in tissue characterization in vivo. METHODS AND RESULTS: A total of 25 patients with stable angina pectoris who underwent directional coronary atherectomy (DCA) were included in the investigation, whereby OCT was performed before and after a single debulking. The debulked region was determined on OCT and classified into fibrous tissue, lipid, calcification, thrombus, and macrophage accumulation, which were compared with histology. Changes in OCT signal intensity in the deeper intimal region after DCA were also visually evaluated. Fibrous tissues were detected in all cases, while thrombus was identified only in 1 case, by both OCT and histology. The sensitivity, specificity, positive and negative predictive values, and predictive accuracy for lipid detection by OCT were 88.9%, 75.0%, 66.7%, 92.3%, and 80.0%; those for calcification were 50.0%, 100%, 100%, 91.3%, and 92.0%; and those for macrophage accumulation were 85.7%, 88.9%, 75.0%, 94.1%, and 88.0%, respectively. The false positive diagnoses for lipid were mostly attributed to the extracellular matrix accumulation containing less collagen. The false negative diagnoses for calcification were explained by the presence of lipid around the calcification. The OCT signal intensity in the deeper intimal region substantially increased after DCA in all cases. CONCLUSIONS: The current study showed excellent predictive accuracy of in vivo OCT in tissue characterization, whereas the limitations of OCT were highlighted by an over-detection of lipid, under-detection of calcification, and underestimation of the deeper intimal matrix.
BACKGROUND: The histopathological validation of optical coherence tomography (OCT) in visualizing atherosclerotic plaques has been reported only in ex vivo studies. We sought to evaluate the accuracy of OCT in tissue characterization in vivo. METHODS AND RESULTS: A total of 25 patients with stable angina pectoris who underwent directional coronary atherectomy (DCA) were included in the investigation, whereby OCT was performed before and after a single debulking. The debulked region was determined on OCT and classified into fibrous tissue, lipid, calcification, thrombus, and macrophage accumulation, which were compared with histology. Changes in OCT signal intensity in the deeper intimal region after DCA were also visually evaluated. Fibrous tissues were detected in all cases, while thrombus was identified only in 1 case, by both OCT and histology. The sensitivity, specificity, positive and negative predictive values, and predictive accuracy for lipid detection by OCT were 88.9%, 75.0%, 66.7%, 92.3%, and 80.0%; those for calcification were 50.0%, 100%, 100%, 91.3%, and 92.0%; and those for macrophage accumulation were 85.7%, 88.9%, 75.0%, 94.1%, and 88.0%, respectively. The false positive diagnoses for lipid were mostly attributed to the extracellular matrix accumulation containing less collagen. The false negative diagnoses for calcification were explained by the presence of lipid around the calcification. The OCT signal intensity in the deeper intimal region substantially increased after DCA in all cases. CONCLUSIONS: The current study showed excellent predictive accuracy of in vivo OCT in tissue characterization, whereas the limitations of OCT were highlighted by an over-detection of lipid, under-detection of calcification, and underestimation of the deeper intimal matrix.