Histology-validated comparison of angioscopy, IVUS, and OFDI for assessing stent strut coverage in femoropopliteal arteries with thin neointima

In-stent thrombotic occlusion remains a major clinical challenge after femoropopliteal stenting, and delayed healing is believed to contribute to this problem. However, conventional intravascular imaging may struggle to evaluate vascular healing due to limited resolution, particularly in thin neointima. This study aimed to validate the diagnostic performance of angioscopy for assessing endothelial strut coverage in thin neointima using histology as the reference standard. In a healthy swine model, 22 femoropopliteal arteries were evaluated one month after stenting. Ex vivo angioscopy, intravascular ultrasound (IVUS), and optical frequency domain imaging (OFDI) were performed. Endothelial strut coverage was assessed in segments with neointimal thickness < 1000 μm (thin neointima) using histology as the gold standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detecting endothelial-covered struts were calculated. A total of 112 co-registered image sets were obtained, of which 62 were classified as thin neointima. Histology identified endothelial-covered struts in 8 of 62 segments (12.9%). Angioscopy color assessment showed a sensitivity of 100%, specificity of 92%, PPV of 60%, and NPV of 100%. In contrast, IVUS and OFDI demonstrated a high sensitivity for detecting endothelial-covered struts; however, overestimated coverage and failed to distinguish endothelial-covered struts from fibrin-covered struts (sensitivity 100%, specificity 0%, PPV 15%). While IVUS and OFDI overestimate endothelial stent coverage in thin neointima, angioscopy offers superior diagnostic accuracy for identifying fibrin-covered struts and may serve as a valuable modality for assessing vascular healing in femoropopliteal arteries, potentially facilitating the optimization of antithrombotic therapy.