Quantitative Evaluation of Incomplete Stent Apposition in Intracranial Aneurysms Using Optical Coherence Tomography: A Porcine Model Study

Background Incomplete stent apposition (ISA) of intracranial stents is recognized as a significant issue in aneurysm treatment leading to in-stent thrombosis and aneurysm recurrence. Traditional imaging techniques like DSA have limitations in accurately assessing stent apposition. This study aimed to explore the efficacy of optical coherence tomography (OCT) in the detection of ISA after stent-assisted coiling (SAC) and its impact on stent endothelialization and aneurysm healing in a porcine model. Materials and Methods Twelve healthy minipigs with surgically established common carotid artery sidewall aneurysm were utilized and treated with SAC. DSA and OCT were used immediately post-procedure and during follow-ups at 4 and 12 weeks to assess aneurysm occlusion and stent apposition. Histopathology ultimately assessed stent endothelialization and aneurysm healing. ISA distance, measured by OCT, was analyzed using logistic regression to predict the association between ISA severity and stent endothelialization outcome. Results OCT detected ISA sites (n = 30) in all subjects at the aneurysm neck, stent ends, and locally in the stent, with a mean ISA distance of 639.65 ± 146.82 µm immediately after the procedure. One experimental pig developed in-stent occlusion after 4 weeks, resulting in death. OCT detected residual ISAs in 54.2% (13/24) at 4 weeks, decreasing to 16.7% (4/24) at 12 weeks in the remaining 11 subjects. DSA showed complete aneurysm occlusion in the remaining subjects at 12 weeks. An ISA distance of > 600 µm was found to be associated with significantly higher rates of poor stent endothelialization at the 12-week follow-up. Conclusion OCT demonstrated higher sensitivity in detecting ISA after SAC. ISA distance > 600 µm can be a critical prognostic factor, associated with poor outcomes.