158 Preclinical Direct Endoluminal Assessment of Endothelialization After Flow Diversion With Microangioscopy

INTRODUCTION: Endoluminal imaging (ELI) is an emerging adjunct in endovascular cerebral aneurysm management. Indirect ELI, as with optical coherence tomography, may be useful in detecting malapposition after flow diversion (FD). Direct ELI technologies, such as with our previous described microangioscope, have been shown to be able to delineate between different thrombi and visualize neoepithelialization after stent placement with high resolution. METHODS: In a rabbit model we implanted each left common carotid artery (CCA) with a shielded FD (Medtronic Pipeline Vantage) and non-shielded FD (Medtronic Pipeline Flex) in the right CCA. We studied 9 animals in 3 groups: 1) no periprocedural antiplatelet therapy, 2) aspirin 81 mg daily, 3) aspirin 81 mg and clopidogrel 75 mg daily. FD thrombosis, stenosis, malapposition, and neoepithelialization were all evaluated by diagnostic cerebral angiography (DSA) and microangioscopy after 30 days. DSA and angioscopic video were analyzed by independent evaluators and compared with histopathologic analysis. RESULTS: In the aspirin and DAPT groups, there were no significant observed differences in stent thrombosis, stenosis, malapposition, or neoepithelialization between the shielded and non-shielded FDs in each rabbit as measured by histologic analysis. There was significantly more thrombus formation in Group 1. Neointimal thickness as measured by the microangioscope was highly correlated with histology (r = 0.72, p = 0.016). Inter-rater agreement of microangioscope videos was highest for FD thrombosis and stenosis. CONCLUSIONS: There were no significant differences between in-stent thrombosis, stenosis, malapposition, or neopithelialization between shielded and non-shielded FDs. Microangioscopy measurements for neointimal thickness were highly correlated with pathology, and thus may be a helpful adjunct to DSA in FD follow-up.