Transbronchial microwave ablation: feasibility and safety assessment in a porcine model

Abstract

<b>Objective:</b> Assess the feasibility and safety of virtual bronchoscopy-guided transbronchial microwave ablation in normal pig lung using radiologic and histologic evaluation. <b>Methods:</b> We performed virtual bronchoscopy-guided thermal ablation (90W, 5min) in 4 pigs with a custom microwave catheter. Pigs were euthanized at 2 (n=2) and 13 days (n=2) post-ablation. CT scans were taken prior to euthanasia, and also at day 2 for the 13 day group. Ablated and adjacent lung tissue was excised, stained with TTC for macroscopic viability analysis, and formalin-fixed for H&amp;E staining and microscopic analysis. <b>Results:</b> No adverse events were observed during ablation procedures and pigs maintained normal behavior and appetite through the survival period. At day 2, CT imaging overestimated ablation diameter compared to macroscopic analysis, likely due to inflammation obscuring the ablation boundary. At day 13, the CT measurement corresponded with the macroscopic analysis. Measurements provided in Table 1. At day 2, microscopic analysis identifies a central zone of thermal fixation (absence of erythrocytes and maintained architecture) with remnant alveoli filled with edema and fibrin, a surrounding marginal zone of hemorrhage and edema, and a peripheral zone with intra-alveolar macrophages and less edema. At day 13, a 1-2mm granulation tissue rim separates the ablation zone from adjacent aerated lung; the central zone is similar to day 2. <b>Table 1:</b> Ablation diameters from CT and macroscopic analysis <b>Conclusions:</b> We demonstrated the feasibility and safety of delivering bronchoscopy guided pulmonary microwave ablation in a porcine model.