RESUMO
PURPOSE: The purpose of this study was to investigate the development and evolution of the microwave ablation (MWA) lesion in the normal lung by using a swine model at various time points and to compare post-procedural computed tomography (CT) and gross pathologic findings during the first month post-ablation. MATERIALS AND METHODS: Twenty-seven percutaneous MWA procedures were performed on swine lungs at 100W for either 2min (low dose, 18 ablations) or 10min (high dose, 9 ablations). Animals were sacrificed at either 2 days (n=5) or 28 days (n=5) after ablation. All animals underwent CT imaging immediate post-treatment and prior to sacrifice, with additional imaging at 7 and 14 days for the 28-day cohort. After euthanasia, lungs and trachea were removed en bloc and underwent gross pathology analysis. RESULTS: In both dose treatment groups, CT measurements of the ablation zone were maximum at Day 7 (low dose: 7.50±3.08 cm3; high dose: 24.87±11.34 cm3) and significantly larger compared to the immediate post-ablation measurements (low dose: 2.54±1.81 cm3; P=0.00011; high dose: 9.14±3.42 cm3; P=0.00374). No significant differences in dimensions were observed between CT and gross pathologic images for both high and low dose ablations in both cohorts. CONCLUSION: The treatment zone following MWA in the lung can vary in the sub-acute setting, achieving largest size at 7 days post-treatment. Furthermore, measurements from CT closely matched with gross pathologic ablation size.