Assessment of thermal damage to myometrium during microwave ablation of uterine fibroids

Thermal ablation techniques are increasingly used for the treatment of symptomatic uterine fibroids. Thermal protection of myometrial tissue adjacent to the fibroid from ablation is critical to maximally preserve the uterus. This study presents a bench top experimental setup, using ex vivo bovine muscle as a surrogate tissue, for evaluating collateral thermal damage in tissues during fibroid ablation. The study reports on the effect of applicator insertion angles (67.5° and 90°) into a mock fibroid on the efficacy of treatment. 6 experiments were performed (3 for each insertion angle) with 30 W applied power at 2.45 GHz. The heating duration was restricted to the time at which a thermal dose of 10 cumulative equivalent minutes at 43 °C (10 CEM 43) was accrued at the boundary of the mock fibroid. Results showed that the volume of ablation inside the mock fibroid dropped considerably from 66% to 17% when the applicator insertion angle was changed from 90o to 67.5o, suggesting that insertion angle plays an important role during microwave ablation of fibroid. The proposed setup provides a method for validating computational models for accurate and safe delivery of ablation to target tissues in fibroid treatment.