In Vivo Evaluation of Lung Microwave Ablation in a Porcine Tumor Mimic Model

Abstract

To evaluate the microwave ablation of created tumor mimics in the lung of a large animal model (pigs), with examination of the ablative synergy of multiple antennas. Fifty-six tumor-mimic models of various sizes were created in 15 pigs by using barium-enriched minced collected thigh muscle injected into the lung of the same animal. Tumors were ablated under fluoroscopic guidance by single-antenna and multiple-antenna microwaves. Thirty-five tumor models were treated in 11 pigs with a single antenna at 75W for 15min, with 15 measuring 20mm in diameter, 10 measuring 30mm, and 10 measuring 40mm. Mean circularity of the single-antenna ablation zones measured 0.64±0.12, with a diameter of 35.7±8.7mm along the axis of the antenna and 32.7±12.8mm perpendicular to the feeding point. Multiple-antenna delivery of 75W for 15min caused intraprocedural death of 2 animals; modified protocol to 60W for 10min resulted in an ablation zone with a diameter of 43.0±7.7 along the axis of the antenna and 54.8±8.5mm perpendicular to the feeding point; circularity was 0.70±0.10 A single microwave antenna can create ablation zones large enough to cover lung tumor mimic models of ≤4cm with no heat sink effect from vessels of ≤6mm. Synergic use of 3 antennas allows ablation of larger volumes than single-antenna or radiofrequency ablation, but great caution must be taken when 3 antennas are used simultaneously in the lung in clinical practice.