To compare the changes in the ablation zone of porcine lung tissue in vivo between low-power (40 W) and high-power (100 W) microwave ablation (MWA).

Microwave ablation was performed on porcine lungs in vivo. The ablation was divided into two groups based on power: 40 W and 100 W. Ablation times were set at 1 min, 3 min, 5 min, 8 min, and 10 min, with each group repeated three times, for a total of 30 ablations. The maximum long axis, short axis/thickness, volume, and aspect ratio of the ablation zone were recorded, and histological examination of the ablation zone was performed.

When the ablation power was constant, the long axis, short axis/thickness, and volume of the ablation zone increased gradually with time (all P<0.05). For the 40 W group with ablation times ranging from 1 to 10 minutes, the long axis of the ablation zone was 13.6±6.0 mm, the short axis/thickness was 10.4±3.8 mm, and the aspect ratio was 1.3±0.2. For the 100 W group with ablation times ranging from 1 to 10 minutes, the long axis of the ablation zone was 31.1±9.1 mm, the short axis/thickness was 19.9±6.5 mm, and the aspect ratio was 1.6±0.2. In the 40 W group, the increase in long axis, short axis/thickness, and volume of the ablation zone became stable at 8 min and 10 min of ablation, with neither long diameter nor short diameter/thickness exceeding 20 mm, and the aspect ratio remained between 1.3 and 1.4. In contrast, the long axis and short axis/thickness of the ablation zone in the 100 W group continued to increase within the same time frame, with the aspect ratio maintained between 1.4 and 1.5. Histologically, the ablation zone showed a coagulative necrosis zone at the center, surrounded by a zone of pulmonary tissue congestion, edema, and inflammatory cell infiltration, with visible inflammatory cell infiltration.

When the ablation time is the same, high-power (100 W) microwave ablation generates a larger ablation zone compared to low-power (40 W) microwave ablation and is more suitable for the ablation treatment of lesions with a diameter greater than 20 mm. Further investigation into its clinical application is warranted.