[Experimental study on ablation zone and characteristics of microwave ablation in porcine kidney in vitro].

OBJECTIVE: To observe the ablation zone and characteristics of microwave ablation with different power and time in the model of porcine kidneys in vitro. METHODS: 2 450 MHz water circulative-cooling microwave needles were used, and the length of the anterior pole was 1.10 cm. The independent variables were power (50-70 W), time (240-600 s) and ablated with different combinations. The ablation shape, zone and pathological characteristics were observed. RESULTS: The effective ablation shape was similar to a chestnut and the ablation zone enlarged with the increasing of power and time. When combined with 50 W/480 s, 60 W/300 s, 70 W/240 s, the largest transverse-diameter of the ablated tissue was close to 3.00 cm and the length-diameter was about 3.30 cm. The pathological characteristics indicated that renal tissues of carbonization zone were thoroughly necrotic.Coagulative necrosis was observed in coagulation area, though there were residual profile of glomerulus, renal tubular and vessels, they had lost activity. Most of the tissues in transition zone were normal, however, some cells were swelling because of thermal damage. CONCLUSION: Microwave ablation is an emerging thermal therapy which can be safely, effectively used in the treatment of renal tumors that are smaller than 3 cm.