Experimental And Clinical Study On Microwave Ablation Of Porcine Livers And Liver Carcinoma With 915mhz Implanted Internally Cooled Antenna

Objective:1. To explore the ablation shapes and sizes of 915MHz implanted internally cooled microwave in ex vivo and in vivo porcine livers and determine the relationship between power, duration and size of coagulated zones.2. To explore the feasibility and effectiveness of this technique for treating large hepatocellular carcinoma (diameter>4.Ocm).Methods:1. Ex Vivo study:The antenna of 915MHz implanted internally cooled microwave was inserted into porcine livers in ex vivo and in vivo, the shape and size of coagulated area were evaluated. The size of ablation zone was measured under four power outputs(50W,60W,70W,80W) at an ablation time of 600s.2. Clinical study:8 HCC patients with 10 nodules (diameter 5.6x4.4cm).915 inplanted cooled microwave ablation was performed in these liver nodules under power output 50-60W at an ablation time of 420-680s. Size of the tuomor and ablation zone was measured by contrast-enhanced ultrasound and the ehtrapeutic results were assessed by contrast-enhanced ultrasound, contrast-enhanced CT or MRI..Results:1. Ex Vivo study: During ablation the temperature of antenna of 915MHz implanted internally cooled microwave ranged from 38 to 45℃. After ablation the antenna was pulled out without any resistance and no coagulated tissue was adhered.The cross-section of ablation samples displayed as ellipsoidal coagulation mode and had distinct margin from the normal liver tissue. No remarkable "tail" was found in ablation zone.Experiment in vitro:The average ablation coagulation zone was 5.8×3.3cm at the power output of 60W×600S,the average ablation coagulation zone was 6.3X4.3cm at the power output of 60W×1200S.No statistical significance was found in the coagulation volume between the power output of 60W×1200S and the power output of 60W×1500S.Experiment in vivo:After an ablation time of 600s. the long-axis coagulation diameters enlarged with the increasing power output ranging from 50W,60W,70W to 80W, the short-axis coagulation diameters also enlarged with increasing power output ranging from 50W to 70W.but no statistical significance was found in short-axis diameters while the power output increasing from 70W to 80W..2. Clinical study:8 HCC patients with 10 nodules(average size 5.6x4.4cm). The average ablation zone displayed by contrast-enhanced ultrasound was 6.7x4.9cm and covered all the nodules. No recurrence, intra-hepatic or extra-hepatic metastases were observed. No major complications like uncontrollable hemorrhage or bile fistula occurred. Conclusion:1.The implanted internally cooled system of 915MHz microwave could decrease the temperature of antenna shaft.2.The experiment of 915MHz implanted internally cooled microwave in vitro and vivo indicated that with the increase of power output at fixed ablation time, the ellipsoidal coagulation zone would enlarge, especially in the long-axis diameter.3.When ablation time prolonged to 1200s, the role of increasing ablation time to enlarge coagulation zone was limited.4.915 inplanted cooled microwave ablation was proved to be safe and effective for large liver carcinoma and would provide a promising method to treat liver tumors.