Comparison between biliary cirrhosis and normal porcine liver treated with microwave ablation using a cooled-tip electrode

Abstract

To elucidate the difference in both in vivo and ex vivo microwave ablation in a biliary cirrhotic porcine liver model using a cooled-tip antenna. Two months after biliary ductal ligation, liver biopsy was performed to confirm the establishment of biliary cirrhosis in 4 Tibetan miniature pigs. Microwave ablation with cooled-tip antenna was conducted under laparotomy using 70 W for five minutes in the experimental group (4 pigs). The control group (2 pigs) also received microwave ablation using the same settings but no surgery. Both in-vivo and ex-vivo ablations were performed in the two groups. Morphological and pathological characteristics of the ablation areas were compared. Paired comparison among the groups were conducted using t-test. In the cirrhotic liver group, after ablation at 70 W for five minutes, the short and long axes and volume of in vivo ablation areas were (1.90 ± 0.10) cm, (2.95 ± 0.12) cm, and (6.0 ± 0.8) cm(3) compared to (2.08 ± 0.08) cm, (3.08 ± 0.75) cm, and (7.0 ± 0.5) cm(3) of ex vivo ablation. In the normal liver group the dates were (2.04 ± 0.05) cm, (3.14 ± 0.11) cm and (6.8 ± 0.5) cm(3); (2.30 ± 0.18) cm, (3.60 ± 0.08) cm and (10.0 ± 1.7) cm(3), respectively. In vivo ablation area was smaller than ex vivo ablation area in terms of short and long axes and volume (P = 0.028 0.026, 0.008, respectively). With the same ablation settings, both in vivo and ex vivo ablation areas in normal pig liver were larger than their counterparts in cirrhotic liver in terms of the short and long axes and volume (P = 0.019, P = 0.000; P = 0.024, P = 0.036, respectively), but the differences in the short axes of in vivo and ex vivo ablation areas failed to reach significance. Both in vivo and ex vivo ablation areas in biliary cirrhotic pig liver were smaller than their counterparts in normal pig liver suggesting that, the ablation time or power should be relatively prolonged to enlarge the ablation zone within cirrhotic liver in order to prevent incomplete ablation with viable residual tumor.