Radiofrequency ablation of the liver in a rabbit model: creation of artificial ascites to minimize collateral thermal injury to the diaphragm and stomach

PURPOSE: To assess whether the creation of artificial ascites during radiofrequency (RF) ablation of the subcapsular portion of the liver can minimize collateral thermal injury to the diaphragm and stomach. MATERIALS AND METHODS: A total of 20 percutaneous RF ablation procedures were performed in the livers of 10 rabbits (control, n = 5; experimental, n = 5) with use of an internally cooled electrode (1-cm active tip). In the experimental group, artificial ascites was established before RF ablation by dripping 320 mL of normal saline solution via a 20-gauge sheathed needle to separate the liver from the diaphragm and stomach. In each rabbit, two subcapsular ablation zones were made in the inferior tip of the left lobe of the liver adjacent to the stomach and in the far dome of the right lobe next to the diaphragm consecutively. After the animals were killed 3 days after the procedure, the frequency, size, and degree of thermal injury were compared between the experimental and control groups. The degree of thermal injury was graded by visual inspection according to a four-point scoring system. Representative cases underwent gross and histologic analysis. RESULTS: Artificial ascites was achieved successfully with a single puncture in all rabbits in the experimental group. Mean procedure time for the formation of artificial ascites was 9 minutes. There was no difference in the size of the RF ablation zones in the liver between the two groups (P > .05). Thermal injury in the adjacent organs was observed significantly more frequently in the control group compared with the experimental group (diaphragm, 100% vs 0; stomach, 80% vs 20%; P < .05). CONCLUSION: Creation of artificial ascites may be a simple and useful technique that can be used to reduce the frequency and severity of thermal injury during RF ablation of subcapsular hepatic tumors.