Comparison of tissue pressure and ablation time between the LeVeen and cool-tip needle methods

A block of pig liver sealed in a rigid plastic case was used as a model of an HCC tumor with a capsule. The multi-step method with the LeVeen electrode resulted in the lowest pressure as compared with the single-step or cool-tip methods. There was no significant difference in the ablation time between the multi-step and cool-tip ablation methods, although the single-step methods had longer ablation times than the other ablation procedures. In HCC cases, the multi-step method had a significantly shorter ablation time than the single-step or cool-tip methods.We demonstrated that the multi-step method was useful to reduce the ablation time and to suppress the increase in pressure. The multi-step method using a LeVeen needle may be a clinically applicable procedure for RFA.Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Most of HCC patients suffer from virus-induced liver injury and most have underlying liver cirrhosis [1]. Percutaneous ethanol injection therapy (PEIT) has been used widely for the treatment of unresectable HCC [2]. Many reports showed that the efficacy of PEIT for small HCC tumors was comparable to that of hepatic resection; however, PEIT demands multiple sessions to achieve complete necrosis, resulting in protracted hospitalization [3]. Furthermore, many patients suffer from local recurrence after PEIT, which is attributable to intra-tumor septa that prevent the injected ethanol from infiltrating the entire tumor [4,5]. We reported that local recurrence after PEIT should be prevented as much as possible because it is one of the most important negative prognostic factors for HCC patients [6].It has been reported that radio frequency ablation (RFA) is an effective procedure for hepatocellular carcinoma (HCC) as well as for metastatic liver tumors [7,8]. However, it has also been shown that it is not uncommon for RFA to cause various complications [9,10]. During or just after the procedure, peritoneal bleeding, hepatic abscess,