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

Abstract

Background: Radio frequency ablation (RFA) has been accepted clinically as a useful local treatment for hepatocellular carcinoma (HCC). However, intrahepatic recurrence after RFA has been reported which might be attributable to increase in intra-tumor pressure during RFA. To reduce the pressure and ablation time, we developed a novel method of RFA, a multi-step method in which a LeVeen needle, an expansion-type electrode, is incrementally and stepwise expanded. We compared the maximal pressure during ablation and the total ablation time among the multi-step method, single-step method (a standard single-step full expansion with a LeVeen needle), and the method with a cool-tip electrode. Finally, we performed a preliminary comparison of the ablation times for these methods in HCC cases.

Results: 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.

Conclusion: 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.

Figure 1

The maximal pressure (A) and total ablation time (B) on the porcine liver model, compared for the various tested methods. The multi-step method with a LeVeen needle resulted in a significantly lower pressure than the cool-tip procedure or the single-step method, and a total ablation time equal to that of the cool-tip procedure. All measurements were performed four times, and the results are expressed as mean ± SD. Statistical comparisons for the maximal pressure and the total ablation time were made using ANOVA and Scheffe's test. ^ap < 0.05 vs. cool-tip; ^bp < 0.05 vs. single-step.