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.