Hepatic lesion ablation with bipolar saline-enhanced radiofrequency in theaudible spectrum

Rationale and Objectives. The authors' purpose was to create larger and mor e regular liver lesions in vitro by testing a new hyperthermia approach tha t uses a bipolar saline-enhanced electrode for radiofrequency (RF) in the a udible spectrum and a greater power supply. Materials and Methods. The authors' hyperthermia approach (group A, n = 23) was used in excised porcine livers, and the results were compared with tho se of a previously described monopolar saline-enhanced electrode procedure (group B, n = 23). In each set of experiments, RF in the audible spectrum c urrent (50 Hz) was provided For 15 minutes with a similar ablation protocol . Electrical variables (impedance, current, voltage, power, and energy), te mperatures in the lesions, volume size, regularity ratio of the lesion, and microscopic findings were measured. Results, In group A, the mean volume size and the mean regularity ratio val ues were 144.8 cm(3) +/- 59.8 and 0.78 +/- 0.1, respectively. In group B, t he mean volume size and regularity ratio values were 62.1 cm(3) +/- 36.4 an d 0.62 +/- 0,1, respectively. The values in group B were thus significantly lower than those in group A (P < .01). The lesions in group A were also mo re homogeneous. No significant differences were found in electrical variabl es. Conclusion, The new bipolar saline-enhanced electrode produced larger, more regular, and more homogeneous lesions ex vivo than the previously used mon opolar saline-enhanced electrode method. Using a greater power supply incre ased the amount of coagulative necrosis.