Radiofrequency ablation: in vivo comparison of four commercially available devices in pig livers

To compare in vivo coagulation necrosis obtained with four radiofrequency (RF) ablation devices, to determine shape and reproducibility of induced coagulation by means of three-dimensional measurements of the ablation zone, and to achieve representations of the coagulated areas in three-dimensional spaces.

Four commercially available RF devices (perfusion, internally cooled cluster, and nine- and 12-tine expandable electrodes) that represent the most widely used systems on the market were tested. Sixteen in vivo ablation procedures were performed in porcine livers (four ablations for each RF system). After macroscopic and histopathologic analyses of 3-mm-thick liver sections, morphometric and volumetric findings in the central zone of white coagulation necrosis were assessed. Coagulation volume, diameter, length, and shape were determined digitally. After analysis of variance, measurements with each system were tested with the Tukey post hoc test.

Mean coagulation volumes were 31.5 cm3 +/- 15.8 (SD) for the perfusion electrode, 20.5 cm3 +/- 2.6 for the cluster electrode, 16.2 cm3 +/- 7.3 for the 12-tine electrode, and 9.8 cm3 +/- 3.2 for the nine-tine electrode (P <.05, perfusion vs nine-tine electrode). No significant differences were observed regarding the mean short axis perpendicular to the needle shaft: 2.30 cm +/- 0.94, 3.04 cm +/- 0.26, 3.44 cm +/- 0.21, and 2.70 cm +/- 0.76, respectively. Variation coefficients were 0.50, 0.13, 0.45, and 0.33, respectively.

Larger coagulation volumes were obtained with the perfusion and internally cooled cluster devices. More spherical volumes of ablation were achieved with the 12-tine and cluster electrodes. The former proved superior with regard to the short axis perpendicular to the needle shaft. The cluster and nine-tine electrode produced better reproducibility, which is suggestive of improved predictability of the extent of coagulation with these systems.