RESUMO
The efficacy of radiofrequency ablation (RFA) and RFA with concurrent ethanol injection (EI-RFA) was compared. RFA (3-cm-electrode) was applied to bovine liver using three types of RFA equipment; Radionics, RITA and Radio Therapeutics Corporation (RTC). For EI-RFA, 5 ml of 99.5% ethanol was injected around the electrode. A total number of 40 RFA and EI-RFA treatments were performed. We compared RFA with EI-RFA by examining the size, shape of ablation zone, treatment time, power, and needle tip temperature. Liver specimens were examined for pathological changes. EI-RFA produced a larger zone of ablation than RFA alone using Radionics and RITA (Radionics, 35.3+/-7.4 cm(3) vs 23.2+/-7.7 cm(3), p<0.05; RITA, 30.7+/-10.3 cm(3) vs 19.7+/-4.7 cm(3), p<0.05), corresponding to shortest diameters of coagulation zone (Radionics, 3.7+/-0.4 cm vs 3.0+/-0.4 cm, p<0.05; RITA, 3.8+/-0.4 cm vs 3.1+/-0.3 cm, p<0.01). However, a larger ablation zone was not seen with the RTC device. The ablated volume per energy and the ablated volume per current density administered were greater with EI-RFA than with RFA using Radionics (p<0.05). The shape of the ablated zone changed from ellipsoid to spherical with EI-RFA using Radionics. No pathological differences between RFA and EI-RFA samples were detected. For a given amount of energy and current administered, ethanol injection caused a better ablation effect, in terms of the size and shape of the ablated zone, than RFA with Radionics and RITA equipment.