Objectives. We performed this study of a commercially available 100-Watt radiofrequency ablation (RFA) generator with a 3.5 cm diameter needle electrode compared to a new 200-Watt generator and 4.0 cm diameter needle electrode to determine 1) the size of the zone of complete thermal ablation and 2) the time needed to achieve thermal ablation.
Methods: Malignant liver tumors 2.1-5.0 cm diameter were treated with a 100-Watt RF generator with a 3.5 cm diameter multiple array needle electrode (N = 85 tumors) or a 200-Watt RF generator with a 4.0 cm diameter multiple array needle electrode (N = 52 tumors). The number of deployments of the needle electrode required to totally ablate the tumor, the total RFA treatment time, and the size of the radiographic zone of coagulative necrosis was recorded.
Results: The more powerful RF generator with the larger diameter multiple array needle electrode produced equivalent to larger zones of coagulative necrosis with fewer deployments of the needle electrode and in a significantly shorter time. The treatment time per deployment was also shorter using the novel generator and electrode (P < 0.05). These results are summarized in the table below.
Conclusions: A novel 200-Watt RFA generator and larger diameter multiple array needle electrode produces 1) zones of thermal ablation equivalent or slightly larger than the zones produced by commercially available equipment but 2) does it in a significantly shorter time period with fewer deployments of the multiple array electrode. Evaluation of this more powerful generator to treat tumors larger than 5 cm in diameter is ongoing.
RF Generator/Needle Electrode Diameter
100-W/3.5 cm 200-W/4.0 cm
n = 85 tumors n = 52 tumors
No. of deployements median (range) 6 (2-9) 2* (1-3)
Treatment time median (range) 48.5 min (14-95 min) 18.3 min* (6-39 min)
Diameter of RFA lesion median (range) 3.8 cm (2.9-5.5 cm) 4.3 cm (3.2-6.5 cm)
*P<0.05, 200-W/4.0 cm vs. 100-W/3.5 cm