Randomized Controlled Trial Comparing the Efficacy of Impedance Control and Temperature Control of Radiofrequency Interstitial Thermal Ablation for Treating Small Hepatocellular Carcinoma

OBJECTIVES: A randomized controlled trial was conducted to evaluate the efficacy of impedance control of a radiofrequency interstitial thermal ablation system (RITA) used to treat hepatocellular carcinoma (HCC). METHODS: Fifteen patients with hypervascular HCCs <20 mm in diameter were randomly treated with radiofrequency ablation (RFA) using conventional temperature control (group A) or impedance control methods (group B). RITA needle electrodes were used in all cases. We compared ablation time, extent of lesion ablation, and energy use between the two groups. RESULTS: The median long and short diameters of the axial cross sections of radiofrequency-induced necrotic areas visualized by CT were 32 mm (range, 26-36) and 25 mm (20-31) in group A and 32 mm (28-40) and 31 mm (24-37) in group B, respectively. The short diameter of group B patients was significantly greater than that of group A patients (p = 0.029). The median ablation time was 18.8 min in group A and 13.4 min in group B, thus significantly shorter in group B (p = 0.001). The energy requirement did not differ significantly between the groups. CONCLUSIONS: Impedance control of the RITA system resulted in an increased size of the ablation zone and a decreased ablation time.