A Comparison of US-guided Percutaneous Radiofrequency Ablation of Medium-sized Hepatocellular Carcinoma with a Cluster Electrode or a Single Electrode with a Multiple Overlapping Ablation Technique

Purpose: To compare ablation zone, local therapeutic efficacy, and complications of ultrasound (US)-guided percutaneous radiofrequency (RF) ablation of medium-sized hepatocellular carcinomas (HCCs) with a cluster electrode versus a single electrode with multiple overlapping ablations. Materials and Methods: From February 2005 to January 2009, a total of 79 consecutive patients (57 men, 22 women; mean age, 58.6 y) with 79 HCCs (range, 2.5-4.0 cm) underwent percutaneous RF ablation with a cluster electrode (n = 37) or a single electrode with multiple overlapping ablations (n = 42). These methods were compared in terms of ablation zone size on immediate follow-up computed tomography and the rates of technique effectiveness and cumulative local tumor progression on further follow-up (range, 12.0-46.2 mo; median, 24.3 mo). Results: Baseline characteristics did not differ between groups. The ablation zone in the cluster group was significantly smaller in the longitudinal dimension (43.7 mm +/- 4.8 vs 46.5 mm +/- 5.9; P = .03), but greater in the short axial dimension (30.7 mm +/- 3.9 vs 27.3 mm +/- 5.5; P = .03), compared with that in the overlapping ablation group. Technique effectiveness rates in the cluster and overlap groups were 100% and 92.9% (39 of 42), respectively (P = .24). The cumulative local tumor progression rate was significantly lower in the cluster group than in the overlapping group (1- and 3- year follow-up: 8.1 and 18.8% vs 23.8 and 42.2%, P = .04). Complications were more frequent in the cluster group than in the overlapping group (27.0% vs 7.1%; P = .03). Conclusions: In US-guided percutaneous RF ablation of medium-sized HCCs, the cluster electrode showed better local therapeutic efficacy than the single electrode with multiple overlapping ablations, probably because of the favorable shape of the ablation zone; however, complications occurred more frequently.