Percutaneous radiofrequency ablation of HCC: reduced ablation duration and increased ablation size using single, internally cooled electrodes with an optimized pulsing algorithm

Purpose: To assess the use of optimized radiofrequency (RF) to achieve larger, spherical ablation volumes with short application duration for hepatocellular carcinoma (HCC). Materials and methods: Twenty-two patients (M:F=17:5, median age 69.6year, range 63-88) with 28 HCCs due to HCV+liver cirrhosis underwent RFA. 20/28 (71.4%) were tumors <= 3cm diameter, and 8/28 (28.6%) ranged from 3.2 to 4.2cm. RF was applied using up to 2500mA via an optimized pulsing algorithm with real-time ultrasound monitoring to detect hyperechogenic changes. Single insertions of an internally cooled electrode were performed using exposed tips of 2 or 3cm for 13 HCCs and 4cm for 15 HCCs. All patients were followed-up for a minimum of 5years with contrast-enhanced computed tomography (CECT). Results: Technical success was achieved without adverse events in all cases. The mean ablation time was 8.52.6min. In 21/28 (75%), ablation duration ranged from 3 to 9min, with 12min duration applied in only 7/28 (25%). Mean coagulation diameters were 2.4 +/- 0.14, 3.3 +/- 0.62, and 4.4 +/- 1.0, for 2, 3 and 4cm electrodes, respectively (p < 0.01). The sphericity index was 74.9 +/- 12.8 for 4cm electrodes and 81.9 +/- 8.0 for shorter electrodes (p=0.091). At 5-year follow-up, no tumor <= 3cm had recurrence and only 2/8 (25%) > 3cm tumors developed local progression. One patient had multifocal disease with no local progression. Conclusion: Efficient delivery of RF energy can considerably decrease the ablation time in many instances while achieving larger, relatively spherical, and reproducible areas of ablation with extremely low rates of local tumor progression and adverse events.