Ablation Volume Measurement After Percutaneous Cryoablation Using a Two-cryo-probe Technique for Small Hepatocellular Carcinomas

PURPOSE: To calculate the ablation volume of percutaneous cryoablation (PCA) with a two-cryo-probe technique for small hepatocellular carcinomas (HCCs) and to assess risk factors for local tumor recurrence (LTR). MATERIALS AND METHODS: Between January 2013 and June 2017, 96 patients (mean age, 60.7 years; range, 37-83 years) with 106 small HCCs were retrospectively analyzed. The ablation volume, technical success, LTR rates, and complications were evaluated. Ablation volume was measured after the first freezing and immediately after completing PCA twice via computed tomography imaging. Prognostic factors associated with LTR were analyzed. RESULTS: Technical success was achieved in all patients. The mean final ablation volume was 19.1 ± 4.8 cm3, which was significantly higher than the first freezing ablation volume (14.7 ± 4.3 cm3, p < 0.001). During the median follow-up period of 16.7 months (range, 5-52 months), LTR-free survival rates based on Kaplan-Meier analyses at 6 months, 1 year, and 2 years were 87.7%, 84.0%, and 80.2%, respectively. Only one major complication of post-procedural arterial bleeding occurred. A final ablation volume/tumor volume < 10 was a significant risk factor for LTR (p = 0.044). CONCLUSIONS: A ratio of final ablation volume to tumor volume < 10 was a significant prognostic factor for LTR. Therefore, the measurement and prediction of the final ablation volume are important to reduce LTR.restrictio