Radiofrequency ablation assisted by real-time virtual sonography for hepatocellular carcinoma inconspicuous under sonography and high-risk locations

Radiofrequency ablation (RFA) is an effective and real-time targeting modality for small hepatocellular carcinomas (HCCs). However, mistargeting may occur when the target tumor is confused with cirrhotic nodules or because of the poor conspicuity of the index tumor under ultrasonography (US). Real-time virtual sonography (RVS) can provide the same reconstruction computed tomography images as US images. The aim of this study is to investigate the usefulness of RVS-assisted RFA for HCCs that are inconspicuous or conspicuous under US. A total of 21 patients with 28 HCC tumors - divided into US inconspicuous and high-risk subgroup (3 tumors in 3 patients), US inconspicuous and nonhigh-risk subgroup (5 tumors in 4 patients), US conspicuous and high-risk subgroup (16 tumors in 14 patients), and US conspicuous and nonhigh-risk subgroup (4 tumors in 3 patients) - underwent RVS-assisted RFA between May 2012 and June 2014 in our institution. The mean diameter of the nodules was 2.0 ± 1.1 cm. The results showed that the complete ablation rate is 87.5% (7/8) in the US undetectable group and 75% (15/20) in the US detectable group. A comparison between six tumors with incomplete ablation and 22 tumors with complete ablation showed higher alpha-fetoprotein level (mean, 1912 ng/mL vs. 112 ng/mL) and larger tumor size (mean diameter, 26 mm vs. 16 mm) in the incomplete ablation nodules (both p < 0.05). In conclusion, RVS-assisted RFA is useful for tumors that are difficult to detect under conventional US and may also be useful for tumors in high-risk locations because it may prevent complication induced by mistargeting.