Bipolar RFA Using Twin ICW Electrodes vs. Switching Monopolar RFA for Recurrent HCC

Inclusion Criteria: * radiologic or pathologic diagnosis of HCC recurrence after locoregional treatment * HCC nodules measuring 1 cm or larger and smaller than 5 cm Exclusion Criteria: * more than three HCC nodules * tumors with major vascular invasion or abutment to the central portal or hepatic vein with a diameter \> 5mm * extrahepatic metastasis * Child-Pugh class C * severe coagulopathy (platelet cell count of less than 50,000 cells/mm3 or prothrombin time international normalized ratio (PT-INR) prolongation of more than 50 %)