RFA is one of commonly used local therapies for primary or secondary liver tumors. For successful and safe procedure, safe route of electrode and lesion visibility are essential for RFA, and the conditions are usually evaluated on pre-RFA planning ultrasonography (USG). However, RFA is sometimes aborted due to limited sonic window of various cause and challenging identification of small isoechoic tumors or hepatocellular carcinomas among dysplastic nodules . Therefore, precise targeting and assuring safe route would be of clinical importance. In this preliminary study, investigators attempted to determine US and CT/MR fusion technique would be able to improve RFA feasibility in patients with liver tumors in comparison with conventional US alone technique.