The purpose of this study is to determine whether fusion technique of pre-radiofrequency ablation (RFA) cross-sectional imaging (CT or MR) and real-time ultrasonography would improve feasibility of RFA in patients with liver tumor in comparison with ultrasonography guidance alone.

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.

Inclusion Criteria: all conditions should be satisfied for inclusion.

• referred to Radiology in our institution for liver tumor RFA
• available pre-RFA liver CT or liver MR imaging within 6 weeks

Exclusion Criteria: patients with any of following condition should be excluded.

• any contraindication of liver RFA
• any patients who received treatment between pre-RFA imaging and planned RFA
• patients referred for palliative purpose.