For the technical success of radiofrequency ablation (RFA), the tumor and a sufficient ablative margin must be included in the ablative area. However, the safety margin cannot be evaluated accurately on ultrasound (US) during and immediately after RFA because the strong acoustic scattering due to ablation often obscures the tumor. US-US overlay fusion is a new image fusion technology showing preoperative and postoperative US images side-by-side synchronously. The overlays can demonstrate an ablative hyperechoic zone including the colorized tumor. Therefore, US-US overlay fusion can visualize the ablative margin and predict the early response of treatment assessment with high accuracy. US-US overlay fusion guidance can contribute to obtaining sufficient margins to RFA therapy. We call this "precision RFA".
