Radiofrequency ablation of liver tumors: the role of microbubble ultrasound contrast agents.

Radiofrequency ablation (RFA) is currently indicated for the treatment of primary and metastatic hepatic malignancies. Real-time ultrasound (US) is generally used during the procedure to guide electrode placement, but for evaluating the results of treatment, contrast-enhanced computed tomography and magnetic resonance imaging have traditionally been considered more effective. This view has changed, however, with the recent development of contrast-enhanced ultrasound (CEUS) (eg, using sulfur hexafluoride microbubbles), which can provide valuable information on the effects of RFA more rapidly and economically than computed tomography or magnetic resonance imaging without exposing the patient to ionizing radiation. In our center, CEUS is performed in patients with liver tumors before and immediately after RFA, in selected cases during the procedure as well, and in the follow-up. Between January 2003 and June 2005, we performed CEUS on 350 patients scheduled for RFA of primary or metastatic liver tumors. In 14 (13.4%) of the 96 patients whose disease was metastatic, CEUS revealed lesions that had been missed on the conventional US examination. In most of these cases, the result was a more complete treatment performed under CEUS guidance. In the remaining 2 (14%) of 14, the results of the examination allowed us to avoid subjecting the patient to useless treatment. In our experience, the use of CEUS also improved the management and follow-up of patients undergoing interstitial therapy.