Virtual sonographic radiofrequency ablation of hepatocellular carcinoma visualized on CT but not on conventional sonography.

OBJECTIVE Some nodules cannot be visualized clearly on conventional sonography but can be visualized on CT. In the present study, we evaluated the usefulness of real-time percutaneous ablation therapy under virtual sonographic guidance for these nodules. SUBJECTS AND METHODS In vitro experiments were performed with gelatin gel to evaluate the accuracy of virtual sonography. We also studied 50 patients with 58 hepatocellular carcinoma nodules, of whom 18 patients (21 nodules) underwent radiofrequency ablation by virtual sonography. This was the initial treatment for seven of these patients and an additional treatment for 11 patients. Thirty-two patients (37 nodules) received radiofrequency ablation without virtual imaging. The patients receiving standard radiofrequency ablation were retrospectively selected as the historical control group under the same conditions as the study group. RESULTS The in vitro gelatin gel study revealed that all punctures had been performed accurately. In both the initial-treatment group and the additional-treatment group, the mean number of treatments with virtual sonography was significantly lower than that without virtual sonography (p = 0.003 for both groups). The rates of local recurrence and complications did not differ significantly between the two groups. CONCLUSION In the treatment of nodules not depicted on sonography, radiofrequency ablation assisted by virtual sonography is an efficacious alternative.