Carbon dioxide-enhanced sonographically guided radiofrequency ablation combined with transcatheter arterial chemoembolization for sonographically undetectable hepatocellular carcinoma.

A 73-year-old man was diagnosed as having hepatitis C virus-related liver cirrhosis 11 years ago. Two years ago, he developed hepatocellular carcinoma in segment 6 of the right lobe and received radiofrequency ablation. This time, he was admitted to our hospital with a local recurrence in segment 6 of the liver. Standard sonography could not visualize the lesion clearly. However, carbon dioxide-enhanced sonogram clearly showed the whole lesion, so a needle electrode could be inserted precisely, allowing safe and accurate radiofrequency ablation. By combining radiofrequency ablation with transcatheter arterial chemoembolization, complete tumor necrosis was achieved without the need to perform additional ablation. In conclusion, carbon dioxide-enhanced sonographically guided radiofrequency ablation combined with transcatheter arterial chemoembolization is useful for complete cure of localized tumors, such as recurrent hepatocellular carcinoma, which cannot be detected clearly by conventional sonography.