- Carbon dioxide-enhanced sonographically guided radiofrequency ablation combined with transcatheter arterial chemoembolization for sonographically undetectable hepatocellular carcinoma. Ohmoto, K., Yoshioka, N., Tomiyama, Y., Shibata, N., Kawase, T., Yoshida, K., Kuboki, M., Yamamoto, S. Hepatogastroenterology (2005)