Fig. 1.

69-year-old female with hepatocellular carcinoma (HCC) of liver.

A. Axial arterial phase T1 weighted image (repetition time/echo time, 4.4/2.1 ms) shows 3 cm-sized enhancing HCC (arrowheads) in segment 5 of liver. B. On planning sonography for radiofrequency ablation (RFA) obtained 7 d after MR imaging, index tumor is seen as heterogeneous, low-echoic lesion (arrowheads). Index tumor measured 3.8 cm in longest diameter which is much larger than MR measurement (3.0 cm). C. After chemoembolization, near compact iodized oil has accumulated in tumor (arrowheads). D. RFA was performed 2 weeks after chemoembolization. To minimize thermal injury to adjacent abdominal wall, 500 mL of artificial ascites was introduced immediately before RFA procedure. Anteroposterior (superior images) and its corresponding lateral (inferior images) fluoroscopic images show electrodes obliquely placed in index tumor with retained iodized oil. Total of 9 overlapping ablations were performed using retained iodized oil, as Anatomic landmark. Retained iodized oil remained almost unchanged through multiple overlapping treatments. Total ablation time was 32 min. E. On sonography after initial electrode placement, echogenicity of index tumor (arrowheads) is slightly increased compared to that of on planning ultrasonography. Electrode was inserted until exposed tip (arrows) passed through tumor, enough to obtain sufficient ablative margin. F. After ablating upper part of index tumor (black asterisk), electrode tip and margin of tumor was invisible due to echogenic zone produced by prior ablations. In addition, margin of lower part of tumor not yet ablated (white asterisk), is also obscured by echogenic zone and its shadow. G. Portal venous phase axial CT image obtained immediately after RFA shows HCC with iodized oil retention (arrow) and nonenhancing area surrounding tumor (arrowheads), indicating technical success.