Four-dimensional ultrasonography for therapeutic radiofrequency ablation for hepatocellular carcinoma.

Background/Aims: We examined whether four-dimensional real-time flow imaging on ultrasonography (US) is valuable to display the accurate position of percutaneous radiofrequency ablation (RFA) needle in the nodule of hepatocellular carcinoma (HCC). Methodology: Ten patients with 12 HCC nodules were studied; nine were infected with hepatitis C virus (HCV) and one was diagnosed as non-B non-C. Diagnosis was done by helical dynamic CT and/or celiac angiography. Tumor vascularities in the early arterial and post-vascular phases after injection of a microbubble contrast agent were assessed by real-time US scanning of coded harmonic imaging and intermittent interval-delay scanning with a wide-band power Doppler technology. Percutaneous RFA was performed with four-dimensional real-time flow imaging under US to display the accurate position of cool-tip needle. Results: It was possible to obtain accurate position of the needle during RFA procedure in all 12 nodules. The needle was confirmed to be inserted into the center of the tumor nodule by various angles. The simultaneous study before RFA therapy showed the inflow of arterial blood and tumor staining in all nodules at early arterial phase of coded harmonic angio on contrast-enhanced US scan. Posttreatment study to evaluate the therapeutic efficacy showed no blood flow at both early vascular and post-vascular phases. No residual blood flow was noted on early phase of CT scan with adequate safety margin. There was no discrepancy in the finding at early phase between contrast-enhanced US and dynamic CT. Conclusions: It appeared that four-dimensional real-time US provided more perceptible information on the spatial relationship between RFA needle and the target lesion, and resulted in accurate therapeutic efficacy for percutaneous RFA procedure.