Jin Woong Kim MD, Abstract Co-Author: Nothing to Disclose

Sang Soo Shin MD, Presenter: Nothing to Disclose

Suk Hee Heo MD, Abstract Co-Author: Nothing to Disclose

Hyo Soon Lim MD, Abstract Co-Author: Nothing to Disclose

Sung Mo Kim, Abstract Co-Author: Nothing to Disclose

Yong-Yeon Jeong MD, Abstract Co-Author: Nothing to Disclose

Heoung-Keun Kang MD, Abstract Co-Author: Nothing to Disclose

To prospectively compare multi-detector CT and MR imaging in assessment of ablative margin (AM) and index tumor within ablation zones immediately after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC).

Based on our preliminary data, necessary number of patients was estimated to be at least 30 when an α error of 0.05 and a β error of 0.2 were applied. A total of 33 consecutive patients with 42 HCCs, who had successfully undergone contrast-enhanced CT and MR imaging after RFA, was enrolled in this study. CT and MR imaging were performed within 3 and 7 hours after completion of RFA, respectively. Both CT and MR images were reviewed in consensus by two radiologists in two separate sessions regarding visual discrimination between AM and index tumor and status of AM within ablation zones. The status of AM was classified as AM plus (AM completely surrounded tumor), AM zero (AM was partly discontinuous, without protrusion of tumor beyond postulated border of ablated area) and AM minus (AM was partly discontinuous, with protrusion of tumor). Any ablation zone with AM plus or AM zero was considered as imaging evidence to predict technical effectiveness, which was based on one-month follow-up CT, as well as to represent technical success.

With CT and MR imaging, visual discrimination between AM and index tumor was possible in 4 (9.5%) and 34 (81%) of 42 ablation zones, respectively (P< .001). Among 4 and 34 ablation zones in which status of AM could be evaluated on CT and MR imaging, respectively, all of 4 ablation zones were classified as AM plus on CT images, whereas 34 ablation zones were categorized into AM plus (n=28), AM zero (n=5) and AM minus (n=1) on MR images. Based on CT and MR imaging, technical success was determined to be achieved in 4 (9.5%) and 33 (78.6%), respectively (P< .001). The technical effectiveness was noted in all of ablation zones on one-month follow-up CT. CT and MR imaging predicted technical effectiveness in 4 (9.5%) and 33 (78.6%), respectively, (P< .001).

MR imaging was superior to multi-detector CT for assessment of ablative margin and index tumor within ablation zones immediately after RFA.

MR imaging performed immediately after RF ablation can provide sufficient information regarding necessity of additional ablation after RF ablation with more confidence than contrast-enhanced CT.

Kim, J, Shin, S, Heo, S, Lim, H, Kim, S, Jeong, Y, Kang, H, Imaging Evaluation of Ablative Margin and Index Tumor Immediately after Radiofrequency Ablation for Hepatocellular Carcinoma: Comparison between Multi-detector CT and MR Imaging.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012536.html