Coil-assisted RFA of poorly visible liver tumors: Effectiveness and risk factors of local tumor progression

Objectives: This study was designed to determine the effectiveness of a percutaneously inserted coil as a landmark before radiofrequency ablation (RFA) of poorly visible liver tumors on unenhanced computed tomography and ultrasound. Methods: This was a single-center, retrospective study of 46 consecutive patients treated from January 2008 to June 2012 with RFA under CT guidance for 57 poorly visible liver tumors after percutaneous coil insertion. Effectiveness was evaluated by the rate of local tumor progression (LTP), and the risk factors of LTP were evaluated by multiple univariate analysis. Results: After a mean follow-up of 15.9 months, the overall rate of LTP was 22.8 % (13/57). An increase in the distance between the coil and the center of the tumor was a predictive factor of LTP (p = 0.005) and resulted in an increase in time to place the RFA probe. LTP was significantly reduced in case of coil placed within the tumor (10 vs. 43.5 %, p = 0.009). Conclusions: The effectiveness of the "coil-assisted" RFA for poorly visible liver tumors is improved by centering the coil in the tumor in order to facilitate the placement of the RFA probe and equal to the results of RFA under direct image guidance.