MRI-Guided radiofrequency thermal ablation of implanted VX2 liver tumors in a rabbit model: Demonstration of feasibility at 0.2 T

Successful radiofrequency (RF) thermal ablation was performed on VX2 tumors implanted in 23 rabbit livers under magnetic resonance (MR) guidance using a C-arm-shaped low-field 0.2 T system. RF application and immediate postpr ocedure MRI of all animals was performed [T-2-weighted, turbo short tau inv ersion recovery (STIR), T-1-weighted before and after gadopentetate dimeglu mine administration). Follow-up MRI with a superparamagnetic iron oxide (SP IO) contrast medium was performed in nine rabbits at 2 weeks and in four ra bbits at 1 month post RF ablation, All livers were harvested for pathologic examination, T-2-weighted and turbo-STIR images demonstrated the highest t umor-to-RF-thermal lesion contrast-to-noise ratios (CNRs; means 4.5 and 3.8 , respectively) on postprocedure images; this was redemonstrated at 2- and 4-week follow-up imaging. T-2-weighted imaging never overestimated patholog ic lesion size by more than 2 mm, and the radiologic-pathologic correlation coefficient was not less than 0.90. In conclusion, MRI-guided RF thermal a blation in implanted liver tumor is feasible using a C-arm-shaped low-field 0.2 T system. The thermal lesion size can be most accurately monitored wit h T-2-weighted and turbo-STIR images. Magn Reson Med 42:141-149, 1999. (C) 1999 Wiley-Liss, Inc.