Development of an in vivo tumor-mimic model for learning radiofrequency ablation

Radiofrequency ablation requires accurate probe placement using ultrasound guidance. The purpose of this study was to develop an in vivo tumor-mimic m odel fur learning open and laparoscopic radiofrequency ablation. Tumor-mimi cs were created in ex vivo porcine livers by injecting a mixture of 3% agar ose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, which formed 1 cm hyperechoic, discrete lesions on ultrasound. Open and laparoscopic (using a box-trainer) ablation techniques were practiced. Ln vivo experiments were then conducted in 10 pigs. Three tumor-mimics were created in each animal using a laparoscopic approach. Lesions were characterized sonographically, ablated using an open (n = 5) or laparoscopic (n = 5) approach, and examine d pathologically. An ablation in normal liver tissue was performed as a con trol. Tissue impedance was recorded. Target creation took 81 minutes per an imal and 96% of injections were successful. Tissue impedance (48.8 +/- 5.8 vs. 49.6 +/- 5.4) and ablation size (25.1 +/- 3.4 vs. 24.3 +/- 5.1) were no t significantly different fur controls (n = 8) and tumor-mimics (n = 26), r espectively One animal died of a pulmonary embolism following injection of agarose into a hepatic vein. The agarose-based tissue-mimic creates realist ic sonographic targets for learning ultrasound-guided open and laparoscopic radiofrequency ablation in an in vivo model.