Radiofrequency Ablation of Spine An Experimental Study in an Ex Vivo Bovine and In Vivo Swine Model for Feasibility in Spine Tumor

Study Design. An experimental study of radiofrequency ablation (RFA) of spine in an ex vivo bovine and in vivo swine animal model. Objective. To study the feasibility of RFA for spine tumors close to the spinal cord, to examine the safety and efficacy of RFA, and to suggest quantitative guidelines for clinical application. Summary of Background Data. RFA has received increased attention as an effective and minimally invasive method for treating soft tissue tumors. However, there is currently only anecdotal evidence to support RFA of spinal tumors and only a few experimental studies have been conducted. Methods. We performed ex vivo experiments by producing 10 RFA zones in extracted bovine spines and an in vivo study by producing 8 RFA zones in a swine spine using internally cooled electrodes. The volume and diameter of ablation zones were evaluated and analyzed by the corresponding energy and ablation times. Results. In the ex vivo study, the average diameters of the ablation zones were 3.05 cm, 1.85 cm, and 1.26 cm, for the D1, D2, and D3 zones, respectively, and the average ablation volume was 4.19 cm(3). In the in vivo study, the average diameters were 2.51 cm, 2.05 cm, and 1.28 cm, respectively, and the ablation volume was 6.80 cm(3). The ablation zones demonstrated a positive correlation with ablation time, but the coefficients were 0.942 ex vivo and 0.257 in vivo. The temperature in the ex vivo study was inversely proportional to distance, with a maximal temperature of 63.7 degrees C at 10 mm; however, the maximum temperature was 38.2 degrees C in the in vivo study. Conclusion. This study demonstrated that sufficient RFA zone volume could be induced, which suggests that RFA is feasible and safe for application to human spinal tumors with predictability.