Percutaneous tumor ablation: Increased coagulation by combining radio-frequency ablation and ethanol instillation in a rat breast tumor model

PURPOSE: To determine if percutaneously applied radio frequency (RF) combin ed with percutaneous ethanol instillation (PEI) can increase the extent of ablation in rat breast tumors. MATERIALS AND METHODS: R3230 mammary adenocarcinoma was implanted bilateral ly in the mammary fat pads of 18 female rats. The tumor nodules measured 1. 2-1.5 cm. Eight tumors each were treated with (a) conventional, monopolar R F (96 mA +/- 28; 70 degreesC for 5 minutes); (b) PEI (250 muL of ethanol in fused over 1 minute); (c) combined therapy of PEI immediately followed by R F ablation; or (d) combined therapy of RF ablation immediately followed by PEI. Four tumors were not treated and served as controls. Histopathologic e xamination included staining for mitochondrial enzyme activity. Resultant c oagulation necrosis was compared between treatment groups. RESULTS: Coagulation necrosis was observed only within treated tumors. Tumo rs treated with RF alone had 6.7 mm +/- 0.6 of coagulation surrounding the electrode, and those treated with PEI alone had 6.4 mm +/- 0.6 of coagulati on around the instillation needle (not significant). Significantly increase d coagulation of 10.1 mm +/- 0.9 (P < .001) was observed with the combined therapy of PEI followed by RF. RF followed by PEI did not increase coagulat ion (6.4 mm +/- 0.8 around the needle; not significant). CONCLUSION: PEI followed by RF ablation therapy increases the extent of ind uced coagulation necrosis in rat breast tumors, as compared with either the rapy alone.