Radio-frequency tissue ablation of VX2 tumor nodules in the rabbit lung.

RATIONALE AND OBJECTIVES: The authors investigated whether small pulmonary malignancies could be treated with computed tomography (CT)-guided, percutaneously placed radio-frequency (RF) electrodes. METHODS: Pulmonary tumors were created in 11 New Zealand white rabbits by using CT-guided injection of a VX2 sarcoma cell suspension into the lower portion of the right lung. Tumors were allowed to grow 14-21 days to achieve a diameter of 6-12 mm. Electrodes were placed coaxially into the tumors via insulated 19-gauge Turner needles. Seven tumors were treated with RF for 6 minutes at 90 degrees C. Four tumors served as controls and were not treated. Follow-up CT and histopathologic analysis were performed on days 0-28. Specimens from treated rabbits were examined histopathologically on days 0 and 3 (n = 2 each), and days 1, 5, and 28 (n = 1 each). RESULTS: Immediately following treatment, CT images showed rounded opacities enveloping the tumor. This corresponded histologically to coagulation necrosis of tumor and surrounding alveoli. In all cases, at least 95% of treated tumor nodules were necrotic at histopathologic analysis. Peripheral residual nests of histologically viable tumor were seen in three rabbits (43%). Control rabbits showed growing tumor nodules without necrosis at autopsy (mean survival, 23 days after inoculation). Two RF-treated rabbits (29%) and one control rabbit (25%) had pneumothoraces. CONCLUSION: Percutaneous RF tissue ablation can be used to successfully treat small parenchymal tumor nodules within the lung in an animal model.