Figure 3b. Results of RF ablation in a 78-year-old woman with emphysema and a right suprahilar mass. Results of biopsy showed squamous cell carcinoma. The patient was a poor surgical candidate due to comorbid conditions (heart disease, emphysema). (a) CT scan obtained prior to external-beam radiation therapy shows an electrode inserted into the mass for percutaneous RF ablation. (b) CT scan obtained 3 months after RF ablation (6 weeks after radiation therapy) shows the mass with adjacent parenchymal stranding but no retraction. (c) CT scan obtained 27 months after RF ablation demonstrates shrinkage of the tumor with parenchymal fibrosis and contraction medially. This dramatic response in such a large tumor would be unusual in a patient treated with irradiation alone. Tissues treated with RF ablation become cicatricial, and the lesions may still be apparent at imaging.