Radiologic appearance and complications of percutaneous computed tomography-guided radiofrequency-ablated pulmonary metastases from colorectal carcinoma

Objectives: To describe the morphologic appearance over time of percutaneously radiofrequency-ablated pulmonary metastases from colorectal cancer and to focus on the occurrence of the most common complications. Methods: Twenty patients have been treated with computed tomography (CT)-guided radiofrequency ablation (RFA) for 41 pulmonary metastases using the expandable 14-gauge StarBurst XL RF electrode along with the 1500 generator (RITA Medical Systems, Mountain View, CA). The average number of lesions per patient was 2.05, ranging from I to 4 lesions. Results: The typical feature of the radiofrequency-ablated site immediately after the procedure was a light bulb-shaped opacification surrounding the probe. This became a more spherically shaped feature over time and steadily decreased in size. At 3 months after RFA, the lesion was approximately the same size as at baseline. The lesion subsequently shrank within the following 3 months, usually with a small scar remaining. Pneumothorax occurred in 50% of the patients, and a chest tube was required in 50% of the patients affected. Cavitation occurred in 24% of the lesions. Intraparenchymal hemorrhage was observed in 7.5% of the cases. Conclusions: Image-guided pulmonary RFA is a safe minimally invasive therapy modality with acceptable morbidity. Ablated lesion size usually exceeds the dimensions of the initial tumor for the first 3 months after ablation and continuously shrinks thereafter.