Figure 2a: Transverse CT scans of 42-mm colon cancer metastasis of the left lower lobe obtained in the prone position. (a) Scan obtained during RF ablation shows deployed RF tines in the deepest part of the tumor. (b) Scan obtained 9 minutes after start of ablation shows a pneumothorax that caused anterior displacement of the tumor, but the electrode remained stable in the same location. The pneumothorax was aspirated with a 5-F needle catheter, and no chest tube was needed.