Figure 4c. Images in a 64-year-old woman with adenocarcinoma of the left upper lobe treated with chemoradiation. Follow-up CT results could not exclude persistent tumor. (a) Transverse CT image shows a masslike appearance (arrows) to the radiation fibrosis in the left upper lobe that was concerning for recurrent tumor. The air bronchograms typically seen in radiation fibrosis are not evident. (b) Coronal CT reconstruction shows the extent of the mass (arrow) above the aortic arch (A). (c) Coronal fused PET/CT image obtained to evaluate the mass shows no increased FDG uptake (arrow), indicating no malignancy. Follow-up imaging for 9 months continued to show no increased FDG uptake within the mass, thus confirming stable radiation fibrosis. A = aortic arch.