A-C, Ground-glass opacification (GGO). A, Axial unenhanced CT scan image in a 47-year-old man with a history of papillary thyroid cancer, 4 months after treatment with iodine-131, shows right upper lobe peribronchovascular GGO. The GGO is hypermetabolic on a fluorine-18 fluorodeoxyglucose-PET/CT scan (B), with less intense activity also noted in a new smaller area of GGO in the left upper lobe in an axial unenhanced CT scan image (C). Transbronchial biopsy results were consistent with organizing pneumonia.