PET response in a lesion non-measurable by CT. Pretreatment PET (A) and CT (B) of a patient with a bony metastatic lesion. The black arrow points to the area of PET avidity on the pretreatment PET (A). PET (D) and CT (E) 1 month after completion of SBRT shows what seems to be stable disease (SD) on CT, but RECIST criteria cannot be used for bony lesions. Post treatment PET shows almost complete response (CR). Pretreatment biopsy (C) and SBRT plan (F) are also depicted.