Fluorodeoxyglucose uptake in absence of CT abnormality on PET-CT: What is it?

Figure 6 Urine activity in the prostatic urethra. A 65-year-old man with history of lung cancer had fluorodeoxyglucose positron emission tomography-computer tomography (PET-CT) for restaging. Axial PET image of the lower pelvis shows a focus at the midline of the prostate, corresponding to the dilated urethra on CT (arrows). The finding represents urine retention in the urethra of previous trans-urethral prostate resection site.