The clinical significance of incidental soft tissue uptake on whole body 18F-sodium fluoride bone PET-CT

18F-sodium fluoride (NaF) is a PET bone imaging agent and is commonly used in imaging patients with cancer; however, similar to technetium-99m medronic acid (99mTc-MDP), it can be useful in the evaluation of benign bone and joint conditions. NaF is an excellent bone-seeking agent with high bone uptake due to rapid single-pass extraction. It has negligible plasma protein binding, rapid blood, renal clearance, high bone uptake and almost all NaF delivered is retained by bone after a single pass of blood; however, uptake of NaF can be observed in non-osseous structures such as the arterial vasculature, gastrointestinal tract, genitourinary tract, and viscera. In this article, we present a spectrum of clinical cases with non-osseous NaF uptake in patients referred for cancer staging.