18F-Sodium fluoride positron emission tomography: History, technical feasibility, mechanism of action, normal bio-distribution, and diagnostic performance in bone metastasis detection compared to other imaging modalities.

The skeleton is overall the third most common metastatic site after the lungs and liver. Accurate diagnosis of osseous metastasis is critical for initial staging, treatment planning, restaging, treatment monitoring and survival prediction. Currently, 99mTc-methylene diphosphonate (99mTc-MDP) whole-body scan is the cornerstone of imaging to detect osseous metastasis. Though 18F-sodium fluoride (18F-NaF) was one of the oldest medical tracers but was replaced by other tracers until recently, owing to its physical properties. Continued development of positron emission tomographic (PET) scanners have opened a new era for 18F-NaF and given its higher sensitivity, there have been increasing applications in imaging. In this review, we will discuss the history, technical aspects, radiobiology, and bio-distribution of this tracer. Finally, we compared the accuracy of 18F-NaF PET with other conventional imaging for detection of osseous metastasis.