Na18F

Na18F is a radiopharmaceutical used in positron emission tomography (PET) bone imaging. It consists of sodium fluoride in which the fluoride ion is the radioactive isotope fluorine-18, enabling PET visualization of skeletal metabolism.

Production and preparation involve generating fluorine-18 in a cyclotron via the 18O(p,n)18F reaction from enriched 18O-water. The resulting 18F fluoride is isolated, converted to sodium fluoride, and formulated in sterile saline to produce Na18F for intravenous administration. The preparation is carried out in a radiopharmacy under appropriate regulatory controls.

Mechanism and imaging with Na18F rely on fluoride’s affinity for bone mineral. The radiotracer distributes rapidly in extracellular fluid and accumulates at sites of active bone remodeling by binding to hydroxyapatite. Uptake correlates with blood flow and osteoblastic activity, producing high-contrast bone images typically 60 minutes after injection. Quantification is possible using standardized uptake values (SUVs) on PET/CT.

Clinical use includes detection and staging of osseous metastases and evaluation of benign bone conditions such as fractures, infections, and inflammatory processes. Compared with conventional Tc-99m MDP bone scintigraphy, Na18F-PET generally offers higher sensitivity and faster imaging, and it is used when bone metastases are suspected or when treatment response needs monitoring.

Safety and logistics involve administering a typical adult activity of about 185–370 MBq intravenously, with renal excretion being a major elimination route. Radiation exposure considerations apply, and use is generally avoided in pregnancy. Na18F is prepared in radiopharmacies and requires access to cyclotron-produced isotopes or regional supply networks.