Biodistribution and bone accumulation of 18 F-fluoride in naïve mice. (A) Positron emission tomography (PET) scans (maximum intensity projection) of a naïve mouse after intravenous 18 F-fluoride tail vein injection. Radiotracer was immediately distributed in the whole organism via the circulation and rapidly accumulated in the skeletal elements. (B) The 90-minute 18 F-fluoride time–activity curve reveals rapid 18 F-fluoride clearance from the bloodstream (via the venae cavae) and subsequent 18 F-fluoride accumulation in the bones of the fore- and hindpaws. SUV, Standardized uptake value.