Post-mortem migration of bone-seeking radionuclides in the rat and rabbit and its effect on estimates of bone uptake

1. The continued uptake of 18F, 85Sr and 47Ca by bone after death has been studied in rats and rabbits after aortic injection followed by quick killing, a period of recirculation of tracer before death, and perfusion of the carcase. In each case an approximately linear increase of bone radioactivity was observed during a period of 1 h at about the same rate. The proportionate increase depended on the initial concentration of bone-seeking nuclide, ranging from a factor of 1.5 to 4.5. Boiling the carcase did not increase the migration rate. 2. Delay between death and dissection may therefore lead to spuriously high bone concentrations of these radionuclides, leading to over-estimates of bone uptake, extraction ratio or bone blood flow.