Distribution of 99Tcm-labelled phosphorus compounds, 45Ca and 85Sr in diphosphonate-treated rats.

A similar distribution of 99Tcm, 45Ca and 85Sr was obtained when injected in rats as 99Tcm-labelled pyrophosphate or ethylene-1-hydroxy-1,1-diphosphonate (EHDP), 45Ca-chloride and 85Sr-choloride respectively. The highest concentrations occurred in bone and teeth. In EHDP-treated rats, isotopes were accumulated at sites of ectopic calcifications in the lung, kidney and stomach wall as well as in mineralized tissues. These results indicate that 99Tcm, when administered as 99Tcm-labelled EHDP accumulates predominatly in the inorganic rather than organic tissue components.