Factors affecting uptake and retention of technetium-99m-diphosphonate and 99m-pertechnetate in osseous, connective and soft tissues.

The bone scanning complex, 99mTc-Sn-EHDP, consisting of the nuclide technetium-99m, stannous ion and ethane-1-hydroxy-1,1-diphosphonate, administered intravenously is retained in soft tissues in proportion to increasing calcium content of the tissues. Within bone tissue, the retention is proportional to vascularity and to surface area of calcium phosphate in bones and not necessarily to calcium and phosphate concentration. The nuclidic agent 99mTcO4-BUT NOT THE 99MTc-diphosphonate is selectively taken up by the thyroid and this uptake can be blocked by administering sodium perchlorate. Among the connective tissues studied, the tracheal cartilage seems to have the greatest potential to calcify with increasing age of the animal and man. Soft tissue does not retain the bone scanning complex 99mTc-Sn-EHDP but does retain 99mTcO4-.