The value of Tc99m-diphosphonate (HEDSPA) as a skeletal scanning agent. 
A new "bone seeking" agent, namely the organic compound diphosphonate labeled with Tc99m was tried in 21 patients for skeletal scanning.  In 3 cases, although the clinical and roentgenographic evidence of bone lesions was absent, bone metastases were found, and these were confirmed histologically.  The organic diphosphonate is more stable compared to the inorganic polyphosphates and the images obtained are excellent.