Clinical Comparison: Concise Communication

99m polyphosphate for bone imaging (1-3), a num ber of Ic-99m-labeled phosphate and phosphonate compounds have been introduced for clinical bone imaging, including pyrophosphate (4-6), hydroxy ethylidine diphosphonate (7-10), methylene diphos phonate (1 1, 12), trimetaphosphate (13), and mon ofluorophosphate (14). Ihe relative merits of certain of these agents have been evaluated clini cally and in animal models (15-19). Ihe most corn prehensive comparisons have been by Subramanian and McAfee (/2,20) and by Davis and Jones (21). Although there is still some disagreement, the meth ylene and hydroxyethylidene disphosphonates (MDP and HEDP) are considered superior. Ihese two organic phosphates are closely related and the term “diphosphonate†• is occasionally used in the literature without specifying which agent had been actually used (22,23). Despite their structural si