title: Tc-99m methylene diphosphonate versus Tc-99m pyrophosphate: biologic and clinical comparison.
abstract: The biologic and imaging characteristics of Tc-99m MDP and Tc-99m PPi were compared in animals and patients using freeze-dried bone-imaging kits. Biodistribution data in rabbits showed Tc-99m MDP had slightly higher bone uptake, significantly lower blood levels, and faster urinary excretion compared with Tc-99m PPi. Duplicate studies performed on ten patients showed the following: (a) blood clearance of Tc-99m MDP was more prompt and complete, resulting in significantly lower blood levels at 4 hr; (b) urinary excretion was greater with Tc-99m MDP than with Tc-99m PPi; and (c) Tc-99m PPi showed significant red-cell labeling, whereas Tc-99m MDP did not. Image quality was generally better with Tc-99m MDP than with Tc-99 m PPi, although there was no obvious difference in diagnostic sensitivity between the two agents.
mesh_terms: D000818:Animals; D001842:Bone and Bones; D011756:Diphosphates; D004164:Diphosphonates; D005260:Female; D006801:Humans; D011817:Rabbits; D011877:Radionuclide Imaging; D013667:Technetium
chemical_list: D011756:Diphosphates; D004164:Diphosphonates; D013667:Technetium