[Clinical comparison of the kinetics of 99mTc pyrophosphate and 99mTc methylene diphosphonate (author's transl)].

In a series of 10 patients the hematic and plasmatic clearances of 99mTc-pyrophosphate (PYP) and 99mTc-metylene-diphosphonate (MDP) have been studied. The analysis of the results shows that the elimination both hematic and plasmatic of MDP is significantly faster than that of PYP. Moreover the plasmatic elimination of PYP is faster than its hematic elimination. This fact is probably due to a partial absorption of the radionuclide on the surface of the red cells. No significant differences result in the urinary elimination of both radionuclides. As a consequence the MDP has a lower fundus activity and a lower irradiation dose to the blood and to the whole body. For those reasons this radionuclide is proposed as the preferred agent in bones scintigraphy.