[A phosphine-substituted diphosphonic acid (HMPD) for improved scintigraphic detection of bone lesions]

Although the radiopharmaceuticals used for bone scintigraphy are of very high quality, the search for an "ideal" agent continues. To optimise the detectability of bone lesions, we analysed 244 different 99mTc-labeled phosphonates in animal experiments. In osteosarcoma-carrying rats 99mTc-labeled 1-Hydroxy-3-methyl-phosphinic-1, 1-propanediphosphonic acid (HMPD) was shown to produce the best lesion/normal bone ratio. 99mTc-MDP was used as reference. The ratio was found to be 1.28 for 99mTc-HMPD. The transferability of our results in animals to the situation in man was studied in 10 patients with bone metastases. There was for 99mTc-HMPD an improvement of the lesion/normal bone ratio by more than 60% but also an additional reduction of the soft tissue contrast by about 40%. 15% of the metastases were detected by scintigraphy using 99mTc-HMPD only and not with 99mTc-MDP. The new agent should make possible a better and earlier discrimination of bone lesions in the scintigram.