摘要：

Chelating compounds which comprise one or more sulfur atoms and are to be radiolabeled with metal radionuclides to form the corresponding chelates are disclosed. The chelating compounds comprise thioacetal or hemithioacetal sulfur protecting groups which are displaced during the radiolabeling reaction, which is conducted at acidic pH, such that bonds form between said sulfur atoms and said radionuclide. The resulting metal radionuclide chelates have diagnostic and therapeutic medical uses.

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