Abstract: Aqueous solutions of .sup.99 technetium salts wherein the .sup.99 technetium is in reduced valencey state, when administered to mammals, permit identification of the skeleton and of calcareous tumors by scintigraphy (radiographic scanning). The solutions are conveniently prepared by mixing one ore more phosphonic acids (or their salts) with one or more reducing salts, and adding the mixture to an aqueous solution of a pharmaceutically acceptable .sup.99 pertechnetate salt. Reduction of the valence of the technetium occurs rapidly, and the resulting solution is adequately stable for use in scintigraphy.The phosphonic acid and reducing salt components can be premixed. Aqueous solutions of the premix are stable for long periods of time in the absence of free oxygen and the premix is stable to air so long as it is dry.

Abstract: Aqueous solutions of .sup.99 technetium salts wherein the .sup.99 technetium is in reduced valencey state, when administered to mammals, permit identification of the skeleton and of calcareous tumors by scintigraphy (radiographic scanning). The solutions are conveniently prepared by mixing one or more phosphonic acids (or their salts) with one or more reducing salts, and adding the mixture to an aqueous solution of a pharmaceutically acceptable .sup.99 pertechnetate salt. Reduction of the valence of the technetium occurs rapidly, and the resulting solution is adequately stable for use in scintigraphy.The phosphonic acid and reducing salt components can be premixed. Aqueous solutions of the premix are stable for long periods of time in the absence of free oxygen and the premix is stable to air so long as it is dry.