Imaging cardiac infarcts with radioactive metals complexed with phosphonate derivatives of dicyclopentadienebis (methylamine)

The imaging of cardiac infarcts with complexed radioactive metals is improved by employing as the complexing agent a compound of a formula wherein substituents A,B,X, and Y are earch independently selected from radicals including hydrogen; hydroxyalkyl (wherein the alkyl group contains 2-6 carbon atoms); phosphonic; sulfonic; methylenephosphonic; methylene-, ethylene-, and propylenesulfonic; carboxylic acid radicals (having 2-4 carbon atoms); and the alkali metal, alkaline earth metal, ammonia, and amine salts thereof; and wherein at least one A,B,X, or Y is methylenephosphonic acid or a salt thereof. In particular Tc-99m complexes have been found useful for imaging damaged cardiac tissue