| http://www.w3.org/ns/prov#value | - An imaging agent for radiation diagnosis comprising a compound composed of a polynuclear type compound of the formula I or II: ##STR3## wherein each X is a hydrogen atom or a bifunctional ligand, at least one of them is a bifunctional ligand and each of m and n is an integer of 1 to 6, and at least one radioactive metal ion being coordinated with at least one bifunctional ligand moiety, said radio
|