the compositions of the invention can also be employed for delivery of either radiopharmaceuticals or heavy metals for x ray contrast into the body for use in diagnostic and therapeutic radiopharmaceuticals the complexed metal ion must be radioactive radioisotopes of the elements technetium rhenium indium gallium copper yttrium samarium and holmium are suitable for use as x ray contrast applications the complexed metal ion must be able to absorb adequate amounts of the x rays these metal ions are generally refered to as radioopaque suitable elements for use as the radioopaque metal ion include lead bismuth gadolinium dysprosium holmium and praseodymium the compositions of the invention can be formulated into diagnostic compositions for enteral or parenteral administration these compositions contain an effective amount of the paramagnetic ion complex along with conventional pharmaceutical carriers and excipients appropriate for the type of administration contemplated for example parenteral formulations advantageously contain a sterile aqueous solution or suspension of from about 0 05 to about 1 0m of a paramagnetic ion complex according to this invention parenteral compositions may be injected directly or mixed with a large volume parenteral composition for systemic administration preferred parenteral formulations have a concentration of paramagnetic ion complex of about 0 1m to about 0 5m such solutions also may contain pharmaceutically acceptable buffers and.