Diagnostic radiopharmaceuticals for localization in target tissues exhibiting a regional pH shift relative to surrounding tissues

Claim 1

A radiopharmaceutical chemical composition for deposition in a selected target organ or tissue of a mammal having a lower intracellular pH than the blood of the mammal, which composition comprises a compound containing a radioactive isotope, selected from the group consisting of tellurium 123m, technetium 99m, ruthenium 97, tin 117m, lead 203, indium 111, indium 113m, gallium 67, gallium 68, scandium 44, and selenium 75, in chemical combination with at least one amine group, said compound having pH dependant lipid solubility comprising a lipophilicity sufficiently high at a pH of 7.6 to permit passage of the compound from the blood into the target organ or tissue and sufficiently low at a pH of 6.6 to prevent rapid return of the compound from the target organ or tissue to the blood, said compound having a percent protein binding of less than ninety percent, said compound having no overall net positive charge at pH 12 and no overall net negative charge at pH 6.0, said radioactive isotope being a gamma ray, X-ray or positron emitting isotope, at least seventy-five percent of the gamma rays in gamma ray emitting isotopes being emitted at energies of between 80 and 400 kiloelectron volts together with a pharmaceutical diluent; provided that, iodine isotopes are not present in the compound.