A new and improved method for extending the half life of pharmaceutical compounds for use in diagnostic imaging or therapy uses a novel linker to attach a diagnostic or therapeutic moiety to a targeting peptide or another diagnostic or therapeutic moiety. The resulting compound may have the general formula M-N-O-P-Q, wherein M is the diagnostic or therapeutic moiety, N-O-P is the linker of the present invention, and Q is the targeting peptide. In another embodiment the compounds may have the formula M-N-O-P-M, wherein M is independently a diagnostic or therapeutic moiety and N-O-P is the linker of the invention. Methods for imaging or treating a patient using the compounds of the invention are also provided. Methods and kits for preparing a diagnostic imaging agent from the compound are further provided. Methods for radiotherapy of a patient using the compounds are further provided, as are methods for preparing a radiotherapeutic agent from the compounds.