Abstract: Methods and compositions for diagnosing, staging disease, monitoring therapeutic effect of drugs and imaging a patient are provided, including radiopharmaceutical formulations. Compositions comprising Ga-AMBA complexed with a radioactive isotope are provided; as are methods of imaging Gastrin Releasing Peptide receptor (GRP-R) bearing tissue and methods of diagnosing or staging disease in patients suspected of having disease associated with aberrant GRP-R function. Further, methods of monitoring therapeutic effect of a drug targeted to a receptor that crosstalks with GRP-R are provided; as are methods of pre-dosing/co-dosing non-target tissues containing GRP-R.