title: Radiolabeled peptide-receptor ligands in tumor imaging.
abstract: BACKGROUND
  Targeted molecular imaging techniques have become indispensable tools in modern diagnostic, providing accurate and specific disease information. Conventional non-specific contrast agents suffer from low targeting efficiency; thus, the use of molecularly targeted imaging probes is needed depending on different imaging modalities. The overexpression of peptide receptors in many human cancers has attracted an enormous interest in targeting molecules for the development of tumor-specific radiopharmaceutical compounds for diagnostic imaging and therapy of cancers. The use of solid-phase peptide synthesis and the availability of a wide range of bifunctional chelating agents for the radiolabeling of bioactive peptides with radionuclides have produced a wide variety of useful radiopharmaceutical molecules.
  
  
  METHODS
  This review is an overview of the critical steps involved in the development and optimization of radiolabeled peptide-based targeting probes. The authors also discuss their diagnostic and therapeutic potential for a number of cancers.
  
  
  CONCLUSIONS
  'Seeing is believing' is the driving force of molecular imaging. Selective detection of tumor cells while sparing normal tissue is possible and peptide-receptor ligands are the tools for obtaining the probes needed to explore specific biological and pathological processes in both animals and humans.
authors.affiliation: Institute of Biomolecular Chemistry of CNR , Padova Unit, via Marzolo 1, 35131 Padova , Italy +1 39 049 827 5282 ; +1 39 049 827 5239 ; paolo.ruzza@cnr.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ruzza
authors.forename: Andrea
authors.initials: A
authors.lastname: Calderan