Physiopathological premises to Nuclear Medicine Imaging of pancreatic neuroendocrine tumours.

Abstract

BACKGROUND\nPancreatic neuroendocrine tumors (P-NETs) are a challenge in terms of both diagnosis and therapy; morphological studies need to be frequently implemented with non standard techniques such as Endoscopic Ultrasounds , Dynamic CT, functional Magnetic Resonance.\n\n\nDISCUSSION\nThe role of nuclear medicine s, being scarcely sensitive F-18 Fluorodeoxyglucose, is mainly based on the over-expression of somatostatin receptors (SSTR) on neuroendocrine tumor cells surface. Therefore SSTR can be used as a target for both diagnosis, using radiotracers labeled with gamma or positron emitters, and therapy. SSTRs subtypes are capable of homo- and hetero-dimerization in specific combinations that alter both response to ligand activation and receptor internalization.\n\n\nCONCLUSIONS\nAlthough agonists usually provide efficient internalization, also somatostatin antagonists (SS-ANTs) could be used for imaging and therapy. Peptide receptor radionuclide therapy (PRRT) represents the most successful option for targeted therapy. The theranostic model based on SSTR doesn t work in insulinoma, in which different radiotracers such as F-18 FluoroDOPA or tracers for the glucagon-like peptide-1 receptor have to be preferred.