Role of Combined (68)Ga DOTA-Peptides and (18)F FDG PET/CT in the Evaluation of Gastroenteropancreatic Neuroendocrine Neoplasms

This review article summarizes the role of combined (68)Ga DOTA-peptides and (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the evaluation of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). Patients with GEP-NENs can initially present themselves to a gastroenterologist or endocrinologist rather than cancer specialist; hence, it is vital for a wider group of clinicians to be familiar with the range of tests available for the evaluation of these patients. The role of PET scanning by using (68)Ga DOTA-peptides has a high sensitivity in the diagnosis of GEP-NENs and to guide patient selection for treatment with somatostatin analogues (SSA) and/or peptide receptor radionuclide therapy (PRRT). The loss of somatostatin receptor (SSTR) expression was found to be associated with an increased glucose metabolism in cells. However, the routine use of SSTR targeted radiotracers in combination with (18)F-FDG to evaluate glucose utilization in GEP-NENs is still debatable. In our opinion, in patients with NENs, (18)F-FDG PET should be performed in the case of a negative or slightly positive (68)Ga DOTA-peptides PET scan for assessing the dedifferentiation status, to guide correct therapeutic strategy and to evaluate the prognosis. The approach of combined receptor and metabolic imaging can improve diagnostic accuracy, especially considering the heterogeneity of these lesions. Therefore, (68)Ga DOTA-peptides and (18)F-FDG PET should be considered complementary in patients with GEP-NENs.