Neuroendocrine tumors (NETs) constitute approximately 0.5% of malignancies. To date, diagnosis at an increasingly early stage of the disease is possible thanks to recent technological advances in biomedical imaging. In particular, the traditional work-up for these pathologies includes endoscopy, magnetic resonance imaging (MRI) and computed tomography (CT). Furthermore, the integrated positron emission tomography methods (PET/CT and PET/MRI) are innovative molecular imaging techniques and represent a continually expanding field of research in the oncology setting. In particular, PET is taking on an increasingly relevant role for the study of neuroendocrine tumors, also thanks to the introduction of increasingly accurate radiopharmaceuticals (targeted towards somatostatin receptors), thus opening the way to new possibilities for the diagnosis andcharacterization of these tumors, is in the staging and restaging phase .

Inclusion Criteria:

• Adult patients affected by neuroendocrine tumors; Patients who have performed at least one PET study with 18F-FDG and/or 68Ga- DOTATOC for the staging or diagnosis of their pathology.

Exclusion Criteria:

• Patients < 18 years old;
• Lack of availability of clinical data and PET imaging useful for analyses.

In this study, adult patients suffering from neuroendocrine tumors who have undergone PET examination (PET/CT or PET/MRI) with 18F-FDG or 68Ga-DOTATOC at the U.0 of Nuclear medicine at the RCCS San Raffaele will be considered for clinical reasons both in the staging and restaging phases.