NETs lesions can be difficult to characterize with conventional anatomic imaging (CT and MRI). Functional imaging techniques, and especially PET imaging, are very useful for detecting small neuroendocrine tumors that would not be seen with other techniques. The role of nuclear medicine in the localization, staging, restaging, treatment and monitoring of neuroendocrine tumors (NETs) has become progressively more relevant due to: the availability of tracers on new targets, tracers for positron emission tomography (PET); the development of cyclotrons and generators that allow this availability; as well as to hybrid systems (SPECT/CT, PET/CT and PET/MRI) that, by joining the functional and anatomical image, improve the quality of the images. Teragnosis, a new emerging therapy, in NET used receptor-mediated or nonreceptor- mediated mechanism to facilitate penetration and high-affinity binding between the radiopharmaceutical and the tumor cell. Teragnosis offers the possibility of personalized targeted radionuclide therapy.