It concerns the management of neuroendocrine tumors (Neuroendocrine tumors (NETs) start in cells of the neuroendocrine system.) With the following objectives: - detection and localization of the primary tumor. - assessment of the extent of metastases and pre-treatment classification. - detection of recurrence and tumor progression as part of monitoring. - monitoring and evaluation of the therapeutic effect of surgery, chemotherapy and radiotherapy. -patient selection for therapeutic octreotide