Inclusion Criteria:  • Written informed consent.  Patients of either gender, aged ≥ 18 years. Histologically confirmed diagnosis of Metastatic, well-differentiated neuroendocrine tumor. A diagnostic computed tomography (CT) or magnetic resonance imaging (MRI) of the tumor region within the previous 6 months prior to dosing day is available. At least 1 measurable lesion based on RECIST v1.1.  Blood test results as follows (White blood cell: ≥ 3*10^9/L, Hemoglobin:  ≥ 8.0 g/dL, Platelets: ≥ 50x10^9/L, Alanine aminotransferase / Aspartate aminotransferase / Alkaline phosphatase: ≤ 5 times upper limit od normal (ULN), Bilirubin: ≤ 3 times ULN)  Serum creatinine: within normal limits or < 120 μmol/L for patients aged 60 years or older. Calculated Glomerular filtration rate (GFR) ≥ 45 mL/min.  Exclusion Criteria:  • Known hypersensitivity to Gallium-68, to NODAGA, to JR11, to TATE or to any of the excipients of Gallium-68 NODAGA-JR11 or Gallium-68 DOTATATE.  Presence of active infection at screening or history of serious infection within the previous 6 weeks. Therapeutic use of any somatostatin analog, including long-acting Sandostatin (within 28 days) and short-acting Sandostatin (within 2 days) prior to study imaging. If a patient is on long-acting Sandostatina, then a wash-out phase of 28 days is required before the injection of the study drug. If a patient is on short-acting Sandostatin, then a wash-out phase of 2 days is required before the injection of the study drug. Any neuroendocrine tumor-specific treatment between antagonist and agonist scans. Prior or planned administration of a radiopharmaceutical within 8 half-lives of the radionuclide used on such radiopharmaceutical including at any time during the current study. Pregnant or breast-feeding women. Current history of any malignancy other than neuroendocrine tumor; patients with a secondary tumor in remission of > 5 years can be included. Any mental condition rendering the patient unable to understand the nature, scope and possible consequences of the study, and/or evidence of an uncooperative attitude.