Somatostatin receptor(SSTR) was expressed in neuroendocrine tumor cells and SSTR-targeting molecular imaging(68Ga-DOTATATE PET/CT) could be a promising technique to evaluate the primary tumor and metastatic lesions of neuroendocrine tumors with higher accuracy. This prospective study is going to investigate whether radiolabeled somatostatin analogs 68Ga-DOTATATE PET/CT may be valuable for diagnosis, risk stratification, and prognostic evaluation of neuroendocrine tumors and compared it with 18F-FDG PET/CT.

Neuroendocrine tumor(NET)can be derived from endocrine glands, endocrine tissues and endocrine cells from any parts of body. Due to its occult onset and heterogeneity, it is hard to be detected by conventional imaging like CT and it is often at late stage when diagnosed. New imaging modality such as 18F-FDG PET/CT have been well-accepted as a practical way to evaluate the aggressive of tumor. 18F-FDG PET/CT has been used to improve the efficacy in assessing the extent and severity of NET, but the diagnostic accuracy of 18F-FDG PET/CT decreased in low proliferation tumor cells and inflammation. Recent studies showed somatostatin receptor (SSTR) was expressed in NET cells and SSTR-targeting molecular imaging-68Ga-DOTATATE PET/CT could be a promising technique to evaluate the extent of NET with higher accuracy. Especially in some well differentiated tumor, 18F-FDG PET/CT can be negative, while 68Ga-DOTATATE PET/CT can be positive. However, the results can be varied in these two imaging modalities and characterized this disease at multiple levels such as clinical presentation, biologic characteristics, treatment response, and clinical outcome.This prospective study is going to investigate whether 68Ga-DOTATATE PET/CT may be superior to 18F-FDG PET/CT for diagnosis, risk stratification, and prognostic evaluation of NET.

Inclusion Criteria:

• suspected or confirmed untreated NET patients previously performed 18F-FDG PET/CT signed written consent.

Exclusion Criteria:

• pregnancy breastfeeding known allergy against TATE any medical condition that in the opinion of the investigator, may significantly interfere with study compliance.