Background To evaluate the clinical and prognostic value of PET/CT with combination of 68Ga-DOTATATE and 18F-FDG in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). Method 83 patients of GEP-NENs who underwent 68Ga-DOTATATE and 18F-FDG PET/CT were enrolled between June 2013 and December 2016. Well-differentiated (WD) NETs are divided into group A (Ki-67 < 10%) and group B (Ki-67 ≥ 10%), and poorly differentiated (PD) NECs are defined as group C. The relationship between PET/CT results and clinicopathological characteristics was retrospectively investigated. Result For groups A/B/C, the sensitivities of 68Ga-DOTATATE and 18F-FDG were 78.8%/83.3%/37.5% and 52.0%/72.2%/100.0%. A negative correlation between Ki-67 and SUVmax of 68Ga-DOTATATE (R = −0.415; P ≤ 0.001) was observed, while a positive correlation was noted between Ki-67 and SUVmax of 18F-FDG (R = 0.683; P ≤ 0.001). 62.5% (5/8) of patients showed significantly more lesions in the bone if 68Ga-DOTATATE was used, and 22.7% (5/22) of patients showed more lymph node metastases if 18F-FDG was used. Conclusions The sensitivity of dual tracers was correlated with cell differentiation, and a correlation between Ki-67 and both SUVmax of PET-CTs could be observed. 68Ga-DOTATATE is suggested for WD-NET and 18F-FDG is probably suitable for patients with Ki-67 ≥ 10%.

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Somatostatin receptors are overexpressed in neuroendocrine tumors, whose endogenous ligands are somatostatin. DOTA-TATE is an analogue of somatostatin, which shows high binding affinity to somatostatin receptors. We aim to evaluate the Ga/Lu-labeling DOTA-TATE kit in neuroendocrine tumor model for molecular imaging and to try human-positron emission tomography/computed tomography imaging of Ga-DOTA-TATE in neuroendocrine tumor patients. DOTA-TATE kits were formulated and radiolabeled withGa/Lu for Ga/Lu-DOTA-TATE (M-DOTA-TATE). In vitro and in vivo stability of Lu-DOTA-TATE were performed. Nude mice bearing human tumors were injected withGa-DOTA-TATE or Lu-DOTA-TATE for micro-positron emission tomography and micro-single-photon emission computed tomography/computed tomography imaging separately, and clinical positron emission tomography/computed tomography images ofGa-DOTA-TATE were obtained at 1 h post-intravenous injection from patients with neuroendocrine tumors. Micro-positron emission tomography and micro-single-photon emission computed tomography/computed tomography imaging of Ga-DOTA-TATE andLu-DOTA-TATE both showed clear tumor uptake which could be blocked by excess DOTA-TATE. In addition, Ga-DOTA-TATE-positron emission tomography/computed tomography imaging in neuroendocrine tumor patients could show primary and metastatic lesions.Ga-DOTA-TATE and Lu-DOTA-TATE could accumulate in tumors in animal models, paving the way for better clinical peptide receptor radionuclide therapy for neuroendocrine tumor patients in Asian population.

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