Clinical and Prognostic Value of PET/CT Imaging with Combination of 68 Ga-DOTATATE and 18 F-FDG in Gastroenteropancreatic Neuroendocrine Neoplasms.

Background: To evaluate the clinical and prognostic value of PET/CT with combination of 68 Ga-DOTATATE and 18 F-FDG in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs).

Method: 83 patients of GEP-NENs who underwent 68 Ga-DOTATATE and 18 F-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 68 Ga-DOTATATE and 18 F-FDG were 78.8%/83.3%/37.5% and 52.0%/72.2%/100.0%. A negative correlation between Ki-67 and SUVmax of 68 Ga-DOTATATE ( R = -0.415; P ≤ 0.001) was observed, while a positive correlation was noted between Ki-67 and SUVmax of 18 F-FDG ( R = 0.683; P ≤ 0.001). 62.5% (5/8) of patients showed significantly more lesions in the bone if 68 Ga-DOTATATE was used, and 22.7% (5/22) of patients showed more lymph node metastases if 18 F-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. 68 Ga-DOTATATE is suggested for WD-NET and 18 F-FDG is probably suitable for patients with Ki-67 ≥ 10%.