Functional Imaging of neuroendocrine tumors with combined PET/CT using 68Ga-DOTATATE (Dota-DPhe1,Tyr3-octreotate) and 18F-FDG

BACKGROUND. The aim was to assess the relevant distribution of the novel PET tracer Ga-68-DOTATATE in neuroendocrine tumors (NETs) with combined positron emission tomography/computed tomography (PET/CT) and compare its performance with that of F-18-FDG PET/CT. METHODS. The imaging findings with 68 Ga-DOTATATE and F-18-FDG on 38 consecutive patients with a diagnosis of primary or recurrent NET were compared and correlated with tumor grade on histology based on ki67 and mitotic index. RESULTS. The sensitivity of 68Ga-DOTATATE PET/CT was 82% (31 of 38) and that of F-18-FDG PET/CT was 66% (25 of 38). The sensitivity of combined Ga-68-DOTATATE and F-18-FDG PET/CT was 92% (35 of 38). There was greater uptake of Ga-68-DOTATATE than F-18-FDG in low-grade NET (median SUV 29 vs 2.9, P <.001). In high-grade NET there was higher uptake of 18F-FDG over 68 Ga-DOTATATE (median SUV 11.7 vs 4.4, P=.03). There was a significant correlation with predominant tumor uptake of Ga-68-DOTATATE or 18F-FDG and tumor grade on histology (P <.0001). CONCLUSIONS. Ga-68-DOTATATE PET/CT is a useful novel imaging modality for NETs and is superior to F-18-FDG for imaging well-differentiated NET. Functional imaging with both Ga-68-DOTATATE and F-18-FDG has potential for a more comprehensive tumor assessment in intermediate- and high-grade tumors.