MKI67 and neuroendocrine carcinoma: Guidelines (both form the European Association of Nuclear Medicine (EANM) and the European Neuro-Endocrine Tumor Society (ENETS)) [22,27,51] suggest the use of 18F-FDG PET/CT in G3 NET, NEC, and higher-grade G2 (e.g., Ki-67 10–20%) NEN, which generally show higher glucose metabolism and 18F-FDG avidity.