Lesion-by-lesion correlation between uptake at FDG PET and the Ki67 proliferation index in resected pancreatic neuroendocrine tumors

Ki67 proliferation index and tumor uptake on 18fluorodeoxyglucose positron-emitting tomography (FDG-PET) could be correlated in pancreatic neuroendocrine tumors (PanNET), but the evaluation of the former is subject to tumor heterogeneity. Explore the correlation between Ki67 and FDG-PET uptake at the lesion scale in PanNET. We identified target lesions ≥10 mm in patients operated on for a PanNET and/or associated metastases with preoperative FDG-PET and without neoadjuvant treatment. We assessed the lesion-by-lesion correlation between Ki67 and the tumor-to-liver SUVmax ratio (SUVmax T/L), and between pathological grade (G) and metabolic grade (mG) (mG1, SUVmax T/L ≤ 1, mG2, SUVmax T/L 1–2.3 and mG3, SUVmax T/L > 2.3). Twenty-one patients underwent pancreatic (n = 12), liver (n = 2) or combined surgery (n = 7). Overall, 36 target lesions (21 primary PanNET, 13 liver metastases and 2 lymph-node metastases) were identified, of median Ki67 4%. Ki67 correlated with SUVmax T/L (r = 0.55, p