Value of ⁶⁸Ga-DOTANOC PET/CT imaging in primary diagnosis and staging of pancreatic neuroendocrine neoplasms

Objective: To evaluate the value of ⁶⁸Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid-1-Nal3-octreotide (DOTANOC) PET/CT imaging in the diagnosis and staging of pancreatic neuroendocrine neoplasms (pNENs). Methods: Data of 48 patients (18 males, 30 females, age: 23-86 (50.0 ± 14.7) years) who underwent ⁶⁸Ga-DOTANOC PET/CT imaging from June 2016 to June 2018 were retrospectively analyzed. The histopathological results were considered as the gold standard. The diagnostic efficacies of ⁶⁸Ga-DOTANOC PET/CT imaging and conventional imaging (CI) for pNENs were analyzed and compared (McNemar test). Imaging characteristics of true positive lesions in ⁶⁸Ga-DOTANOC PET/CT imaging were analyzed. The maximum standardized uptake value (SUV_max ) in different pathological grades of pNENs lesions were compared (Kruskal-Wallis rank sum test). Accuracy for TNM staging by ⁶⁸Ga-DOTANOC PET/CT imaging and the correlations between the staging results and clinical TNM stages were analyzed (R × C contingency table). Results: (1) The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ⁶⁸Ga-DOTANOC PET/CT imaging were 93.8% (30/32), 14/16, 93.8% (30/32), 14/16 and 91.7% (44/48). All true positive lesions detected by PET/CT showed focal uptake of ⁶⁸Ga-DOTANOC with SUV_max of 30.52 ± 23.57. There were 26 patients with confirmed pathological grades of G1 (n = 10; SUV_max: 28.20 (17.60, 49.22)), G2 (n = 13; SUV_max: 27.60 (13.05, 56.08)) and G3 (n = 3; SUV_max: 13.68 (10.02, 27.80)), with no significant difference in SUV_max among 3 groups (H = 0.495, P > 0.05). (2) Of the 48 patients, 95.8% (46/48) also underwent CI concurrent with PET/CT. The sensitivity, specificity, PPV, NPV and accuracy of CI were 60.0% (18/30), 9/16, 72.0% (18/25), 9/21 and 58.7% (27/46). The diagnostic efficacy of ⁶⁸Ga-DOTANOC PET/CT imaging was significantly higher than that of CI (P = 0.041). (3) The accuracies of ⁶⁸Ga-DOTANOC PET/CT imaging for T, N, M staging were 93.3% (28/30), 6/6, 9/10, respectively, and the staging results were significantly correlated with clinical TNM stages (r = 0.880, P < 0.05). Conclusion: ⁶⁸Ga-DOTANOC PET/CT imaging has great values in the diagnosis and staging of pNENs. (authors)