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 (SUVmax) 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 SUVmax of 30.52±23.57. There were 26 patients with confirmed pathological grades of G1 (n=10; SUVmax: 28.20 (17.60, 49.22)), G2 (n=13; SUVmax: 27.60 (13.05, 56.08)) and G3 (n=3; SUVmax: 13.68(10.02, 27.80)), with no significant difference in SUVmax 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. Key words: Pancreatic neoplasms; Neuroendocrine tumors; Octreotide; Gallium radioisotopes; Positron-emission tomography; Tomography, X-ray computed