68Ga-exendin-4 PET/CT for the localization of insulinomas

Abstract

Objective To determine whether glucagon-like peptide-1 (GLP-1) receptor PET/CT with 68Ga-exendin-4 is accurate in localizing insulinomas, by comparing with conventional imaging techniques. Methods In this prospective cohort study, patients with biochemically proven endogenous hyperinsulinemic hypoglycemia from March 2014 to November 2016 were recruited consecutively. 68Ga-exendin-4 PET/CT, CT, MRI, endoscopic ultrasound (EUS), and SSTR imaging were performed before elective surgery. Surgical pathology results were considered as the gold standard. Sensitivity based on patient-analysis and positive predictive value (PPV) based on lesion-analysis were calculated and compared using χ2 test and generalized score test. Results A total of 109 patients were recruited (47 males, 62 females; average age (45.1±14.8) years), and 96 of them with insulinomas proved pathologically were included in the main assessment. Thirteen patients with positive 68Ga-exendin-4 PET/CT findings did not undergo surgical intervention. Based on patient-analysis, the sensitivities of 68Ga-exendin-4 PET/CT, CT, MRI, EUS and SSTR imaging for detecting insulinomas were 98.96%(95/96), 81.25%(78/96), 79.41%(54/68), 81.40%(35/43) and 21.84%(19/87), respectively. Based on lesion-analysis, the PPV of the above 5 methods were 100%(102/102), 97.56%(80/82), 95.16%(59/62), 83.72%(36/43) and 90.48%(19/21), respectively. 68Ga-exendin-4 PET/CT showed the highest diagnostic sensitivity than others (all P<0.01) and higher PPV than MRI, EUS and SSTR imaging (all P<0.05). Conclusion 68Ga-exendin-4 PET/CT is a highly sensitive imaging technique for detection of insulinoma. Key words: Insulinoma; Positron-emission tomography; Tomography, X-ray computed; Glucagon-like peptide 1; Gallium radioisotopes