Glucagon-Like Peptide-1 Receptor PET/CT with 68Ga-NOTA-Exendin-4 for Detecting Localized Insulinoma: A Prospective Cohort Study
Preoperative localization of insulinoma is a clinical dilemma. We aimed to investigate whether glucagon-like peptide-1 receptor (GLP-1R) PET/CT with (68)Ga-NOTA-MAL-cys(40)-exendin-4 ((68)Ga-NOTA-exendin-4) is efficient in detecting insulinoma. In our prospective cohort study, patients with endogenous hyperinsulinemic hypoglycemia were enrolled. CT, MRI, endoscopic ultrasound, and (99m)Tc-hydrazinonicotinamide-TOC SPECT/CT were done according to standard protocols. GLP-1R PET/CT was performed 30-60 min after the injection of (68)Ga-NOTA-exendin-4. The gold standard for diagnosis was the histopathologic results after surgery. Of 52 recruited patients, 43 patients with histopathologically proven insulinomas were included for the imaging studies. Nine patients did not undergo surgical intervention. (68)Ga-NOTA-exendin-4 PET/CT correctly detected insulinomas in 42 of 43 patients with high tumor uptake (mean SUVavg ± SD, 10.2 ± 4.9; mean SUVmax ± SD, 23.6 ± 11.7), resulting in sensitivity of 97.7%. In contrast, (99m)Tc-hydrazinonicotinamide-TOC SPECT/CT showed a low sensitivity of 19.5% (8/41) in this group of patients; however, it successfully localized the tumor that was false-negative with GLP-1R PET/CT. The sensitivities of CT, MR, and endoscopic ultrasonography were 74.4% (32/43), 56.0% (14/25), and 84.0% (21/25), respectively. (68)Ga-NOTA-exendin-4 PET/CT is a highly sensitive imaging technique for the localization of insulinoma.