Glucagon-like peptide-1 receptor PET/CT in gastrinomas: a case series demonstrating the precise characterization to guide surgical and medical treatment

Abstract Gastrinoma is a rare type of neuroendocrine tumor with ectopic secretion of gastrin causing Zollinger–Ellison syndrome (ZES). Accurate localization of gastrinomas and their metastases is important for developing precise treatment strategies. We reported three cases of metastatic gastrinomas evaluated with 68Ga-exendin-4 and 68Ga-DOTANOC PET/CT. Despite most gastrinomas highly expressing somatostatin receptor (SSTR), these patients showed no or heterogeneous uptake on 68Ga-DOTANOC PET/CT, whereas 68Ga-exendin-4 PET/CT sensitively detected the primary tumor, lymph node metastasis, liver metastasis, and bone metastasis, facilitating accurate tumor assessment and supporting clinical decision-making. The findings were correlated with enhanced CT and MRI and confirmed the location of the hormone-related tumors. This highlights the potential utility of 68Ga-exendin-4 PET/CT as a promising imaging modality for evaluating gastrinomas with no or heterogeneous SSTR expression and guiding precise treatment strategies.