Qualitative and Quantitative Analyses of Noninvasive Diagnosis of Insulinoma Using [18F]FB(ePEG12)12-Exendin-4 PET/CT.

CONTEXT: This study represents the first interim report from a phase 2 clinical trial. Accurate localization of insulinomas remains a clinical challenge despite the availability of various imaging modalities. OBJECTIVE: The current study aimed to evaluate the efficacy of positron emission tomography/computed tomography (PET/CT) using [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4), a novel 18F-labeled PEGylated glucagon-like peptide 1 (GLP-1) receptor-targeted imaging probe, for the noninvasive detection of insulinomas. METHODS: This prospective single-center study enrolled patients with biochemically confirmed hyperinsulinemic hypoglycemia suggestive of insulinoma. All patients underwent 18F-exendin-4 PET/CT, with scans performed at 60 and 120 minutes after injection. The findings of 18F-exendin-4 PET/CT were then compared with those of conventional imaging modalities performed before and after 18F-exendin-4 PET/CT in actual clinical settings, with all findings being verified through surgical and pathological findings. RESULTS: 18F-exendin-4 PET/CT successfully identified insulinomas in all 12 patients (100% sensitivity), showing significantly higher uptake in tumor tissues than in the surrounding pancreatic tissues and organs. The detection rate of 18F-exendin-4 PET/CT exceeded that of the conventional imaging modalities (CT, 83%; magnetic resonance imaging, 63%; endoscopic ultrasonography, 90%; selective arterial calcium stimulation, 89%). All identified lesions were surgically confirmed to be insulinomas, with complete clinical resolution of hypoglycemia after resection. CONCLUSION: 18F-exendin-4 PET/CT demonstrated effective sensitivity for noninvasive insulinoma detection, offering a reliable and practical diagnostic alternative to invasive procedures for precise and prompt preoperative localization with functional evaluation. This novel imaging approach may therefore improve the management of patients with suspected insulinomas.