Glucagon-like peptide-1 receptor PET/CT with ⁶⁸Ga-exendin-4 for localizing insulinoma: a real-world, single-center study.

PURPOSE: Accurate preoperative localization is imperative for the treatment of insulinomas. Glucagon-like peptide-1 receptor (GLP-1R) imaging has demonstrated remarkable efficacy in localization of insulinomas. The aim of this study was to assess the diagnostic performance of GLP-1R PET/CT with Ga-exendin-4 in localization of insulinoma, and to provide evidence for clinical practice from a real-world study. METHODS: This is a retrospective analysis of our prospective cohort study of Ga-exendin-4 PET/CT in insulinoma (NCT02560376). Patients with endogenous hyperinsulinemic hypoglycemia and definite final diagnosis were enrolled. Results of contrast-enhanced CT (CECT) with pancreatic perfusion scan, MRI, endoscopic ultrasound, and Tc-HYNIC-TOC SPECT/CT were collected. The gold standard for diagnosis was histopathology (for insulinoma) or a definite clinical diagnosis of the etiology of hyperinsulinemic hypoglycemia after hospitalization in the endocrinology department (for non-insulinomatous hypoglycemia). RESULTS: A total of 357 patients (including 296 insulinoma patients and 61 non-insulinoma patients) with were included. The overall sensitivity, specificity, accuracy, PPV, and NPV of Ga-exendin-4 PET/CT in localizing insulinoma were 94.93% (95%CI, 91.78%˜97.14%), 100.00% (95%CI, 94.13%˜100%), 95.79% (95%CI, 93.16%˜97.63%), 100.00% (95%CI, 98.32%˜100%), 80.26% (95%CI, 71.29%˜86.94%), respectively. The area under the ROC of Ga-exendin-4 PET/CT for diagnosing insulinoma was 0.975 (95%CI, 0.953 ˜ 0.988), which was superior to that of CECT (AUC = 0.873 [95%CI, 0.833 ˜ 0.906]), MRI (AUC = 0.825 [95%CI, 0.773 ˜ 0.869]), EUS (AUC = 0.746 [95%CI, 0.652 ˜ 0.825]) and Tc-HYNIC-TOC SPECT/CT (AUC = 0.618 [95%CI, 0.562 ˜ 0.672]). The lesion-based sensitivity of Ga-exendin-4 PET/CT in sporadic benign insulinoma was 95.47% (95%CI, 92.22%˜97.64%), and the PPV was 99.61% (95%CI 99.60%˜99.62%). In contrast, the diagnostic efficacy of Ga-exendin-4 PET/CT was found to be less effective in cases of sporadic malignant insulinoma or inherited syndromes, yielding a lesion-based detection rate of 66.43% and 68.04%, respectively. CONCLUSION: Ga-exendin-4 PET/CT is a preferred imaging modality in diagnosing insulinoma, particularly in sporadic benign insulinomas.