Ga-68-NODAGA-Exendin-4 PET/CT Improves the Detection of Focal Congenital Hyperinsulinism

Abstract

Surgery with curative intent can be offered to congenital hyperinsulinism (CHI) patients, provided that the lesion is focal. Radiolabeled exendin-4 specifically binds the glucagonlike peptide 1 receptor on pancreatic beta-cells. In this study, we compared the performance of F-18-DOPA PET/CT, the current standard imaging method for CHI, and PET/CT with the new tracer Ga-68-NODAGA-exendin-4 in the preoperative detection of focal CHI. Methods: Nineteen CHI patients underwent both F-18-DOPA PET/CT and Ga-68-NODAGA-exendin-4 PET/CT before surgery. The images were evaluated in 3 settings: a standard clinical reading, a masked expert reading, and a joint reading. The target (lesion)-to-nontarget (normal pancreas) ratio was determined using SUVmax. Image quality was rated by pediatric surgeons in a questionnaire. Results: Fourteen of 19 patients having focal lesions underwent surgery. On the basis of clinical readings, the sensitivity of Ga-68-NODAGA-exendin-4 PET/CT (100%; 95% CI, 77%-100%) was higher than that of F-18-DOPA PET/CT (71%; 95% CI, 42%-92%). Interobserver agreement between readings was higher for Ga-68-NODAGA-exendin-4 than for F-18-DOPA PET/CT (Fleiss kappa = 0.91 vs. 0.56). Ga-68-NODAGA-exendin-4 PET/CT provided significantly (P = 0.021) higher target-to-nontarget ratios (2.02 +/- 0.65) than did F-18-DOPA PET/CT (1.40 +/- 0.40). On a 5-point scale, pediatric surgeons rated Ga-68-NODAGA-exendin-4 PET/CT as superior to F-18-DOPA PET/CT. Conclusion: For the detection of focal CHI, Ga-68-NODAGA-exendin-4 PET/CT has higher clinical sensitivity and better interobserver correlation than F-18-DOPA PET/CT. Better contrast and image quality make Ga-68-NODAGA-exendin-4 PET/CT superior to F-18-DOPA PET/CT in surgeons' intraoperative quest for lesion localization.