GLP1R and pancreatic insulinoma: PET/CT imaging with [68Ga]Ga-DOTA-exendin-4 or [68Ga]Ga-NOTA-MAL-Cys39-exendin-4 provides an accurate localization of the primary lesion due to high tumor-to-background ratio, GLP-1 expression levels of insulinoma, and spatial resolution [89,90].