The evidence level for direct comparison of GLP-1R imaging and 18F-DOPA PET is scarce: we showed in a subpopulation of our latest prospective GLP-1R imaging study who received both PET/CT scans (5/52 patients) a better performance of 68Ga-DOTA-exendin-4 PET/CT compared to 18F-DOPA PET/CT without carbidopa (insulinoma detection rate was 93% versus 0%) (Antwi et al. 2018). Here, GLP1R is linked to pancreatic insulinoma.