Despite the background fluorescence signal in the pancreas resulting from uptake of the tracer in healthy pancreatic β-cells, visualization and delineation of insulinomas in humans using this approach is most likely possible, since insulinomas have a high GLP-1R density in almost 100% of cases (higher than healthy pancreatic islets) (28) and visualization with high tumor-to-background ratios has been achieved with radiolabeled exendin (7). The gene discussed is GLP1R; the disease is neoplasm.