 A novel nuclear medicine scanning method using radioactive exendin-4 111In-exendin-4 has recently been developed for imaging of insulinomas. 111In-exendin-4 accumulates specifically in insulinoma cells via the glucagon-like peptide-1 GLP-1 receptor. The accumulation of 111In-exendin-4 can be visualised by the use of a special camera Single Photon Emission Computed Tomography SPECT camera that detects radioactivity and lights up tumours as hot spots. 