Which is the initial Imaging modality of choice for Insulinoma?

For PETs in the pancreas, EUS is highly sensitive, localizing 77-100% of insulinomas, which occur almost exclusively within the pancreas. Tests for location of pNET: Somatostatin Receptor Scintigraphy is the initial imaging modality but is less available. Helical CT scan has a sensitivity of 82-94%. Gadolinium based MRI has sensitivity of 85%. If above scans are negative, then Endoscopic ultrasound will be able to pick up the insulinoma which is usually <1.5 cm in size. If all the above tests turn negative then calcium stimulated angiography can be used to localize the tumor. The intra-aerial calcium test also allows differentiation of the cause of the hypoglycaemia and indicates whether it is due to an insulinoma or a nesidioblastosis.