For children with congenital hyperinsulinism (CHI), low blood sugar is caused by cells in the pancreas that release too much insulin. Some children with CHI have these cells throughout their pancreas (called diffuse disease); others have them located in specific areas of the pancreas (called focal disease). Children who have focal disease located in specific areas of the pancreas may be cured with surgery. F-DOPA is a radioactive drug that is picked up by these cells and used for positron emission tomography (or PET), an imaging technique used in nuclear medicine departments. In this study, researchers will validate the efficacy and safety of using PET/CT with F-DOPA in the pre-operative localization of focal disease in children with hyperinsulinism.