Children with congenital hyperinsulinism (CHI) have low blood sugar, and some of these children may require surgery. In this study, researchers affiliated with the University of Pennsylvania will test how well a radioactive drug (called F-DOPA) can detect a form of hyperinsulinism that may be cured by surgery. Eligible participants in this study will have positron emission tomography (PET) scans with F-DOPA prior to surgery.