Congenital hyperinsulinism — a severe imbalance of insulin — is the most common cause of persistent hypoglycemia in infants and children. If it is not controlled, it can cause irreversible brain damage. If the disease is limited to a section of the pancreas, it can be cured by surgically removing the focal lesions. However, focal lesions are difficult to identify at surgery and cannot be detected with conventional imaging methods such as CT or MRI. Furthermore, interventional radiological techniques are invasive, technically difficult and unreliable. As reported in the February issue of the Journal of Pediatrics, Dr. Olga T. Hardy and her colleagues from the Children’s Hospital of Philadelphia assessed the accuracy of using PET scans to diagnose focal versus diffuse disease and to locate focal lesions. The researchers injected 18F-fluoro-L-dihydroxyphenylalanine into 24 infants and took five or six consecutive 10-minute-long scans with a PET camera designed and built by the physics and instrumentation group at the University of Pennsylvania. The camera had both axial and transverse fields of view of 25 cm, which is suitable for imaging the whole body of a newborn. Compared with the findings at pathology, the diagnosis with PET of focal or diffuse disease was correct in 23 of the 24 patients. PET also identified all 12 diffuse cases and 11 of 12 focal disease cases. The investigators believe that the results indicate that PET should be considered for use in all infants who have congenital hyperinsulinism and who may need to have surgery.