Fluorine-18-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET) can be used to localize insulinoma or beta-cell hyperplasia in adult patients, according to a report in The Journal of Clinical Endocrinology & Metabolism. Fluorine-18-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET) can be used to localize insulinoma or beta-cell hyperplasia in adult patients, according to a report in the April issue of The Journal of Clinical Endocrinology & Metabolism.

Conventional imaging studies have long been used for tumor localization in patients with insulinoma or beta-cell hyperplasia, the authors explain, but all such methods either have limited sensitivity or are invasive procedures.

Dr. Pirjo Nuutila from Turku University Hospital, Finland and colleagues compared the diagnostic sensitivity of 18F-DOPA PET with conventional methods in ten hyperinsulinemic and hypoglycemic adults.

The PET images localized the lesion in six of seven patients with insulinoma, in the case of insulinoma metastatic to the liver, and in the two patients with beta-cell hyperplasia, the authors report.

18F-DOPA PET was more sensitive (90 per cent) than CT (30 per cent) or MRI (40 per cent) in identifying the disease focus, the report indicates, and 18F-DOPA provided additional information for surgery that was obtained with none of the other imaging procedures.

Symptoms of hypoglycemia resolved after operation in nine of the ten patients, the researchers note. One patient developed severe pancreatitis leading to death after the pancreatic enucleation.

"Because L-DOPA also accumulates physiologically in the normal pancreas, 18F-DOPA PET is a useful diagnostic tool only for patients with confirmed inappropriate insulin secretion," the investigators say.

"Future studies are likely to be performed with hybrid PET/CT scanners, which enable correlation of anatomical and functional information within one imaging session," they add, concluding: "18F-DOPA PET has the potential to become the functional imaging method of the future, once the results reported here are confirmed in a larger patient population.