Localization of pancreatic insulinomas with MR imaging at 0.5 T

Objective: To determine the role of MR imaging in the localization of pancr eatic insulinomas in patients with clinical and laboratory diagnosis of ins ulin-producing tumor. Material and Methods. Thirty-one patients presenting with signs and symptom s of pancreatic insulinomas were prospectively included in our study. Twent y-six patients underwent surgery, and pathologic specimens were examined: 5 patients, in whom the initial diagnosis of insulinoma was excluded, were a lso studied and then followed up. All patients were studied with a high gra dient power 0.5 T magnet. Images were evaluated by 2 radiologists blinded t o previous investigations, tests and results. Results: MR imaging correctly localized 24 of the 26 insulinomas (2 were fa lse-negative and 1 false-positive) and was correctly negative in the 5 cont rol patients. The interobserver agreement had a kappa value of 0.89. Conclusion. MR imaging was accurate in localizing pancreatic insulinomas an d as a consequence, patients in our institution are now submitted to surger y directly after the MR examination. Invasive methods are considered only i n cases in which, despite clear biochemical results, MR imaging has not dem onstrated a pancreatic focal lesion.