USE OF INTRAOPERATIVE ULTRASONOGRAPHY TO LOCALIZE ISLET-CELL TUMORS

Because approximately 50% of insulinomas and a similar proportion of g astrinomas are not evident on preoperative imaging studies, precise in traoperative localization of these small tumors is imperative. Recentl y the use of high-resolution real-time B-mode ultrasonography has dram atically facilitated the operative detection of pancreatic islet cell tumors. The tumor appears sonolucent compared to the more echo-dense s urrounding pancreas. This operative technique has been especially usef ul in patients with insulinoma because these tumors are generally loca ted within the pancreas. In fact, it is so helpful during explorations for insulinoma some suggest that extensive preoperative localization studies are no longer indicated-that the patient can simply be explore d with intraoperative ultrasonography (IOUS). It has not been as usefu l for gastrinomas because of their common extrapancreatic location. Ac cumulating evidence suggests that IOUS is an effective tool to aid in the operative localization and resection of pancreatic islet cell tumo rs. Not only can it precisely localize the tumor, it can accurately do cument the relation of the tumor to other vital pancreatic structures including ducts, veins, and arteries.