We evaluated the use of high-resolution, real-time, B-mode, intraoperative ultrasound (IOUS) compared to simple manual palpation to localize gastrinomas during laparotomies in 10 consecutive patients with Zollinger-Ellison syndrome (ZES). All patients had clear biochemical evidence of ZES, and patients with metastatic gastrinoma identified preoperatively were excluded. Preoperative localization studies including ultrasound, computed tomography, and selective arteriography localized gastrinoma in 3 patients. Transhepatic portal venous sampling (PVS) for gastrin localized gastrin gradients to the pancreatic head region in 8 patients, and found no significant gastrin gradient in 2 patients. Gastrinomas were found at laparotomy and proven pathologically in 6 patients. Four patients had gastrinomas in the pancreatic head area as predicted by PVS; however, one patient had a tumor in the pancreatic tail and another in the jejunal wall. Palpation was the most sensitive intraoperative method to localize a gastrinoma (100% sensitivity). IOUS correctly imaged 3 gastrinomas (50% sensitivity). Palpation had 1 false-positive finding (80% specificity) and IOUS had 2 false-positive findings (60% specificity). All palpable masses that were also sonolucent on IOUS proved to be gastrinomas (3 patients). Thus, a combined positive finding raised the specificity and positive predictive value to 100%. We conclude that IOUS has utility in explorations for gastrinomas. Although not as sensitive or specific as palpation, IOUS can confirm, noninvasively, a suspicious palpable nodule. If IOUS fails to image a palpable nodule, our results suggest that the surgeon should still attempt to resect the nodule.
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