INDIUM-111-PENTETREOTIDE SCANNING VERSUS CONVENTIONAL IMAGING TECHNIQUES FOR THE LOCALIZATION OF GASTRINOMA

Background. The present study evaluates In-111-pentetreotide scanning as a method for detection of gastrinomas. Operative findings serve as the benchmark for comparison of the efficacy of In-111-pentetreotide versus conventional imaging studies. Methods. Twelve patients (seven female and five male; age, 37 to 80 years) with histologic confirmation of gastrinoma underwent thin section dynamic computed tomography (CT) scanning and In-111-pentetreotide scanning. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of In-111-pentetreotide and CT scanning are compared on the basis of tumor size and location. Results. Thirty discrete foci of intrahepatic and extrahepatic tumors were detected at operation. CT scanning detected three of nine pancreaticoduodenal lesions, whereas eight of these nine extrahepatic primary tumors were imaged by In-111-pentetreotide scanning. No false-positive In-111-pentetreotide scans were noted. The sensitivity of CT scanning for detection of metastatic disease was 56% versus 94% for the In-111-pentetreotide scan. Successful CT imaging was highly dependent on tumor size. No tumor smaller than 1 cm was imaged by CT, whereas four fo seven lesions greater than 1 cm were imaged by In-111-pentetreatide scintigraphy. The smallest gastrinoma imaged by In-111-pentetreotide scanning was a 4 mm duodenal tumor. Conclusions. In-111-pentetreotide scanning was superior to CT scanning for localizing gastrinomas. Further studies are required to determine whether In-111-pentetreotide scans will complement or replace traditional imaging methods.