Role of (111)In-DTPA-pentetreotide scintigraphy in accurate diagnosis of neuroendocrine gastroenteropancreatic tumors

Most gastroenteropancreatic neuroendocrine tumors contain high-affinity binding sites for somatostatin, and somatostatin-receptor scintigraphy has been introduced for the in-vivo evaluation of such tumors. We report two patients with gastroenteropancreatic neuroendocrine tumors, in whom it was quite difficult to localize the tumors by conventional techniques, and in whom we found that (111)In-DTPA-pentetreotide scintigraphy was useful for accurate information on tumor localization. In the first patient, who had gastrinoma, multiple tumors were shown in the gastrinoma triangle, but we could not clarify whether there were any tumors in the pancreatic body. The selective arterial secretin injection (SASI) test diagnosed that the gastroduodenal artery was the feeder of the gastrinomas, and (111)In-DTPA-pentetreotide scintigraphy with single-photon emission computed tomography indicated the absence of tumors in the pancreatic body. In the second patient, who had insulinoma, multiple liver tumors and a large mass in the hilum of the spleen were shown. (111)In-DTPA-pentetreotide scintigraphy was useful in determining that there was no secretion of insulin from the tumor in the hilum of the spleen. In conclusion, X-ray computed tomography is superior for detection of neuroendocrine tumors, because not all neuroendocrine tumors have somatostatin receptors; however, somatostatin receptor scanning, as well as the SASI test, may be useful for the surveillance of patients with known primary tumors, for monitoring patients with disseminated disease, and for following the treatment of these patients.