Intraoperative localization of gut endocrine tumors with radiolabeled somatostatin analogs and a gamma-detecting probe.

Gut endocrine tumors are sometimes difficult to localize by radiological techniques. Carcinoids and gastrinomas, however, possess high density of somatostatin receptors, thus, scintigraphy with radiolabeled somatostatin analogs may prove useful for detection of occult gastro-enteropancreatic endocrine tumors when conventional diagnostic methods fail. A novel method of radioguided surgery with a hand-held gamma-detecting probe (GDP) has been used to localize gut endocrine tumors by binding radiolabeled somatostatin analogs. We also applied the method in a patient with occult carcinoid: after injecting 125-Iodine (125I)-octreotide intraoperatively, we obtained accurate localization of the jejunal carcinoid and of a liver metastasis previously undetected. Seventeen cases of gut endocrine tumors detected by this technique that have been reported in the literature are reviewed and discussed. Intraoperative localization of gastrointestinal endocrine tumors with radiolabeled somatostatin analogs and a GDP expands the possibility of accurate tumor detection one step beyond that obtained by conventional imaging and by intraoperative inspection and palpation.