Noninvasive imaging of insulinomas and gastrinomas with endoscopic ultrasonography and somatostatin receptor scintigraphy

Background. Classic morphological techniques are of limited value for imaging endocrine duodenopancreatic tumors, and invasive procedures such as intraarterial stimulation are often used. Two noninvasive procedures, endoscopic ultrasonography (EUS) and somatostatin receptor scintigraphy (SRS), were recently described with promising results. Methods. In this study we correlated the results of preoperative EUS (n = 34) and SRS (n = 30) with operative findings in patients with histologically proven insulinoma (n = 20) or gastrinoma (n = 21). Results. The sensitivity and positive predictive value (PPV) of EUS were respectively 77% and 94% for pancreatic tumors (insulinomas and gastrinomas) 40% and 100 % for duodenal gastrinomas, and 58% and 78% for metastatic lymph nodes. The sensitivity and PPV of SRS for insulinoma were 60% and 100 %, respectively. In patients with gastrinoma, the sensitivity and PPV of SRS were respectively 25 % and 100 % for pancreatic gastrinomas, 72 % and 100 % for duodenal gastrinomas or periduodenal metastatic lymph nodes, and 67% and 80 % for liver metastasis. In patients with multiple endocrine neoplasia, neither one of the two techniques detected all tumors. Overall sensitivity of combined EUS and SRS was 89 % for insulinoma (n = 9) and 93 % for gastrinoma (n = 14). Conclusions. EUS and SRS for gastrinomas and insulinomas should be considered as the initial preoperative imaging-procedures and may render invasive procedures unnecessary for most patients.