VALUE OF SOMATOSTATIN RECEPTOR SCINTIGRAPHY FOR PREOPERATIVE LOCALIZATION OF CARCINOIDS

Most carcinoid primary tumors are small and do not cause symptoms unti l complications (e.g. intestinal obstruction) or symptoms and signs of the carcinoid syndrome occur. Therefore in most cases an assessment o f the primary tumor and its metastases must be performed. To determine the value of somatostatin receptor scintigraphy (SRS) for localizing carcinoid tumors, we compared the results of SRS with those obtained w ith computed tomography (CT) and ultrasonography (US) in 22 patients w ho had not undergone surgery for removal of the primary tumor. We coul d not find an advantage of SRS over CT and US for detecting the primar y lesions. Tumors > 2 cm in diameter were regularly detected using all methods. SRS was not superior to CT or US for the detection of liver metastases. SRS showed the liver metastases in 16 of 18 patients, wher eas CT and US detected liver metastases in all patients. For localizat ion of extrahepatic abdominal and extraabdominal metastases (lymph nod es, bone), whole-body SRS showed an advantage over CT and US. We concl ude that SRS is not superior to CT or US for localization of primary c arcinoid tumors or liver metastases, although it did prove successful for visualizing extrahepatic and extraabdominal tumor spread. Addition ally, SRS is useful for identifying receptor-positive metastases that map be treated by somatostatin analogs. Thus SRS should be performed i n patients with a known carcinoid tumor, except those with an appendic eal carcinoid measuring < 1 cm in diameter.