Somatostatin-receptor imaging of neuroendocrine gastroenteropancreatic tumors

Background: Gastroenteropancreatic neuroendocrine tumors are often difficult to localize. This study was conducted to examine the value of somatostatin-receptor scintigraphy for visualization of gastroentero-pancreatic neuroendocrine tumors. Methods: Applying the recently developed indium-labeled somatostatin analogue 111In-pentetreotide to 40 patients with gastroenteropancreatic neuroendocrine tumors, the diagnostic power of pentreotide-receptor scintigraphy was evaluated in comparison with conventional imaging techniques. Results: Expression of somatostatin receptors was observed in the majority of patients (11 of 17 in the foregut, 14 of 16 in the midgut, and 7 of 7 in metastatic neuroendocrine tumors with unknown primary). Comparative imaging by computerized tomography, magnetic resonance imaging, and transabdominal ultrasonography yielded false-negative results for somatostatin-receptor scintigraphy in 8 of 40 patients; however, in 16 patients, tumor tissue that had escaped conventional imaging techniques was detected by 111In-pentetreotide scintigraphy. Conclusions:111In-pentetreotide scintigraphy is a practical, safe, and sensitive procedure for in vivo imaging of gastroenteropancreatic neuroendocrine tumors.