BACKGROUND: Many imaging methods have been used to detect
neuroendocrine tumors of the gastrointestinal system. There is no gold standard for identifying the location of primary
tumors and their potential
metastases, and most conventional imaging techniques cannot detect
tumors less than 1.0 cm in size. METHODS: The authors have investigated the use of 111-In-pentetreotide as an imaging agent for abdominal
neuroendocrine tumors. RESULTS: The agent is cleared rapidly by the kidneys and is primarily excreted intact with a
biologic half-life of six hours. The largest radiation burden is to the spleen and kidneys. A nine-center study conducted in Europe involved 365 patients with gastroenteropancreatic
neuroendocrine tumors that were also imaged by other methods. The results of 111-In-pentetreotide were in agreement with those obtained by other methods for 79% of
tumor locations. An additional 110
tumor localizations were detected that were not seen with conventional methods. The smallest
gastrinoma imaged by 111-In-pentetreotide was a 4-mm duodenal
tumor. CONCLUSIONS: Scintigraphy with 111-In-pentetreotide is effective in visualizing various
somatostatin receptors characteristic of
neuroendocrine tumors of the gastrointestinal tract.
Insulinomas, however, are not well imaged. Concurrent computed tomography scanning is advised to minimize the risk of missing liver
metastases.