[Imaging of neuroendocrine tumors]

Neuroendocrine tumors (NET) of the pancreas are distinguished in functional (85%) and non functional (15%) in relation to the production and release of the hormone produced. Functional tumors show early, because the neoplasm release the hormone produced when they are still small. Non functional tumors show late when the tumor grows. The localization and the evaluation of the extensive of these tumors has come fundamentally important both in correct presurgical detection and also in the diagnosis of metastases which excluded surgery. Also, as the survival of 20% of the patients with metastases is only five years, the use of non-invasive imaging techniques is very important for the evaluation of results of the various therapies (chemotherapy, interferon, somatostatin). Recent studies have shown that in patients with Zollinger-Ellison syndrome, SRS is the most sensitive non invasive method in localizing primitive tumors and metastases. The accuracy of this technique has not yet been provided in the study of tumors like insulinomas which do not have a high percentage of somatostatine receptors on their cell membranes. The sensitivity obtained in recent studies on a large number of patient and the low cost, lower than all the other imaging technique in use today, surely make SRS the first choice in the study of NET. Where SRS is negative and surgery is possible, Spiral CT or better still MRI is the best tool to check the results of chemotherapy in patients with hepatic metastases (already detected by SRS), because it is easier to compare the changes in size and morphology of metastases.