Neuroendocrine tumors of the gastrointestinal tract

Neuroendocrine tumors (neuroendokrine Tumoren) are rare entities. They can be found in all organs and show substantial biologic heterogeneity depending on involved organ, clinical symptoms and histopathologic morphology. Involvement of organs like larynx, cervix uteri, ovary, gallbladder, liver or kidney is extensively rare. The majority of neuroendokrine Tumoren are found in gastrointestinal tract and lung and are classified as neuroendokrine Tumoren of foregut (stomach, duodenum, pancreas, lung), midgut (jejunum, ileum, appendix, right side of the colon) and hindgut (left side of the colon, rectum). The role of imaging is to localize and delineate the primary tumor and to detect metastases. In the diagnosis of neuroendokrine Tumoren radiologic techniques like computed tomography (CT) and magnetic resonance imaging (MRI) are applied. In certain cases nuclear medicine techniques like somatostatin receptor scintigraphy (SRS) and positron emission tomography (PET) using radioactively labelled somatostatin analogues are used. The present article reviews characteristic imaging findings of neuroendokrine Tumoren of the gastrointestinal tract. (orig.)