Imaging of Gastrointestinal Neuroendocrine Tumors

Gastrointestinal neuroendocrine tumors (NETs) are a diverse group of neoplasms that arise from cells of the diffuse neuroendocrine system. Neuroendocrine tumors occur throughout the gastrointestinal tract. These tumors can produce a variety of hormones resulting in specific symptoms that may aid in their detection and classification. While all NETs have malignant potential, these tumors vary in their biologic characteristics and potential for metastatic disease. Although several classification schemes for neuroendocrine tumors have been proposed, the World Health Organization classification is currently the most widely accepted that will be reviewed in this paper. Various imaging modalities and techniques have evolved in recent years, including both morphologic and functional imaging techniques that will be explored in this paper. A thorough knowledge of the most recent classification schemes greatly aids radiologists in the assessment of gastrointestinal neuroendocrine tumors. Appropriate application of both morphologic and functional techniques is likewise essential for proper diagnosis and surveillance of gastrointestinal neuroendocrine tumors.