Published online Sep 28, 2015. doi: 10.4329/wjr.v7.i9.220
Peer-review started: May 5, 2015
First decision: June 3, 2015
Revised: June 18, 2015
Accepted: August 4, 2015
Article in press: August 7, 2015
Published online: September 28, 2015
Processing time: 162 Days and 15.5 Hours
Small-bowel carcinoid tumors are the most common form (42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare (3%-6% of all gastrointestinal neoplasms), carcinoids still represent the second most common (20%-30%) primary small-bowel malignancy after small bowel adenocarcinoma. Their imaging evaluation is often challenging. State-of-the-art high-resolution multiphasic computed tomography together with advanced postprocessing methods provides an excellent tool for their depiction. The manifold interactive parameter choices however require knowledge of when to use which technique. Here, we discuss the imaging appearance and evaluation of duodenal, jejunal and ileal carcinoid tumors, including the imaging features of the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. A protocol for optimal lesion detection is presented, including the use of computed tomography enterography, volume acquisition, computed tomography angiography and three-dimensional mapping. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of possible disease in the small bowel and mesentery, the range of possible appearances in the bowel itself on multiphase data and extraluminal findings such as the desmoplastic reaction in mesentery and hypervascular liver metastases. Typical imaging pitfalls and pearls are illustrated.
Core tip: Small-bowel carcinoid tumors are neuroendocrine tumors and represent most common form of gastrointestinal carcinoids. Although primary small bowel neoplasms are overall rare, carcinoids still represent the second most common primary small-bowel malignancy. State-of-the-art high-resolution multiphasic computed tomography with advanced postprocessing methods provides an excellent tool to overcome the challenges of their depiction. Here, we discuss their imaging appearance, focusing on the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. Guidance for imaging protocol selection is given. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of disease. Typical imaging pitfalls and pearls are illustrated.