Carcinoids from 2% of all gastrointestinal tumors and are the second most common small-bowel malignancy . they belong to a category of tumors called apudomas (amine precursor uptake and decarboxylation tumors) because they arise from endocrine amine precursor uptake and decarboxylation cells that can be found throughout the gastrointestinal tract and in other organs such as the pancreas and the lung. The tumor arises in the wall of the bowel as a submucosal mass that may result in scarring and kinking of the surface. Tumours originating from the foregut develop in the stomach, duodenum, and pancreas; those arising in the midgut develop in the small bowel, appendix, and right colon; and those arising from the hindgut develop in the transverse colon, left colon, or rectum. Small-bowel carcinoids are multiple in 29–41% of patients and will be associated with a second primary malignancy, usually in the gastrointestinal tract, in a significant percentage (29–53%) of patients most common in fifth or sixth decade with average of hormonal symptoms dating for 9 yrs arise from the Kulchitsky's cells in the crypts of Lieberkühn. Therefore, they grow as submucosal nodules, Visualization of the enhancing mural mass is improved if water is given as an oral contrast agent and if multiplanar reconstructions or 3D imaging software is used
CT could detect mesenteric infiltratin or liver metastases On early (arterial) phase imaging after the administration of an IV contrast agent, these metastases enhance brightly. On delayed imaging, these lesions may become isodense with the liver parenchyma.
On MRI the primary tumor appears as a discrete mass that enahnces with gadolinium. The appearance of unenhanced T1- and T2-weighted images varies. Most tumors are isointense to muscle on T1-weighted images and either hyperintense or isointense to muscle on T2-weighted images . During the portal venous phase, many lesions become isointense. In some cases, somatostatin receptor scintigraphy or biopsy may be necessary.
Case Submitted by Dr MGK Murthy, MD, Sr Consultant Radiology
Bowel Carcinoid-MRI Reviewed by Sumer Sethi on Monday, September 22, 2008 Rating: