Intraluminal contrast agents for MR imaging of the abdomen and pelvis

Magnetic resonance (MR) imaging of the abdomen and pelvis with use of gastrointestinal (GI) contrast agents is slowly emerging as a valuable diagnostic tool. In the past few years, considerable effort has been expended on developing an oral contrast agent to serve as a bowel marker during abdominal and pelvic imaging. Four major categories of agents have been studied: compounds with positive contrast-enhancing characteristics (ie, which increase signal intensity), which may be either miscible or immiscible with bowel contents, and compounds with negative contrast-enhancing characteristics (ie, which decrease signal intensity), which also may be miscible or immiscible. Compared with precontrast images, MR images acquired after administration of GI contrast agents have shown increased anatomic delineation of the bowel lumen, pancreas, and paraaortic nodes, allowing increased detection of pancreatic lesions, improved assessment of bowel wall lesions, and distinction between intrahepatic and extrahepatic lesions. This review focuses on the general physics and requirements for intraluminal GI contrast media for MR imaging, the currently used intraluminal agents and their regulatory status, current and near-future availability, and cost considerations.