Contrast agents for MR enterography

Abstract

Magnetic resonance enterography is primarily indicated for inflammatory bowel diseases. The study of the gastrointestinal tract using MRI has become feasible due to the emergence of ultrafast sequences with higher spatial resolution and phased-array coils enabling wider fields of view. However, to ensure the quality of the examination, it is essential to have prior preparation with oral or rectal contrast to distend the lumen and improve the definition of the intestinal wall. These contrast agents can be positive, negative or biphasic, depending on the signal intensity they induce in the intestinal lumen. Most commonly used biphasic contrasts agents behave as hyperintense in T2 and hypointense in T1. Achieving a “black” intestinal lumen in 3D T1-weighted sequences with intravenous contrast injection is crucial for mucosal assessment and parietal enhancement. Although more cost-effective and accessible, biphasic agents like PEG and mannitol are relatively discomforting for patients. While negative agents are preferred, they are currently unavailable. The purpose of this article is to review the different types of contrast agents mentioned in the literature and their application in intestinal resonance, analyzing the effects they generate on the image, their possible indications and associated limitations.