MRI contrast media: what clinicians need to know

Magnetic resonance imaging (MRI) is an imaging modality that uses the differential spinning of protons (hydrogen) in the body when exposed to an external magnetic field, to produce cross-sectional images of the body. The advent of MRI is a boon to mankind as it does not involve ionizing radiation and provides superior soft tissue contrast even without administration of contrast media. The contrast media used in MRI were developed many years after MRI was already in use, the first being gadopentetate dimeglumine--a non-specific extracellular gadolinium chelate. Extracellular agents are the most widely used, although tissue-specific agents have been developed and are used as problem-solving tools in specific conditions. Tolerance to gadolinium-based contrast agents is excellent. The tissue-specific agents do have some adverse effects, though none of them are life-threatening. However, identification of a condition called nephrogenic systemic fibrosis has forced a rethink about the liberal usage of MRI contrast agents.