Gadolinium-based contrast agents (GBCAs) are widely used for the diagnosis and monitoring of many diseases. However, emerging research published recently in The Lancet Neurology suggests that these MRI contrast agents accumulate in the brain.

Certain characteristic physical properties of tissues related to behavior in a magnetic field, such as T1 and T2 relaxation times, affect the signal intensity of an MRI image. GBCAs shorten the T1 relaxation time of water protons near the contrast agent, and this causes tissues with a high concentration of contrast agent to appear brighter than tissues containing less contrast agent.

Healthcare providers routinely inject gadolinium-based contrast agents into patient veins to brighten tissues in MRI images. Since the introduction of these contrast agents in 1987, providers have administered more than 300 million doses. Previously, the only recognized risks associated with these agents were allergic and adverse reactions, and nephrogenic systemic fibrosis in patients with renal failure.

"Small amounts of gadolinium deposit in certain parts of the brain in people who undergo repeated gadolinium-based contrast agent enhanced exams," said Vikas Gulani, M.D., Ph.D., in a press release. Gulani is an associate professor of radiology, urology and biomedical engineering at Case Western Reserve University School of Medicine and director of magnetic resonance imaging at University Hospitals Cleveland Medical Center.

"The ISMRM response is a review of the literature and a series of recommendations on what the community ought to do in response to this phenomenon."

Gulani served as first author for the review, featured on the cover of The Lancet Neurology, and helped craft the new recommendations. Gulani and other experts contributing to the review suggest holding the gadolinium if it is not needed for a particular exam. They also suggest performing a risk-benefit analysis for all exams.

"Nearly everyone needs an MRI scan at some point, often contrast enhanced," Gulani said. "The idea that some gadolinium could be depositing in the brain is disconcerting to patients. In that situation, putting the risk and benefits into context is important."

Providers should administer contrast in cases where it is necessary, and the choice of agent should be dependent on a number of factors in addition to the deposition phenomenon.

GBCAs have a proven record for accurate diagnosis and treatment monitoring of cancer, heart disease, neurological pathology, liver disease and a number of conditions affecting adults and children. Gadolinium-based contrast agents are associated with few side effects. The most serious of GBCA-associated side effects are extremely infrequent and affect only those patients who are already sick with severe kidney failure.

The authors of the review do not suggest making sweeping changes in the way practitioners use MRI contrast agents as there is currently no evidence that links the brain deposits to health risks. The review does clarify the phenomenon of gadolinium deposition in the brain, which was previously unknown, and it provides guidance for future research.