Review Shows MRI Contrast Agents Accumulate in Brain

A new review of studies provides guidance and recommendations for the clinical and research use of gadolinium-based contrast agents.

Researchers at Case Western Reserve University (CWRU; Cleveland, OH, USA), the University of Melbourne (UNIMELB; Parkville, Australia), and other institutions acting on behalf of the International Society for Magnetic Resonance in Medicine (ISMRM; Concord, CA, USA) conducted a review of literature that suggests that gadolinium-based contrast agents, used to enhance magnetic resonance imaging (MRI) scans since their introduction in 1987, leave deposits in the brain.

The evidence confirms that gadolinium accumulates in brain tissue, most notably in the dentate nuclei and globus pallidus, but that the extent of gadolinium deposition varies between different contrast agents. Although some linear contrast agents appear to cause greater MRI signal changes than some macrocyclic agents, deposition of gadolinium has also been observed with macrocyclic agents. But while the deposition itself has been confirmed, the clinical significance of the retained gadolinium in the brain remains unknown. The review was published on August 10, 2017, in The Lancet Oncology.

“Small amounts of gadolinium deposit in certain parts of the brain in people who undergo repeated gadolinium-based contrast agent enhanced exams,” said lead author Vikas Gulani, MD, PhD, Associate Professor of Radiology, Urology, and Biomedical Engineering “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.”

Gadolinium--a rare earth heavy metal--is used for enhancement during MRI. Neurotoxic effects have been seen in animals and when a GBCA is given intrathecally in humans. On its own, gadolinium can be toxic; therefore, when used in contrast agents, gadolinium is bonded with a chelating agent in order to control distribution within the body. In July 2015, the U.S. Food and Drug Administration (FDA) stated that it was unknown whether gadolinium deposits in the brain were harmful.

Related Links:
Case Western Reserve University
University of Melbourne
International Society for Magnetic Resonance in Medicine