Following a nearly two-year review, federal drug regulators have been unable to find any negative side effects from brain retention of gadolinium; which is used in many MRI contrast agents.
In a drug safety communication on May 22, the FDA acknowledged that it does appear MRI gadolinium builds up in the brain, bones and skin. However, the agency indicates that it has not been able to identify any adverse health effects from the accumulation.
Gadolinium based contrast agents are used to enhance the magnetic resonance imaging (MRI) results, allowing physicians interpreting the exam to distinguish blood vessels from nearby tissue. According to the American College of Radiology (ACR), gadolinium-based contrast agents are used on about 30 million patients annually.
In April 2015, a study published in the medical journal Radiology examined the brains of cadavers and found that those who had received gadolinium injections had deposits in the brain, while those who had not received such injections did not.
In June 2015, a study by European researchers in the journal Investigative Radiology found similar deposits in the brains of rats injected with Omniscan, a GBCA (gadolinium-based contrast agent) made by GE Healthcare. The rats developed significant, persistent MRI abnormalities over time, and high levels of gadolinium were found deep in the rats’ brains.
In July 2015, the FDA launched a review of MRI contrast agents following a number of studies that suggested individuals injected with the chemicals may experience a buildup of gadolinium in the brain. European regulators later launched a similar review and also failed to find any harmful side effects.
In July 2016, the ACR issued new, updated guidelines, urging doctors to consider a number of factors when deciding whether gadolinium MRI contrast agents should be used, due to growing concerns about the buildup of gadolinium in the brain.
However, the FDA has decided not to place any restrictions on gadolinium-based contrast agents (GBCAs) at this time.
“As is appropriate when considering the use of any medical imaging agent, health care professionals should limit GBCA use to circumstances in which additional information provided by the contrast agent is necessary, and assess the necessity of repetitive MRIs with GBCAs,” The FDA recommends. “Patients, parents, and caregivers should talk to their health care professionals if they have any questions or concerns about the use of GBCAs with MRIs.”
Gadolinium Contrast Safety Concerns
Although the MRI dyes are generally believed to be safe, several years ago concerns emerged about a link between MRI gadolinium contrast agents and a severe and life-threatening skin condition, known as nephrogenic systemic fibrosis (NSF), which was found to occur among patients with impaired kidney function, causing their skin to thicken and harden, severely restricting movement.
Sometimes referred to as gadolinium associated systemic fibrosis, NSF is a painful disorder that has no known cure and often results in confinement to a wheelchair and then death.
In 2007, the FDA limited gadolinium contrast doses in most patients and contraindicated it for others, which limited the risk of NSF. In September 2010, the FDA went even further and banned the use of Bayer’s Magnevist on patients with kidney problems, due to the heightened risk of NSF.
The agency also required label changes for all gadolinium agents, warning healthcare professionals to screen patients before injecting gadolinium to identify those suffering from acute kidney injury or chronic, severe kidney disease.
Following its more recent review, the FDA indicated that NSF should still be the adverse side effect of concern involving gadolinium-based contrast agents. The FDA is continuing to assess their safety, and its National Center for Toxicological Research is currently conducting a study on gadolinium brain retention in rats.
The FDA indicates that it will schedule a public hearing on its findings and the safety of GBCAs at a future date.