Magnetic resonance imaging (MRI) is a body scan that provides detailed images particularly good for viewing soft tissue (versus a traditional X-ray that’s better for seeing bone). Sometimes, drugs are injected before you have an MRI to add contrast, making the images sharper. But some of the drugs in those agents might be toxic.
We recently wrote about another risk of certain diagnostic scans including MRIs, when people are not told about the risks of radiation. Now, according to ProPublica.org, it seems as though the brain can be damaged by a heavy metal the contrast drugs contain called gadolinium.
Marcie Jacobs, a woman profiled in the story, had a family history of breast cancer. In 2001, she decided to have an MRI for preventive care. She was injected with a contrast agent, and later began experiencing strange cognitive effects. At first they were fairly minor, like forgetting about work meetings.
As she continued to have MRIs over several years, the problems got worse. She was a finance manager, and her math skills deteriorated so much that she had to stop working and go on disability.
“She stopped worrying about cancer,” said ProPublica, “and started worrying about imaging drugs.”
A few weeks ago, two prominent radiologic researchers, Dr. Emanuel Kanal and Michael Tweedle wrote an editorial in the journal Radiology, calling for more scientific scrutiny of the use of gadolinium for its potential toxicity in brain tissue.
Of the nine gadolinium-based contrast agents sold in the U.S., the two are of serious concern — Omniscan, made by GE Healthcare, and Magnevist, by Bayer HealthCare. ProPublica reported that both companies said they are monitoring the issue, but that the new studies had not found any clinical impact, including brain injury.
This isn’t the first time safety questions have been raised about contrast agents. In 2007, the FDA slapped a black box warning on them (the most severe of that agency’s cautionary notifications) after they were linked to a sometimes fatal condition called nephrogenic systemic fibrosis (NSF). It’s an impairment of the kidneys, which can have trouble excreting gadolinium.
In 2009, ProPublica reported that the FDA had ignored two of its own medical reviewers who wanted to ban Omniscan for patients with severe kidney disease. By 2010, the feds finally recommended that the GE drug and two other drugs, Magnevist and Optimark, sold by Mallinckrodt Pharmaceuticals, shouldn’t be given to patients with compromised kidneys.
But the recent research cited by Kanal and Tweedle show that even patients with healthy kidneys are retaining gadolinium from Omniscan and Magnevist. It’s estimated, said ProPublica, that 1 in 3 of the 20 million annual MRIs in the U.S. rely on one of the nine contrast agents.
People scheduled for MRIs using contrast agents now are screened for kidney problems, and the incidence of NSF, according to ProPublica, “has essentially disappeared.” And even though the new studies don’t address potential clinical effects of gadolinium in the brain, Kanal told the reporters that their results should make radiologists seriously ponder which agents to prescribe.
“We can use an agent today that does not retain gadolinium in the brain to the degree that [Omniscan and Magnevist] do,” he said. And because the alternatives are at least as good as those two, he asked, “Why are some still prescribing the agents that do accumulate in the brain over the other options?”
That degree of consideration came too late for Marcie Jacobs, even though she can’t prove that those drugs were responsible for her disability.
Her records showed that she had received Omniscan for her first 11 MRIs and Magnevist before the last one, in 2007. Eventually, tests showed that traces of gadolinium had accumulated in her breast, thigh, liver and brain, even though she had no history of kidney disease and did not present a risk for kidney impairment.
Kanal, who advises the FDA and chairs the American Board of MR Safety, said the new studies have “the entire international radiological community – and the FDA – on edge, as this is an entirely unanticipated finding.”
And what does the FDA have to say? That it’s “carefully reviewing” the new studies to “better understand the potential consequences to determine what further action is needed, which may include taking steps to ensure the public is aware of these preliminary findings.”
GE found “no signs or symptoms of potential injury to the brain” associated with Omniscan and “no evidence of cytotoxicity (cell toxicity) in published autopsy studies.” It believes that “continued use of Omniscan according to approved product labeling” is appropriate.
Bayer told ProPublica patient safety is its “primary concern” and wants the authors of the original research studies “to clarify their findings,” even though “none of these studies indicate any clinical implications.”
ProPublica noted that both GE and Bayer have settled hundreds of lawsuits – many involving deaths – while denying liability for their contrast agents, so might we suggest they monitor less and do more to make their products safer?
As we always advise, don’t undergo diagnostic screenings unless there’s a very good reason. Your doctor should make very clear what those reasons are, what the risks of the procedure are, what is expected to be learned from the results and what options are there to having the scan.
To read more about the potential harms of overscreening, see our blogs on the topic.