09-04-2025
Scientists Discover How Much Toxic Metal Used in MRI Scans Invades Human Tissue
New research suggests that MRI with contrast may create nanoparticles that infiltrate your tissues.
The research is preliminary, and more work needs to be done.
Doctors stress that MRI with contrast is a generally safe procedure.
A magnetic resonance imaging (MRI) scan is an important tool to help doctors see what's happening inside your body. But new, preliminary research suggests that a contrast agent used in some MRIs could spark a chain reaction that ends up with nanoparticles of metal embedded in your tissues.
Meet the experts: Jamie Alan, Ph.D., an associate professor of pharmacology and toxicology at Michigan State University; Kelly Johnson-Arbor, M.D., a toxicologist at MedStar Health; Richard Reitherman, M.D., Ph.D., a radiologist and medical director of breast imaging at MemorialCare Breast Center at Orange Coast Medical Center in Fountain Valley, CA; Jeffrey Luci, Ph.D., research assistant professor of biomedical imaging physics at the Rutgers Center for Advanced Human Brain Imaging Research
The research is in early stages, and there's a lot more work that needs to be done before drawing any major conclusions. Still, it's fair to have questions. Here's what the study found, plus what two toxicologists, a radiologist, and a biomedical researcher want you to know about the safety of MRIs.
The study, which was published in the journal Magnetic Resonance Imaging, conducted test tube experiments to look for the presence of oxalic acid, a compound found naturally in many plant-based foods, that binds with metal ions.
The researchers looked at the impact of oxalic acid on gadolinium, a metal that's used as an MRI contrast agent. (In case you're not familiar, MRI contrast is a substance injected into the body that changes the presence of water molecules to create better-quality images.)
The researchers discovered that oxalic acid caused small amounts of gadolinium to seep out of the contrast and create nanoparticles that then infiltrated the cells of different organs.
Again, the research was done in a test tube, so the researchers didn't find that getting an MRI with contrast would actually cause this. But it definitely raises the possibility.
Gadolinium is a rare earth metal that is used in MRI contrast, explains Richard Reitherman, M.D., Ph.D., a radiologist and medical director of breast imaging at MemorialCare Breast Center at Orange Coast Medical Center in Fountain Valley, CA. It's found naturally in the earth's crust, although it's usually in minerals like bastnasite.
Gadolinium is usually tightly bound to other molecules and is excreted from the body after the MRI (usually through urine), Dr. Reitherman says. As a result, it doesn't typically cause any bad health effects in most people. However, some studies have found gadolinium lingering in the kidney and the brain after MRI with contrast, and it can also be detected in blood and urine years after someone is exposed to it.
Gadolinium isn't used in every MRI. 'In general, it is not used for musculoskeletal MRIs,' Dr. Reitherman says. 'However, it is used for brain, breast, pelvic, and abdominal MRIs.' Meaning, if your healthcare provider suspects that you ruptured a disc in your spine, you're unlikely to get an MRI with contrast. But if you have a suspected case of appendicitis or a tumor, you'll often get an MRI with contrast.
'Contrast is used for a lot of things and millions of people have had millions of doses of this with no issue,' Dr. Reitherman says.
This is a little complicated. The gadolinium atom on its own is toxic, says Jeffrey Luci, Ph.D., research assistant professor of biomedical imaging physics at the Rutgers Center for Advanced Human Brain Imaging Research. 'But when used in a contrast agent for MRI, it is basically wrapped up in a large organic molecule that's designed to prevent it from becoming free,' Luci says.
'The purpose of that is so it can be excreted out of the body so it doesn't degrade and turn into something bad,' Dr. Reitherman says. 'The stuff that's injected is not toxic.'
People can experience side effects from gadolinium-based contrast agents, including a burning or cool feeling around the injection site, headache, or nausea, according to the U.S. National Library of Medicine.
However, people can have more severe complications of contrast agents, including kidney injury, brain damage, and 'significant' changes to the skin, says Jamie Alan, Ph.D., an associate professor of pharmacology and toxicology at Michigan State University. Just keep in mind that this is rare, with one older study suggesting that serious complications happen in just 0.03% of gadolinium-based contrast injections.
Some people are more susceptible to complications than others, though. 'Although gadolinium is used as an MRI contrast agent on a daily basis in hospital settings and is generally considered to be safe when used as directed, it is associated with adverse effects in certain patient populations,' says Kelly Johnson-Arbor, M.D., a toxicologist at MedStar Health. 'In people with chronic kidney disease, exposure to certain types of gadolinium contrast agents is associated with an increased risk of developing a condition called nephrogenic systemic fibrosis (NSF). NSF is a disease characterized by skin swelling, thickening, and pain.'
As for whether these gadolinium nanoparticles will build up in your body over time and cause health issues, that's not clear at this point. 'No one has been able to show that gadolinium [accumulation in the body] is doing anything bad,' Luci says. 'But that doesn't mean we shouldn't be looking for reasons to make sure it's safe.'
However, this is different from heavy metal poisoning, which is when metals like lead, mercury, arsenic, and cadmium can build up in the body and cause symptoms. (As of right now, there are no symptoms linked with these nanoparticles.)
'This is a preliminary study,' Alan agrees. 'This was not done in humans and may not translate. We really need more research to completely understand the long-term health effects and potential treatments.'
If your doctor orders an MRI with contrast, experts agree that it's really best to get it done. 'This might be very important for diagnosis of your condition,' Alan says. 'Typically, MRIs are not scheduled unless they are absolutely needed because of cost and availability.'
Dr. Reitherman agrees. 'Contrast is only used when it's necessary,' he says. But he also adds that potentially life-threatening health issues like tumors need gadolinium to be used in order for it to show up in imaging.
Still, Dr. Reitherman says that more work is needed to learn about these nanoparticles, the potential impact they have on the body, and if they even form in humans. 'This is the basic science, and it's where we start,' he says. 'But it needs to move on to human experimentation and prove that this actually causes disease. Right now, the conclusions are theoretical.'
If you have questions, Alan recommends talking to your doctor. 'Generally, this imaging is safe,' she says. 'Serious adverse reactions are rare.'
Luci also stresses that you shouldn't be scared to get an MRI if your doctor says it's medically necessary. 'We really don't want to give people the wrong message and make them think that this is indicative of a risk or danger level that really isn't there,' he says.
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