What are the Risks Associated with Contrast Dyes for MRIs?

Contrast dye may not be eliminated completely from the body

Gadolinium Contrast Reveals Active Disease in MS
Gadolinium Contrast Reveals Active Disease in MS. Morsa Images/Getty Images

Magnetic resonance imaging (MRI) is the gold standard test for diagnosing and monitoring the progress of multiple sclerosis. The great thing about MRIs is that they can provide valuable information about a person's health without being invasive.

An important part of a MRI involves the administration of a contrast dye. This dye is a gadolinium-based contrast agent given through a person's vein. It brightens MS lesions on the MRI, allowing a neurologist to determine if a person's MS is active, like if they are currently or recently experienced a relapse.

Brain  Deposits and Gadolinium-Based Contrast Dyes

While gadolinium-based contrasts may cause mild side effects like a headache, nausea, dizziness, or a cold sensation when injected, one major concern that has come to light is that the gadolinium contrast may not be completely removed from a person's body after receiving it.

In fact, in 2015, after studies were conducted, the FDA issued a Safety Communication indicating that people with MS who receive multiple MRIs with contrast may get small amounts of the gadolinium-based contrasts agent deposited in certain parts of their brains.

It's still unclear what these deposits mean, like whether retention of them will cause harm to a person in their future. In addition, it's not wholly clear whether certain gadolinium-based contrast agents are less or more likely to be deposited in the brain than others.

The good news is that researchers are actively investigating this new finding.

A study in Investigative Radiology found that administration of gadolinium-based contrast dyes was dose-dependent (meaning the more times a person received contrast, the more brain deposits they were likely to have).

The study also concluded that there was no link between the brain deposition of gadolinium-based contrast agents and a person's kidney function, age, gender or the period of time between their contrast exposure (their last MRI) and death.

It's also important to note that bone deposits may occur as well—actually, research shows that bone deposition is more common than brain deposition. 

Overall, the big take home point here is that researchers need to continue studying this phenomenon to determine its potential for harm.

Other Contrast Dye Risks with MRI

Rarely, certain types of gadolinium contrast may cause a severe disease called nephrogenic systemic fibrosis in people with significant kidney dysfunction. This condition causes the skin to tighten and also causes damage to internal organs.

This is why it's extremely important to tell your doctor about any kidney problems prior to your MRI. You doctor may need to take a blood test to check your kidney function, as well.

This all being said, with the use of non-contrast MRIs, reduced dosages of contrast agents, and lower-risk contrast agents, this condition is extremely rare now.

Also rarely, some people have an allergy to gadolinium contrast. Usually, their reaction is mild and entails skin itching. Very rarely, a person can develop a severe allergic reaction to gadolinium.

Can an MRI be Done Without Contrast in MS?

Certainly, MRI scans can be done with or without a contrast dye.

But in MS, the contrast dye "lights up" plaques on nerve fibers, making it much easier to identify and quantify lesions. Lesions that brighten with contrast administration indicate active inflammation.

For example, a person experiencing a suspected MS relapse may complain of blurry vision and pain when moving their eyeball (symptoms suggestive of optic neuritis). A new lesion on the optic nerve, as seen as a bright spot on an MRI with contrast, can then confirm this suspicion.

That being said, if your doctor is not suspecting active inflammation and is simply monitoring the periodic progression of your disease, contrast is generally not be needed.

Other Potential Risks of MRIs

MRI imaging uses magnetism and radio waves to create pictures of internal organs. Unlike X-rays, which can image only hard structures such as bones, MRI's can create images of soft structures and tissues. With that, though, pacemakers, artificial bones or joints, and even IUD's can cause problems, as the MRI uses very strong magnets to create images.

In addition, MRI machines are also problematic for people with claustrophobia, though more imaging centers are using open MRI's that produce less anxiety.

If you are undergoing an MRI, be sure to tell your doctor and the MRI technologist if you have any metal, claustrophobia, allergies, or kidney problems. They will be able to tell you what is and what is not safe and how to best proceed.

A Word From Verywell

Because gadolinium is the best-known tool for observing the progress of MS, it is still used in most instances. That being said, if you have concerns, the best approach is to discuss options with your doctor. While it is possible to have a non-contrast MRI, it cannot help identify active MS inflammation, like that seen during a relapse.

Sources:

McDonald RJ et al. Intracranial gadolinium deposition after contrast-enhanced MR imaging. Radiology. 2015 Jun;275(3):772-82.

Murata N et al. Macrocyclic and other non-group 1 gadolinium contrast agents deposit low levels of gadolinium in brain and bone tissue: Preliminary results from 9 patients with normal renal function. Invest Radiol. 2016 Jul;51(7):447-53.

National Multiple Sclerosis Society. (September 2015). FDA to Study Potential Risks Related to a Commonly Used MRI Contrast Agent.

Ramalho et al. Gadolinium-based contrast agent accumulation and toxicity: An update. AJNR Am J Neuroradiol. 2016 Jul;37(7):1192-8

US Food and Drug Administration. (July 2015). FDA Drug Safety Communication: FDA evaluating the risk of brain deposits with repeated use of gadolinium-based contrast agents for magnetic resonance imaging (MRI).

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