Magnetic resonance imaging (MRI) doesn't use X-rays, so there's no radiation exposure. Yet this test isn't safe for everyone.
There are a few reasons why you might need to avoid MRI and choose another test instead.
You Have Metal in Your Body
An MRI machine uses powerful magnets that can attract any metal in your body. If this happens, you could get hurt.
It can also damage equipment that’s implanted in your body -- a pacemaker or cochlear implant, for instance. Also, metal can reduce the quality of the MRI image.
Let your doctor know before the test if you have any of these:
- An implantable cardioverter defibrillator (ICD) or pacemaker
- An implanted drug infusion pump or an insulin pump
- Artificial joints, limbs, or heart valves
- Body piercings
- Cochlear implants (which help with hearing)
- Metal fragments, bullets, or shrapnel anywhere in your body
- Surgical clips, plates, pins, staples, wire mesh, or screws
- Tattoos (some inks contain metal)
You Have Kidney Problems
Some MRI scans use a contrast dye that contains the metal gadolinium. This dye helps your doctor see the MRI picture more clearly. Usually it's very safe. But if you have severe kidney disease, the dye can cause problems. In that case, you might not get that dye made with gadolinium.
Rarely, the dye can cause what’s called “nephrogenic systemic fibrosis” in people with kidney disease. This condition causes thickened and hardened tissue to form on the skin, joints, and organs.
You Recently Became Pregnant
Although MRI doesn't seem to harm a growing baby, it can raise the temperature inside your body. For this reason, you shouldn't have this test during your first trimester, when your baby's organs are developing.
You may need to wait to have an MRI until after your first 3 months of pregnancy or have a different test. Your doctor probably won't use contrast dye at all while you're pregnant.
If you have a newborn, an MRI might affect your ability to breastfeed. The makers of contrast dye say women should not nurse for 1 to 2 days after their test. Ask your doctor whether it's safe for you to breastfeed or if you need to wait.
You're Allergic to the Contrast Dye
The contrast dye can cause an allergic reaction in some people. Symptoms of a reaction include:
A more serious reaction to the contrast is very rare, but it can cause symptoms such as these:
- Swelling of the lips and mouth
- Trouble breathing
You're Afraid of Tight Spaces
A traditional MRI is an enclosed tube surrounded by a magnet. If you're afraid of tight spaces (claustrophobic), you might not be comfortable inside the tube.
You don't have to skip the MRI entirely, but you may want to talk with your doctor beforehand about taking medicine to relax you. Or, you can ask about whether an open MRI, in which the machine is open on all sides, is available.
You Can't Lie Still
You'll have to lie still in the MRI machine for 30 minutes or more to get a clear image.
If you've had a recent injury or surgery, or you have other health problems, it might be hard for you to lie still for the whole test.
Talk to Your Doctor
To avoid any problems, talk to your doctor or radiologist before your MRI.
Tell them about any devices you wear or medical conditions you have. Ask about the risks of having an MRI. Make sure any benefits to you outweigh potential problems.