Skip to content
My WebMD Sign In, Sign Up

Information and Resources

Font Size
A
A
A

Magnetic Resonance Imaging (MRI)

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Pregnancy. An MRI test usually is not done during pregnancy. But MRI may be done to get more information about a possible problem that cannot be seen clearly with ultrasound.
  • Medical devices that use electronics, such as a pacemaker or medicine infusion pump. The MRI magnet may cause problems with these devices, and that may keep you from having an MRI.
  • Medical devices that have metal in them. The metal might make some of the detailed MRI pictures blurry. This may prevent your doctor from seeing the organ that is being looked at. For example, an intrauterine device (IUD) with metal may prevent your doctor from seeing the uterus clearly.
  • Inability to remain still during the test.
  • Obesity. A person who is very overweight may not fit into standard MRI machines.

Many modern medical devices that do not use electronics—such as heart valves, stents, or clips—can be safely placed in most MRI machines. But some newer MRI machines have stronger magnets. The safety of MRI scans with these stronger MRI magnets in people with medical devices is not known.

What To Think About

  • Sometimes your MRI test results may be different from the results of CT, ultrasound, or X-ray tests, because the MRI scan shows tissue differently.
  • MRI is a safe test for looking at structures and organs inside the body. It costs more than other methods and may not be available in your area.
  • Open MRI machines are now made so that the magnet does not completely surround you. But these machines may not be available in all medical centers. Open MRI is useful for people who are claustrophobic or obese.
  • Magnetic resonance angiogram (MRA) is a special MRI method that studies blood vessels and blood flow. To learn more, see the topic Magnetic Resonance Angiogram (MRA).
  • MRI spectroscopy is a special MRI method that identifies certain medical problems by looking for specific chemicals in body tissues.
  • Contrast material that contains gadolinium may cause a serious skin problem (called nephrogenic fibrosing dermopathy) in people with kidney failure. Before having an MRI scan, tell your doctor if you have serious kidney disease or if you have had a kidney transplant.

MRI can be used to check different parts of the body, such as the head, belly, breast, spine, shoulder, and knee.

Other Works Consulted

  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

WebMD Medical Reference from Healthwise

Last Updated: May 16, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Hot Topics

Health Solutions From Our Sponsors

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

tea
What you should eat.
Woman sitting in front of UV lights
Is yours working?
woman using breath spray
What's causing yours?
colon xray
Get the facts.
MS Overview
Recognizing symptoms.
bowl of yogurt with heart shape
Eat for a healthy heart.
woman doing pushups
To help you get fit.
Colored x-ray of tooth decay
Know what to look for.
Woman sitting with child
Do you know the symptoms?
fruit drinks
Foods that can help you focus.
Sad dog and guacamole
Don't feed this to your dog.
Thyroid exam
See how much you know.

Women's Health Newsletter

Find out what women really need.