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MedlinePlus is a service of the National Library of Medicine (NLM), the world's largest medical library, which is part of the National Institutes of Health (NIH). It was built as an online health information resource for patients and their families and friends.

MedlinePlus presents high-quality, easy to understand, relevant health and wellness information that is trusted.

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MRI Scans

What is an MRI scan?

Magnetic resonance imaging (MRI) is an imaging test that is usually painless and uses magnets, radio waves, and a computer to create detailed pictures of the inside of your body. MRI scans show organs and soft tissues clearly and can help tell healthy from unhealthy tissue in many cases.

Who needs an MRI scan?

MRI scans are often used to diagnose conditions that affect soft tissues and to monitor treatment.

MRI may be used to look at:

  • The brain, spinal cord, and nerves
  • Muscles, ligaments, and tendons
  • Joints, such as the knee or shoulder

MRI does not use x-rays or other radiation. Because of this, it may be used when repeat imaging is needed.

How do you prepare for an MRI scan?

MRI machines use powerful magnets. Metal objects or implants can interfere with the scan and may be unsafe.

Before your MRI, you will need to remove items such as:

  • Jewelry and watches
  • Hairpins
  • Hearing aids

Before your MRI, tell your health care provider if you:

  • Are pregnant
  • Are breastfeeding, especially if you may receive contrast material (a substance that helps some parts of your body show up more clearly on the images)
  • Feel anxious in enclosed spaces (claustrophobic)
  • Have kidney problems
  • Have metal in your body, such as bullets, shrapnel, or other metal fragments
  • Have metal or electronic devices in your body, such as a pacemaker, artificial joint, or other implants
  • Have tattoos or permanent makeup, since some darker inks may contain metal
How is an MRI scan done?

You will usually change into a hospital gown. Sometimes before the test, you may receive contrast, which is usually given through a vein (intravenously or IV).

During the scan, you lie on a table that slides inside a large, tunnel-like machine. Some facilities use an open MRI machine, which is less enclosed. The machine makes loud noises as it takes pictures. You may be given earplugs or headphones.

The scan can take some time, depending on the part of your body being examined. You will need to stay very still during the scan.

What should I expect after an MRI scan?

After most MRI scans, you can return to normal activities right away. If you were given medicine to help you relax, someone will need to take you home.

A specialist called a radiologist reviews the images and shares them with your provider.




 
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