MRI Scans: What They Show, How to Prepare and What to Expect

What an MRI is

Magnetic resonance imaging (MRI) is a usually painless imaging test that uses magnets, radio waves and a computer to make detailed pictures of the inside of the body. It shows organs and soft tissues clearly and can often tell healthy from unhealthy tissue. Because it uses no x-rays or other radiation, it can be used when repeated scans are needed.

What it's used for

MRI is often used to diagnose conditions of the soft tissues and to monitor treatment, looking at:

• the brain, spinal cord and nerves;
• muscles, ligaments and tendons;
• joints, such as the knee or shoulder.

Getting ready

MRI machines use powerful magnets, so metal can interfere with the scan or be unsafe. You'll need to remove things like jewelry, watches, hairpins and hearing aids. Tell your provider beforehand if you:

• are pregnant, or breastfeeding — especially if you may get contrast material, a substance that helps some parts of the body show up more clearly;
• feel anxious in enclosed spaces (claustrophobic);
• have kidney problems;
• have metal in your body, such as bullets, shrapnel or other fragments;
• have metal or electronic devices in your body, such as a pacemaker, artificial joint or other implant;
• have tattoos or permanent makeup — some darker inks may contain metal.

During the scan

You'll usually change into a hospital gown. Some scans use contrast, usually given through a vein (IV). You lie on a table that slides into a large, tunnel-like machine — some places use an open MRI, which is less enclosed. The machine makes loud noises as it works, so you may get earplugs or headphones. The scan can take a while, depending on the body part, and you'll need to stay very still.

Afterward

Most people can return to normal activities right away. If you were given medicine to help you relax, someone will need to drive you home. A radiologist — a specialist in reading images — reviews the pictures and shares the results with your provider.

Sources

Based on "MRI Scans," MedlinePlus, National Library of Medicine; a work of the United States government in the public domain.