Magnetic Resonance Safety and Guidelines

Unlike x-ray exams, which use radiation, magnetic resonance (MR) images are created with magnetic fields and radio waves. MR scanning is a very safe and effective technique for examining the body’s soft tissues, such as organs, muscles, ligaments and tendons. However, because MR scanning uses a powerful magnet, patients need to know about some special precautions and check-in procedures.

No metal is allowed in the room where MR scans are performed because metal objects are attracted to the magnet. The magnet is always on, whether or not scanning is going on. On rare occasions, patients and health care professionals have been injured when an object suddenly was drawn to the magnet. Also, metal objects can create artifacts on MR scans, making it difficult or impossible to see the patient’s anatomy. For your own safety and comfort, for the safety of the staff who will care for you, and to ensure a high-quality diagnostic exam, please follow these guidelines.

You will not be allowed to wear a watch or any jewelry, including body piercing, during the exam. It may be best to leave these items at home, although some facilities provide a safe place to store your valuables during your exam. Barrettes, hairpins, eyeglasses, dentures and hearing aids also must be removed. Some types of cosmetics contain small amounts of metal, so avoid wearing any makeup the day of your exam. Also avoid clothing with metal zippers, rivets, buttons or metallic fabric. Empty your pockets of all metal items, including coins, money clips, credit cards, pens, pocket knives, keys, safety pins and paper clips. Permanent metal dental work, such as crowns, fillings and nonremovable braces, do not normally cause a problem during MR scans.

Metal wheelchairs and oxygen tanks are not permitted near the MR magnet. However, special MR-safe versions may be available at the facility where your exam will be performed. If you have questions about any medical equipment you use, ask the MR technologist who will perform your exam. He is a skilled professional educated in anatomy, positioning and the safe use of magnetic resonance technology.

The technologist will screen you before your exam. He will check you for metal objects and ask you a series of questions about metal that might be in or on your body. Think carefully about these questions, answer them truthfully and ask the technologist if there is anything you don’t understand.

Be sure to tell the technologist if you have any of the following:

  • A pacemaker or artificial valve in your heart.
  • Metal pins, plates, rods, screws or nails anywhere in your body.
  • Wire sutures or surgical staples.
  • An intrauterine device (IUD) or diaphragm.
  • An insulin pump.
  • An aneurysm clip.
  • A joint replacement.
  • An ear implant.
  • A stent, filter or coil in any blood vessel.
  • Any type of prosthesis, including a penile implant or artificial eye.
  • Permanent (tattooed) makeup, such as eyeliner or lip coloring.

It also is important to tell the technologist if you ever have suffered a gunshot wound or any type of accident that may have left metallic particles in your body. Depending on the type of metal and where it is located, you may not be able to have an MR exam. A radiologist, a physician trained in interpreting medical images, will decide if you should have the exam.

By knowing these important precautions and cooperating fully with the MR technologist, patients can help ensure that they have a safe and useful exam.