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What can affect magnetic resonance imaging (MRI)?

Several things can affect the accuracy of magnetic resonance imaging (MRI) and/or the safety of having one. An MRI uses radio waves and a magnetic field to create detailed images projected onto a computer screen of organs and other internal body structures.

Having an MRI may not be recommended or possible if you:

  • are pregnant
  • are very obese
  • are unable to stay still during the procedure

Because MRIs use a magnetic field, any metallic object, whether implanted in your body or worn on the outside, may affect your MRI. According to the American College of Radiology and the Radiological Society of North America, the following objects may present a health hazard if you were to have an MRI:

  • a cardiac pacemaker or implantable defibrillator
  • a catheter that has metallic components
  • a ferromagnetic metallic vascular clip
  • an implanted or external medication pump (such as that used to deliver insulin or a pain-relieving drug)
  • a cochlear (inner ear) implant
  • a neurostimulation system

Objects or factors that may affect the quality of the MRI images could include:

  • a metallic spinal rod
  • plates, pins, screws or metal mesh used to repair a bone or joint
  • joint replacement or prosthesis
  • metallic jewelry (including body piercings)
  • some (especially black or blue pigmented) tattoos or tattooed eyeliner
  • makeup, nail polish or other cosmetic that contains metal
  • bullet, shrapnel or other type of metallic fragment
  • metallic foreign body within or near the eye (metal workers are most likely to have this problem)
  • dental fillings, orthodontic braces and retainers

The staff at the MRI facility may ask you to be sure to remove any of the following items before your MRI:

  • purse, wallet, money clip, credit cards, cards with magnetic strips
  • electronic devices such as beepers or cell phones
  • hearing aids
  • metal jewelry, watches
  • pens, paper clips, keys, coins
  • hair barrettes, hairpins
  • any article of clothing that has a metal zipper, buttons, snaps, hooks, underwire or metallic threads
  • shoes, belt buckles, safety pins

The medical staff at your MRI facility should have you go through a comprehensive screening process to ensure the safety and accuracy of your MRI. It is important to be completely honest in answering the questions, and to follow directions for preparing for the MRI carefully.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.