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CancerQuest > Introduction to Patient Information > Introduction to Cancer Detection and Diagnosis > Introduction to MRI > MRI: Preparation and Precautions

MRI: Preparation and Precautions

The MRI unit is an extremely strong magnet, so patients should avoid wearing jewelry and other accessories because they could interfere with the machine's magnetic field. The following items are not allowed to enter the exam room:

• Jewelry, watches, credit cards, and hearing aids (all can be damaged)
• Pins, hairpins, metal zippers, and similar metallic items (can alter images taken)
• Removable dental work
• Pens, pocketknives, eyeglasses⁽¹⁾

Most of the time, MRI is safe for patients who have implants made of metal. However, the technologist should know if the patient has medical/electronic devices in his/her body including:

• artificial heart valves
• implanted drug infusion ports
• implanted electronic devices
• artificial limbs or metallic joint prostheses
• implanted nerve stimulators
• metal screws, plates, or surgical staples⁽²⁾

If there is any doubt about the presence of metal in the patient's body, an x-ray should be taken.

Very rarely, dyes used in tattoos contain iron which may heat up during an MRI, so the patient should communicate any concerns with his/her physician.

Other things to keep in mind before you receive an MRI:

• Patients with claustrophobia or anxiety may want to request a mild sedative from their physicians.⁽²⁾
• If an MRI scan will involve contrasting agent, the patient should tell the physician about any allergies including hay fever, hives, allergic asthma, or food and drug allergies.⁽³⁾
• The radiologist should also be informed if the patient has any type of serious health problems such as kidney disease or sickle cell anemia because it may affect whether or not contrasting agent is used with the MRI scan.
• Women who may be pregnant may be asked to give a urine sample beforehand since risks of MRI scanning to the fetus are not yet known. Pregnant women should not have an MRI exam unless the potential benefit from MRI is greater than the potential risks to the fetus.⁽¹⁾
• Continue taking normal medications prior to the exam unless told otherwise by the physician.

Those who have a cardiac pacemaker, defibrillator, or ear implant absolutely cannot be scanned and should take caution to not enter the MRI exam room because the strength of the magnet could cause serious problems.⁽¹⁾

References for this page:

1. "MRI of the Body (Chest, Abdomen, Pelvis)." Radiology Info (accessed on 01-27-08) [http://www.radiologyinfo.org/en/info.cfm?pg=bodymr&bhcp=1]
2. "Imaging (Radiology) Tests." American Cancer Society (accessed on 08-03-2010) [http://www.cancer.org/docroot/PED/content/PED_2_3X_Imaging_Radiology_Tests.asp?sitearea=PED]
3. Bellin, MF. "MR contrast agents, the old and the new." European Journal of Radiology. 2006 Dec;60(3):314-23. [PUBMED]