Preparing for an MRI

What It Is

MRI is generally a safe test, but the strong magnetic field and radio waves create specific safety concerns. Metal objects outside the body can become projectiles, some implants can move, malfunction, or heat up, and certain metal can distort the images. For this reason, every person, and anyone accompanying them into the scanner room, goes through screening.

The FDA classifies devices as "MR Safe," "MR Conditional," or "MR Unsafe." Many pacemakers, defibrillators, joint replacements, and other implants made in recent years are MR Conditional, but the exact device model and the scanner settings matter. Imaging teams check device information before the scan.

Beyond safety, preparation may include instructions about eating and drinking, medications, comfort, and arrival time. These depend on the body part and whether contrast or sedation is planned.

Common Terminology

MR Safe

An item that poses no known hazards in any MRI environment, such as certain plastic items.

MR Conditional

An item shown to be safe in MRI only under specific conditions, such as a certain magnet strength or scan settings.

MR Unsafe

An item known to pose hazards in an MRI environment, which is kept out of the scanner room.

Safety screening form

A questionnaire completed before an MRI covering implants, metal exposure, surgeries, pregnancy, and other relevant history.

Claustrophobia

Fear of enclosed spaces, which some people experience inside an MRI scanner.

Wide-bore or open MRI

Scanner designs with a larger opening or open sides that some people find more comfortable.

Why the Test Is Done

Preparation steps exist mainly to keep the exam safe and the images clear. They help to:

• Identify implants or devices that may need special scanner settings or may not be safe to scan.
• Find metal fragments in the body, such as from metalworking or injuries, that could move or heat up.
• Reduce the chance of image blurring from movement or from metal near the area being imaged.
• Plan for contrast, sedation, or other needs ahead of time.
• Help the person feel more comfortable and know what to expect.

What the Results Generally Describe

The preparation process does not produce results itself, but screening generally documents:

• Any implanted devices, with their make and model when available.
• Prior surgeries and any metal hardware such as clips, stents, screws, or joint replacements.
• History of metal fragments, especially in the eyes; an x-ray may be used to check in some cases.
• Pregnancy status, allergies, kidney health, and prior contrast reactions.
• This information is reviewed by the MRI technologist and radiologist, who decide whether and how the scan proceeds.

How the Test Is Done

On the day of an MRI, steps commonly include:

• Checking in and completing or reviewing the safety screening form.
• Removing jewelry, watches, hair accessories, hearing aids, removable dental work, and items like phones and cards.
• Changing into a gown or metal-free clothing, since some clothing contains metal threads or fasteners.
• Placing an IV if contrast is planned.
• Positioning on the table with a coil, cushions, and hearing protection before entering the scanner.

Preparation and What to Expect

General points about preparation and the experience include:

• Some abdominal or pelvic exams involve not eating or drinking for several hours; facilities give exam-specific instructions.
• People typically continue their usual medications unless their care team says otherwise.
• Medication patches containing metal foil may need to be addressed with the care team before the scan.
• Tattoos and permanent makeup rarely cause problems, but people may notice warmth; staff ask people to report any discomfort.
• Staying still is important, and the technologist can talk with the person between image sets.
• For children or people who cannot stay still, sedation or anesthesia may be planned, with its own instructions.

When Results Are Discussed With a Clinician

Before the scan, people often discuss these topics with their care team or imaging facility:

• Whether an implanted device is compatible with MRI and what information the facility needs.
• Options for anxiety or claustrophobia, including scanner types or medication for relaxation.
• Any special preparation such as fasting, and how it fits with conditions like diabetes.
• Whether contrast is planned and what screening is needed for it.
• How and when results will be shared after the exam.

Questions to Ask a Healthcare Professional

General questions people often find useful to bring to an appointment:

• Is there any special preparation for this specific MRI?
• What information do you need about my implants or devices?
• Can I eat and drink normally beforehand?
• What options are available if I feel claustrophobic?
• How long will I be in the scanner?
• Will I be able to drive myself home afterward?

Sources

This guide was written in plain language from the following authoritative references.

1. MRI Safety — RadiologyInfo.org (RSNA and ACR)
2. MRI (Magnetic Resonance Imaging): Benefits and Risks — U.S. Food and Drug Administration (FDA)
3. MRI — MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine)

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