Magnetic Resonance Imaging

(Imaging, Magnetic Resonance; MRI Scan; MRI)

by Cynthia M. Johnson, MA

Definition

An MRI scan uses magnetic waves and computers to make pictures of the inside of the body. It can make 2- and 3-dimensional pictures.

Reasons for Test

An MRI scan may be done to diagnose a problem or look for injuries. MRI scans can look at any body part. They can also be used to see if medicine or treatment is working for a disease.

MRI Scan of Brain Injury

Possible Complications

Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen. For example, MRI scans can be harmful in someone who has metal inside the body, such as:

Devices likes pacemakers, ear implants, insulin pumps, and shunts
Joint replacements, plates, or metal pins
Metal objects or pieces

A contrast dye may be used to take clearer pictures. Some people may have a reaction to this dye. Talk to your doctor about any allergies you have. Tell your doctor if you have liver or kidney problems. These problems may make it hard for your body to get rid of the dye.

Pregnant women should talk to their doctors about the risks of having an MRI scan.

What to Expect

Prior to Test

The staff may meet with you to talk about:

Anesthesia that may be used
Any allergies you may have
Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the scan
Whether you have something in or on your body that would cause problems with an MRI, such as a medical device, joint replacement, or metal object
Fasting before the scan, such as avoiding food or drink
Whether you need a ride to and from the scan
Tests that will need to be done before the scan, such as an x-ray to check for metal objects in the body

Anesthesia

Certain people may be given:

Sedation—you will be relaxed
General anesthesia—you will be asleep

Description of Test

The MRI machine makes a loud banging noise. You may be given ear plugs or headphones before the scan.

A contrast dye may be injected into your hand or arm. You will lie very still on a sliding table. Monitors may be used to track your pulse, heart rate, and breathing. The table will slide into a narrow, enclosed tube.

The technician will leave the room. You will be given directions through an intercom. You can reply through the intercom. The pictures will be taken. You will exit the machine. Any IV needles used will be removed.

How Long Will It Take?

40 to 90 minutes

Will It Hurt?

The exam is painless.

Results

The images will be studied. A report will be sent to your doctor. Your doctor will talk to you about the results and any further tests or treatment.

Call Your Doctor

Call the doctor if you have:

Lightheadedness
Any allergic symptoms, such as a rash or swelling if contrast dye was used
Problems urinating
Nausea or vomiting
Worsening of symptoms

If you think you have an emergency, call for medical help right away.

RESOURCES

NIH Clinical Center
https://www.cc.nih.gov

Radiology Info—Radiological Society of North America
https://www.radiologyinfo.org

CANADIAN RESOURCES:

Canadian Association of Radiologists
https://car.ca

Canadian Radiation Protection Association
http://www.crpa-acrp.ca

References:

Magnetic resonance imaging (MRI)—body. Radiology Info—Radiological Society of North America website. Available at: https://www.radiologyinfo.org/en/info.cfm?pg=bodymr. Accessed August 18, 2020.

National Institute for Health and Care Excellence (NICE). Prostate cancer: diagnosis and treatment. NICE 2019 May:NG131.

Prostate cancer diagnosis and staging. EBSCO DynaMed website. Available at: https://www.dynamed.com/evaluation/prostate-cancer-diagnosis-and-staging. Accessed August 18, 2020.

Last reviewed March 2021 by EBSCO Medical Review Board James P. Cornell, MD
Last Updated: 3/3/2021

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