Magnetic resonance imaging (MRI) is a noninvasive, painless technology that uses strong magnets, radio waves and a computer to created detailed, 3D images of internal organs and systems. Images are stored on a computer or printed on film.

MRI:

• Doesn’t use X-ray or other potentially harmful radiation, so it’s safer for conditions that need frequent monitoring.
• Has no known side effects. (Rarely, some contrast agents may cause an allergic reaction.)
• Provides better images of soft tissues than CT. (CT may work better for bones.)

Diagnostic Use

Doctors use MRI to diagnose or monitor numerous conditions, including:

• Brain disorders, such as aneurysm, brain injury or stroke.
• Breast cancer.
• Eye or inner ear problems.
• Heart, liver and abdominal diseases.
• Back, knee, shoulder or other skeletal injuries, including damage to muscles, ligaments and tendons.
• Multiple sclerosis.
• Pelvic disorders in women, such as fibroids or endometriosis.
• Spinal cord injuries.

What Happens During MRI

In some situations, you may receive an injection of a contrast agent before the MRI procedure. This helps create brighter images.

You’ll lie flat on a moving bed that will slide inside a large tube. You’ll have to stay completely still during the process. You might feel twitching as the MRI stimulates nerves; this is normal and causes no harm.

You’ll hear loud clicking and beeping. Staff can provide earplugs or nonmetal headphones to block out the noise or pipe in calming music. You and the technician will be able to communicate via an intercom and a handheld help button at any time.

MRI can take 20 to 90 minutes, depending on the body part and the number of images your doctor wants.

Before MRI, Talk to Your Doctor About …

Metal implants. Because MRI uses a strong magnetic field, no metal is allowed in the MRI room. Tell your doctor if you have any metal in your body, such as:

• Aneurysm clip.
• Artificial heart valve.
• Body piercings.
• Capsule(s) from an endoscopic procedure.
• Cochlear implant.
• Deep brain stimulator.
• Insulin pump.
• Loop recorder.
• Metal fragments, such as shrapnel.
• Pacemaker
• Pins, staples or screws.

Pregnancy. According to the American College of Obstetricians and Gynecologists, MRI should be used prudently during pregnancy but is considered safe. ACOG recommends limiting the use of gadolinium contrast agents during pregnancy.

Claustrophobia. If tight spaces make you anxious, MRI can be difficult. To help:

• Ask if your MRI location has an open (wide-bore) machine and if it can be used for your exam.
• Get familiar with the machine and process ahead of time.
• Discuss possible sedatives or mindfulness techniques to reduce stress.
• Listen to music.
• Close or cover your eyes.
• Use the help button if your anxiety increases too much.

Kidney disease. People on dialysis for kidney disease should use caution with certain gadolinium contrast agents, which may be linked to a rare but serious side effect.