What is an MRI?
An MRI is a painless, noninvasive imaging test, or scan, that uses large magnets, radio waves, and a computer to produce detailed images of organs and body structures. This includes ligaments, cartilage, tendons, blood vessels, bones, spinal discs, and organs such as the pancreas or brain.
An MRI, also called magnetic resonance imaging, provides information not available with X-rays, CT scans, or ultrasounds. Sometimes, patients receive a contrast agent or dye to further improve the clarity of MRI images.
A radiologist will review your MRI images and discuss them with your doctor, who will discuss the results with you. Together, you will decide what next steps, if any, you need to take based on the MRI results.
An MRI is only one method used to diagnose diseases, disorders and conditions. Discuss all of your testing options with your doctor to understand which options are right for you.
Types of MRIs
Doctors order MRIs to make detailed images of the organs and structures of the head, chest, abdomen, pelvis, spine, bones and joints. An MRI may be combined with other imaging techniques, such as ultrasound or CT scan. There are also a variety of specialized types of MRIs including:
Functional MRI (FMRI) uses MRI to identify areas of active brain function during specific tasks. FMRI can help plan certain types of brain surgery.
Interventional MRI uses MRI images to guide minimally invasive procedures.
Magnetic resonance angiography (MRA) makes images of blood vessels.
Positron emission tomography/MRI (PET/MRI) is a type of nuclear imaging test that creates detailed images using a radioactive substance and a special camera combined with an MRI.
Real-time MRI captures real-time, continuous pictures of the body’s organs or structures in action, such as a beating heart or a moving joint.
Why is an MRI performed?
Your doctor may recommend to diagnose, screen or monitor the following:
Eye and inner ear disorders including eye tumors, thyroid ophthalmopathy, and Meniere's disease
Female pelvic conditions including fibroids, endometriosis, and uterine abnormalities that cause infertility
Joint and bone problems including spinal cord injuries, spinal disc problems, and bone infections
Tumors and cysts including benign masses and cancer in many parts of the body such as the breast, pancreas and kidney
MRIs are also used to:
Evaluate a fetus during pregnancy
Guide procedures including stent placements
Plan surgery and other treatments including coronary artery bypass grafting (CABG) and organ transplant surgeries
Who performs an MRI?
A radiologic technologist, under the supervision of a doctor, performs an MRI. A radiologic technologist is a healthcare provider who performs imaging procedures and takes care of patients during the procedures.
The following types of doctors may supervise the radiologic technologist performing your MRI, and interpret the results of the MRI:
Radiologists specialize in using radiation and other imaging techniques to diagnose and treat a wide variety of conditions from broken bones and birth defects to cancer.
Diagnostic radiologists focus on performing and interpreting imaging tests, such as ultrasounds, X-rays, angiograms, CTs, and MRIs.
Pediatric radiologists specialize in diagnosing and treating diseases and conditions of children using imaging technologies.
Radiation oncologists focus on treating cancer and related diseases with radiation.
How is an MRI performed?
Your MRI will be performed in a hospital or outpatient imaging setting. The test will take from 30 to 90 minutes, depending on the type of MRI, and generally includes these steps:
You will undress as needed to allow access to the body part and put on a patient gown. You will need to remove all jewelry, hair accessories, and loose objects and devices. No metal objects are allowed in the MRI room. Examples include iPods, glasses, dentures, dental bridges, prostheses, and medication patches.
You will lie on a padded, movable MRI table. Your radiologic technologist will position you in a way that makes the best images for a specific type of MRI.
Children and people who are very anxious may receive a light sedative to help them relax and stay still.
You may receive a contrast material, depending on the type of MRI. This is usually given through an IV.
The MRI table will move through the hole and into the center of a large doughnut-shaped MRI scanner. The MRI scanner is deeper and more enclosed than a CT scanner, although some MRI scanners have a more open structure.
The radiologic technologist will leave the room to start the MRI, but will see you at all times through a window and can communicate with you through a speaker system.
You may not be allowed to talk during the MRI because it creates movements that can interfere with the images. You will have an emergency squeeze ball to alert the technologist if you need help.
MRIs are loud, so you will use earplugs to block the noise. You may be offered headphones to listen to music to block out MRI noise and to talk to the radiologic technologist (if talking is allowed).
You will need to lie completely still during the MRI. You will need to take regular, even breaths and possibly hold your breath for short periods.
You will wait briefly while the radiologic technologist checks the images to make sure they are clear. Then the radiologic technologist will remove your IV.
You will go home right away after an outpatient MRI.
Will I feel pain?
Your comfort and relaxation is important to both you and your care team. The MRI scanner never touches you and is not painful. Your positioning on the table should be comfortable. If it is not comfortable, or if it makes it difficult for you to breathe, tell your radiologic technologist.
An MRI is not painful or invasive, but it does create loud humming, thumping and knocking noises. Some people feel enclosed, anxious and claustrophobic inside the MRI scanner. Tell your care team if you think the noise or feelings of claustrophobia will bother you. Light sedation will help you relax, and special earplugs or headphones can reduce the noise.
If you need IV contrast, you may feel a brief stick or pinch during IV insertion. You may also feel a fleeting warm or cool sensation when the contrast is injected. Take a few long, deep breaths to help yourself relax. If any discomfort does not pass not pass quickly, tell your radiologic technologist.
What are the risks and potential complications of an MRI?
An MRI is generally a safe procedure, and there are no known harmful side effects of brief exposure to the strong magnetic field of an MRI scanner. Additionally, an MRI does not use radiation, which slightly increases the risk of cancer and birth defects, like X-rays and CT scans do.
Allergic reactions to contrast agents or dyes are rare, but can occur. MRI teams are well prepared to handle allergic reactions. Telling all members of your care team if you have any allergies.
Patients with poor kidney function who have an IV contrast agent may have a rare complication, called nephrogenic systemic fibrosis.
How do I prepare for my MRI?
You are an important member of your own healthcare team. The steps you take before your test can improve your comfort and help obtain the most accurate results.
You can prepare for an MRI by:
Answering all questions about your medications, allergies, and medical history, especially kidney disease. Medications include prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.
Informing your radiologic technologist or doctor about all internal and external medical devices you may have including pacemakers, artificial limbs or joints, metal clips, intrauterine device (IUD) and medication patches. These devices can malfunction or heat up causing burns during the MRI.
Leaving all jewelry and metal objects at home. Any loose metal object may cause damage or injury if it is pulled toward the magnet.
Telling your doctor and your radiologic technologist if you have claustrophobia or feel nervous or anxious about lying still or having the MRI.
Telling your doctor if there is any possibility of pregnancy or if you are breastfeeding. You may need to wait for a period of time after an MRI to breastfeed.
Telling your doctor and radiologic technologist about any tattoos or tattooed eyeliner, which may cause skin or eye irritation.
Questions to ask your doctor
Preparing for medical testing can be stressful. It is common for patients to forget some of their questions during a doctor’s office visit. You may also think of other questions after your appointment. Contact your doctor with concerns and questions before your procedure and between appointments.
It is also a good idea to bring a list of questions to your appointments. Questions can include:
Why do I need an MRI? Are there any other options for diagnosing or screening my condition?
Will I need contrast for my MRI? How will I receive the contrast?
How long will the procedure take? When can I go home?
When and how will I receive the results of my test?
What other tests or treatments might I need?
When should I follow up with you?
How should I contact you? Ask for numbers to call during and after regular hours.
What can I expect after my MRI?
Knowing what to expect after an MRI can help you get back to your everyday life as soon as possible.
How will I feel after the MRI?
You should be able to return to all your normal activities right away after an outpatient MRI or as advised by your doctor.
When can I go home?
Most people go home immediately after an outpatient MRI. A brief observation and recovery time is necessary for some specialized MRIs, such as MRA (magnetic resonance angiography). If you are hospitalized, you will likely stay in the hospital for further evaluation and treatment.
When should I call my doctor?
You should keep your follow-up appointments after an MRI. Contact your doctor if you have any concerns between appointments.