MRI (Magnetic Resonance Imaging)

Radiology & Imaging

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Radiology & Imaging

MRI (Magnetic Resonance Imaging)

Magnetic resonance imaging (MRI) is a sophisticated and highly accurate imaging technique used to diagnose diseases of the brain, spine, skeleton, chest, abdomen, pelvis and blood vessels. In many cases, MRI can lead to early detection and treatment of disease without surgery or biopsy.

MRI is a completely safe, non-invasive and painless diagnostic procedure, without the use of harmful x-rays. With a large magnet, radio waves and a computer, MRI produces detailed cross-sectional pictures of your internal organs and structures without using ionizing radiation.

During your MRI exam, you will be placed in a strong magnetic field that aligns the nuclear magnetism of protons in your hydrogen atoms, which make up 95 percent of your body.

When a radio wave passes through those protons, they generate a radio signal that is processed by computer in the form of tomographic images. Your doctor will use those images to make an accurate diagnosis and plan your treatment.

How to prepare for an MRI

We have lockers and locking dressing rooms for your personal belongings, clothing, jewelry and other metallic items. Jewelry and other metallic items should be kept to a minimum because they might interfere with the scan. Clothing with zippers, hooks and snaps will need to be removed. We have gowns and scrubs for you to change into. If you prefer, you may wear your own sweats, shorts or other loose clothing.

  • Metallic objects limit the accuracy of MRI, and the magnetic field can interfere with some surgically implanted devices. If any of the following apply to you, tell your doctor:

    • Pregnancy
    • Cardiac pacemaker or artificial heart valve
    • Metallic implant
    • Insulin pump or other infusion pump
    • Intrauterine device
    • If you are a metal worker
    • Inner ear implant
    • Previous gunshot wound
    • Joint or bone pins
    • Permanent tattoos or eyeliner
    • Aneurysm clips
  • Eat and take any prescription medications as usual, unless your doctor tells you otherwise.
  • If you'd like, ask a friend or relative to accompany you to the exam.
  • If you are afraid of closed-in spaces, tell your doctor in advance. Your doctor can prescribe a sedative to help you relax. In that case, you will need someone to drive you home after the exam.
  • If you feel you will be unable to remain still for 30 to 60 minutes due to pain, please inform your physician.
  • We have lockers and locking dressing rooms for your personal belongings, clothing, jewelry and other metallic items. Jewelry and other metallic items should be kept to a minimum because they might interfere with the scan. Clothing with zippers, hooks and snaps will need to be removed. We have gowns and scrubs for you to change into. If you prefer, you may wear your own sweats, shorts or other loose clothing.
  • Avoid wearing eye makeup (many eye shadows contain metallic flakes).
  • Plan to arrive 30 minutes before your exam to provide medical and insurance information.
  • Please bring previous imaging study results (x-ray, MRI, CT, ultrasound) such as reports, films or CD-roms if available.

What to expect

During the test

  • An MRI exam generally takes between 30 minutes and an hour. The length of your exam will depend on the type of study your doctor has ordered.
  • You will be asked to lie down on the scanning table, usually on your back. We will make you comfortable with the aid of pillows, blankets and sponges. The technologist will help you lie on an automatic, cushioned scanning table. You'll be able to select music to listen to during the exam. You'll rest on your back with your head in a cushioned headrest.
  • Once you are completely comfortable, the technologist will position a device, called a "coil," over or under the area being scanned. The coil acts as an antenna directing the magnetic energy to that area and helps produce the clearest picture of the area of interest.
  • When you are properly positioned, the table will slide into the opening of the machine and the exam will begin. It's important that you remain as still as possible throughout the exam. You won't feel a thing, but you will hear a muted thumping or knocking sound for several minutes at a time. This is completely normal.
  • If you become uncomfortable or have questions at any time, you'll be able to communicate with the technologist through a built-in intercom. When the exam is complete, the technologist will help you off the table and you'll collect your personal belongings.
  • In some cases, your doctor may order a contrast agent to enhance the images. The agents, which are completely safe and FDA-approved, are injected into a vein in your arm.

After the exam

  • A radiologist who specializes in a specific area of the body will review your images.
  • The radiologist prepares a diagnostic report to share with your doctor.
  • Your doctor will consider this information in context of your overall care, and talk with you about the results.

Get more info/prep instructions

Contact Radiology & Imaging

Call 651-232-5500 to make a radiology appointment at St. John's Hospital, St. Joseph's Hospital or Woodwinds Health Campus. This appointment line is open between 7 am and 6 pm.

Frequently asked questions about MRI


Q: Is MRI safe?

A: The strength of the magnetic field and the frequency of the radio waves have no known harmful effects. There are some patients who may not be able to have an MRI test due to certain pacemakers or other metallic objects in the body. However, not all metallic or implanted devices prevent you from having an MRI. Consult your doctor or HealthEast Radiology for clarification.

Q: Does my doctor need to refer me for an MRI?

A: In order to perform the study we need a referral from your physician. Your doctor will provide us with the necessary information to perform the most accurate study.

Q: What is magnetic resonance angiography (MRA)?

A: This is a way to look at the blood vessels in the neck and brain and evaluate the characteristics of blood flow. In the neck, areas of irregularity or narrowing in the carotid arteries can be associated with symptoms of temporary blindness, weakness of the extremities, amnesia or loss of speech. Within the brain, MRA can be used to screen for the presence of vascular malformation, aneurysm and vasculitis.

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Q: What do I need to tell the technologist before the scan?

A: Advise the technologist of any pacemaker, or other implanted devices in your body. Also make the technologist aware of any previous surgeries, including heart surgery for pacemaker or other implanted devices, brain surgery for aneurysm clips, back surgery, cochlear implants, pregnancy, history of working with metal, or in the metal trades.

Q: Are there any people who cannot or should not have an MRI?

A: MRI poses no danger to the majority of patients. Certain medical conditions will prevent someone from having an MRI. The strong magnetic field can cause disruption to internally placed devices such as pacemakers, heart valves and aneurysm clips.

Q: Can my child have an MRI?

A: Yes. A parent may stay in the scan room with the child, and hold their hand during the scan. This is a great way to relieve any apprehension the child or the parent may have about the procedure.

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Q: May I have an MRI exam when I am pregnant or breastfeeding?

A: While an MRI scan has no known side effects, it is not recommended for pregnant women unless it is medically indicated. If you are breastfeeding and have contrast as part of your exam, please suspend nursing for 24 hours after the exam.

Q: Why is the scanner so noisy?

A: The scanner works with strong magnetic fields, which builds up energy. The energy is released as loud knocking sounds. Earplugs are available. We provide an assortment of music to help you relax. You are welcome to bring your own CD or cassette. There is a two-way intercom providing communication between you and the technologist.

Q: How is MRI different from a CT or an x-ray?

A: Unlike x-ray exams, MRI does not use ionizing (x-ray) radiation. Instead, MRI creates high-quality images through the combination of a strong magnetic field and radio waves. MRI can detect certain diseases much earlier than other medical imaging techniques can, making it the diagnostic tool of choice for many physicians.

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Q: What body parts can the MRI scanner evaluate?

A: Physicians use the MRI scanner to examine one part of the body at a time. The scanner can take pictures of the head, neck, back, abdomen, pelvis, shoulder, elbow, knee, ankle, foot, blood vessels and more.

Q: How long does the exam take?

A: Exams take approximately 25 minutes or more depending on the body part being scanned. Please feel free to bring along your favorite tape or CD to help you relax during the exam.

Q: Why is it so important to remove any metallic objects before I enter the scanning room?

A: You'll need to remove all metal objects for safety reasons and because they cause artifacts to appear on the MRI image.

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Q: Will there be a problem if I have had surgery in which metal has been implanted?

A: As a general rule, no. However, please be sure to inform your technologist of any prior surgeries before your exam. Patients with a pacemaker or certain types of aneurysm clips should not have an MRI.

Q: What does the scanner look like?

A: The scanner is wide open on both ends, and well-lit and ventilated throughout. It also has a nurse call button and two-way intercom system so that you can communicate with the technologist at all times.

Q: Is there any risk?

A: MRI is very safe. There are no health risks associated with the magnetic field or the radio waves used by the machine nor have any side effects been reported.

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