MRI of the Heart: About This Test

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What is it?

MRI (magnetic resonance imaging) is a test that uses a magnetic field and pulses of radio wave energy to make pictures of the organs and structures inside the body. An MRI of the heart looks at the structures and blood vessels of the heart.

When you have an MRI, you lie on a table and the table moves into the MRI machine. A special dye (contrast material) may be put in a vein (IV) in your arm or hand to make the blood vessels easier to see on the scan.

Why is this test done?

An MRI of the heart is done to look at the structures and blood vessels of the heart. These may include:

  • The heart muscle and the sac around the heart (pericardium).
  • The heart valves.
  • The coronary arteries. These are the blood vessels that bring blood to your heart muscle.
  • The blood vessels that carry blood from the lungs to the heart.
  • The aorta, which is a large blood vessel that carries blood from the heart to the rest of the body.

How can you prepare for the test?

Talk to your doctor about all of your health conditions before the test. For example, tell your doctor if:

  • You are allergic to any medicines.
  • You are or might be pregnant.
  • You have a pacemaker, an artificial limb, any metal pins or metal parts in your body, metal heart valves, metal clips in your brain, metal implants in your ears, or any other implanted or prosthetic medical device.
  • You have an intrauterine device (IUD) in place.
  • You get nervous in confined spaces. You may need medicine to help you relax.
  • You wear a patch that contains medicine.
  • You have kidney disease.

What happens before the test?

  • You will remove all metal objects. These include hearing aids, dentures, jewellery, watches, and hairpins.
  • You will take off all or most of your clothes and then change into a gown. If you do leave some clothes on, make sure you take everything out of your pockets.

What happens during the test?

  • You may have contrast material (dye) put into your arm or hand through a tube called an IV.
  • You will lie on your back on a table that is part of the MRI scanner.
  • Small pads or patches (electrodes) will be attached to your skin on each arm and leg and on your chest. A special paste or pad may go between the electrode and your skin. The electrodes are hooked to a machine that traces your heart activity onto a paper.
  • The table will slide into the space that contains the magnet.
  • Inside the scanner you will hear a fan and feel air moving. You may hear tapping, thumping, or snapping noises. You may be given earplugs or headphones to reduce the noise.
  • You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
  • You may be alone in the scanning room. But the technologist will watch you through a window. You will be able to talk to him or her through an intercom.

What else should you know about the test?

  • An MRI does not hurt.
  • If a dye is used, you may feel a quick sting or pinch and some coolness when the IV is started. The dye may give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache.
  • If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.
  • You may feel warmth in the area being examined. This is normal.

How long does the test take?

  • The test usually takes 30 to 60 minutes but can take as long as 2 hours.

What happens after the test?

  • You will probably be able to go home right away, depending on the reason for the test.
  • You can go back to your usual activities right away.
  • If you had dye, drink plenty of fluids for 24 hours after the test to help flush it out of your body.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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