What is a heart MRI?

Magnetic resonance imaging (MRI) uses magnets and radio waves to capture images inside your body without making a surgical incision. It allows your doctor to see the soft tissues in your body, along with your bones.

An MRI can be performed on any part of your body. However, a heart or cardiac MRI looks specifically at your heart and nearby blood vessels.

Unlike a CT scan, an MRI does not use ionizing radiation. It’s considered a safer alternative for pregnant women. If possible, it’s best to wait until after the first trimester.

Your doctor might order a heart MRI if they believe you’re at risk for heart failure or other less severe heart problems.

A cardiac MRI is a common test used to assess and diagnose several conditions. Some of these include:

Because MRIs show cross sections of the body, they can also help explain or clarify the results of other tests, such as CT scans and X-rays.

There are no risks for an MRI and few side effects, if any. The test does not use ionizing radiation, and to date, there have been no documented side effects from the radio and magnetic waves it uses. Allergic reactions to the dye are rare.

If you have a pacemaker or any sort of metal implant from previous surgeries or injuries, you may not be able to receive an MRI because it uses magnets. Be sure to tell your doctor about any implants you have before the test.

If you are claustrophobic or have a hard time in enclosed spaces, you may feel uncomfortable in the MRI machine. Try to remember that there is nothing to fear. Talk to your doctor about your concerns before the test. They may prescribe an anti-anxiety medication to help with your discomfort.

Before the test, tell your doctor if you have a pacemaker. Depending on your type of pacemaker, your doctor may suggest another testing method, such as an abdominal CT scan. However, some pacemaker models can be reprogrammed before an MRI so they aren’t disrupted during the examination.

Because an MRI uses magnets, it can attract metals. You should alert your doctor if you have any type of metal implant from previous surgeries. These may include:

  • artificial heart valves
  • clips
  • implants
  • pins
  • plates
  • screws
  • staples
  • stents

Your doctor may need to use a special dye to highlight your heart. This dye is a gadolinium-based contrast agent that’s administered through an IV. It’s different from the dye used during a CT scan.

Allergic reactions to the dye are rare. However, you should let your doctor know before the IV is given if you have any concerns or a history of allergic reactions in the past.

An MRI machine may look intimidating. It’s made up of a bench that slowly glides into a large tube attached to a doughnut-shaped opening. As long you have followed your doctor’s instructions to remove all metal, such as body jewelry, watches, and earrings, you will be completely safe.

The technologist will ask you to lie back on the bench. You may be given a pillow or blanket if you have trouble lying on it. The technologist will control the movement of the bench using a remote control from another room. They will be able to communicate with you through a microphone.

The machine will make loud whirring and thumping noises as it takes pictures of your body. Many hospitals offer earplugs. Others may provide television shows or headphones with music to help you pass the time.

The technologist will ask you to hold your breath for a few seconds as the pictures are being taken. You won’t feel anything during the test because the machine’s magnets and radio frequencies — similar to FM radios — can’t be felt.

The entire process can take anywhere from 30 to 90 minutes.

After the test, you should be able to drive yourself home, unless you were given anti-anxiety medicine or sedation.

It may take some time for your doctor to review and interpret the images.

Preliminary results from your heart MRI may be available within a few days. However, comprehensive results can take up to a week or more. When the results are available, your doctor will review them with you and discuss any follow-up steps you should take.