Key Points

• Cardiac magnetic resonance imaging (MRI) is a safe, noninvasive test that uses radio waves, magnets, and a computer to create detailed pictures of the heart.
• Unlike computed tomography (CT) scans and standard x rays, MRI doesn't use ionizing radiation or carry any risk of causing cancer.
• Cardiac MRI is a common test. It can help diagnose and evaluate a number of heart diseases and conditions. The test helps doctors decide how to treat people who have heart problems.
• Often during cardiac MRI, a contrast agent is injected into a vein to highlight portions of the heart or blood vessels.
• People who have certain types of implanted medical devices in their bodies shouldn't have cardiac MRI. For example, a cardiac MRI can cause implanted cardiac pacemakers and defibrillators to malfunction. Your doctor will let you know if you shouldn't have a cardiac MRI because of a medical device.
• Cardiac MRI usually takes 45 to 90 minutes, depending on how many pictures are needed. The test may take less time with some newer MRI machines.
• During the test, you'll be asked to lie still on a sliding table that goes inside a tunnel-like machine. You may be given medicine to help you relax. Cardiac MRI is painless and harmless.
• A doctor who has experience with MRI will provide your doctor with the results of your test. Your doctor will discuss the findings with you.
• Cardiac MRI produces no side effects from the magnetic fields and radio waves. Serious reactions from the contrast agent used for MRI are rare.
• In some cases, cardiac MRI can replace coronary angiography to look at the flow of blood through the coronary arteries. This helps avoid the need to use x-ray radiation and iodine-based dyes.
• Researchers are finding new ways to use cardiac MRI. In the future, cardiac MRI may be used to guide invasive procedures such as cardiac catheterization.