Magnetic resonance imaging (MRI) uses a magnetic field, computer and radio waves to create 3D images of internal organs and structures. A cardiac MRI, or heart MRI, gives doctors detailed pictures of a heart and its surrounding structures. Doctors use cardiac MRIs to diagnose and monitor heart conditions.
Cardiac MRI Scan Uses
Heart MRIs help doctors diagnose and monitor heart conditions, plan for surgery and evaluate the results of surgery. They are particularly useful for diagnosing heart muscle diseases and conditions.
Cardiac MRI scans show:
- Heart and blood vessel anatomy and function
- Blood flow through the heart and major blood vessels
- Heart muscle diseases
- Heart valve disorders
- Structural heart or blood vessel defects
- Tissue damage from a heart attack or virus (myocarditis)
- Heart tumors
What to Expect During a Cardiac MRI Scan
Cardiac MRIs are noninvasive, painless, and safe. For this test, your child goes to a special room that has an MRI machine. Most MRI machines have a table that slides into a large metal tube.
Although most MRI scans can be performed without general anesthesia, children between the ages of six months and six years generally cannot lay still for the time required for the scan. The exact age range requiring anesthesia depends on the child and the imaging required. This decision will be made by your doctor (in conjunction with your input) and the anesthesiologists working in the imaging center.
Preparing for a cardiac MRI
It’s important to remove any objects that may contain metal from your child before an MRI scan. Make sure to remove items such as:
- Clothes with metal zippers or buttons
- Hair pins
- Hearing aides
- Jewelry or watches
- Metal retainers
- Underwire bras
Cardiac MRI process
During a cardiac MRI:
- The MRI technologist usually places electrocardiogram (EKG) electrodes (small tabs) on your child to synchronize the images with your child’s heartbeat. Some children may have other monitors to track things like breathing and pulse during the scan.
- If the doctor orders a cardiac MRI with contrast, a nurse gives your child an intravenous line (IV) before the scan. After taking some images without contrast, the technologist injects the contrast dye into the IV and takes more images.
- When it’s time for the scan, your child lies down on the table. It’s important for your child to lie still during the scan to capture a clear image. Young children or children who cannot keep still may receive anesthesia to put them to sleep during the test. With video goggles, anesthesia is often not needed in children as young as 4 or 5 years of age because they can watch a movie that is started before they are moved into the scanner, taking away the feeling of an enclosed space.
- The technologist returns to the monitoring booth to perform the test. Children who are awake during the test can communicate with the technologist through a speaker in the machine.
- The MRI machine makes loud thumping noises during the scan. Children may receive earplugs or headphones to listen to music or watch a movie to help make the test more comfortable.
- Cardiac MRI scans take images in multiple sequences. Each sequence may last up to several minutes. A full cardiac MRI scan takes 30 to 90 minutes.
Cardiac MRI Risks
Cardiac MRI scans do not use radiation or iodine-containing contrast dyes like some other imaging tests do. As a result, cardiac MRIs are safe, and your child is not exposed to any radiation. For MRIs with contrast, there is a small chance of allergic reaction to the dye (around 1 in 1,000 cases). But if they occur, reactions are typically mild and may result in nausea or vomiting. The radiology department is prepared to treat allergic reactions if they happen.
Ask your doctor if a cardiac MRI is safe if your child:
- Has a pacemaker
- Has a stent, artificial heart valve, or vascular coil (these are safe but disrupt the images)
- Has any kind of metal implant (most are certified safe for MRI)
- Has a stent or artificial heart valve
- Has kidney problems
- Has had a prior reaction to either MRI or CT contrast
- Has tattoos
- May be pregnant
Cardiology Care at Children’s Hospital Los Angeles
At CHLA, your child receives excellent care from world-class experts. Learn more about our pediatric heart programs and services.