​Children's Heart Center

Cardiac MRI

Cardiac magnetic resonance imaging, or MRI, is a diagnostic tool that uses a magnet, radio waves and a computer to create very detailed still and moving images of major blood vessels and the heart as it is beating. Our experienced cardiologists and technologists perform more than 100 cardiac MRI exams every year.

Cardiac magnetic resonance imaging is often used for children and adults with congenital heart disorders instead of invasive diagnostic procedures such as cardiac catheterization. Cardiac MRI helps doctors assess the size of the heart’s chambers, how its structures look, how well the heart is functioning, how much blood it pumps and whether the heart muscle has been injured.

Cardiac MRI is often useful in diagnosing patients with these conditions:

  • Tetralogy of Fallot
  • Coarctation of the Aorta
  • Hypoplastic Left Heart Syndrome, or HLHS, and other single-ventricle diseases
  • Transposition of the Great Arteries
  • Cardiomyopathy
  • Aortic Disease
  • Myocarditis
  • Fontan Surgery Follow-up

Performing a Cardiac MRI

  • The time required to complete the exam itself can range from 45 to 120 minutes, during which time the patient needs to hold still.
  • Our technologists, nurses and other specialists will help the patient to relax before, during and after the exam. They offer many distractions, relaxation techniques and entertainment options, including age-appropriate music, movies, games and toys.
  • The MRI machine looks like a tunnel. A table slides in and out of the tunnel. A technologist will help position the patient on the table.
  • An electrocardiogram (EKG) will be used during the exam to monitor the patient’s heart rate.
  • The technologist will operate the MRI machine from behind a glass window with the cardiologist. For certain protocols, patients will be asked to hold their breath for six to 10 seconds many times during the exam.
  • The MRI machine can be noisy. Headphones or earplugs will protect the patient’s ears.
  • The technologist will talk with the patient to make sure he or she is comfortable during the exam.
  • To get 3-D images of the heart, a contrast dye will be administered through an intravenous line, or IV. When these types of images are requested by the cardiologist, a nurse will place an IV in the patient’s arm before the exam starts. The dye may feel cool when injected.

Use of Sedation and Anesthesia for Cardiac MRI

Many patients have feelings of anxiety about being in the tunnel of the scanner. This anxiety often goes away. If necessary, sedatives can be used to help patients relax. This requires the expertise of doctors and nurses with advanced training in pediatric anesthesiology and sedation.

Patients who can’t lie still, including adults with special needs, may need general anesthesia so they can be completely asleep during the MRI. Anesthesia is administered through a breathing mask or an IV. The anesthesiologist will maintain the patient’s breathing during the scan with a breathing tube. When anesthesia is required, one of our board-certified pediatric anesthesiologists will perform and monitor the sedation. When the exam is completed, the breathing tube will be removed and the patient will recover in a special-care area.

With sedation or anesthesia, the patient may feel groggy, tired or sleepy for a period of several hours after the exam. However, these effects will usually disappear within a day or so.