Cardiac MRI

Cardiac magnetic resonance imaging (cardiac MRI) is a pediatric 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 300 cardiac MRI exams every year.

Why is cardiac MRI used?

mri scanner

Children's Hospital of Wisconsin uses cardiac magnetic resonance imaging, sometimes called cardiovascular MRI, for children and for adults with congenital heart disorders. Cardiac MRI is often used instead of invasive diagnostic procedures which require surgery or inserting a tube into the body. Cardiac MRI helps doctors assess the size of the heart’s chambers, how its structures look (such as valves and vessels), how well the heart is functioning, how much blood it pumps, and whether or not the heart muscle has been injured.

Heart MRI is often useful for patients with these conditions:

  • Tetralogy of fallot
  • Coarctation of the aorta
  • Hypoplastic left heart syndrome (HLHS) and other single ventricle diseases
  • Transposition of the great arteries
  • Cardiomyopathy
  • Aortic disease
  • Myocarditis
  • Fontan procedure follow-up

What happens during a cardiac MRI?

MRI Scan

Here are some things to know about a cardiac MRI.

  • The exam takes about 45 to 90 minutes, during which time the patient needs to hold still.
  • Our Child Life Specialists will help your child to relax before, during, and after a scan. They offer many distractions, relaxation techniques, and entertainment options, including music, movies, games, and toys.
  • Parents or spouses can stay in the scan room if they are not pregnant.
  • 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 your child’s heart rate.
  • The technologist will operate the MRI machine from behind a glass window with the cardiologist. Patients will be asked to hold their breath for 6 to 10 seconds many times during the exam.
  • The MRI machine can be noisy. Headphones or earplugs will protect your child’s ears. Parents and spouses in the scan room during the study need to wear earplugs, too.
  • The technologist will talk with your child to make sure he or she is comfortable during the scan.
  • To get 3-D images of the heart, a contrast dye, called gadolinium, can be given to your child through an intravenous line (IV). If the cardiologist requested these images, a nurse will have numbed the insertion site and placed the IV in the patient’s arm before the exam started. The dye may feel cool when injected.

Is anesthesia used for a cardiac MRI?

Feelings of anxiety about being in the scanner often go away once children get used to it. Special medicine (sedatives) can help him or her relax, too, if necessary, and requires the expertise of pediatric doctors and nurses with advanced training in pediatric anesthesiology and sedation.

Babies and children who can't lie still for any reason may need general anesthesia so they can be unconscious during the MRI. Anesthesia medicine is given through a breathing mask or an IV. The anesthesiologist will maintain the child’s breathing during the scan with a breathing tube. If your child needs anesthesia, one of our 35 board-certified pediatric anesthesiologists will perform and monitor the sedation. If a child needs general anesthesia, parents will not be allowed in the room during the scan. When the scan is done, the tube will be removed and the child’s anesthesia will wear off in a special recovery room.