What is Magnetic Resonance Imaging?
Magnetic Resonance Imaging is a safe, noninvasive test that creates
detailed pictures of organs and tissues. MRI uses a magnet, radio waves and a computer to create those pictures. It is not an X-ray and does not use radiation.
What is cardiac MRI?
Cardiac Magnetic Resonance Imaging creates still and moving images of major blood vessels and the heart as it is beating. CMR provides doctors with information they can't get through other tests. It also helps avoid an invasive cardiac catheterization.
Why is cardiac MRI necessary?
Children's Hospital uses CMR for both pediatric patients and adults with congenital heart disorders. It helps determine heart chamber volumes and the size of other cardiac structures (such as valves and vessels), calculation of heart function, measurement of blood flow and assessment of injury to the heart muscle.
Cardiac MRI can be useful for patients with these conditions:
- Tetralogy of fallot.
- Coarctation of the aorta.
- Hypoplastic left heart syndrome and other single ventricle diseases.
- Transposition of the great arteries.
- Aortic disease.
What happens during the exam?
- An IV (plastic tube inserted into a vein) will be placed by a pediatric nurse for the end of the MRI when the technologist obtains a contrast-enhanced image.
- The technologist will position the patient on the table.
- The patient's skin will be prepped with a special gel to make it ready for the EKG leads that will be placed on the chest.
- The patient will lie on a table that slides into the scanner. The MRI scanner looks like a cylinder.
- The patient can watch a movie or listen to music during the exam. Parents or spouses can stay in the scan room. They will be asked to wear earplugs. For safety reasons, pregnant women are not allowed to stay in the room.
- The MRI will make loud noises as pictures are taken. Headphones or earplugs will protect ears.
- The patient will be asked to hold still during the scan.
- The technologist (person taking the images) will operate the MRI machine from behind a glass window with the cardiologist. They will ask the patient to hold his or her breath for about 6 to 10 seconds many times during the MRI.
- The technologist will make sure the patient is comfortable during the scan.
- The IV will be used at the end of the CMR to get a 3-D image of the heart. The patient may feel a cool sensation as the contrast (gadolinium) is injected into the heart.
- It takes about 45 to 90 minutes to get all images for the cardiologist.
Is anesthesia used?
It is important for the cardiologist to get diagnostic MRI pictures. Young children or patients who can't cooperate may need general anesthesia. General anesthesia causes the patient to be unconscious during the MRI. If a child needs general anesthesia, parents will not be allowed in the room during the scan.
The medicine patients get will get either is inhaled through a breathing mask or run through an intravenous line (a plastic tube inserted into a vein). A breathing tube will be inserted into the windpipe so the anesthesiologist can maintain the patient's breathing during the scan. When the MRI scan is done, the anesthesiologist stops the anesthetic and the medication wears off. Complete recovery for the patient continues in the recovery room.
Some patients get anxious while in the MRI scanner. Often, the anxiety goes away after getting used to the scanner. If the anxiety does not go away, we can use a special medicine to help relax him or her.