Cardiac

Magnetic resonance imaging is becoming very important in the initial diagnosis and subsequent management of heart disease. MRI can help physicians to look closely at the structures and function of the heart and major vessels quickly and thoroughly, without the risks associated with traditional, more invasive procedures. Using MRI, physicians can examine the size and thickness of the chambers of the heart, and determine the extent of damage caused by a heart attack or progressive heart disease.

After a heart attack, for example, an MRI examination can help the cardiologist understand how well the heart is pumping, whether the heart muscles are damaged or whether the lining of the heart is swelling. This is critical knowledge needed to administer prompt and effective treatment.

MRI has demonstrated potential for showing not only the structure, but also the function of the heart muscles, valves and vessels. Cardiac MRI creates movie-like images of the beating heart that doctors can use to diagnose a variety of cardiovascular problems. More and more, MRI is being used as part of the traditional cardiac stress test to help physicians with earlier diagnosis and treatment of heart disease and to assess the patient’s recovery after treatment.

What to expect with your procedure

Because the strong magnetic field used for MRI will pull on any iron-containing object in the body, MRI staff will ask whether you have a heart pacemaker or implanted defibrillator, implanted port, infusion catheter (often referred to by brand names such as Port-o-cath, Infusaport or Lifeport), intrauterine device (IUD), or any metal plates, pins, screws or surgical staples in your body. In most cases, surgical staples, plates, pins and screws pose no risk during MRI. Red dyes used in tattoos and permanent eyeliner may contain metallic iron oxide and could heat up during MRI; however, this is rare. You will be asked if you have ever had a bullet or shrapnel in your body or ever worked with metal. If there is any question of metal fragments, you may be asked to have an x-ray that will detect any metal objects.

The radiologist or technologist may ask about drug allergies and whether you have undergone any surgery in the past. If you are or might be pregnant, mention it to the MRI staff. Some patients who undergo MRI in an enclosed unit may feel confined or claustrophobic. If you are not easily reassured, a sedative may be administered. Fewer than one in 20 patients will require medication.

Preparing for your procedure

The patient is placed on a sliding table and positioned comfortably for the MRI examination. Then the radiologist and technologist leave the room, and the individual MRI sequences are performed. The patient is able to communicate with the technologist at any time by using an intercom. 

Depending on how many images are needed, the exam will generally take 15 to 45 minutes, although a very detailed study may take longer. You will be asked not to move during the actual imaging process.

For examination of the heart, contrast material may be used to enhance the visibility of the heart’s chambers and major vessels. A small needle connected to an intravenous line is placed in an arm or hand vein. A saline solution will drip through the intravenous line to prevent clotting until the contrast material is injected, about two-thirds of the way through the exam.

When the exam is over, the patient will be asked to wait until the images are examined to determine if more images are needed.

MRI causes no pain, but some patients find it uncomfortable to remain still during the examination. Others experience a sense of being closed in, though the more open construction of many new MRI systems has helped reduce that reaction. You may notice a warm feeling in the area under examination; this is normal, but tell the radiologist or technologist if it bothers you.

If a contrast material is used, there may be discomfort at the injection site, and you may have a cool sensation at the site during the injection. The loud tapping or knocking noises heard at certain phases of the imaging exam disturb some patients; earplugs may help.