What is cardiac MRI?
Cardiac magnetic resonance imaging (MRI) is a noninvasive medical test that helps your physician diagnose and treat certain heart conditions. MRI uses a powerful magnet and a computer to produce detailed pictures of your heart and surrounding structures. The images can then be examined on a computer monitor by the radiologist. MRI does not use ionizing radiation (X-rays).
Detailed MRI images allow your physician to better evaluate your heart and determine the presence of certain conditions that may not be assessed adequately with other imaging methods.
Using cardiac MRI, your physician can:
- Examine the size and thickness of the chambers of your heart
- Determine the extent of myocardial (heart muscle) damage caused by a heart attack or progressive heart disease
- Assess your recovery following treatment
Your doctor will determine if you are a candidate for cardiac MRI. If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your physician for a prescription for a mild sedative prior to the scheduled examination. If you feel the need for this, you MUST be driven to and from the test by someone else.
Some MRI examinations may require you to receive an injection of contrast into the bloodstream. Inform us of any allergies when making your appointment. The contrast material most commonly used for an MRI procedure, gadolinium, does not contain iodine and is less likely to cause side effects or an allergic reaction.
Some conditions, such as severe kidney disease, may prevent you from being given contrast material for an MRI. If there is a history of kidney disease, it may be necessary to perform a blood test to determine whether the kidneys are functioning adequately.
Women should always inform us if there is any possibility that they are pregnant. MRI procedures are considered generally safe in pregnancy.
In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the following implants cannot be scanned and should not enter the MRI scanning area unless explicitly instructed to do so by a radiologist or technologist who is aware of the presence of any of the following:
- Internal (implanted) defibrillator or pacemaker
- Cochlear (ear) implant
You should tell your doctor if you have medical or electronic devices in your body, because they may interfere with the exam or potentially pose a risk, depending on their nature and the strength of the MRI magnet. Examples include but are not limited to:
- Artificial heart valves
- Implanted drug infusion ports
- Implanted electronic device, including a cardiac pacemaker
- Artificial limbs or metallic joint prostheses
- Implanted nerve stimulators
- Metal pins, screws, plates, stents or surgical staples
In general, metal objects used in orthopedic surgery pose no risk during MRI.
What to expect
Upon arrival to our facility, you will be asked to fill out paperwork that will include questions that verify if this is a safe test for you. Once the safety questionnaire is cleared, you will be asked to change into a gown and an IV will be placed in your arm. Belongings can be placed in a provided locker.
You will be brought into the MRI room and asked to lie flat on the MRI table. The doctor or technologist will place EKG leads on your chest to monitor your heart. Additional wires will also be connected to your body, and pads will be placed around your arms and legs to keep them safe and to make you comfortable.
You will be placed in the machine, which is shaped like a donut. You will go all the way into the center of the machine. However, your face will be no more than 10 inches from the outside. Additionally, the newer MRI machines have a larger "donut" hole so that it does not feel cramped. If it helps, you can close your eyes during the examination. Remember, a doctor and technologist will be immediately next door and can see and speak with you at all times. You can request to have someone in the room with you during the exam for support.
You will be required to hold your breath for 12-18 seconds at a time during the examination. This will be done multiple times. The technologist or doctor will give you specific breathing instructions. While you are holding your breath, you will hear noises from the machine while it is taking pictures. Earplugs and headphone with music will be provided, as the machine can be noisy at times.
You should expect the exam to take from 50-80 minutes, depending on how many pictures need to be taken. Patients requiring contrast should expect to take closer to 80 minutes, while those not receiving contrast should expect to be closer to 50 minutes.
How to prepare
You should not eat for four hours prior to your cardiac MRI exam. You may drink water and take your regular medications.
The following items should be left at home (if feasible) or in a locker at our facility, which will be provided upon arrival:
- Jewelry, watches, credit cards and hearing aids, all of which can be damaged by the MRI machine
- Pins, hairpins, metal zippers and similar metallic items, which can distort MRI images
- Removable dental work
- Pens, pocket knives and eyeglasses
- Body piercings
Following a cardiac MRI, you will be able to drive yourself home and return to your normal daily activities.
Results from your MRI may take a few days to a week or more. When results are available, your doctor will review them with you and discuss any necessary follow-up steps.