How do I prepare for a cardiac MRI or MRA?
You should remove all metal objects (e.g., jewelry, belts, underwire bras) before a cardiac MRI or MRA. The preparation will vary depending on the type of test you are having; for some, there is no special preparation. If you are having a chemical stress MRI, a cardiac MRA, or you have asked for a sedative, you may be asked not to eat or drink anything for up to 8 hours before the test. If you have diabetes, you should discuss dietary concerns with your healthcare provider to control your blood sugar levels. Talk to your doctor about any medications or dietary supplements you are taking in case they affect the accuracy of the test.
What does a cardiac MRI or MRA entail?
You will wear a hospital gown; you may wear clothing such as a T-shirt and panties underneath, but you cannot wear a bra. You will lie on a bed that slides into the machine, which is a large tube. Some people experience claustrophobia inside the MRI machine because it is a closed space. For some tests, you are strapped down on the bed. You can request to be given a mild sedative if you think you might experience claustrophobia; otherwise, you will be awake for the entire test. If you are prone to claustrophobia, you may ask your healthcare provider if there are any “open” MRI scanners available in your area.
There will be several imaging periods, lasting from 1 to 15 minutes each, during which you must lie very still. At some points, you will be asked to hold your breath.
When inside the machine you will hear loud clanging noises, which are a normal part of the MRI procedure. You can ask for ear plugs before the test starts, or you may be given headphones to wear. You will still be able to hear the technician's instructions. Some testing facilities use an intercom through which you can talk to the technician if necessary, and he or she will periodically make sure you are comfortable. In other locations, the technician cannot hear you and you are given a handheld “panic” button to press if you are uncomfortable and want to get out of the machine. A contrast dye may be injected into your arm though an IV line depending on the type of test your healthcare provider has ordered. If a contrast dye is used, you may feel a warm sensation throughout the body. A cardiac MRI or MRA can last from 45 minutes to one and a half hours.
What happens after a cardiac MRI or MRA?
After either test, you can leave immediately with no side effects. If you choose to take a sedative (because of claustrophobia), you will be monitored after the test until the effects of the sedative have passed, and a friend or relative will need to drive you home. If you had a chemical stress test, you may experience some minor side effects from the medication including nausea, heart palpitations, numbness in the arms or legs, flushing, chest pain, or headaches. The test results are recorded on film and a radiology report is sent to your healthcare provider. What does a negative (normal) test indicate?
Because cardiac MRI testing is relatively new, there are few studies that have followed people over time to see how they fare after a negative or positive test. So far, it seems that women with a negative (normal) cardiac MRI have a similar low risk of having a heart attack or dying from heart disease as women with a normal echo or nuclear test.3