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What is Cardiac MRI and how does it work?
|Allegheny General Hospital's Cardiac Magnetic Resonance Imaging Department, the only dedicated lab in the region, provides AGH physicians with additional information for the diagnosis and treatment of complex cardiac conditions.|
Cardiac magnetic resonance imaging (MRI) is a noninvasive procedure that produces detailed high resolution pictures of the heart. The scanner that performs the cardiac MRI test creates a magnetic field that directs radio waves at the heart, causing the heart tissues and blood to produce radio waves of their own.
These radio waves are processed by a computer that produces a 3-dimensional image of the heart and surrounding large blood vessels. Once this 3-dimensional image is obtained, it can be examined in detail. Blood flow can also be evaluated. There is no exposure to ionizing radiation (X-rays) or need for an arterial injection. Typically, there is no pain associated with the test. The test lasts for approximately 30 – 60 minutes, depending on the ordering physician’s test requests. After an MRI scan, the patient can resume his or her normal daily activities, unless a sedative was administered prior to the test or otherwise directed.
Why did my Doctor send me for a Cardiac MRI Test?
In general, cardiac MRI is useful in evaluating the following:
- Left and right cardiac structure and function
- Evaluation of recovery after a heart attack, including viability and perfusion
- Congenital heart disease
- Thoracic aortic disease, including dissections and aneurysms
- Large artery and vein disorders
- Pericardial disease
- Evaluation of coronary artery disease, including resting and stress perfusion
- Tumors around the heart or blood vessels
- Valvular disorders
A cardiac MRI test may generally also be ordered for patients in whom echocardiography is not technically feasible or when unsatisfactory echocardiographic images are produced. A cardiac MRI test may also be requested if a doctor would like a second opinion about any cardiovascular disease or to gain a better understanding of your medical condition.
Is a Cardiac MRI Test Safe?
A cardiac MRI test avoids exposure to ionizing radiation (X-ray) and the possible complications associated with angiography. There is no pain associated with a cardiac MRI test. However, a very small number of people will feel claustrophobic (feeling of fear in a closed space) when they lie inside the MRI scanner. Though rarely required, a mild sedative may be administered prior to the test, if requested.
On occasion, a few cardiac MRI tests require injection of a contrast-enhancing agent into a small vein (not an artery). This agent does not contain iodine. Your medical history will be reviewed prior to the test to determine if you are allergic to any medications or contrast-enhancing agents. Current medical guidelines will be followed if a contrast-enhancing agent is to be administered.
The physicians and staff of The Cardiac MRI Center follow a set of safety guidelines in place to ensure your safety during this test.
What do I need to know for my Cardiac MRI Test?
There are a few things that you should know about your cardiac MRI test prior to the exam:
- Unless required by your doctor, there are usually no special pre-tests, diets or medications needed. You will be asked to take all your required medications unless otherwise contacted by your doctor. There is no need to fast prior to your MRI scan unless specifically told to do so.
- One of our staff members will call to pre-register you for this test. This involves answering some basic questions about yourself and providing a brief medical history. Please be prepared to tell our staff member your weight and height.
- Because of the strong magnets used in MRI, the MRI staff will follow a set of safety guidelines for your protection. There will be no metallic objects allowed into the room where the MRI scanner is located. These include items such as credit cards, coins, hearing aids, removable dental work, jewelry in or on your body, keys, metal belts, watches, eye glasses, and similar metallic objects. You will be asked to leave these items at home or deposit them in a locker when you arrive for your test. You will be asked to walk through a metal detector prior to entering the area where the MRI scanner is located. This allows the staff to check for metal objects on your person and prevent the risk of injury during your test.
It is not possible to routinely undergo a cardiac MRI test if certain medical conditions as well as medical hardware are present. These include:
- Heart pacemaker/defibrillator
- Ear implants for the hearing impaired
- Medical pumps (insulin pump, narcotics pump)
- Foreign metallic objects in the body
- Implanted nerve stimulator
You may have other medical conditions or medical hardware present in or on your body. Please tell this to the staff when scheduling your appointment. Let us also know if you think that you may be claustrophobic. You will then be given special instructions to follow. The Cardiac MRI Center staff makes the final determination of patient eligibility for a cardiac MRI test.
How long will it take for my Cardiac MRI test?
We ask that you allow two hours for your MRI exam. Although the typical test lasts about 30 - 60 minutes, the staff needs time to register you, review your medical history, explain your test and MRI instructions to you, and answer any questions that you may have. You also need time to change into a hospital gown.
What can I expect to happen when I arrive for my Cardiac MRI test?
We ask that you arrive at the hospital registration area 30 minutes prior to your scheduled scan time. After you complete the registration process, proceed to the Cardiac MRI Center . Upon arrival, you will be met by one of our staff members and directed to our waiting area. A MRI technologist and/or clinical nurse will review your medical history with you and ask if you have any questions. If you are a research patient, you will be asked to sign a consent form. Prior to your test, you will be asked to change into a hospital gown and remove all jewelry and metallic objects from your body. All personal items will be placed in a secure locker in the MRI suite.