MRI is short for Magnetic Resonance Imaging.
MRI is very sensitive to changes in body tissue and has a very high resolution. This allows a radiologist to see changes that may not be visible in other imaging exams. MRI excels at imaging soft tissues. While MRI is a very powerful and versatile technology, it is not used in all circumstances. Your doctor will let you know if cardiac MRI is the right exam for you.
MRI does not use ionizing radiation, as CT scans and x-rays do. Instead, MRI generates images using a very strong magnet and radio waves. The images are cross sections like CT scans, but MRI can also produce images in lengthwise planes without the patient having to change position.
Cardiac MRI scans often require the use of a contrast medium called gadolinium. The contrast, which is given intravenously, highlights the cardiac tissue so the radiologist can better see any abnormalities.
Conventional MRI machines have a donut shape with a tube that is usually about 3 feet in length. This exam may cause anxiety for some people who are claustrophobic. If you know you are claustrophobic, please let the facility staff know at the time of scheduling. You may be given a mild sedative to help you relax.
Reasons for Having a Cardiac MRI
MRI of the heart may be done to assess signs or symptoms that may suggest:
- Atherosclerosis: This is a gradual clogging of the arteries by fatty materials and other substances in the blood stream. It develops over many years.
- Cardiomyopathy: This happens when the heart muscle becomes thick and weakened.
- Congenital heart disease: These are defects in the heart that happen as the fetus forms. An example is a hole in the wall between the two lower chambers of the heart (ventricular septal defect).
- Heart failure: This condition means the heart muscle is weak and can’t pump enough blood to the body.
- Aneurysm: This is a widening and weakening of a part of the heart muscle or the aorta.
- Heart valve disease: When heart valves become damaged, it can block blood flow in the heart.
- Cardiac tumor: A tumor of the heart may happen on the outside surface or inside the heart.
There may be other reasons for your healthcare provider to recommend an MRI of the heart.
Risks Involved in a Cardiac MRI
MRI uses a very strong magnet. It could be dangerous to be in the magnetic field if you have any of the following:
- Aneurysm clips in the brain
- Implanted electronic devices such as nerve stimulators or medication pumps
- Metal fragments or splinters in the eye from grinding metal or welding
- Implants in the inner ear (cochlea)
There is also the possibility of a reaction to the contrast medium used for this exam; however, this is rare.
Contact your personal physician for a referral for this exam. Call the hospital site your physician sends you to in order to schedule your procedure. These exams are only performed in the hospital setting.
Cardiac MRI scans are usually covered by insurance when ordered by a physician. Check with your insurance company to be sure. Please bring your insurance card with you to your exam.
Conditions to Let Us Know About
In advance of your exam, let your scheduler or technologist know if any of the following circumstances apply to you:
- Currently pregnant
- Previous reaction to MRI contrast medium (gadolinium)
- Metallic fragments or splinters in your eye
- Aneurysm clips in the brain
- Any metallic, magnetic, mechanical or electronic devices
- Previous welding or grinding of metal without eye protection
- Weight over 300 lbs.
- Unable to lie on your stomach
The following are the general preparation instructions for this exam. You may receive additional or differing guidelines based on your specific situation.
- For safety reasons, street clothes are not allowed in the MRI. Gowns or scrub tops and scrub pants will be provided for you to wear during imaging. You will be provided with a locker in which to store your clothes and belongings during the MRI procedure.
- Take all prescribed medications.
- Bring any related images done prior to your MRI.
- Notify your doctor of any conditions you have under the Conditions to Let Us Know About section.
- Leave valuables, jewelry and watches at home, if possible.
- Any jewelry that is difficult to remove should be taken off at home prior to the exam.
- Arrive 30 minutes prior to your appointment time to complete necessary paperwork.
Cardiac MRI with Sedation
Following are additional guidelines for patients who have been scheduled to receive sedation for their cardiac MRI:
- Nothing by mouth for 8 hours before the exam (except small amount of water if needed to take medication).
- Arrange for someone to drive you to and from the exam.
The nurse will administer the IV sedation and monitor your vital signs throughout the MRI scan. The sedation will help you relax, but it will not put you to sleep.
What to Expect During the Exam
Here is generally what will happen during a cardiac MRI:
- A technologist will review safety questions with you.
- You will remove all metal and metallic objects, such as eyeglasses, belts, hair accessories and jewelry.
- You will change into a gown and/or scrubs. You will use a secure locker for your personal items during your exam.
- A small IV will be placed in your arm or hand.
- You will go to the exam room. The technologist will help position you on the MRI table. You will lie on your back. The technologist will place ECG pads on your chest and attach leads to track your heart rate and rhythm during the scan.
- The table will slide into the MRI for scans to be taken. The MRI machine will make buzzing and banging sounds. You will be provided with earplugs or headphones to protect your hearing. It is extremely important not to move any part of your body during the MRI scan to avoid blurring the images. You will be asked to hold your breath for many of the scans. The breath holds are usually less than 20 seconds each.
- The table will slide out of the MRI scanner and you will be given contrast through the IV.
- The table will slide into the MRI for additional scans. Again, it is extremely important not to move any part of your body during the MRI scan to avoid blurring the images.
- The IV will be removed after the exam is completed.
- You will change back into your clothes.
The technologist will not stay in the room during the scan, but you can speak with him or her throughout the exam by intercom.
The exam lasts about 60-90 minutes.
If you require copies of your MRI images, please notify the technologist before your exam begins.
You can return to your normal activities immediately after your MRI unless you received a sedative. If you were sedated, you cannot drive after the exam.
A board-certified radiologist experienced in the interpretation of cardiac MRI scans will analyze the data and results from your exam. The results will be reported to your physician. Your physician will pass the results onto you.
During the exam, the technologist will be happy to answer questions about the exam itself; however, they will not immediately provide you with the results of your exam.