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Magnetic resonance imaging
Magnetic resonance imaging (MRI): MRI uses large magnets and radio-frequency waves to produce pictures of the body's internal structures; no X-ray exposure is involved. MRI acquires information about the heart as it is beating, creating moving images of the heart throughout its pumping cycle.
Your doctor uses the MRI to evaluate:
- The anatomy and function of the structures of the chest: heart, lungs, great vessels, and pericardium
- Presence of disease, including ischemic heart disease, thoracic aortic disease, pericardial disease, right ventricular abnormalities, cardiac tumors, valve disease, heart muscle disease (cardiomyopathy), pulmonary artery disease, and complex congenital heart disease
How to prepare:
This procedure uses powerful magnets to create its images. For reasons of safety, anyone undergoing a scan should be free of certain metallic or magnetic items. Ask your doctor about whether an MRI scan is advisable for you and for a list of items that should be avoided when having a scan.
If you are not claustrophobic, you will not require any sedation, so beforehand you can eat and take your medications as usual. If you are claustrophobic, you may want to ask your doctor to schedule your MRI with sedation. If you do so:
- You may not eat any solid food for six hours before receiving your sedative to avoid nausea. You may have clear liquids (apple juice, gelatin, black coffee or tea, water) up to two hours before your medication time.
- You should consult with your doctor about taking your medications.
- You should have a companion to drive you home.
What to expect:
An MRI technologist will place small sticky, electrode patches on your chest and back. Men may have their chest partially shaved to help the electrodes stick. The electrodes are attached to an electrocardiograph (EKG) monitor, which charts your heart's electrical activity during the test. Most likely, an intravenous (IV) line will be inserted into a vein in your arm for non-iodine-based contrast (dye) administration.
The MRI scanner unit is a long tube that scans the body as you lie on a platform bed. It is fully lighted and ventilated and open at both ends. An intercom system allows you to talk to the scanner operators during the test. You will lie on your back on the scanner bed, with your head and legs elevated for comfort. During the exam, you will be asked to lie as still as possible. The technologist will ask you to hold your breath periodically for short periods to reduce blurring of the images from breathing motion.
During scanning, you may hear loud banging noises, which can be muffled with headphones or earplugs you will receive before scanning begins.
The MRI scan takes about 30 to 75 minutes, depending on the extent of the imaging needed.
After the procedure you may resume your usual activities and normal diet immediately if you did not receive sedation. If you did, someone else should drive you home, and your doctor will give you instructions on when you can eat, drink, and return to normal activities.
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