Heart MRI
Alternative names:
magnetic resonance imaging - cardiac; MRI of the heart; NMR - cardiac; nuclear magnetic resonance - cardiac
How the test is performed:
The MRI scanner is in an area that has been shielded from outside magnetic fields. You are asked to lie on a narrow table that can slide inside a large tunnel-like tube within the scanner. The scanner creates a magnetic field around you, then pulses radio waves at the tissues in question. Several sets of images are usually required, each taking from 2 to 15 minutes. The complete scan takes about 1 hour; some scans take more than 90 minutes.
How to prepare for the test:
No preparatory tests, diets, or medications are usually needed. Occasionally the person may be asked to fast for 4 to 6 hours prior to the scan. You must sign a consent form before the scan.
Because of the strong magnets, no metallic objects are allowed into the room. Items such as jewelry, watches, credit cards, and hearing aids can be damaged by the strong magnets. Pins, hairpins, metal zippers, and similar metallic items can distort the images. Frequent exposure to ferrous metals (such as a sheet metal worker has) may make MRI difficult. A hospital gown may be recommended, or you may be allowed to wear "sweats" or similar clothing without metal fasteners. Take out removable dental work just prior to the scan.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feel:
There is no pain. The magnetic field and radio waves are not felt. The primary discomfort is the claustrophobic feeling that some people experience from being inside the scanner. The table may be hard or cold, but you can request a blanket or pillow. The machine produces loud thumping and humming noises. Ear plugs are usually given to reduce the noise. A technologist observes you during the entire procedure and may enter the room to speak to you or may speak with you through an intercom in the scanner.
Excessive movement can blur MRI images. If you have difficulty lying still or are very anxious, you may be given a sedative. There is no recovery required (unless you have been sedated). After an MRI scan, you can resume normal diet, activity, and medications.
Why the test is performed:
MRI provides detailed pictures of the heart and blood vessels and can distinguish structure from moving blood. It can differentiate between myocardial and pericardial tissues. It can clarify findings from previous X-rays or CT scans, or it may be recommended to avoid obstruction of the view of the heart by overlying bones. It can show the heart from multiple planes. MRI clearly shows blood vessels and is a noninvasive procedure that can evaluate blood flow. MRI is useful in the diagnosis of congenital abnormalities, abnormal growths, and tumors. It can distinguish tumors or other lesions from normal tissues.
MRI is sometimes used to avoid the dangers of angiography, repeated exposure to radiation, or exposure to contrast dye. It is preferred over echocardiogram when echocardiogram is unclear, because MRI can transmit through bone or air and create views of the heart from any plane. It provides a wider view and better spatial resolution than echocardiogram.
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