Heart MRI

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Heart, section through the middle

Heart MRI

Definition:

Heart magnetic resonance imaging (MRI) is a non-invasive procedure that uses powerful magnets and radio waves to produce pictures of the heart without exposure to ionizing radiation (X-rays). The heart may be scanned by itself, or a heart MRI may be part of a chest MRI.

Alternative Names:
Magnetic resonance imaging - cardiac; NMR - cardiac; Nuclear magnetic resonance - cardiac; MRI of the heart
How the test is performed:

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MRI uses radio waves very close in frequency to those of ordinary FM radio stations, so the scanner must be located within a specially shielded room to avoid outside interference.

The patient is lies on a narrow table which slides into a large tunnel-like tube within the scanner. Small devices may be placed around the head, arm, or leg, or adjacent to other areas to be studied. These are special body coils which send and receive the radio wave pulses, and are designed to improve the quality of the images. An IV may be placed in the patient's hand or forearm if contrast medium will be used.

A technologist will operate the machine and observe the patient from an adjacent room during the entire study.

Several sets of images are usually required, each taking from 2-15 minutes. A complete scan, depending on the sequences performed, and need for contrast enhancement may take 1 hour or more. Newer scanners may complete the process in less time.

How to prepare for the test:

No preparatory tests, diets, or medications are usually needed. An MRI can be performed immediately after other imaging studies. Depending on the area of interest, the patient may be asked to fast for 4 to 6 hours prior to the scan.

Certain metallic objects are not allowed into the room. Items such as jewelry, watches, credit cards, and hearing aids can be damaged. Pins, hairpins, metal zippers, and similar metallic items can distort the images. Removable dental work should be taken out just prior to the scan. Pens, pocketknives, and eyeglasses can become dangerous projectiles when the stronge MRI magnet is activated and should not accompany the patient into the scanner area.

The MRI's strong magnetic fields can disrupt cardiac pacemakers cannot be scanned and people with them should not be scanned or even enter the MRI area. MRI also should not be used for people with metallic objects in their bodies such as inner ear (cochlear) implants, brain aneurysm clips, some artificial heart valves, older vascular stents, and recently placed artificial joints.