Abdominal MRI

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Digestive system

Abdominal MRI

Definition:

Abdominal magnetic resonance imaging (MRI) is a noninvasive procedure that uses powerful magnets and radio waves to produce pictures of the inside of the abdomen without exposure to ionizing radiation (X-rays).

Alternative Names:
Nuclear magnetic resonance - abdomen; NMR - abdomen; Magnetic resonance imaging - abdomen; MRI of the abdomen
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 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 a small vein of the 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 complete the process in less time.

How to prepare for the test:

No preparatory tests, diets, or medications are usually needed, unless the colon needs to be cleansed (with preparations such as a laxative or an enema). 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.

Because of the strong magnets used in MRI, 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 magnet is activated and should not accompany the patient into the scanner area.

Strong magnetic fields can displace or disrupt the action of implanted metallic objects, so people with cardiac pacemakers cannot be scanned and should not 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.