Medical Health Encyclopedia

MRI

Several sets of images are usually required, each taking from 2 to 15 minutes. A complete scan, depending on the organs studied, sequences performed, and need for contrast enhancement may take up to one hour or more. Newer scanners with more powerful magnets utilizing updated software and advanced sequences 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 - 6 hours prior to the scan.

Text Continues Below

---

Because of the strong magnets, 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.

Because the strong magnetic fields can displace or disrupt the action of implanted metallic objects, 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
• Recently placed artificial joints

Sheet metal workers, or persons with similar potential exposure to small metal fragments, will first be screened for metal shards within the eyes with x-rays of the skull.

The patient will be asked to sign a consent form confirming that none of the above issues apply before the study will be performed.

A hospital gown may be recommended, or the patient may be allowed to wear a sweatsuit or similar clothing without metal fasteners.