MRI of the head

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Brain

Lobes of the brain

MRI scans

Several sets of images are usually required, each taking from 2 to 15 minutes. Depending on the sequences performed and the possibility of the need for a contrast dye, a complete scan may take up to a hour or more. Newer scanners with more powerful magnets, updated software, and advanced sequences may complete the process in less time.

No special tests, diets, or medications are usually needed. An MRI may be performed immediately after other imaging studies.

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 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, and recently placed artificial joints. The technologist will usually provide you with a questionnaire which lists the potentially dangerous items.

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 sweat suit or similar clothing without metal fasteners.

There is no pain. The magnetic field and radio waves are not felt. Some people experience a claustrophobic feeling from being inside the scanner. The table may be hard or cold, but you can request a blanket or pillow.