Because MRI does not involve the use of x-rays, it is safe for the majority of people.
Certain people, however, may be unable to undergo the procedure. These include:
- Those who have implanted medical devices, including heart pacemakers and inner ear implants
- Those with metal close to or in an important organ, for example a piece of metal in the eye possibly from an old injury, or metal clips in the brain following treatment for a brain aneurysm
The reason for these limitations is that the powerful magnetic field of the scanner may interfere with the internal mechanism of some of these medical devices, which may be dangerous, as well as the fact that the presence of metal will cause poor quality pictures if it is near the part being scanned.
While there are no known hazards, MRI is not proven to be safe during pregnancy.
