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MRI Hazards: Missile Effect, Electronics, and Implants

Magnetic Resonance Imaging (MRI) uses powerful magnets and radio waves to produce detailed images of the body. While the magnets and radio waves are inherently safe, the powerful magnetic field can attract magnetic items and adversely affect electronic equipment.

The most dangerous hazard presented by the magnetic field is the Missile Effect. The Missile Effect occurs when magnetic items are quickly pulled into the bore (center) of the MR scanner. Standard, 1.5 Tesla MR scanners can attract items such as keys, paper clips or scissors at forty miles per hour. The more mass an item has, the stronger the attractive force on it will be. Heavier items, such as wheelchairs, can be pulled in just as quickly as smaller objects. The Missile Effect will not only damage equipment, but can fatally injure someone that is located between the item and the MR scanner.

The magnetic field poses other serious hazards if proper precautions are not taken. The magnet can twist and dislocate metallic components in electronics, power tools and surgically implanted medical devices. Aneurysm clips can be pulled or twisted from their original position, causing dangerous internal bleeding. Not all metallic objects are magnetic, but it is impossible to tell if an object is magnetic by sight alone. Testing is done on every item brought into the MR Suite to confirm its safety for that particular MR environment.

The magnetic field negatively affects electromagnetic devices brought into the MR suite. This poses a potentially fatal danger to those with surgically implanted medical devices. Pacemakers, neurostimulators, insulin pumps and intrathecal pumps can malfunction inside the MR scanner room.

While not as hazardous as the Missile Effect or the disruption of medical implants, the powerful magnet can also erase information from storage devices. Some common items that contain stored information are ID badges, credit cards, cell phones and flash drives.

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