The MRI magnet is ALWAYS on. This means no person is allowed to enter the MRI scan room without clearance and permission from a certified technologist. Metallic objects (such as fingernail clippers, pocket knives and even pens) can lead to serious bodily injury if brought within the magnetic field.
Projectiles are one of the biggest dangers associated with the MRI scanning environment and occur when the strong magnetic fields of the MRI magnet attract ferromagnetic (metal) objects which then become airborne. Even small objects such as paperclips or scissors can be quickly jerked from your hands and severely injure anyone nearby. Metallic objects in the body can also have dangerous effects when placed in a magnetic field. Some metal implants, including some metal fragments, may move inside the body causing internal injury.
All potential MRI research subjects must be screened for items that may be hazardous to themselves or others prior to entering the MRI scan room. It is strongly recommended that anyone involved in the recruitment of MRI research subjects include all items from the MRI Screening Sheet found below when screening subjects.