Always use hearing protection, especially at high field strength. As magnetic field strength increases, the resonant frequency rate increases. Shorter exposures give the same effect at higher field strengths. Magnetic fields are invisible. MRI can cause serious injury or death if the wrong things are allowed into the scan room.
Many people have metal in their bodies.
Most metal implants are safe for the MR scanner. Need complete medical history of patient for MR staff to determine safety. Don t allow extraneous metal objects into scan room - potential to harm patient, degrade images and damage MR scanner. Metallic aneurysm clips. Cochlear implants and many inner ear wires.