Generally, joint and limb prostheses presents low MRI risks of heating and magnetic attraction, but image artifacts can be caused by them.

If possible, prostheses should be removed prior to the MR examination. Risks are depending on the field strength, the used material, the shape and the length of prostheses. A material like titanium alloy is safely. The use of a low to mid field MRI device presents also a high safety.

The interactions between the most tested heart valve prostheses and the magnetic field of MRI devices are of no significance. However, there are many different types of heart valve prostheses and in the particular case their MRI safety should be checked.

Prosthetic heart valves, depending on the type and the material, are not necessarily considered to be dangerous in fields up to 3T. Patients should not undergo high field MRI examinations if valve dehiscence is clinically suspected.

Quenching is the cryogen boil off (liquid helium) which is used to cool the superconducting magnet coils of high field MRI systems. This results in a loss of superconductivity in the magnet, in a rapid increase in the resistivity of the magnet, which generates heat that results in further evaporation of the cryogen.

A quench can cause total magnet failure and should be avoided.

Time-dependent electromagnetic fields are significantly attenuated by conducting media (including the human body); the skin depth gives a measure of the average depth of penetration of the RF field. A high power frequency tunable RF source can be rapidly switched on and off. This produces a large RF field perpendicular to the magnetic field. This RF field is focused by the body coil. The RF source and coils must be tunable in both frequency and impedance to 'match the impedance' of the patient's body.

The skin depth may be a limiting factor in MR imaging at very high frequencies (high magnetic fields). The skin depth also affects the Q of the coils.

Pharmaceutical products in transdermal skin patches may cause burns due to the absorption of RF energy.

Such patches must be removed prior to MR examinations.