Cryogen Effects in MRI Safety

The magnetic field of most MRI systems is in force at all times, and dissipating or quenching this field requires skilled personnel to prevent or control the escape of cryogenic gases from the instrument. Cryogen liquids, typically helium or nitrogen, are present in MRI devices to cool the magnet. Although these liquids are safe while contained in the instrument, the accidental or deliberate exposure of these liquids to the air results in the immediate boiling to a gaseous state, which can result in catastrophic consequences. Most systems have a venting system that releases these gases to the ambient air, usually through the roof, in the event that quenching is required. The release of cryogenic gases to the MRI suite could result in frostbite-type burns due to the extremely low temperature of these liquids, asphyxiation due to a replacement of oxygenated air with the cryogenic gases, fire hazards, or a hyperbaric pressure environment.3 To reduce the risks posed by the unlikely escape of cryogenic gases, the ACR recommends the inclusion of an emergency exhaust system, in addition to measures to provide passive pressure relief in the event of an accident, within Zone IV of the MRI facility

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