Why are cryogens used in MRI scanners?

Cryogens are critical in MRI scanners primarily to maintain the superconductivity of the magnet coils. Superconducting magnets, which are commonly used in MRI machines, require extremely low temperatures to function efficiently. The use of cryogens, such as liquid helium, allows the magnet coils to stay at these low temperatures, typically around 4 Kelvin. This superconductivity is essential because it minimizes electrical resistance and significantly enhances the magnet's performance, producing strong and stable magnetic fields necessary for high-quality imaging.

The role of cryogens is not related to factors such as faster gradient field switching or directly reducing patient heating during image acquisition. Instead, it is fundamentally about ensuring that the magnetic field produced by the coils remains homogeneous and powerful, which is crucial for achieving optimal imaging results. Also, while cryogens do help maintain low temperatures and thus impact the magnet coil wires indirectly, the primary reason they are utilized in MRI scanners leans more towards maintaining the superconductivity of the magnet rather than focusing only on the temperature of the coil wires themselves.