Why is liquid helium useful for cooling MRI magnets?

Liquid helium is essential for cooling the magnets in magnetic resonance imaging (MRI) scanners because of its exceptionally low boiling point, which allows it to maintain the extreme cryogenic temperatures required for superconductivity.1

Superconductivity is the phenomenon where a material loses all electrical resistance when cooled to a specific critical temperature. In an MRI machine, powerful electromagnets are used to generate the intense magnetic fields necessary for imaging. If these magnets were not superconducting, the high electrical currents required to generate such strong fields would produce immense heat, potentially melting the equipment.234

By using liquid helium to cool the magnet's cables to approximately 4 K, the system can sustain these high currents without generating heat through electrical resistance. While ceramic superconductors that operate at higher temperatures exist, they are often brittle and difficult to process, making conventional metal alloy superconductors cooled by liquid helium the standard for MRI technology.42