What is the approximate temperature of liquid helium used in MRI systems?

Liquid helium is used in MRI systems primarily for its properties as a cryogenic coolant, specifically to keep the superconducting magnets in a state conducive to the operation of the MRI machine. The boiling point of liquid helium at standard atmospheric pressure is approximately 4.2 Kelvin (K), which is why the temperature is typically rounded to about 4K. This temperature is crucial because superconducting magnets operate most efficiently at such low temperatures, facilitating stable magnetic fields necessary for high-resolution imaging.

Using liquid helium, which maintains its temperature around this crucial point, allows for the superconductivity necessary to achieve the strong and consistent magnetic fields required in MRI technologies. Thus, the answer of 4K reflects the standard operating temperature for liquid helium in this context. This precision in temperature is vital for maintaining the efficacy and reliability of MRI systems.