MRI machines require approximately 1,700 to 2,000 liters of liquid helium to keep their magnets cold enough to operate.

Magnetic Resonance Imaging (MRI) relies on superconductivity, a phenomenon first discovered by Heike Kamerlingh Onnes in 1911. To achieve this state, the niobium-titanium coils inside the scanner must be cooled to approximately 4 Kelvin, or -452°F (-269°C). Liquid helium is the primary coolant because it has the lowest boiling point of any element at -269°C.A standard 1.5 Tesla MRI scanner typically contains about 1,700 to 2,000 liters of liquid helium. This extreme cooling eliminates electrical resistance in the wire coils. Without resistance, a massive electrical current can flow indefinitely without generating heat, creating the stable and intense magnetic field required to align hydrogen protons in the human body.The global supply of helium is finite, making this technology both expensive and logistically challenging. Most modern systems are designed with "zero-boil-off" technology that recycles the helium by re-condensing the gas back into liquid. However, if the magnet loses its superconductivity in an event called a "quench," the helium can rapidly boil off and must be replaced at a cost of tens of thousands of dollars.Researchers at institutions like the University of Oxford are currently developing "dry" or "helium-free" MRI magnets to reduce dependence on this rare resource. These newer designs use high-temperature superconductors or closed-loop cryocoolers. Despite these advances, the vast majority of the world's approximately 50,000 active MRI machines still rely on large reservoirs of liquid helium to operate safely and effectively.