"A lot of the increased need for helium was fueled by the semiconductor market, but with the economy down, there are less plasma screen televisions selling," says Baldwin.

Notwithstanding the amount of helium needed for party balloons, manufacturing semiconductor computer chips, or pressurizing liquid propellants used by the space shuttle, liquid helium is essential to keep MRI magnets at sub-freezing temperatures.


This coldest-on-earth substance requires expert handling which translates to more costs. The special transport and delivery process sounds uncomplicated but isn't. Liquid helium is transported by truck in 250 or 500 liter dewars, "containers," which are analogous to Thermos® bottles and which minimize the loss of liquid during the transport.

In simplified terms, from the dewar, a helium siphon is used to transfer the liquid to the MRI magnet. It is critical to have a properly working siphon to promote an efficient transfer.

Oxford Instruments was one of the first producers of MRI magnets and sold to major manufacturers. Freund, who has been with the company over 20 years, talks about the MRI service process. "Many MRI units use a special material to create the electromagnetic field needed for imaging. Superconducting wire [a product of Oxford Instruments in Carteret, NJ] is a wire that has amazingly low electrical resistance when kept at temperatures below 4.2 degrees Kelvin, the temperature of liquid helium.
Magnets large enough to surround the part of a person's body that needs to be imaged are wound with this wire."

Freund continues, "Because the properties of the wire are so special, very high magnetic fields can be created by energizing the wire with high currents (300-700 amps in most cases). Since the wire has such low resistance, the power source can be removed once the magnet is energized with almost no loss of magnetic field. The helium in many MRI magnets boils away under normal conditions. Therefore, special magnet designs and refrigeration systems are used to minimize this loss, and even in some cases eliminate it. For those whose systems do boil-off helium, routine top offs of the liquid are required. This is also a service that Oxford Instruments performs."

Filling of liquid helium for MRIs is also a service Praxair provides. Maureen Fama, Manager, Employee and Marketing Communications for Praxair said, "Our ability to respond to emergencies, and our high-efficiency transfill equipment set us apart. We also provide a magnet monitoring system to monitor cryogen levels. We also schedule the transfill. If levels go too low, the magnet quenches, causing a very expensive repair."

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