Clearly you want to be sure your servicers know what they're doing. A mistake can be not just costly but dangerous. For example, odorless helium or nitrogen can quickly displace oxygen if they leak into the suite. This can cause suffocation so technicians need personal oxygen monitors. To work on the magnet, the technicians use a variety of specialized tools and instruments including turbo-molecular vacuum pumps and mass spectrometer leak detectors.

"The quench may occur for any number of reasons: procedural, hardware failure, magnet problem such as ice or air getting in through a leaking venting connection...this could divert the helium fill to the exhaust line, not the magnet," cautions Mike Profeta, President, Magnetic Resonance Technologies. "Or, if the vacuum line is compromised the liquid might turn to gas being pumped into the magnet instead of liquid-it's not as cold and the magnet can quench."


Profeta recommends choosing MRI servicers carefully: Check the credentials of those you are dealing with. Ask for written procedures. And confirm who is responsible for the cryogens. "Some [companies] do the cool down but you provide the cryogen. Put a cap on that or they may use too much helium or not take the needed time with the nitrogen soak [pre-cool]," Profeta suggests. "Qualify responsibility for cryogen and quantify amounts."

You may want to find technicians such as independent service organizations that can also provide related MRI services such as maintenance of the cold head component of the MRI refrigeration system. Another MRI service is shimming, which is the adjustment of the magnetic field to ensure uniformity. Ramping the magnet is yet another specialized process since electrical current is introduced gradually when you place the unit into operation.

Future Trends

MRI manufacturers are coming up with new cooling techniques to lower maintenance costs and reduce downtime for the equipment. For example the older MRIs require helium to be added every few weeks while some of the newest designs claim they need filling only every few years. Other technologies are also on the horizon.

"Right now companies are working on using liquid neon instead of liquid helium. The expense and scarcity of liquid helium is driving the market," says Marc Fessler, Partner, Independence Cryogenic Engineering. "Manufacturers are trying to find ways to use less liquid helium and to keep what you have longer, to recycle or re-condense the liquid that boils off using cryogenic pumps and a cold head that can reach liquid helium temperature. These trends add to our business because in the past people let cold heads and compressors run till they weren't efficient. Now it's more optimal to do preventive maintenance."

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