MXR Imaging acquired Oxford Instrument Healthcare in May 2020 |
An Exploration of MRI Helium in the Modern Medical Setting
Modern Medicine and MRI Helium Use
MRIs use powerful magnets to capture
cross-sectional images that allow doctors to more accurately diagnose their
patients. A massive amount of energy is required to produce the powerful
magnetic field needed to capture such detailed diagnostic images. In order to
use that much energy, the MRI system must be superconductive, which requires
the wires in the MRI magnet to operate at a temperature of near zero degrees.
To maintain such a cold temperature, liquid helium is used.
A History of Helium in MRI Use
Oxford Instruments, founded in 1959,
invented the world's first superconducting magnet. This led directly to the
development of the world's first MRI system. Oxford Instruments Healthcare,
part of the service division of Oxford Instruments, is now a leading ISO 13485
certified organization offering a comprehensive range of refurbished equipment,
maintenance service and quality parts for MRI.
MRIs are a relatively new
technology. In addition to Oxford Instruments, there are several individuals
who are credited with helping to advance MRI technology, including Paul C.
Lauterbur, who won the Nobel Prize in Physiology of Medicine for his work that
contributed to the use of MRI in medical research and diagnostics, and Raymond
Damadian, who was the first person to perform a full body scan to diagnose
cancer back in 1977. It wasn't until 1980 that the first commercial MRI
system was manufactured.
These first commercial MRI systems
were built with two cryogen chambers, one containing liquid helium, the other
liquid nitrogen. However, these MRI systems were not very efficient--the liquid
helium had to be refilled every month to maintain the proper levels and the
liquid nitrogen had to be refilled every week. By the 1990s, new MRI machines
were introduced that only used liquid helium. By 2000, more efficient models
became available in which the liquid helium only needed to be replaced every
two to three months.
These days there are zero boil-off magnets available, meaning some of the newer MRI systems do not require regular liquid helium refills. However, a helium loss can still occur. The failure of a part in the cooling system, such as the coldhead, could result in a loss of liquid helium, requiring a refill.
Why Do MRI Systems Need Helium?
MRI systems use superconducting magnets to capture diagnostic images. In order for the magnet to be superconductive, it needs to be kept at a temperature near zero. This is done with the use of liquid helium, which continuously soaks the wires to keep them cold. Liquid helium has a temperature of -452.11 degrees Fahrenheit, making it the most effective liquid to keep the magnet of an MRI at the proper temperature.
Other liquids boil off much more quickly, so liquid helium is more effective due to its cold nature. Even before zero boil-off magnets were designed, most MRI machines could go two to three months without having to refill their liquid helium.
Why is Helium So Expensive?
Although liquid helium is the
perfect substance for keeping a superconductive magnet cool, it's extremely
expensive. This is because helium is a non-renewable resource. Once helium is
released as a gas into the atmosphere it will eventually escape earth due to
how light it is. Most helium found on earth today is created by the natural
radioactive decay of thorium, uranium, and other heavy radioactive
elements.
Helium supplies have been quickly
dwindling, which has led to calls for banning it for leisure use--such as in
balloons (which use a very minuscule amount of helium compared to what is
needed for an MRI). Fortunately, a new reserve of helium was found under the
Great Rift Valley in Tanzania a couple of years ago containing enough helium to
fill 1.2 million MRI systems. It's believed that this source of helium was
released from rocks as a result of the heat caused by the volcanic activity in
the area.
While this discovery helps to allay fears that the planet's helium resources are about to run out--and gives hope that there may be other undiscovered deposits of helium out there--helium still remains a scarce nonrenewable resource that will run out eventually. On top of that, the average MRI system requires around 2,000 liters of helium to operate. It's because of these factors that liquid helium is so expensive and why MRI systems are costly to purchase and maintain.
What About The Future Of Helium?
Helium is a scarce, non-renewable resource, which means that the cost of helium is quite high. Unfortunately, it's needed by the science community to both operate new technology and to do important research. The price of helium tends to fluctuate wildly due to an unstable market. All of these factors make the future of helium incredibly difficult to predict. Currently, there are new helium plants being built in Qatar and Russia. You can learn more about these helium sources here.
An Unstable Market
The demand for liquid helium and its scarcity aren't the only factors contributing to the volatile prices of liquid helium. In fact, one of the main reasons for its erratic pricing (which has led to many scientific research projects being canceled) can be traced back to 1996, when Congress passed a law to gradually shut down and sell off its massive helium reserve in Amarillo, TX. The Federal Helium Reserve contained a billion cubic meters of helium inside of a huge cavern. By passing this law, Congress depressed prices, throwing the market into chaos and discouraging competition. An attempt to rectify this mistake was made in 2013, but it only ended up discouraging competition in even more ways.
An Increased Demand
Helium becomes a liquid at the
lowest temperature of any known element in the universe, meaning it is
invaluable to scientific research. For example, physicists can use liquid
helium to power dilution refrigerators, allowing them to cool their samples
down to a fraction of a degree above absolute zero. This, in turn, gives them
the opportunity to measure extremely small quantum effects that would have been
obscured at higher temperatures. Liquid helium is also used to minimize the
fluctuations in telescopes, allowing scientists to observe the universe more
accurately.
Besides all of its uses in scientific research, helium is also used as an inert gas for welding, as a way to quickly cool down components and control heat transfer in the semiconductor industry, as a way to detect leaks to test containers that will be subjected to high pressure, and, of course, to cool down superconducting magnets in MRI systems. As technology and science continue to advance, the demand for helium will likely only continue to grow.
Will MRI Machines Need Helium in The Future?
MRI technology has advanced quite a
bit since the first commercial machines were built in the 1980s. They no longer
waste nearly as much helium as they once did. In fact, new zero boil-off
magnets help eliminate the need for regular refills, and the risk of helium
leaks during quenches has been greatly reduced as well.
Newer systems also no longer need as
much liquid helium to keep their superconducting magnets cool as they once did.
Nevertheless, MRI systems still rely on helium--and the need for more MRI systems,
both to replace outdated systems and to meet the demands of an increasing
population, will only grow.
However, we can be optimistic that
one day MRI technology will advance to the point where helium will no longer be
needed in the operation of an MRI. Considering the massive leaps that MRI
systems have made in the short period of time that they have been in use, it is
feasible that a non-helium MRI machine isn't far from being developed. A couple
products that may provide alternatives in the near future are GE’s “freelium” technology, and Philips Ingenia magnet with “Blueseal”
technology.
Rex
Lindsey |
|
