Magnetic resonance imaging (MRI) is widely used for imaging soft tissue in clinical and pre-clinical medicine for many reasons. Not only does MRI provide excellent contrast between various tissue types, but it does not require the use of ionizing radiation such as x-rays (CT Scanners) or gamma-rays (PET scanners). The theory of MRI is based on the interaction of subatomic particles with magnetic fields in a process called nuclear magnetic resonance (NMR), which describes how atomic nuclei with a quantum property called ‘spin’ process in a magnetic field the same way that a gyroscope or a spinning top processes in the earth’s gravitational field (if you’re not familiar with gyroscope precession, watch this video).
For this reason, the primary component of an MRI scanner is a very powerful magnet, which generates a very strong magnetic field (typically 1.5-3 Tesla, or about 3,000 times the strength of the Earth’s magnetic field) where the object is being imaged, and also in the region surrounding the magnet.
Although completely safe for humans and other animals to experience, this powerful magnetic field can be dangerous for other reasons: attractive magnetic forces! If ferromagnetic materials are brought within range of an MRI magnetic field, they can experience massive forces and torques which can accelerate the magnetic objects very rapidly toward the source of the magnetic field (see example picture).
Although pictures like these can be somewhat humorous, the effects of metallic objects flying around rooms can be very dangerous to patients and radiologists alike.
For this reason, there is a relative niche market for both common and uncommon tools which are compatible with MRI suites in hospitals and research centers.
For instance, if something malfunctions on the MRI scanner or even in the same room as the scanner, an engineer must be allowed to enter the MRI suite with the correct tools to fix the issue; tools such as screwdrivers, wrenches, etc. However, most common tools are made of iron, steel, and other metals. Tools made from strong ferromagnetic metals could be immediately be wrenched from the toolbox or pulled from the grip of the engineer and become fastened to the wall of the scanner, possibly damaging the scanner or something in its path. Therefore, the MRI engineer’s tools must be made of materials which do not experience the magnetic forces such as aluminum, copper, or titanium.
Similarly, gurneys, wheelchairs, supports and other medical equipment used in the MRI environment must be made of materials that do not interact with the primary magnetic field of the MRI scanner.
Another example of the necessity of MRI compatibility is in medical implants for two different reasons. Of primary importance is that an implant which experiences the pull of the magnetic field would be extremely dangerous for obvious reasons. Secondarily, materials which have even a small response to the MRI magnet can disrupt the MRI magnetic field, causing distortions in the acquired images. Ideal implant materials would allow accurate imaging in their very near vicinity.
Finally, there are advanced medical procedures where a surgical team actually operates on a person while an MRI scanner acquires images. This is called “MRI-guided surgery”, “interventional MRI”, or “intraoperative MRI”. In these cases, the anesthesiology equipment, surgical tools, instruments, clips, clamps, and other supporting equipment such as sensors and monitors must be safely non-ferromagnetic in nature.
Liquidmetal alloys are not only non-ferrous, but they also exhibit higher hardness and strength than titanium, which may be beneficial for certain surgical tool applications, and even more certain benefits as structural components for other mechanical MRI suite accessories. Liquidmetal also has the additional benefit of being highly resistant to corrosion and pitting since it is a technically a glass and retains some sterilization properties of glassware.
Even more exciting is the process used to generate complex and precision Liquidmetal parts. The manufacturing method does not involve the traditional machining processes associated with most titanium parts (milling, turning, drilling, etc.). Instead, Liquidmetal alloys are formed into final complex parts in a process similar to plastics injection molding where little or no secondary machining steps are necessary.