The biocompatibility, magnetic susceptibility and mechanical properties of commercial pure zirconium metals and zirconium alloys are discussed, and their application prospects as nuclear magnetic resonance compatible implant materials are also discussed.
Zirconium is a non-toxic metal that is biocompatible. Compared with other biocompatible metal materials currently used, in addition to good mechanical properties and excellent corrosion resistance, zirconium-based metal materials also have two unique properties in orthopedic and dental implant applications: It is an internal bone-like intermediate layer formed in the human environment, and the second is a very low magnetic susceptibility. The second characteristic is particularly important for magnetic resonance imaging (MRI).
Because the quality and speed of MRI imaging depend on the magnetic field strength, it is more suitable to increase the magnetic field strength from the current 1.0-1.5T to 3.0-7.0T. However, current metal implant materials such as stainless steel, cobalt-chromium alloys (with high magnetic susceptibility), and titanium alloys can be magnetized under 3.0-7.0T magnetic field conditions. As a result, the implanted material in the body can generate heat, loosen and dislocate the implant, and unexplained pseudo-images can appear in nuclear magnetic resonance.
The magnetic susceptibility of human cortical bone is about -8.9 × 10-6. In general, the magnetic susceptibility of implant materials suitable for nuclear magnetic resonance is expected to be less than 10 × 10-6. Among biocompatible and tough metals, metal zirconium has a very low magnetic susceptibility, but is still much higher than the level of nuclear magnetic resonance compatibility. Preliminary research shows that by adding carefully selected elements to metal zirconium, that is, "alloying", the magnetic susceptibility of metal zirconium can be reduced to a range compatible with nuclear magnetic resonance, and the mechanical properties of the synthesized zirconium alloy can be improved. More suitable as a human implant material. Researchers at the Royal Melbourne Institute of Technology (RMIT) in Australia are studying the use of zirconium alloys with nuclear magnetic resonance compatibility in orthopedics. The research team recently published an article in the journal Advanced Engineering Materials, a rich and insightful review article on the biocompatibility, magnetic susceptibility, and mechanical properties of commercial pure zirconium and zirconium alloys. In addition, the design principles for developing new zirconium alloys for future 3.0-7.0T NMR systems are also discussed.