Au-Pt Alloy Magnetic Susceptibility Matching for MRI Artifacts
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Solution Overview
Problem
Conventional medical alloys used in MRI environments suffer from artifacts due to significant differences in magnetic susceptibility, which hinder accurate surgery and diagnosis, as they are not adequately designed to match the magnetic susceptibility of biopsy tissue.
Innovation Solution
An Au—Pt alloy with a Pt concentration of 24 to 34 mass % is developed, where a Pt-rich phase is precipitated within an Au matrix to adjust the magnetic susceptibility to match that of tissue, achieving a range of −13 to −5 ppm, thus minimizing artifacts in MRI environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional medical alloys (stainless steel, Co-Cr alloy, Pt-W alloy) are used, then biocompatibility and corrosion resistance are achieved, but magnetic susceptibility difference with biopsy tissue causes artifacts in MRI images
Solution Approach 1:
The invention changes the magnetic susceptibility parameter of the alloy by adjusting the Pt concentration to 24-34 mass %. This specific composition range achieves magnetic susceptibility of -13 to -5 ppm, which matches the magnetic susceptibility of biopsy tissue (-9 ppm), thereby eliminating artifacts in MRI images while maintaining biocompatibility and corrosion resistance
Solution Approach 2:
The invention uses an Au-Pt composite alloy system where Au provides the base diamagnetic properties (magnetic susceptibility of -34 ppm) and Pt provides positive magnetic susceptibility (+279 ppm). By combining these two metals in specific proportions, the alloy achieves magnetic susceptibility matching with biopsy tissue, resolving the contradiction between conventional alloy performance and MRI compatibility
2Object-affected harmful factors
If alloy composition is adjusted to reduce magnetic susceptibility, then artifact suppression is improved, but magnetic susceptibility criterion becomes obscure and artifact-free performance is not achieved
Solution Approach 1:
The invention establishes a precise magnetic susceptibility control range of -13 to -5 ppm, which is ±4 ppm from the biopsy tissue value of -9 ppm. This quantified parameter range provides a clear manufacturing criterion that ensures artifact-free performance, resolving the previous obscurity in magnetic susceptibility specifications
Solution Approach 2:
The invention creates a Pt-rich phase with higher Pt concentration distributed within the Au matrix. This local concentration variation of Pt (24-34 mass %) creates regions with different magnetic susceptibility contributions, allowing precise tuning of the overall alloy magnetic susceptibility to match biopsy tissue while maintaining structural integrity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Au—Pt alloy ensures biocompatibility, corrosion resistance, and suitable magnetic susceptibility, making it suitable for medical appliances like embolization coils, suppressing artifacts and ensuring accurate imaging in MRI environments.
Implementation Method 1
the magnetic susceptibility (volume magnetic susceptibility) of the material is approximate to that of a biopsy tissue. Since the magnetic susceptibility of the biopsy tissue results from water as a main constituent, and the magnetic susceptibility of the water is −9 ppm (−9×10−6), the magnetic susceptibility of the biopsy tissue exhibits a slight diamagnetism
Data Source
AI summary
The present invention provides an alloy for medical use including an Au—Pt alloy, in which the Au—Pt alloy has a Pt concentration of 24 mass % or more and less than 34 mass % with the balance being Au, and has at least a material structure in which a Pt-rich phase having a Pt concentration higher than that of an α-phase is distributed in an α-phase matrix, the Pt-rich phase has a Pt concentration that is 1.2 to 3.8 times the Pt concentration of the α-phase, and the Pt-rich phase has an area ratio of 1 to 22% in any cross-section. This alloy is an artifact-free alloy material that exhibits excellent compatibility with a magnetic field environment such as an MRI and has magnetic susceptibility of ±4 ppm with respect to magnetic susceptibility of water.