Au-Pt Embolization Coil Composition for MRI Artifact Reduction
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Solution Overview
Problem
Embolization coils used in treating cerebral aneurysms face challenges with morphological stability and artifact occurrence in magnetic resonance imaging (MRI) environments due to differences in magnetic susceptibility between metal materials and biological tissues, which can hinder accurate diagnoses and surgeries.
Innovation Solution
An embolization coil made from an Au—Pt alloy with a specific composition and thermomechanical treatment to achieve optimal morphological stability and magnetic susceptibility, minimizing artifact occurrence in MRI environments while maintaining biocompatibility and anti-corrosion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional metal materials (Pt, stainless steel, Ti alloy) are used for embolization coils, then biocompatibility and anti-corrosion properties are ensured, but magnetic susceptibility difference with biological tissue causes artifacts in MRI images
Solution Approach 1:
The patent employs a composite material approach by creating an Au-Pt alloy system that combines gold (diamagnetic, −34 ppm) and platinum (paramagnetic, +279 ppm) in specific proportions. This composite alloy structure allows tuning of the overall magnetic susceptibility to match biological tissue (−9 ppm), thereby minimizing MRI artifacts while maintaining the biocompatibility and anti-corrosion properties of both constituent metals.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the Pt concentration within 24-34 mass% range and adjusting the phase distribution (α phase and Pt-rich phase) to achieve a bulk susceptibility of −13 ppm or more and −5 ppm or less. This parameter optimization enables the alloy to match the magnetic susceptibility of water (−9 ppm) while preserving essential medical device requirements.
2Object-affected harmful factors
If Au-Pt alloy is used to reduce magnetic susceptibility difference, then artifact-free MRI performance is achieved, but morphological stability of the coil structure becomes insufficient
Solution Approach 1:
The patent utilizes phase transition principles by controlling the formation and distribution of different phases (α phase and Pt-rich phase) within the Au-Pt alloy. The Pt-rich phase, with higher Pt concentration (1.2 to 3.8 times that of α phase), provides magnetic susceptibility adjustment, while the phase distribution control ensures morphological stability. The phase structure is optimized so that Pt-rich phase occupies 1-22% area ratio on arbitrary cross-section, achieving both artifact-free MRI performance and structural stability.
3Object-affected harmful factors
If Pt concentration is increased to adjust magnetic susceptibility, then magnetic properties improve, but material cost and processing difficulty increase
Solution Approach 1:
The patent optimizes the Pt concentration parameter within a specific range (24-34 mass%) to achieve the desired magnetic susceptibility match with biological tissue. This parameter optimization balances multiple factors: sufficient Pt content to adjust magnetic properties, while limiting it to maintain manufacturability and control processing difficulty. The precise parameter control enables artifact-free MRI performance without excessive cost or processing complexity.
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 embolization coil exhibits improved morphological stability and artifact-free performance in MRI environments, ensuring accurate medical imaging and effective treatment of cerebral aneurysms with enhanced biocompatibility and anti-corrosion properties.
Implementation Method 1
A material property to consider in investigating artifact problems in magnetic field environments is magnetic susceptibility (bulk susceptibility). The Au—Pt alloy has a predetermined metal structure and is made of Pt of 24 mass % or more and less than 34 mass %, with the balance being Au. This Au—Pt alloy is a metal material obtained by: alloying Au, which is a diamagnetic metal (magnetic susceptibility: −34 ppm), and Pt (magnetic susceptibility: +279 ppm); and distributing predetermined metal phases (α phase and Pt-rich phase) in the alloy in a desired manner, thereby making the magnetic susceptibility of the alloy as a whole approximate to the magnetic susceptibility of water.
Implementation Method 2
the wire material has such a material structure that a Pt-rich phase of an Au—Pt alloy having a Pt concentration of 1.2 to 3.8 times a Pt concentration of an α phase is distributed in an α phase matrix. The wire material has a bulk susceptibility of −13 ppm or more and −5 ppm or less. In a material structure of a transverse cross-section of the wire material, an average value of two or more average crystal particle diameters measured by a linear intercept method is 0.20 μm or more and 0.35 μm or less.
Data Source
AI summary
The present invention is an embolization coil having an optimum morphological stability. The embolization coil includes a wire material made of an Au—Pt alloy. The wire material constituting the embolization coil has such a composition that a Pt concentration is 24 mass % or more and less than 34 mass %, with the balance being Au. The wire material has such a material structure that a Pt-rich phase of an Au—Pt alloy having a Pt concentration of 1.2 to 3.8 times a Pt concentration of an α phase is distributed in an α phase matrix. The wire material has a bulk susceptibility of −13 ppm or more and −5 ppm or less. In a material structure of a transverse cross-section of the wire material, an average value of two or more average crystal particle diameters measured by a linear intercept method is 0.20 μm or more and 0.35 μm or less.