Mo-Re Intravascular Members With Low MRI Susceptibility
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Solution Overview
Problem
Existing implantable medical devices face challenges in maintaining advantageous mechanical properties while reducing magnetic susceptibility, particularly when inserted into lumens with small diameters.
Innovation Solution
The use of molybdenum-rhenium (Mo-Re) alloy, optionally alloyed with Ta, Ir, Rh, or Ru, and further enhanced with Hf to reduce magnetic susceptibility, is employed to form the elongate members of intravascular devices, providing improved mechanical properties such as higher Young's modulus and ultimate tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cobalt-chromium (Co-Cr) alloy is used to form stents, then radial force and mechanical strength are improved, but magnetic susceptibility increases causing MRI artifacts and radiopacity decreases
Solution Approach 1:
The patent changes the material composition parameters by using platinum-tungsten alloy with tungsten content of 8-15%, specifically optimizing the ratio to achieve both high radial force and low magnetic susceptibility. This parameter optimization resolves the contradiction between mechanical strength and MRI compatibility.
Solution Approach 2:
The patent employs a composite platinum-tungsten alloy material that combines the advantages of both metals: platinum provides low magnetic susceptibility and high radiopacity, while tungsten contributes high radial force and mechanical strength. This composite material approach simultaneously addresses both requirements.
2Object-affected harmful factors
If platinum-tungsten (Pt-W) alloy with 8% tungsten is used, then magnetic susceptibility is reduced and radiopacity is improved, but radial expansion force becomes insufficient
Solution Approach 1:
The patent increases the tungsten content from the conventional 8% to a range of 8-15%, with specific embodiments at 10%, 12%, and 15%. This parameter change enhances the radial expansion force while maintaining acceptable magnetic susceptibility and radiopacity properties.
3Strength
If tungsten content in platinum alloy is increased to enhance mechanical strength, then handling and manufacturability are improved, but brittleness increases compromising performance
Solution Approach 1:
The patent identifies and applies an optimal parameter range for tungsten content (8-15%). Within this range, the alloy achieves enhanced mechanical strength and manufacturability while avoiding excessive brittleness. The specific embodiments at 10%, 12%, and 15% demonstrate the optimal balance point.
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
This alloy allows for the production of smaller, more robust intravascular devices with better shape retention and delivery capabilities through small catheters, minimizing material brittleness and MRI artifacts.
Implementation Method 1
The use of molybdenum-rhenium (Mo-Re) alloy, optionally alloyed with Ta, Ir, Rh, or Ru, and further enhanced with Hf to reduce magnetic susceptibility, is employed to form the elongate members of intravascular devices, providing improved mechanical properties such as higher Young's modulus and ultimate tensile strength
Implementation Method 2
further enhanced with Hf to reduce magnetic susceptibility
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A
AI summary
An implantable medical device (10, 100, 200, 400, 500), comprising an elongate member (20, 250) made from a material comprising an alloy containing rhenium in combination with zirconium and/or hafnium.