Superconducting Bulk Material MRI Apparatus for Compact High-Field Design
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Solution Overview
Problem
Current MRI apparatuses, particularly dedicated ones, face challenges in reducing size and weight while maintaining or increasing the strength of the static magnetic field, due to limitations in conventional magnetic materials and cooling requirements, and are susceptible to external noise fields due to low signal intensity.
Innovation Solution
The use of permanently magnetized superconducting bulk material, specifically medium critical temperature materials like MgB2, combined with temperature control and magnetization means, to generate a strong and homogeneous magnetic field within a compact MRI apparatus, utilizing a magnetic structure with two parallel magnetic poles and removable magnetization units for efficient cooling and magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional permanent magnets are used to generate static magnetic field, then the MRI apparatus can be made smaller and easier to install, but the size and weight reduction is limited due to the large amount of magnetized material required
Solution Approach 1:
The patent changes the material parameter from conventional permanent magnets to superconducting bulk material, which can generate stronger magnetic fields with less material. The superconducting material's ability to carry high current densities without resistance enables higher magnetic field strength per unit volume, resolving the contradiction between compact size and magnetic field generation capability
Solution Approach 2:
The patent uses composite construction combining superconducting bulk material with ferromagnetic materials (such as ferrite or iron) to create a hybrid magnetic system. This composite approach leverages the high field strength of superconductors and the flux concentration properties of ferromagnetic materials, achieving stronger fields with reduced overall material volume and weight
2Volume of moving object
If medium-low strength static magnetic field is used, then the apparatus size can be reduced, but the apparatus becomes more susceptible to external noise fields due to low signal intensity
Solution Approach 1:
The patent changes the magnetic field strength parameter by using superconducting bulk material that can generate high-strength fields in a compact configuration. The high critical current density of superconductors enables strong magnetic fields without increasing apparatus size, thereby maintaining high signal intensity and reducing noise susceptibility while keeping the apparatus compact
Solution Approach 2:
The patent implements preliminary cooling of the superconducting material below its critical temperature to establish the superconducting state before operation. This preliminary action enables the material to carry high currents without resistance, generating strong magnetic fields that overcome external noise interference while maintaining compact dimensions
3Power
If superconducting coils are used to generate high magnetic field, then strong magnetic field can be achieved, but complex and expensive cooling systems are required
Solution Approach 1:
The patent extracts the cooling requirement from the operational phase by using bulk superconducting material that can maintain its superconducting state with simpler cooling compared to continuous coils. The bulk material's inherent properties allow for more straightforward thermal management, reducing cooling system complexity while maintaining high magnetic field strength
Solution Approach 2:
The superconducting bulk material generates its own magnetic field through persistent currents circulating within the material itself, eliminating the need for external power supplies and complex control systems required by conventional electromagnets. This self-sustaining field generation simplifies the overall system architecture and reduces operational complexity
4Volume of moving object
If dedicated MRI apparatus for specific body parts is designed, then the receiving cavity size can be reduced, but the magnetic structure still requires relatively large amount of magnetized material
Solution Approach 1:
The patent changes the magnetic material parameter to superconducting bulk material, which has superior magnetic moment per unit volume compared to conventional permanent magnets. This parameter change allows achieving the required magnetic field strength for dedicated imaging with significantly reduced material quantity, resolving the contradiction between cavity size reduction and magnetized material requirements
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 approach allows for a significant reduction in the size and weight of MRI apparatuses while achieving a stronger and more homogeneous static magnetic field, reducing susceptibility to external noise and eliminating the need for complex cooling systems, thereby enhancing imaging capabilities.
Implementation Method 1
magnets made of superconducting bulk material are known, wherein magnetization currents are trapped and firmly frozen. The elements made of said material when kept below the critical temperature maintain the magnetization
Implementation Method 2
magnetization currents are trapped and firmly frozen. The elements made of said material when kept below the critical temperature maintain the magnetization and behave like conventional permanent magnets
Data Source
AI summary
An MRI apparatus including a magnetic structure defining a cavity for receiving a body under examination or a part thereof, a mechanism for generating a magnetic field inside the cavity, a mechanism for causing the body under examination or a part thereof to emit nuclear magnetic resonance signals, and a mechanism for receiving the nuclear magnetic resonance signals. The mechanism for generating the magnetic field includes one or more elements made of permanently magnetized material of the so-called superconducting bulk material type and, in combination therewith, a mechanism for keeping the magnetization condition of the superconducting bulk material which includes mechanisms for maintaining the temperature of the permanently magnetized material below the critical temperature thereof and for restoring the magnetization of the superconducting bulk material upon a complete or partial demagnetization.