Superconducting Static Magnetic Field Coil for MRI Material Detection
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Solution Overview
Problem
Existing magnetic resonance imaging (MRI) techniques struggle to accurately detect magnetic materials in the imaging space and its vicinity due to small changes in voltage caused by the magnetic materials, and complex system configurations.
Innovation Solution
A magnetic resonance imaging apparatus equipped with a superconducting static magnetic field generation coil with higher inductance than the high-frequency and gradient magnetic field coils, allowing for accurate detection of magnetic materials by measuring voltage changes with a current less than the rated current, and a simplified configuration without the need for additional detection devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If gradient magnetic field coil or high-frequency coil is used for magnetic material detection, then the detection can be performed using existing coils, but the inductance is small and the voltage change caused by magnetic material is small, resulting in inaccurate detection
Solution Approach 1:
The patent changes the key parameter of inductance by selecting a static magnetic field generation coil with significantly larger inductance compared to gradient or high-frequency coils. This parameter change amplifies the voltage response to magnetic materials, enabling accurate detection. The patent specifies using a superconducting coil with inductance of several henries to tens of henries, whereas conventional coils have inductance in the millihenry range.
2Measurement precision
If a separate magnetic field generation coil is used for detection, then the detection sensitivity can be improved, but the system configuration becomes complicated and large
Solution Approach 1:
The patent makes the static magnetic field generation coil serve dual functions: generating the static magnetic field for MRI operation and detecting magnetic materials through voltage measurement. This multi-functionality eliminates the need for separate detection devices, simplifying the system configuration while maintaining high detection accuracy.
Solution Approach 2:
The patent merges the magnetic material detection function into the existing static magnetic field generation system by measuring voltage across the coil terminals. This combines the detection capability with the magnetic field generation apparatus, avoiding additional complex detection systems while achieving accurate magnetic material detection.
3Force
If the static magnetic field generation coil is energized with rated current, then the magnetic field strength is sufficient for imaging, but the voltage measurement may be affected by saturation or excessive signal
Solution Approach 1:
The patent applies partial energization by using a current smaller than the rated current for detection purposes. This partial action is sufficient to generate detectable voltage signals from magnetic materials while avoiding saturation effects and excessive signals that would compromise measurement accuracy. The detected voltage change is proportional to the inductance change, which remains detectable at reduced current levels.
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
Enables accurate detection of magnetic materials in the imaging space and its vicinity with a simple configuration, preventing image disturbances and allowing for timely responses to detected materials.
Implementation Method 1
a static magnetic field generation coil that has an inductance larger than an inductance of the high-frequency coil and an inductance of the gradient magnetic field generation coil, the static magnetic field generation coil being a superconducting coil
Implementation Method 2
a voltage measurement unit that measures a voltage between current lead terminals of the static magnetic field generation coil; and a magnetic material detection unit that detects a magnetic material existing in an imaging space of the magnetic resonance imaging apparatus and a magnetic material existing in a vicinity of the imaging space based on a first voltage that is a voltage measured in a state in which the static magnetic field generation coil is energized
Implementation Method 3
the static magnetic field generation coil being a superconducting coil
Data Source
AI summary
The magnetic resonance imaging apparatus includes: a high-frequency coil; a gradient magnetic field generation coil; a static magnetic field generation coil which is a superconducting coil having an inductance larger than an inductance of the high-frequency coil and an inductance of the gradient magnetic field generation coil; an energization controller that energizes the static magnetic field generation coil; a voltage measurement unit that measures a voltage between current lead terminals of the static magnetic field generation coil; and a magnetic material detection unit that detects a magnetic material existing in an imaging space of the magnetic resonance imaging apparatus and a magnetic material existing in a vicinity of the imaging space based on a first voltage that is a voltage measured in a state where the static magnetic field generation coil is energized with a first current less than a rated current in capturing the magnetic resonance image.