Plasma Gradient Coils for MRI Noise Reduction
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Solution Overview
Problem
MRI machines suffer from acoustic noise due to solid gradient coils and RF interference from metal RF elements, which affect image quality and patient comfort, and combined MRI/PET devices face interference from metal components blocking gamma radiation.
Innovation Solution
Implementing plasma elements as gradient coils and RF transmitting/receiving elements that are non-metallic, reducing acoustic noise and interference by using plasma conductors that are not affected by magnetic fields and allowing multiple frequency operations without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solid metal gradient coils are used, then the MRI device can generate strong magnetic fields, but acoustic noise is produced due to Lorentz force vibrations
Solution Approach 1:
The patent replaces solid metal gradient coils with plasma gradient coils, substituting a mechanical system (solid conductors subject to Lorentz force vibrations) with a plasma-based system. The plasma, being a non-solid state, does not experience mechanical vibrations from Lorentz forces, thereby eliminating acoustic noise while maintaining magnetic field generation capability through controlled plasma current.
2Use of energy by moving object
If metal RF transmitting and receiving elements are used, then RF energy can be transmitted and received, but RF interference and electromagnetic interference are introduced
Solution Approach 1:
The patent replaces metal RF elements with plasma RF elements, substituting conductive metal structures with plasma-based structures. Plasma, being an ionized gas rather than a solid conductor, interacts differently with electromagnetic fields, reducing unwanted RF interference and electromagnetic interference while maintaining the ability to transmit and receive RF energy for MRI imaging.
3Adaptability or versatility
If metal RF elements are used for multiple frequencies, then different nuclei can be excited, but the elements must be separated laterally causing device complexity
Solution Approach 1:
The patent implements plasma RF elements that can operate across multiple frequencies without requiring separate physical elements for each frequency. The plasma-based design allows a single RF element to be tuned to different frequencies by adjusting plasma parameters, enabling excitation of different nuclei (such as hydrogen, carbon, and phosphorus) without the need for lateral separation of multiple metal elements, thus reducing device 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
Plasma-based MRI machines reduce acoustic noise, improve image quality, and enable simultaneous scanning of multiple body parts, while plasma RF elements minimize interference with PET systems, enhancing diagnostic accuracy and patient experience.
Implementation Method 1
The gradient coils generate strong magnetic fields that are switched. The switched field gradients cause a change in the Lorentz force experienced by the gradient coils.
Implementation Method 2
The switched field gradients cause a change in the Lorentz force experienced by the gradient coils. The Lorentz force produces minute expansions and contractions of the coil itself, which because of their solid construction, results in vibration that produces acoustic noise.
Implementation Method 3
Radio frequency (RF) energy is transmitted into the body. Pulses of RF energy excites certain atomic nuclei in the body. The excited nuclei emit RF energy, which is received by the MRI device.
Implementation Method 4
the elements are subject to thermal noise generated by the metal conductor forming the element. The thermal noise is often a significant factor considering the low level of emitted RF energy by the excited nuclei.
Implementation Method 5
Implementing plasma elements as gradient coils and RF transmitting/receiving elements that are non-metallic, reducing acoustic noise and interference by using plasma conductors that are not affected by magnetic fields
Data Source
AI summary
Apparatus for a nuclear resonance imaging (MRI) machine (100) that includes plasma elements (104, 106, 108). The MRI machine (100) includes gradient coils (104) that generate time-dependent gradient magnetic fields, transmitting elements (106) that excite target molecules (120) with RF energy (122), and receiving elements (108) responsive to RF energy (124) emitted by the excited molecules (120). The gradient coils (104) include plasma conductors (710) in which the plasma (716) is ignited by an exciter (208). The plasma conductors (710) are electrically connected to a gradient amplifier (206) that outputs a signal to produce the gradient fields. The transmitting elements (106) are plasma devices (710) configured to emit RF energy (122). The receiving elements (108) are plasma devices (710) responsive to emitted RF energy (124). An RF exciter (218) selectively and alternatingly ignites said plasma devices (710) to avoid coupling and interference between them.