Superconducting Split Ring Resonator Detuning for MRI Reception
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Solution Overview
Problem
Superconducting split ring resonators used in MRI systems face challenges during transmission due to increased current intensity, leading to loss of superconducting properties and heat generation, making them inefficient for both transmission and reception roles.
Innovation Solution
A specially designed split ring resonator with tapered conductors that break down superconductivity at specific current levels, allowing for detuning during transmission and re-establishing superconductivity for reception, eliminating the need for additional detuning circuits and maintaining cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a superconducting split ring resonator is used as both transmission and reception antenna, then the antenna quality increases with distance from the object, but the superconducting material loses its superconducting property with increasing current intensity during transmission
Solution Approach 1:
The antenna system is segmented into two separate components: a superconducting split ring resonator for reception and a conventional coil for transmission. This segmentation allows each component to be optimized for its specific function, with the superconducting material used only where low-loss reception is critical, away from the high-current transmission zone.
Solution Approach 2:
The superconducting split ring resonator is extracted from the high-current transmission environment and positioned in the direct vicinity of the object to be examined. This extraction protects the superconducting material from the detrimental effects of high current intensity while maintaining its proximity-to-object advantage for high-quality signal reception.
2Power
If the SRR antenna is used for transmission, then the transmission field can be built up, but heat is generated making it more difficult to maintain cooling in the cryostat
Solution Approach 1:
The superconducting SRR antenna is extracted from the transmission function and dedicated solely to reception. This eliminates heat generation in the cryostat during transmission, as the superconducting material is not subjected to high current intensities that would generate heat and challenge cooling maintenance.
Solution Approach 2:
A conventional coil acts as an intermediary for transmission functions. This conventional coil handles the high-power transmission tasks that would otherwise require the superconducting SRR, thereby protecting the superconducting material from heat-generating conditions while maintaining system transmission capability.
3Reliability
If the SRR antenna is merely designed as reception antenna and body coil is used for transmission, then the SRR antenna can be detuned during transmission, but an additional detuning circuit is required
Solution Approach 1:
The superconducting SRR antenna is extracted from the transmission environment and positioned close to the object, where it functions solely as a reception antenna. This spatial extraction eliminates the need for complex detuning circuits during transmission, as the SRR operates independently in a low-interference zone.
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 efficient MRI signal transmission and reception by automatically detuning during transmission and re-establishing superconductivity for high-quality reception, improving antenna performance and reducing heat generation.
Implementation Method 1
The main magnetic field brings about an alignment of the magnetic moments of the nuclei situated in the body to be examined, wherein, in particular, hydrogen nuclei or protons are used for imaging, while the alternating magnetic fields are used as transmission signals or excitation pulses for deflecting or exciting the magnetic moments from such a rest position. This results in a precession movement of the nuclei or the magnetic moments, which in turn brings about an induction of an electrical signal in a receiver coil
Implementation Method 2
use is made of a special circuit in an associated, inductively coupled copper coil that, in the case of transmission by the body coil, causes the SRR antenna to be detuned. The use of, in particular, superconducting split ring resonators that may be arranged in a cryostat cooled, e.g., by nitrogen, was found to be advantageous. In such a superconducting split ring resonator, conductors forming the antenna include a superconducting material
Implementation Method 3
A specially designed split ring resonator with tapered conductors that break down superconductivity at specific current levels, allowing for detuning during transmission and re-establishing superconductivity for reception
Data Source
AI summary
An arrangement includes a superconducting split ring resonator, a cryostat, and a copper coil. The resonator is arranged in the cryostat and includes at least one ring-shaped conductor made of a superconducting material and including an opening and a taper. The copper coil may be used to transmit a MRI excitation signal. This signal causes a current to be induced in the conductor that leads to the breakdown of the superconductivity. The conductor is detuned and therefore no longer develops an interfering effect. It is possible for the effect of the breakdown of superconductivity to be used for detuning in a targeted manner. After the transmission is complete, the conductor returns into the superconducting state and acts as a superconducting reception antenna for the MRI measurement signal. The copper coil is inductively coupled to the conductor and configured to read out the signal induced in the conductor.