Switchable RF Coil with Non-Parallel Rungs for MRI Homogeneity
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Solution Overview
Problem
High-field magnetic resonance imaging systems face challenges in B1 field homogeneity due to wave propagation effects, with existing RF coils being suboptimal for both transmission and reception modes, leading to poor image quality.
Innovation Solution
The design of RF coil devices with non-parallel rungs and switchable RF shield devices, optimized for different modes of operation, allows for separate optimization of RF fields for transmission and reception, improving B1 field homogeneity and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a standard birdcage coil design with rungs extending in the longitudinal direction is used, then coil symmetry is maintained, but B1 field homogeneity is poor due to wave propagation effects in high-field MRI
Solution Approach 1:
The patent applies asymmetry by extending the rung conductors in a direction that is not linear compared to the longitudinal direction of the RF coil. This non-linear extension breaks the standard birdcage coil symmetry but improves B1 field homogeneity in high-field MRI by optimizing the RF field distribution pattern, thereby resolving the contradiction between maintaining symmetry and achieving field homogeneity.
2Manufacturing precision
If the rung conductors are extended in a non-linear direction to improve field homogeneity, then B1 field homogeneity improves, but coil symmetry is broken and no single arrangement is optimal for both transmission and reception modes
Solution Approach 1:
The patent applies dynamics by making the RF coil device switchable between different operational modes. The coil can dynamically reconfigure its electrical connections to optimize performance for either transmission mode or reception mode separately, thereby achieving optimal B1 field homogeneity in each mode while maintaining a single physical coil structure with non-linearly extended rungs.
Solution Approach 2:
The patent applies segmentation by dividing the coil's operational functionality into separate transmission and reception modes that can be independently optimized. The coil structure is segmented into multiple elements whose electrical connections can be reconfigured, allowing each mode to operate with its own optimal parameters while using the same physical hardware.
3Device complexity
If a single RF coil design is used for both transmission and reception modes, then device complexity is reduced, but performance is suboptimal for both modes simultaneously
Solution Approach 1:
The patent applies universality by designing a single RF coil device that can perform multiple functions - both transmission and reception - with optimized performance for each function. The coil incorporates non-linearly extended rungs and switchable electrical connections that allow it to adapt its characteristics for optimal transmission performance or optimal reception performance, thereby achieving multi-functionality without requiring separate dedicated coils for each mode.
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 enables improved B1 field homogeneity and reduced power absorption, enhancing signal-to-noise ratio (SNR) and allowing for better control of local and global Specific Absorption Rate (SAR), thereby improving MR image quality.
Implementation Method 1
RF shielding in different modes entails the technical effect of shielding from different types of radiofrequency fields. The first shield and the second shield are designed in accordance with different modes of operation of a RF coil device.
Implementation Method 2
RF shielding in the RF transmit (TX) mode entails shielding from high power RF fields, such as for excitation (transversely over a spin flip angle), refocusing or inversion of nuclear spins.
Data Source
AI summary
The present invention provides a radio frequency (RF) shield device (124) for a magnetic resonance (MR) examination system (110), whereby the RF shield device (124) comprises a first shield (250) and a second shield (252), the first shield (250) and the second shield (252) are arranged with a common center axis (118), the first shield (250) has a shield structure (254) different from a shield structure (254) of the second shield (252), and the first shield (250) and the second shield (252) are designed in accordance with different modes of operation of a RF coil device (140). The present invention also provides a radio frequency (RF) coil device (140) for a magnetic resonance (MR) examination system (110), whereby the RF coil device (140) comprises a first coil (200) and in a second coil (202), the first coil (200) and the second coil (202) are provided as birdcage coils, the first coil (200) and the second coil (202) are arranged with a common center axis (118), the first coil (200) and the second coil (202) have rungs (204), which are arranged non-parallel to the center axis (118) of the RF coil device (140), the first coil (200) has a coil structure (210) different from a coil structure (210) of the second coil (202), and the first coil (200) and the second coil (202) are switchable to be active for different modes of operation. The present invention further provides a magnetic resonance (MR) imaging system (110), comprising such a RF coil device (140) and/or such a RF shield device (124).