MRI RF Coil Decoupling via Weight-Regulated Phase Shifter
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Solution Overview
Problem
The decoupling performance of body coils in MRI systems decreases due to patient weight, leading to a reduced signal-to-noise ratio (SNR) and compromised image quality.
Innovation Solution
A coil decoupling apparatus and method that utilizes a phase shifter connected between the preamplifier and body coil, regulated by an external voltage signal based on the patient's weight to optimize the operation voltage, thereby enhancing decoupling performance and SNR by adjusting the impedance between the body and surface coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the body coil and surface coil receive MR signals simultaneously to improve SNR, then the signal-to-noise ratio is improved, but the decoupling performance of the body coil decreases due to patient weight
Solution Approach 1:
The patent applies a variable capacitor that can dynamically adjust its capacitance value based on patient weight. The capacitor is connected in parallel with the body coil's tuning capacitor, allowing the resonant frequency and impedance of the body coil to be adjusted dynamically. This dynamic adjustment compensates for the decoupling performance degradation caused by patient weight variations, maintaining optimal decoupling while preserving the simultaneous signal reception capability for improved SNR.
Solution Approach 2:
The patent changes the electrical parameters (capacitance value) of the body coil's tuning circuit based on patient weight. By adjusting the capacitance value, the resonant frequency and impedance matching of the body coil are optimized for different patient weights. This parameter change ensures that the body coil maintains proper decoupling from the surface coil while still allowing simultaneous signal reception, thus resolving the contradiction between SNR improvement and decoupling performance.
2Power
If the body coil is used for transmitting RF excitation pulses, then the excitation capability is maintained, but the decoupling performance decreases when receiving signals due to patient weight
Solution Approach 1:
The variable capacitor enables dynamic adjustment of the body coil's electrical characteristics between transmitting and receiving modes. During receiving mode, the capacitor value is adjusted based on patient weight to optimize decoupling performance. During transmitting mode, the capacitor maintains the body coil's resonant frequency for effective RF excitation. This dynamic adjustment allows the body coil to maintain both excitation capability and receiving decoupling performance.
Solution Approach 2:
The body coil is designed to perform multiple functions: transmitting RF excitation pulses and receiving MR signals. The variable capacitor configuration allows the body coil to maintain optimal performance in both modes. By adjusting the capacitance based on patient weight, the coil achieves proper impedance matching and decoupling in receiving mode while maintaining resonant frequency for efficient transmission in transmitting mode, thus实现ing multi-functionality with optimized performance.
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
The solution effectively compensates for the decrease in decoupling performance caused by patient weight, maintaining a higher signal-to-noise ratio and improving image quality by optimizing the impedance and phase delay of the transmission line.
Implementation Method 1
optimizing the impedance and phase delay of the transmission line
Data Source
AI summary
A magnetic resonance imaging (MRI) system radio frequency (RF) subsystem and a coil decoupling apparatus and method used therein. The MRI system RF subsystem comprises a body coil and a surface coil for receiving MR signals, and also comprises a preamplifier for amplifying the MR signals received by the body coil; the coil decoupling apparatus comprises a phase shifter, which is connected between the preamplifier and the body coil, and used for receiving an external voltage regulation signal to regulate an operation voltage thereof, wherein the voltage regulation signal is determined according to a current patient's weight.