Phase Shift Circuit for MRI Coil Decoupling
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Solution Overview
Problem
Existing magnetic resonance (MR) systems, particularly low-field systems, face complexity in decoupling coil units due to high Q-factors, leading to signal-to-noise ratio (SNR) loss and inductance issues with existing decoupling methods.
Innovation Solution
A coil unit decoupling device utilizing phase shift circuits and crossover elements, such as capacitors or inductors, to achieve 180° phase shift between coil units, thereby offsetting reactance and impedance coupling and simplifying the decoupling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overlapping decoupling is used between adjacent coil units, then decoupling between adjacent coils is achieved, but decoupling between non-adjacent coil units (e.g., coil units 11 and 13, or 12 and 14) cannot be realized
Solution Approach 1:
The patent transitions from spatial overlapping (one-dimensional adjacency) to electrical phase manipulation (introducing a new dimension of phase control). By using phase shift circuits to create 180° phase differences and crossover elements to couple non-adjacent coils through the phase-reversed adjacent coils, the system achieves decoupling coverage beyond physical adjacency constraints.
2Reliability
If inductance decoupling or capacitance decoupling is used, then decoupling between coil units is achieved, but complex adjustments are required during manufacturing and additional SNR loss occurs due to increased wire lengths and inductance loss
Solution Approach 1:
The patent changes the fundamental parameter from inductance/capacitance coupling strength to phase difference (180° phase shift). By controlling the phase relationship between coils through phase shift circuits rather than adjusting coupling inductance or capacitance values, the system achieves decoupling with simpler manufacturing requirements and reduced sensitivity to component tolerances.
3Reliability
If inductance decoupling or capacitance decoupling is used, then decoupling between coil units is achieved, but additional SNR loss occurs due to increased wire lengths and inductance loss
Solution Approach 1:
The patent replaces the mechanical/electrical coupling mechanism (inductance or capacitance elements requiring physical wire connections) with a phase-based control mechanism. By using phase shift circuits to create destructive interference of magnetic fields through 180° phase differences, the system achieves decoupling without the additional wire lengths and inductance losses associated with traditional inductance or capacitance decoupling methods.
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 reduces complexity in decoupling coil units, maintains optimal SNR, and achieves strong decoupling without requiring complex copper structures, even in high Q-factor environments and when coil units are mistuned.
Implementation Method 1
the first phase shift circuit enables the first coil unit to be matched and enables the first coil unit to have a phase shift of 180° between a matched state and a non-matched state
Implementation Method 2
a first connecting end of the first capacitor is connected with the first port of the first coil unit and a first connecting end of the first inductor group, and a second connecting end of the first capacitor is grounded
Implementation Method 3
the first phase shift circuit comprises a first capacitor and a first inductor group, and the first inductor group comprises one inductor or multiple inductors connected in series
Data Source
AI summary
A coil unit decoupling device and a magnetic resonance system. The device comprises a first phase shift circuit, a second phase shift circuit and a first crossover element, and the first crossover element is a capacitor or inductor, wherein a first connecting end of the first phase shift circuit is connected with a first port of a first coil unit, a second connecting end of the first phase shift circuit is connected with a first connecting end of the first crossover element, a first connecting end of the second phase shift circuit is connected with a first port of a second coil unit, a second connecting end of the second phase shift circuit is connected with a second connecting end of the first crossover element, and the first coil unit and the second coil unit are located in a magnetic resonance system.