MRI RF Coil Segmented Rungs Reduce Eddy Current Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic resonance imaging (MRI) systems face issues with heating, vibration, and acoustic noise generated by radio frequency (RF) coils, which can be uncomfortable for patients and affect the efficiency of the system.
Innovation Solution
The RF coil design features a plurality of rungs with individually insulated parallel wires of circular cross-section, reducing eddy currents and resulting heating, vibration, and acoustic noise, while enabling a more uniform excitation field (B1) through improved current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional RF coil design is used, then RF excitation signals can be transmitted and received, but heating, vibration and acoustic noise are generated causing patient discomfort and system efficiency reduction
Solution Approach 1:
The RF coil conductors are segmented into multiple individually insulated parallel wires within each rung, rather than using a single continuous conductor. This segmentation divides the eddy current paths into multiple separate channels, reducing the overall eddy current magnitude and consequently reducing heating, vibration and acoustic noise generation while maintaining the RF excitation signal transmission function
Solution Approach 2:
Each wire within the parallel bundle is individually insulated, creating localized electrical isolation between adjacent wires. This local quality differentiation prevents current coupling between wires and optimizes the current distribution across the conductor bundle, reducing eddy current effects and improving thermal management at each local position within the coil structure
2Adaptability or versatility
If gradient coils generate time-varying magnetic fields for spatial encoding, then magnetic field gradients are produced, but eddy currents are induced in RF coils causing vibration and acoustic noise
Solution Approach 1:
The RF coil rungs are constructed with multiple separately insulated wires instead of a single conductor, segmenting the eddy current pathways. This segmentation reduces the magnitude of eddy currents induced by gradient coil time-varying magnetic fields, thereby reducing vibration and acoustic noise while preserving the RF coil's ability to transmit and receive signals during spatial encoding operations
Solution Approach 2:
The insulating material between adjacent wires acts as an intermediary that prevents electrical coupling and current sharing between wires. This intermediary insulation layer ensures that eddy currents are confined to individual wire paths rather than circulating through the entire coil structure, reducing overall eddy current effects and associated harmful vibrations and noise
3Ease of manufacture
If single wire conductors are used in RF coil rungs, then manufacturing is simpler, but eddy currents cause non-uniform excitation fields and increased heating
Solution Approach 1:
Each rung is divided into multiple parallel wires with individual insulation, creating multiple discrete current-carrying elements. This segmentation provides more uniform current distribution across the rung cross-section, reducing eddy current concentrations and producing a more uniform excitation field while maintaining manufacturing feasibility through standardized wire and insulation components
Solution Approach 2:
The individual insulation on each wire creates localized electrical boundaries that control current distribution at the micro-level. This local quality differentiation ensures uniform current density across each wire surface and between adjacent wires, preventing current concentration effects and improving overall current distribution uniformity while allowing each wire to be manufactured and assembled independently
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 design effectively minimizes heating, vibration, and acoustic noise, while providing a uniform excitation field, enhancing patient comfort and MRI system efficiency.
Implementation Method 1
The acoustic noise generated by the RF coil is typically caused by eddy currents induced in the RF coil conductors by operation of the gradient coils
Implementation Method 2
current pulses are applied (e.g., as part of a pulse sequence) to the gradient coils to generate time-varying magnetic fields. These time-varying magnetic fields can induce eddy currents in an RF coil
Implementation Method 3
Radio frequency (RF) coils are used to create pulses of RF energy at or near the resonance frequency of the hydrogen nuclei. The RF coils are used to add energy to the nuclear spin system in a controlled fashion
Implementation Method 4
MRI uses a powerful magnet to create a strong, uniform, static magnetic field. When a human body is placed in the main magnetic field, the nuclear spins that are associated with the hydrogen nuclei in tissue water become polarized
Data Source
AI summary
A radio frequency (RF) coil for a magnetic resonance imaging (MRI) system includes a plurality of rungs. Each rung includes a plurality of wires positioned parallel to one another. Each wire has a circular cross section and an insulating material disposed around an outside surface of the wire. Using wires with a circular cross-section reduces the eddy currents produced on a rung. As a result, the amount of eddy current produced heating, vibration and acoustic noise is reduced. The plurality of wires also enables a more uniform current distribution along the width of each rung that in turn produces a more uniform excitation field (B1).