MRI RF Transmit-Coil Shield With Capacitor-Bridged Strips

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Solution Overview

Problem

High acoustic noise in MRI systems, particularly in high-field scanners, causes patient discomfort and hearing damage, and existing RF shielding methods fail to adequately reduce this noise while maintaining RF transmit efficiency.

Innovation Solution

A novel RF shield using phosphor bronze mesh strips spaced apart and bridged with capacitors to reduce eddy currents, allowing unobstructed RF energy transfer and minimizing acoustic noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional RF shielding with overlapping copper strips is used, then RF energy transmission is blocked, but acoustic noise is not reduced and RF transmit efficiency deteriorates

Engineering Contradiction:

Improveacoustic noiseVSAvoidRF energy transmission

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The RF shield is divided into discrete longitudinal strips spaced apart from each other, rather than using continuous overlapping copper strips. This segmentation allows RF energy to pass through the gaps between strips while the strips themselves provide acoustic noise reduction through eddy current generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the shield have different properties: the conductive strips provide acoustic noise reduction where present, while the spaced gaps provide RF energy transmission. This local differentiation resolves the contradiction between blocking RF and reducing noise.

Inventive Principle:

Principle #3Local quality

2Reliability

If RF shield with overlapping strips is used, then eddy currents are generated, but acoustic noise increases and RF transmit efficiency decreases

Engineering Contradiction:

ImproveRF shielding functionalityVSAvoidacoustic noise from eddy currents

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

By segmenting the shield into separate strips rather than using continuous overlapping layers, the patent reduces the total eddy current paths available. The spaced arrangement limits eddy current circulation while maintaining sufficient shielding functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts or removes the overlapping strip structure that generates harmful eddy currents. Instead, it uses spaced strips that minimize eddy current generation while maintaining the essential RF shielding function.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If higher field strength MRI is used, then image resolution improves, but acoustic noise increases

Engineering Contradiction:

Improveimage resolutionVSAvoidacoustic noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful acoustic noise generated by high-field MRI into a manageable problem by introducing the spaced strip shield. The shield generates eddy currents that create acoustic noise, but this noise is controlled and confined, allowing high-field imaging to proceed with reduced overall noise impact.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the physical parameters of the RF shield (using spaced strips instead of continuous material) to alter the eddy current characteristics. This parameter change reduces the acoustic noise output while maintaining the shield's effectiveness in high-field MRI systems.

Inventive Principle:

Principle #35Parameter changes

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 RF shield achieves up to 10 dB noise reduction and a 15% increase in RF transmit efficiency, improving patient comfort and image quality without compromising B1 field strength.

Implementation Method 1

capacitors (18) bridging the strips

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

RF shielding has been used in MRI systems to generate a known pattern of eddy currents that is not RF-lossy

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

RF shielding has been used in MRI systems to generate a known pattern of eddy currents

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

This noise is generated by interactions between the static magnetic field and alternating current in gradient coils, resulting in Lorentz forces that vibrate the coils

Methodology Applied

Scientific EffectLorentz force: Lorentz Force

Data Source

PatentUS20250327888A1MRI with RF shield for transmit coils that reduces acoustic noice and increases transmission of RF energy to the imaging volume

Publication Date: 2025.10.23 MR COILTECH LTD

AI summary

An MRI system includes an RF shield that reduces acoustic noise and increases transmission of RF energy from RF transmit coil to the imaging volume compared with conventional double-layer shields. The RF shield comprises strips of electrically conductive material that are elongated in the direction of the main magnetic field and are spaced from each other in the circumferential direction. The strips are bridged with capacitors. The RF shield reduces acoustic noise and eddy currents and increases transmission of RF energy compared with conventional shields of overlapping strips in two radially spaced layers.