Local Coil PCB Design for MRI Signal-to-Noise Ratio
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Solution Overview
Problem
In magnetic resonance tomography (MRT) systems, the signal-to-noise ratio (SNR) of local coils is limited by the size and mutual influence of individual coils, leading to electrical losses at crossing points, which are not effectively improved by increasing the height or width of the copper layer beyond certain thresholds.
Innovation Solution
The use of printed circuit boards with copper-clad plastic carriers and conductor tracks on both sides, where conductor tracks are connected through plated through-holes and designed to cross without electrical contact, minimizing inductive coupling and reducing eddy currents by slotting, thereby optimizing the unloaded quality of the coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of the copper layer is increased, then the unloaded value of the coil improves, but the improvement becomes negligible beyond a height of approximately five times the thickness of the skin
Solution Approach 1:
The patent optimizes the copper layer height parameter to approximately five times the skin thickness, recognizing that further increases yield negligible improvements. This parameter optimization resolves the contradiction by identifying the optimal point where additional complexity no longer provides meaningful improvement in unloaded value.
2Reliability
If the width of the copper layer is increased, then the unloaded value of the coil improves, but the improvement becomes negligible beyond a width of w=pi*D
Solution Approach 1:
The patent establishes an optimal width parameter w=pi*D for the copper layer, beyond which further widening provides negligible improvement. This resolves the contradiction by defining the optimal dimension where the unloaded value is sufficiently improved without excessive complexity.
3Productivity
If the number of individual coils is increased for parallel imaging, then the imaging speed improves, but the mutual influencing of the coils increases and electrical losses arise at crossing points
Solution Approach 1:
The patent introduces an intermediary structure (plastic carrier with specific geometry) that separates and isolates individual coil elements. This intermediary prevents direct electrical contact at crossing points, eliminating eddy currents and mutual inductance effects, thereby reducing electrical losses while maintaining the multi-coil array configuration for parallel imaging.
Solution Approach 2:
The patent segments the coil system into individually isolated coil elements mounted on a plastic carrier. Each coil element is electrically isolated from others, preventing harmful interactions. This segmentation allows multiple coils to operate simultaneously for parallel imaging without suffering from mutual influencing and electrical losses at crossing points.
4Loss of energy
If the distance between coils is increased to reduce mutual influencing, then the electrical losses decrease, but the connection to the patient becomes less effective
Solution Approach 1:
The plastic carrier acts as an intermediary that allows coils to be positioned close to the patient while maintaining electrical isolation. The carrier's geometry enables tight spacing for good patient contact without direct coil-to-coil contact, thus preserving both effective connection and low electrical losses.
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 enhances the signal-to-noise ratio by reducing mutual influencing of coils and minimizing electrical losses, allowing for improved high-resolution imaging in MRT systems.
Implementation Method 1
conductor tracks are connected through plated through-holes
Implementation Method 2
designed to cross without electrical contact, minimizing inductive coupling
Implementation Method 3
reducing eddy currents by slotting
Data Source
AI summary
A local coil for a magnetic resonance tomography device includes a plurality of antenna elements. Each antenna element of the plurality of antenna elements has two conductor tracks. The conductor tracks are disposed on opposite sides of an insulator and are connected electrically conductively to one another by plated through-holes through the insulator. In areas, in which conductor tracks of at least two antenna elements of the plurality of antenna elements cross, at least one antenna element of the at least two antenna elements only has a conductor track on one side of the insulator.