MRI Gradient Coil Parallel Windings for Nerve Stimulation
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Solution Overview
Problem
Current gradient coil units in magnetic resonance imaging (MRI) systems are limited by their maximum achievable gradient amplitude and slew rate, which restricts the generation of gradient moments per unit of time, particularly in neuroapplications, and are often constrained by cooling power and nerve stimulation considerations.
Innovation Solution
A gradient coil system comprising a first primary coil with two windings connected in parallel to a voltage source, allowing for increased nominal gradient amplitude and efficient cooling, while maintaining a conventional control setup and spatial integration, thereby enhancing the gradient moment generation without stimulating peripheral nerves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gradient amplitude is increased to generate higher gradient moments per unit of time, then the performance in neuroapplications is improved, but the risk of stimulating peripheral nerves increases
Solution Approach 1:
The primary coil is divided into two separate windings (first and second primary coil windings) that are radially spaced apart. This segmentation allows the system to achieve higher gradient moments by utilizing both windings simultaneously while distributing the current load, thereby reducing nerve stimulation risk compared to a single high-current winding configuration.
2Productivity
If the nominal gradient amplitude is increased beyond thermal equilibrium limits, then the gradient moment capability is improved, but the cooling power requirements become excessive
Solution Approach 1:
By segmenting the primary coil into two radially spaced windings, the heat generation is distributed across two separate cooling zones. This allows more efficient utilization of available cooling power, as each winding can be cooled independently, enabling higher nominal gradient amplitudes without requiring excessive total cooling power.
Solution Approach 2:
The invention transitions from a single-plane coil configuration to a multi-layer radial configuration. The first and second primary coil windings are arranged at different radial positions, creating additional spatial dimensions for heat dissipation and current distribution, which improves cooling efficiency and enables higher gradient amplitudes.
3Productivity
If a single primary coil winding is used, then the device complexity is reduced, but the gradient moment generation capability is limited
Solution Approach 1:
The primary coil is segmented into two windings with different radial spacings. The first primary coil winding is positioned at a first radial spacing from the center, while the second primary coil winding is positioned at a second radial spacing. This segmentation enables enhanced gradient moment generation through constructive interference of magnetic fields while maintaining a relatively simple overall structure that integrates with conventional MRI systems.
4Temperature
If the radial spacing of coil windings is increased to improve cooling efficiency, then the cooling performance is improved, but the spatial integration in existing MRI devices becomes difficult
Solution Approach 1:
The invention utilizes the radial dimension to accommodate multiple windings at different distances from the center of the MRI bore. By arranging windings in the radial direction rather than simply increasing lateral spacing, the design achieves improved cooling efficiency while maintaining compatibility with the confined spatial dimensions of existing MRI devices.
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 enables a higher gradient moment per unit of time with improved efficiency and reduced nerve stimulation risk, allowing for enhanced MRI performance without the need for significant modifications to existing MRI devices or control systems.
Implementation Method 1
the first primary coil winding and the second primary coil winding being jointly designed to generate a magnetic field gradient in a first direction if the first voltage source induces a first current
Implementation Method 2
A corresponding secondary coil shields the magnetic field gradient generated by the primary coil in such a way that it is compensated for outside the gradient coil unit
Data Source
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AI summary
The invention relates to a gradient coil unit comprising a primary coil (40) and a secondary coil (50), wherein the primary coil comprises a first primary coil winding (41) and a second primary coil winding (42), which first primary coil winding (41) and second primary coil winding (42) are connected to a first voltage source (71) and are jointly configured to generate a magnetic field gradient in a first direction, provided that the first voltage source induces a first current.