Self-Shielded Split Gradient Coil for MRI Gap Integration
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Solution Overview
Problem
Existing MRI gradient coil assemblies for horizontal open MRIs face challenges with magnetic interference and heating issues when used with additional medical devices, particularly due to the placement of conductive instruments within the MRI gap, which induces eddy currents and affects imaging quality.
Innovation Solution
The development of gradient coil assemblies with primary and shielding coils arranged to minimize conductor concentrations near the MRI gap, using cylindrical conductors and direct cooling, and a supporting structure that traverses the gap to reduce eddy currents and ensure uniform radiation attenuation, allowing for the operation of MRI systems with additional medical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gradient coil assemblies are used in horizontal open MRI with instruments placed in the gap, then additional medical devices can be integrated, but eddy currents are induced in the instruments due to magnetic field interference
Solution Approach 1:
The gradient coil assembly is divided into multiple independent coils (X-gradient, Y-gradient, Z-gradient coils) with distinct windings and orientations. This segmentation allows each coil to be optimized for its specific function while minimizing interference with instruments in the gap region.
Solution Approach 2:
Different regions of the gradient coil assembly have different conductor arrangements optimized for local requirements. The coils are positioned and wound to produce desired gradient fields in specific zones while minimizing eddy current induction in the gap region where instruments are placed.
2Measurement precision
If conductors are concentrated near the MRI gap to improve gradient field strength, then imaging quality improves, but heating issues occur due to induced eddy currents
Solution Approach 1:
The gradient coils are arranged in three-dimensional space with different orientations (X, Y, Z gradients) and spatial distributions. This multi-dimensional arrangement allows the magnetic field gradients to be generated effectively while distributing the conductor energy density to reduce localized heating.
Solution Approach 2:
The gradient coil assembly acts as an intermediary system that generates the necessary magnetic field gradients for imaging while being designed to minimize harmful interactions with instruments in the gap. The specific winding patterns and positioning serve as a mediator between the need for strong gradients and the need to reduce eddy current heating.
3Object-affected harmful factors
If shielding coils are added to reduce eddy currents, then interference with medical devices is reduced, but device complexity increases
Solution Approach 1:
The gradient coils and shielding functions are merged into a single integrated coil assembly. The same X, Y, and Z gradient coils perform both gradient generation and shielding functions through their specific winding patterns and positioning, eliminating the need for separate shielding coils and reducing overall system complexity.
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 eddy currents and maintains imaging quality by relocating conductor connections away from the MRI gap and using a supporting structure for alignment and radiation attenuation, enabling the integration of MRI systems with various medical devices without significant interference or heating issues.
Implementation Method 1
Gradient coils are used to produce these linear magnetic field gradients
Implementation Method 2
electrical connections between the primary gradient and shielding coils that may be arranged to be a sufficient distance from the open MM gap so as to reduce eddy currents that may be induced in any instrument that is placed within the gap
Implementation Method 3
each of the primary gradient coils may be directly cooled
Data Source
AI summary
Gradient coil assemblies for horizontal magnetic resonance imaging systems (MRIs) and methods of their manufacture. Some embodiments may be used with open MRIs and can be used with an instrument placed in the gap of the MRI. In general, concentrations of conductors or radially oriented conductors may be moved away from the gap of the MRI so as to reduce eddy currents that may be induced in any instrument placed within the gap. Systems for directly cooling primary gradient and shield coils may be utilized and various coil supporting structures may be used to assist in coil alignment or to facilitate use of an instrument in the MRI gap.