Electromagnetic Resonator RF Field Control in MRI Systems
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Solution Overview
Problem
Conventional high-frequency coils used in MRI devices face limitations at magnetic fields above 3 Tesla, leading to artifacts and poor signal-to-noise ratio due to radiation losses and field homogeneity issues, and existing solutions with high dielectric materials are costly, bulky, and uncomfortable for patients.
Innovation Solution
The use of electromagnetic resonators with adjustable resonance modes and configurations, placed inside or outside the cage coil, to control the distribution of the radiofrequency magnetic field, allowing for homogeneous field adjustment without direct contact with the patient and without high dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high magnetic field intensities (above 3 Tesla) are used to increase signal-to-noise ratio, then imaging quality improves, but artifacts increase due to field inhomogeneity and radiation losses
Solution Approach 1:
The patent changes the physical state and parameters of the dielectric material (permittivity, position, geometry) to modify the RF magnetic field distribution. By adjusting these parameters, the system achieves homogeneous field distribution at high magnetic field strengths without the artifacts that normally occur, thus maintaining high signal-to-noise ratio while eliminating harmful artifacts
Solution Approach 2:
The dielectric material acts as an intermediary element between the RF coil and the patient's body. This intermediary modifies the RF magnetic field distribution through its dielectric properties, preventing direct interaction that would cause artifacts while still enabling high field strength operation for improved signal quality
2Stability of the object's composition
If high dielectric constant materials are used to correct field inhomogeneity, then field homogeneity improves, but device complexity and cost increase
Solution Approach 1:
The patent modifies the dielectric properties of existing materials within the imaging system (such as the patient's body tissues or existing padding materials) rather than introducing complex external high dielectric materials. By changing parameters like material position, geometry, or inherent dielectric properties, the system achieves field homogeneity without increasing device complexity
Solution Approach 2:
The system utilizes the patient's own body tissues or existing system components as the dielectric elements needed for field correction. The body's natural dielectric properties are harnessed to achieve homogeneous field distribution, eliminating the need for additional complex external dielectric materials or devices
3Stability of the object's composition
If high dielectric constant materials are placed against the patient's body to adjust field distribution, then field homogeneity improves, but patient comfort deteriorates
Solution Approach 1:
The patent changes the parameters of existing comfortable materials (such as positioning pads or the patient's own clothing) by adjusting their position, orientation, or geometry rather than introducing new bulky high dielectric materials. This achieves field homogeneity while maintaining patient comfort through familiar, comfortable materials
4Productivity
If conventional RF coils are used at high frequencies (above 128 MHz), then imaging speed improves, but field homogeneity deteriorates leading to artifacts
Solution Approach 1:
The dielectric material serves as an intermediary that mediates between the conventional RF coil and the patient's body at high frequencies. It modifies the RF field distribution to maintain homogeneity even at frequencies above 128 MHz, enabling fast imaging without the field inhomogeneity artifacts that normally plague conventional coils at these frequencies
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 approach enhances the homogeneity of the magnetic field distribution within the region of interest, reducing artifacts and improving signal quality without increasing the Specific Absorption Rate (SAR) or compromising patient comfort, while avoiding the use of costly and toxic materials.
Implementation Method 1
placing an electromagnetic resonator having a resonance mode excited by the rotating magnetic field, the resonance mode and the position of the resonator relative to the cage coil being adapted to adjust the intensity of the rotating magnetic field in an area of the region to be analyzed
Data Source
AI summary
A method for controlling the distribution of the RF magnetic field in a magnetic resonance imaging system, having steps of: placing a cage coil in a permanent magnet supplying a permanent magnetic field along a first axis, and supplying an RF signal to the cage coil in order for the coil to generate an RF magnetic field rotating in a plane that runs perpendicular to the first axis; and putting in place an electromagnetic resonator, the resonance mode of which is excited by the rotating magnetic field, the resonator being placed in a position inside or outside the cage coil and at a distance from a region to be analyzed of an object to be placed in the cage coil, the resonance mode and the position of the resonator in relation to the volumetric antenna being suitable for adjusting the intensity of the rotating magnetic field in an area of the region to be analyzed.