High-frequency coil unit for MRI examination space
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Solution Overview
Problem
Tunnel type MRI devices face challenges in securing a large examination space without increasing manufacturing costs or significantly reducing irradiation efficiency and uniformity of irradiation intensity distribution, particularly when parts of the cylindrical RF coil are removed.
Innovation Solution
A high-frequency coil unit comprising a cylindrical shield with a first and second partial coil, where the coils generate linearly polarized magnetic fields perpendicular to each other, and a high-frequency signal control unit ensures circularly or elliptically polarized magnetic fields are irradiated, maintaining efficient irradiation and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the internal diameter of the static magnetic field magnet is increased to make the examination space larger, then the examination space is enlarged, but the manufacturing cost increases significantly
Solution Approach 1:
The invention extracts and removes a part of the cylindrical RF coil structure to create a semicylindrical configuration. This extraction reduces the overall size and complexity of the coil assembly, allowing for a larger examination space without requiring an increase in the magnet's internal diameter, thereby avoiding significant manufacturing cost increases.
Solution Approach 2:
The RF coil is segmented into a semicylindrical structure with a first cylindrical portion and a second cylindrical portion disposed at different positions. This segmentation allows the examination space to be optimized without uniformly increasing the magnet size, thus controlling manufacturing costs while providing adequate space for patients and instruments.
2Area of stationary object
If parts of the cylindrical RF coil are removed to enlarge the examination space, then the examination space is increased, but the irradiation efficiency and uniformity of irradiation intensity distribution are reduced
Solution Approach 1:
The invention applies quadrature detection (QD) methodology to the semicylindrical RF coil, enabling dynamic control of the magnetic field irradiation. By using two feeding ports with perpendicular orientations and controlling their phase and amplitude, the system maintains high irradiation efficiency and uniformity despite the reduced cylindrical structure.
Solution Approach 2:
The invention changes the operational parameters by implementing QD with specific phase differences (90 degrees) and amplitude ratios between the two feeding ports. This parameter control compensates for the structural reduction, maintaining uniform irradiation intensity distribution and high irradiation efficiency while providing a larger examination space.
3Loss of energy
If two RF coils with perpendicular orientations are used to implement quadrature detection for improving irradiation efficiency, then the irradiation efficiency is improved, but the device complexity increases
Solution Approach 1:
The invention merges the functions of two separate RF coils into a single semicylindrical RF coil structure with two feeding ports. This combining achieves the QD functionality (improved irradiation efficiency) while reducing device complexity compared to using two complete cylindrical coils.
Solution Approach 2:
The semicylindrical RF coil with two feeding ports serves multiple functions: it provides quadrature detection capability for improved irradiation efficiency, maintains uniform field distribution, and creates a larger examination space. This multi-functionality reduces the need for additional separate components, thereby managing device 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
This configuration allows for a larger examination space in MRI devices without increasing manufacturing costs or reducing irradiation efficiency and uniformity, enabling spaciousness for patients and installation of instruments while maintaining image quality.
Implementation Method 1
a first partial coil and a second partial coil facing each other and disposed in the inside of the shield with a predetermined interval for the circumferential direction... the first high-frequency coil and the second high-frequency coil have shapes for generating linearly polarized high-frequency magnetic fields of which directions are perpendicular to each other
Data Source
AI summary
There is provided a technique for securing a large examination space in a tunnel type MRI device without inviting increase of manufacturing cost and without significantly reducing irradiation efficiency or uniformity of the irradiation intensity distribution in an imaging region. Between rungs of a partially cylindrical RF coil, which coil corresponds to a cylindrical RF coil of which part is removed, there are disposed half-loops generating magnetic fields, which are synthesized with magnetic fields generated by loops constituted by adjacent rungs of the partially cylindrical RF coil and rings connecting the rungs to generate a circularly polarized or elliptically polarized magnetic field. Further, high-frequency signals of the same reference frequency having a desired amplitude ratio and phase difference are supplied to the partially cylindrical RF coils and half-loops.