MRI Array Coil Subcoils with Detuned Resonance
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Solution Overview
Problem
Multi-channel array coils in MRI apparatuses face challenges in achieving high sensitivity and large sensitivity areas, especially for deep parts of the imaging subject, due to magnetic coupling issues and the trade-off between coil size and sensitivity, leading to degraded image quality and increased complexity in configuration.
Innovation Solution
The use of subcoils with intentionally adjusted resonance frequencies and magnetic coupling, where at least one subcoil resonates differently and is coupled with another, connected to different impedance signal processing circuits to minimize magnetic coupling and enhance sensitivity area without complicating the configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of channels in multi-channel array coil is increased to expand sensitivity area, then imaging speed is improved, but magnetic coupling between subcoils increases and sensitivity for deep parts decreases
Solution Approach 1:
The patent changes the resonance frequency parameter of subcoils. Specifically, at least one subcoil is designed with a resonance frequency different from the nuclear magnetic resonance frequency, while another subcoil resonates at the nuclear magnetic resonance frequency. This frequency differentiation allows the subcoils to maintain different operational characteristics, reducing magnetic coupling interference while preserving the benefits of multiple channels for expanded sensitivity area and high-speed imaging.
2Area of stationary object
If subcoils are disposed closely to each other to form array coil, then sensitivity area is expanded, but magnetic coupling degrades RF coil performance
Solution Approach 1:
The patent applies parameter changes by assigning different resonance frequencies to different subcoils. At least one subcoil operates at a resonance frequency different from the nuclear magnetic resonance frequency, while another subcoil operates at the nuclear magnetic resonance frequency. This frequency separation reduces magnetic coupling between closely disposed subcoils, allowing the array coil to maintain expanded sensitivity area while preserving RF coil performance.
3Reliability
If multiple magnetic coupling elimination means are provided to reduce magnetic coupling, then magnetic coupling is reduced, but sensitivity of array coil is reduced and configuration becomes complicated
Solution Approach 1:
The patent uses parameter changes (different resonance frequencies) as an inherent design feature rather than adding separate elimination components. By designing subcoils with different resonance frequencies from the outset, magnetic coupling is reduced through the frequency difference itself, avoiding the need for additional magnetic coupling elimination means and their associated 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 approach reconciles multi-channel characteristics with large and deep sensitivity areas, enabling high-speed imaging with improved image quality by optimizing the sensitivity profile of the RF coil.
Implementation Method 1
The first subcoil is adjusted so that it is intentionally magnetically coupled with a second subcoil, which is at least one other subcoil, and thereby made to resonate at the same frequency as the nuclear magnetic resonance frequency
Data Source
AI summary
A technique for reconciling large sensitivity area and high sensitivity for deep part in a multi-channel array coil of an MRI apparatus without complicating the configuration, and realizing both higher speed imaging and high image quality is provided. An RF coil (array coil) of a magnetic resonance imaging apparatus comprising a plurality of subcoils is provided. At least one of the subcoils is a first subcoil of which resonance frequency as that of the subcoil alone differs from magnetic resonance frequency. The first subcoil is adjusted so that it magnetically couples with a second subcoil, which is at least one other subcoil, and thus resonates at the same frequency as the magnetic resonance frequency. Input and output terminals of the first subcoil and the second subcoil are connected to different low input and output impedance signal processing circuits, respectively.