MRI Receiver Coil Sub-coil Arrangement for Coupling Suppression
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Solution Overview
Problem
Current MRI technologies face challenges in achieving short imaging time for wide-field imaging in vertical magnetic field MRI systems, particularly due to electromagnetic coupling and g-factor issues, which affect the signal-to-noise ratio and flexibility in phase encoding directions.
Innovation Solution
A receiver coil configuration comprising multiple sub-coils, including a solenoid coil around the circumference and surface coils with specific geometric arrangements to minimize electromagnetic coupling and optimize sensitivity distributions, allowing for flexible phase encoding in x, y, and z directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple sub-coils are used for parallel imaging to shorten imaging time, then imaging speed is improved, but electromagnetic coupling between sub-coils increases causing noise interference and S/N ratio deterioration
Solution Approach 1:
The receiver coil is divided into multiple independent sub-coils (first coil, second coil, third coil) with distinct geometric arrangements. Each sub-coil is configured to detect signals with different sensitivity distributions, enabling parallel imaging while maintaining electromagnetic independence to prevent noise interference and preserve S/N ratio.
Solution Approach 2:
Each sub-coil is designed with specific local geometric characteristics (different orientations and positions) to create unique sensitivity distributions in different regions. The first coil surrounds the outer circumference, while the second and third coils are positioned at different locations with different orientations, ensuring that each coil optimally detects signals from specific regions without interfering with others.
2Loss of time
If multiple sub-coils are used for parallel imaging, then imaging time is shortened, but geometric arrangement complexity increases affecting sensitivity distribution coverage
Solution Approach 1:
The sub-coils are arranged asymmetrically with different geometric configurations rather than identical symmetric arrangements. The first coil is positioned to surround the outer circumference, while the second and third coils have different orientations and positions, creating complementary sensitivity distributions that collectively cover the entire imaging area efficiently.
Solution Approach 2:
The coil arrangement extends into multiple spatial dimensions with the first coil surrounding the outer circumference, the second coil positioned at one location with a specific orientation, and the third coil positioned at another location with a different orientation. This multi-dimensional arrangement ensures comprehensive sensitivity distribution coverage across different spatial regions.
3Reliability
If sub-coils are arranged to minimize electromagnetic coupling, then S/N ratio is maintained, but flexibility in phase encoding directions is reduced
Solution Approach 1:
The receiver coil system is designed with multi-functional sub-coils that can support phase encoding in multiple directions. The combination of the first coil surrounding the outer circumference, the second coil with one orientation, and the third coil with a different orientation creates a universal detection system that maintains effective sensitivity distributions regardless of which direction is selected for phase encoding.
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 effectively suppresses electromagnetic coupling, maintains a high signal-to-noise ratio, and enables dramatic shortening of imaging time during wide-field imaging with table movement, while allowing flexibility in phase encoding directions.
Implementation Method 1
An MRI apparatus obtains a signal from a test object (a subject being tested) by nuclear magnetic resonance
Data Source
AI summary
An MRI apparatus capable of selecting an optional direction as a phase encoding direction and achieving a preferable S/N, when an imaging time shortening technique is applied. A receiver coil, used as a receiver coil of a vertical magnetic field MRI apparatus, is a combination of a first coil (solenoid coil) forming a current loop around the outer circumference of a test object, second coils forming even-numbered current loops, and third coils forming odd-numbered current loops, in the direction intersecting the plane of the current loop of the first coil. The second coil and the third coil are arranged in such a manner that, as for the current loops in the array direction thereof, a position where a sensitivity of one coil is minimized approximately coincides with a position where the sensitivity of the other coil is maximized, whereby electromagnetic coupling is suppressed.