MRI Image Correction for Gradient Nonlinearity and B0 Distortion
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Solution Overview
Problem
Existing magnetic resonance imaging (MRI) systems suffer from image distortion due to deviations in the linearity of gradient magnetic fields, which current linearity compensation methods do not adequately address.
Innovation Solution
A method involving the separate acquisition of main magnetic field and gradient magnetic field information to derive correction coefficients, which are then applied to correct image data, addressing distortions caused by both main magnetic field non-uniformity and gradient field non-linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gradient magnetic field linearity compensation is applied, then image distortion is reduced, but correction completeness is insufficient
Solution Approach 1:
The patent combines main magnetic field non-uniformity correction and gradient magnetic field non-linearity correction into a unified correction framework. By merging these two previously separate correction processes, the system achieves more complete image distortion correction, addressing the insufficiency of conventional single-method compensation approaches.
Solution Approach 2:
The patent employs a composite correction approach by integrating multiple correction coefficients (main magnetic field correction coefficient and gradient magnetic field correction coefficients) to form a comprehensive correction model. This composite correction strategy similarly to composite materials combines different correction mechanisms to achieve superior correction effectiveness compared to individual methods.
2Manufacturing precision
If separate correction coefficients for main magnetic field and gradient magnetic field are obtained and applied, then image correction effectiveness is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary acquisition and storage of main magnetic field intensity distribution information and gradient magnetic field information before actual imaging. Correction coefficients are pre-calculated and stored, allowing rapid application during image reconstruction without real-time computational burden, thus managing complexity while maintaining high correction quality.
Solution Approach 2:
The correction process is segmented into distinct components: main magnetic field correction and gradient magnetic field correction. Each component has its dedicated correction coefficient and processing pathway. This segmentation allows independent optimization and simplifies the overall complex correction process by breaking it into manageable modular steps.
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 method significantly reduces geometric distortions in MRI images by simultaneously correcting for both main magnetic field non-uniformity and gradient field non-linearity, improving image quality, especially in larger fields of view with smaller signal acquisition bandwidths.
Implementation Method 1
MRI utilizes a magnet having a strong magnetic field to generate a main magnetic field B0. When a part to be imaged of the human body is positioned in the main magnetic field B0, nuclear spins associated with hydrogen nuclei in human tissue are polarized
Implementation Method 2
nuclear spins associated with hydrogen nuclei in human tissue are polarized, so that the tissue of the part to be imaged generates a longitudinal magnetization vector
Implementation Method 3
a gradient system is configured to transmit a layer selection gradient pulse, a phase-encoding gradient pulse, and a frequency-encoding gradient pulse... by using a gradient magnetic field superimposed on the main magnetic field
Data Source
AI summary
Embodiments of the present invention disclose a magnetic resonance system, a magnetic resonance image correction method, and a magnetic resonance imaging method. The magnetic resonance image correction method comprises: separately obtaining main magnetic field intensity distribution information and gradient magnetic field information of a magnetic resonance system, the gradient magnetic field information comprising one or more among X-axis gradient magnetic field information, Y-axis gradient magnetic field information, and Z-axis gradient magnetic field information; obtaining a first correction coefficient based on the main magnetic field intensity distribution information; obtaining, based on one or more among the X-axis gradient magnetic field information, the Y-axis gradient magnetic field information, and the Z-axis gradient magnetic field information, one or more corresponding second correction coefficients; and, correcting image data obtained by means of the magnetic resonance system based on the first correction coefficient and the one or more second correction coefficients.