Sinusoidal Gradient MRI for Artifact Diffusion
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques face challenges in scanning speed, leading to prolonged scanning times and motion artifacts, which affect image quality, and existing fast imaging methods like GRAPPA and SENSE reduce signal-to-noise ratio and introduce aliasing artifacts.
Innovation Solution
A magnetic resonance imaging method involving a three-dimensional imaging sequence with sinusoidal gradient fields on phase and layer selection directions, where the 0-order moments of these fields are 0, allowing for high-power acceleration without introducing additional artifacts, and using a sensitivity map and point spread function for image reconstruction to reduce aliasing and noise amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If parallel imaging techniques like GRAPPA, SENSE, or wave-CAIPI are used to reduce scanning time, then scanning speed is improved, but signal-to-noise ratio is reduced and aliasing artifacts are introduced
Solution Approach 1:
The patent changes the gradient field waveform from traditional linear or trapezoidal shapes to sinusoidal waveforms. This parameter change in the gradient field shape enables the 0-order moment to be zero, which diffuses aliasing artifacts across the entire field of view rather than concentrating them in specific regions, thereby improving signal-to-noise ratio while maintaining accelerated scanning
Solution Approach 2:
The patent employs periodic sinusoidal gradient fields with specific durations that are integer multiples of half-periods. This periodic action ensures that the time integral (0-order moment) of the gradient field is zero, which prevents static aliasing artifacts from forming in fixed locations, thereby reducing g-factor noise amplification during parallel imaging reconstruction
2Productivity
If parallel imaging techniques like GRAPPA, SENSE, or wave-CAIPI are used to reduce scanning time, then scanning speed is improved, but aliasing artifacts are introduced in the reconstructed image
Solution Approach 1:
The patent changes the gradient field waveform from traditional linear or trapezoidal shapes to sinusoidal waveforms. This parameter change in the gradient field shape enables the 0-order moment to be zero, which diffuses aliasing artifacts across the entire field of view rather than concentrating them in specific regions, thereby improving signal-to-noise ratio while maintaining accelerated scanning
Solution Approach 2:
The patent converts the potentially harmful aliasing artifacts into a beneficial diffusion effect. By using sinusoidal gradient fields with zero 0-order moment, the aliasing artifacts are spread uniformly across the entire image rather than appearing as concentrated errors, making them less visually distracting and easier to manage during reconstruction
3Productivity
If traditional gradient fields are used in parallel imaging, then scanning can be performed, but g-factor noise amplification occurs and image quality deteriorates
Solution Approach 1:
The patent changes the gradient field waveform from traditional linear or trapezoidal shapes to sinusoidal waveforms. This parameter change in the gradient field shape enables the 0-order moment to be zero, which diffuses aliasing artifacts across the entire field of view rather than concentrating them in specific regions, thereby improving signal-to-noise ratio while maintaining accelerated scanning
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 method enhances scanning speed and image quality by diffusing aliasing artifacts and reducing the g-factor signal-to-noise ratio, achieving high-power acceleration with minimal artifacts and improved resolution.
Implementation Method 1
The first three-dimensional magnetic resonance imaging sequence may have a first sinusoidal gradient field on a phase direction and a second sinusoidal gradient field on a layer selection direction. Each of a duration of the first sinusoidal gradient field and a duration of the second sinusoidal gradient field is within a duration of a reading platform of a reading gradient field on a reading direction. A 0-order moment of the first sinusoidal gradient field and a 0-order moment of the second sinusoidal gradient field are 0.
Implementation Method 2
Magnetic resonance imaging (MRI) is non-radiative and has high resolution. Therefore, the MRI is widely applied in clinical medicine and medical researches.
Implementation Method 3
a technique of sensitivity encoding (SENSE), and a technique of wave controlled aliasing in parallel imaging (wave-CAIPI), is provided and dramatically reduces the scanning speed of magnetic resonance. With these fast imaging techniques, reconstruction may be performed to under-sampling data based on a sensitivity difference between receiving coils in a space
Data Source
AI summary
A magnetic resonance imaging method includes: obtaining three-dimensional under-sampling data of a target object based on a first three-dimensional magnetic resonance imaging sequence; obtaining a three-dimensional point spread function based on the three-dimensional under-sampling data or a two-dimensional mapping data of the target object; obtaining a sensitivity map of the target object based on the data collected by three-dimensional low-resolution complete sampling; performing imaging reconstruction to the three-dimensional under-sampling data based on the three-dimensional point spread function and the sensitivity map to obtain a reconstructed magnetic resonance image. The first three-dimensional magnetic resonance imaging sequence has a first sinusoidal gradient field on a phase direction and a second sinusoidal gradient field on a layer selection direction. 0-order moments of the first and the second three-dimensional magnetic resonance imaging sequences are 0. A phase difference between the first and the second three-dimensional magnetic resonance imaging sequence is π/2.