MRI Diffusion Imaging Sequences for Nyquist Artifact Suppression
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Solution Overview
Problem
Conventional magnetic resonance echo plane imaging (EPI) is prone to Nyquist and acceleration artifacts due to factors like eddy currents and gradient coil heating, and existing methods struggle to effectively suppress both types of artifacts simultaneously.
Innovation Solution
A magnetic resonance imaging method involving multiple diffusion-weighted imaging sequences in different directions, each with specific pre-dephasing gradient pulse areas, followed by data fusion processing to acquire and combine k-space data sets, thereby suppressing both Nyquist and acceleration artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional echo plane imaging is used to achieve fast imaging, then imaging speed is improved, but Nyquist artifacts and acceleration artifacts appear in the image
Solution Approach 1:
The patent segments the k-space data acquisition into multiple diffusion directions, acquiring data in different directional planes and then combining them through data fusion processing. This segmentation approach allows the system to maintain fast imaging while reducing artifacts by distributing the acquisition across multiple directional views rather than a single EPI trajectory.
Solution Approach 2:
The patent uses data fusion processing to combine k-space data sets from multiple diffusion directions, creating a composite image that leverages information from all directions. This composite approach suppresses artifacts that appear in individual directional views while maintaining the fast imaging capability of EPI.
2Speed
If parallel imaging acceleration is applied to speed up EPI, then imaging speed is improved, but acceleration artifacts appear in edge regions
Solution Approach 1:
The patent introduces a new dimension by acquiring data in multiple diffusion directions rather than relying solely on parallel imaging acceleration within a single plane. This dimensional approach to acceleration reduces dependence on aggressive parallel imaging factors that cause edge artifacts while maintaining overall imaging speed.
3Object-affected harmful factors
If multiple diffusion directions are acquired to improve image quality, then artifact suppression is improved, but scan time increases
Solution Approach 1:
The patent merges the acquisition of multiple diffusion directions into a single signal acquisition process by applying diffusion-weighted imaging sequences in different directions within the same scan. This combining approach achieves artifact suppression from multiple directions without proportionally increasing total scan time.
Solution Approach 2:
The patent maintains continuous useful action by acquiring diffusion-weighted data in multiple directions during a single uninterrupted signal acquisition. This continuous multi-directional sampling improves artifact suppression while minimizing idle time that would otherwise extend the scan duration.
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 effectively suppresses both Nyquist and acceleration artifacts without increasing scan time or requiring additional software, maintaining image quality by adjusting pre-dephasing gradient pulse areas based on diffusion directions and number of acquisitions.
Implementation Method 1
a gradient coil used to generate a gradient pulse
Implementation Method 2
a radio-frequency coil used to generate a radio-frequency pulse
Implementation Method 3
magnetic resonance imaging system and method
Data Source
AI summary
A magnetic resonance imaging system and method is provided. The magnetic resonance imaging method comprises: in a single signal acquisition, applying a plurality of diffusion-weighted imaging sequences in a plurality of diffusion directions, respectively, to acquire a plurality of k-space data sets. Each diffusion-weighted imaging sequence comprising a pre-dephasing gradient pulse and a plurality of phase encoding gradient pulses applied after the pre-dephasing gradient pulse, and the pre-dephasing gradient pulses in the plurality of diffusion-weighted imaging sequences, when sorted according to area values, successively having a first standard area difference determined on the basis of the number of the plurality of diffusion directions. The method further includes performing data fusion processing on the plurality of k-space data sets in the single signal acquisition to obtain a magnetic resonance image.