3D Flow Compensated Interleaved EPI for Susceptibility-Weighted Imaging
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Solution Overview
Problem
Existing susceptibility-weighted imaging (SWI) techniques using 3D-interleaved Echo Planar Imaging (iEPI) face challenges in fully utilizing scanning efficiency due to flow compensation complexities, resulting in vein flow contaminations in SWI images.
Innovation Solution
A method and apparatus for SWI that performs flow compensation in layered, phase, and frequency encoding directions for each excitation, with echoes collected in alternating directions from the central echo, and averaging central echoes from adjacent excitations to reduce flow effects and improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If full-flow compensation is performed for each echo in all three directions (layered encoding, phase encoding, and frequency encoding), then flow artifacts are eliminated, but scanning time increases significantly
Solution Approach 1:
The patent applies partial flow compensation by performing full-flow compensation only for the central echo in all three gradient directions, while using simplified compensation for peripheral echoes. This selective approach eliminates the most significant flow artifacts without requiring complete compensation for all echoes, thereby reducing scanning time while maintaining image quality
Solution Approach 2:
The patent segments the echo train into a central echo and peripheral echoes, applying different compensation strategies to each segment. The central echo receives comprehensive flow compensation in all three directions, while peripheral echoes use reduced compensation, allowing the system to balance artifact reduction with scanning efficiency
2Productivity
If 3D-interleaved Echo Planar Imaging is used to improve scanning efficiency, then scanning time is reduced, but flow compensation becomes more complex and vein flow contaminations increase
Solution Approach 1:
The patent applies local quality by tailoring the flow compensation strategy to specific locations in k-space. Central k-space echoes (which contain most of the image contrast information) receive full flow compensation, while peripheral echoes use simplified compensation. This localized differentiation reduces overall complexity while maintaining scanning efficiency
Solution Approach 2:
The patent changes the flow compensation parameters dynamically based on the echo position in the train. By adjusting the compensation gradients according to which echo is being acquired and its position in the interleaved sequence, the system adapts to the specific requirements of each echo while maintaining overall efficiency
3Productivity
If flow compensation is simplified to reduce scanning time, then scanning efficiency improves, but flow artifacts and vein contaminations increase
Solution Approach 1:
The patent extracts and addresses the most critical flow artifact sources by applying full compensation specifically to the central echo, which contains the predominant signal information. By isolating and treating the most important echo with comprehensive compensation while using simplified methods for others, the system achieves good artifact reduction without sacrificing scanning efficiency
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 reduces the impact of flow effects on SWI images, enhances scanning efficiency, and improves image quality by minimizing vein contaminations and maintaining high signal-to-noise ratio.
Implementation Method 1
then, a gradient magnetic field in the Y direction is opened so that precession speeds of magnetic moments in different Y positions will also vary, and then the Y gradient is closed; thus, the precession speeds of magnetic moments in each position are restored to become the same, but phase deviations in different Y positions vary due to the previous differences in procession speed
Implementation Method 2
next, a gradient in the X direction is opened, with different precession speeds of magnetic moments in different X positions
Implementation Method 3
The FC technique supports a variety of gradient combination modes. By multiple transformations of forward and reverse gradient fields having different areas, phase deviations of fluids having various speeds will ultimately be brought close to zero, which allows elimination of motion artifacts
Implementation Method 4
radio frequency (RF) pulses with a specific frequency are applied to the human body in a magnetostatic field so that hydrogen protons in the human body are excited to allow magnetic resonance (MR); after the application of pulses has stopped, MR signals are generated during the relaxation of the protons
Data Source
AI summary
A method and apparatus for susceptibility-weighted imaging, and a magnetic resonance imaging system. The method includes, in planar echo imaging of a plurality of excitations, performing flow compensation in directions of layered encoding, phase encoding, and frequency encoding for echoes of each excitation; after determination of excitation each time, when a linear reordering mode is adopted, for excitation each time, collecting each echo towards space k in a positive direction or a negative direction from the central echo of the plurality of echoes, and collecting echoes of the current excitation in a direction opposite to a direction of collecting echoes of the previous excitation; and subjecting the collected echoes to susceptibility-weighted imaging. An aspect of the present disclosure allows a reduction of flow artifacts in an image created by susceptibility-weighted imaging based on a planar echo sequence.