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The effect of concomitant gradient fields on MRI with long readout radial-based trajectories
Michael A Malmberg1,2, Henrik Odéen2, Seong-Eun Kim2
1Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA.
Magnetic Resonance in Medicine
|April 3, 2025
Summary
Concomitant gradient fields (CCGF) cause imaging artifacts in radial scans. New helical trajectories with azimuthal rotation effectively reduce these artifacts in MRI.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Medical Physics
- Image Reconstruction
Background:
- Concomitant gradient fields (CCGF) are a known source of artifacts in MRI.
- Radial-based trajectories are susceptible to phase variations induced by CCGF, leading to image distortions.
Purpose of the Study:
- To theoretically and practically demonstrate CCGF-induced artifacts in radial MRI.
- To develop and validate strategies for mitigating these artifacts.
Main Methods:
- Developed a framework linking concomitant gradient phase to point-spread-function distortion.
- Simulated gradient waveforms and evaluated imaging parameters.
- Validated predictions with phantom and in vivo 3T MRI experiments.
Main Results:
- CCGF artifacts increase with gradient strength and contrast index in radial trajectories.
- Artifacts stem from increased concomitant gradient phase variation across view angles.
- Helical EPI and stack-of-stars trajectories with azimuthal rotation significantly diminished artifacts.
Conclusions:
- CCGF cause significant artifacts in long readout radial MRI due to phase variations.
- Azimuthal rotation in helical trajectories effectively mitigates CCGF artifacts.
- Improvements are notable in complex imaging scenarios like nonaxial imaging and high gradient amplitudes.
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