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Understanding the zigzags of multi-echo phase signals by numerical simulations
Zikuan Chen1,2,3, Xiulan Zhai2,3, Zeyuan Chen4,5
1Diagnostic Radiology, City of Hope National Medical Center, Duarte, CA 91010, United States of America.
Biomedical Physics & Engineering Express
|October 12, 2022
Summary
This study explains the MRI phase zigzag signal, an artifact in gradient-recalled echo (GRE) imaging. Understanding this zigzag is key for accurate MRI phase data and detecting eddy current effects.
Area of Science:
- Medical Imaging
- Physics
- Computational Science
Background:
- Multi-echo gradient-recalled (GRE) MRI is crucial for brain imaging.
- Phase data quality is essential for advanced MRI analysis.
- Observed phase zigzag signals in GRE simulations require explanation.
Purpose of the Study:
- To provide a theoretical and computational mechanism for multi-echo phase zigzag formation in MRI.
- To understand the impact of gradient perturbations on MRI phase signals.
- To explain the observed zigzag artifacts in clinical MRI data.
Main Methods:
- Simulated multi-echo GRE complex-valued voxel signals using intravoxel dephasing.
- Introduced perturbations in gradient strength (δG) and duration (δΔ).
- Analyzed clinical one-shot multi-echo T2*-weighted MRI phase images.
Main Results:
- Observed a zigzag pattern in multi-echo phase signals with gradient variations.
- Multi-echo magnitude signals remained invariant to field gradient reversal.
- Clinical MRI data showed similar multi-echo phase zigzags.
Conclusions:
- The study provides a theoretical and computational understanding of multi-echo phase zigzag artifacts.
- Eddy current effects are identified as a cause for these artifacts in one-shot multi-GRE signals.
- This research aids in improving MRI phase data quality and interpretation.
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