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Chemical shift encoding using asymmetric readout waveforms
Henric Rydén1,2, Ola Norbeck1,2, Enrico Avventi1,2
1Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden.
Magnetic Resonance in Medicine
|October 22, 2020
Summary
New asymmetric readout waveforms improve fat/water imaging by shortening scan times up to 30% or increasing signal-to-noise ratio (SNR). This method enhances chemical shift encoding for MRI applications.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Medical Physics
- Biomedical Engineering
Background:
- Conventional MRI techniques for fat/water separation face limitations in speed and signal-to-noise ratio (SNR).
- Optimizing chemical shift encoding is crucial for efficient and high-quality imaging.
Purpose of the Study:
- To introduce and evaluate a novel method for chemical shift encoding using asymmetric readout waveforms.
- To demonstrate enhanced SNR efficiency and reduced scan times in fat/water imaging.
Main Methods:
- Asymmetric readout waveforms (triangle and spline) were developed and compared to conventional shifted trapezoid readouts.
- The method was integrated into a fat/water separated Rapid Acquisition Relaxation Enhancement (RARE) sequence.
- Applications in cervical spine, musculoskeletal (MSK), and optic nerve imaging at 3 Tesla were demonstrated.
Main Results:
- Scan times were reduced by 30% with maintained SNR by eliminating dead times.
- Shorter echo spacing led to reduced motion blurring.
- Maintaining scan times with asymmetric waveforms resulted in improved SNR, consistent with extended sampling.
Conclusions:
- Asymmetric readout waveforms provide greater flexibility in pulse sequence design for chemical shift encoding.
- This technique enables significant reductions in scan time or substantial increases in SNR while maintaining scan duration.
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