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Reduction of eddy-current-induced distortion in diffusion MRI using a twice-refocused spin echo
T G Reese1, O Heid, R M Weisskoff
1Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA. reese@nmr.MGH.harvard.edu
Magnetic Resonance in Medicine
|January 2, 2003
Summary
This study introduces an improved spin-echo diffusion magnetic resonance imaging (MRI) sequence. The enhanced sequence reduces image distortion and artifacts, improving image quality for applications like acute stroke diagnosis.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Diffusion-Weighted Imaging (DWI)
- Biomedical Engineering
Background:
- Field gradient eddy currents cause image artifacts in diffusion-weighted MR images.
- Diffusion-weighted MRI is crucial for diagnosing acute stroke and mapping tissue structure.
- Existing spin-echo (SE) diffusion sequences are susceptible to distortion.
Purpose of the Study:
- To present an improved spin-echo (SE) diffusion sequence for MRI.
- To reduce image distortion and artifacts caused by eddy currents.
- To enhance overall image quality in diffusion-weighted imaging.
Main Methods:
- Implementation of a modified spin-echo diffusion sequence with an additional refocusing pulse.
- Adjustment of diffusion gradient timing to null or reduce eddy currents.
- Demonstration using phantom measurements and diffusion anisotropy imaging of the human brain.
Main Results:
- The new sequence exhibits significantly less image distortion compared to conventional SE sequences.
- Image quality is improved without compromising scanning efficiency or effectiveness.
- Eddy currents with single and similar exponential decay constants are effectively managed.
Conclusions:
- The improved SE diffusion sequence offers superior image quality by minimizing distortion.
- This advancement is beneficial for clinical applications such as acute stroke assessment.
- The sequence allows for more flexible diffusion gradient timing and effective eddy current compensation.