Reduction of eddy-current-induced distortion in diffusion MRI using a twice-refocused spin echo

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.