Robust EPI Nyquist ghost elimination via spatial and temporal encoding.

Area of Science:

• Magnetic Resonance Imaging
• Image Artifacts
• Signal Processing

Background:

• Nyquist ghosts are a common artifact in echo planar imaging (EPI).
• Existing methods like phase labeling for additional coordinate encoding (PLACE) and phased array ghost elimination (PAGE) have limitations.
• PLACE can reduce signal-to-noise ratio in sensitive applications when ghosting varies.

Purpose of the Study:

• To develop a more robust method for Nyquist ghost correction in EPI.
• To integrate PLACE and PAGE techniques for improved artifact elimination.
• To enhance the reliability of EPI for quantitative imaging like arterial spin labeling.

Main Methods:

• Integrated temporal (PLACE) and spatial (PAGE) domain encoding for EPI ghost correction.
• Modulated EPI acquisition trajectories to interleave data for inconsistency removal.
• Coherently combined interleaved data to cancel residual Nyquist ghosts within a PAGE reconstruction framework.

Main Results:

• The integrated PLACE-PAGE method demonstrated significantly better Nyquist ghost correction than either method alone.
• The proposed technique proved more robust to variations in ghosting levels compared to PLACE.
• Successful demonstration of robustness in vivo using arterial spin labeling perfusion imaging despite magnetic field drift.

Conclusions:

• Integrating PLACE into a PAGE-based reconstruction offers superior and more robust Nyquist ghost correction in EPI.
• This enhanced correction method preserves signal-to-noise ratio, benefiting quantitative imaging techniques.
• The developed approach provides a reliable solution for artifact reduction in challenging EPI acquisitions.