Robust prescan calibration for multiple spin-echo sequences: application to FSE and b-SSFP

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Biomedical Engineering

Background:

• Multiple spin-echo (MSE) sequences require precise phase relationships between spin echoes and stimulated echoes.
• Failure to maintain this coherence causes dark banding artifacts due to destructive interference.
• Achieving microsecond-scale precision is challenging with strong diffusion gradients, arbitrary orientations, and high fields.

Purpose of the Study:

• To develop a robust prescan technique for correcting phase coherence issues in MSE sequences.
• To improve image quality for fast spin echo (FSE) and balanced steady-state free precession (b-SSFP) under challenging conditions.
• To enable high-quality MRI at high magnetic field strengths.

Main Methods:

• A readout-projection-based prescan technique was developed and tested on a 4-T whole-body scanner.
• The technique utilizes banding artifacts to automatically adjust gradient balance, ensuring signal coherence.
• The method was applied to FSE and b-SSFP sequences for image acquisition.

Main Results:

• The prescan technique successfully ensured coherent signal formation, eliminating dark banding artifacts.
• Coherent-echo images were robustly acquired under challenging imaging conditions.
• Demonstrated effectiveness for FSE and b-SSFP sequences in human volunteer knee imaging.

Conclusions:

• The developed prescan calibration technique is critical for aligning signal pools in MSE sequences at high magnetic fields.
• This method facilitates the implementation of high-quality, clinically significant FSE and b-SSFP sequences.
• The approach enhances the reliability and quality of advanced MRI techniques.