Fast joint design method for parallel excitation radiofrequency pulse and gradient waveforms considering...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Pulse Sequence Design
• Medical Physics

Background:

• Optimizing k-space trajectories is crucial for efficient MRI data acquisition.
• Previous research has explored optimal phase-encoding (PE) location selection, but the impact of B(0) field inhomogeneity on this selection and ordering remains underexplored.

Purpose of the Study:

• To introduce a fast parallel algorithm for designing excitation pulses in Echo-Volumar (EV) trajectories.
• To investigate the benefits of considering B(0) field inhomogeneity during PE location selection and ordering.
• To improve excitation accuracy and provide effective PE location ordering.

Main Methods:

• Development of a novel fast greedy algorithm for PE location selection and ordering.
• Incorporation of B(0) field inhomogeneity (off-resonance effects) into the algorithm's decision-making process.
• Computer simulations to evaluate the algorithm's performance, including B(1) field inhomogeneity correction.

Main Results:

• The proposed algorithm effectively determines PE locations and their order while accounting for off-resonance effects.
• Simulations demonstrate improved excitation accuracy compared to methods not considering B(0) inhomogeneity.
• The algorithm provides an effective ordering of PE locations, enhancing trajectory performance.

Conclusions:

• The developed fast greedy algorithm offers a significant advancement in excitation pulse design for EV trajectories.
• Considering B(0) field inhomogeneity during PE location selection and ordering leads to improved MRI excitation accuracy.
• This approach provides a practical solution for optimizing k-space trajectories in the presence of field inhomogeneities.