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Sparse parallel transmission on randomly perturbed spiral k-space trajectory.

Yong Pang1, Xiaohua Jiang1, Xiaoliang Zhang1

  • 11 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Department of Electrical Engineering, Tsinghua University, Beijing 100084, China ; 3 UCSF/UC Berkeley Joint Group Program in Bioengineering, San Francisco & Berkeley, CA, USA ; 4 California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA.

Quantitative Imaging in Medicine and Surgery
|May 17, 2014
PubMed
Summary

This study introduces a novel sparse parallel transmission technique for faster MRI excitation. By combining parallel transmission with a modified sparse spiral k-space trajectory, it significantly reduces radiofrequency transmission time.

Keywords:
Parallel transmissionRF pulsek-space trajectorypassbandsparse pulse

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Area of Science:

  • Magnetic Resonance Imaging (MRI)
  • Radiofrequency (RF) Pulse Design
  • Coil Engineering

Background:

  • Parallel transmission (simultaneous RF pulses) accelerates MRI by leveraging coil sensitivity.
  • Sparse k-space sampling reduces data acquisition time but requires optimized trajectories.
  • Integrating these techniques offers potential for faster MRI excitation but poses design challenges for k-space trajectories.

Purpose of the Study:

  • To develop and evaluate a novel sparse parallel transmission technique for accelerated MRI excitation.
  • To design an optimal, randomly perturbed sparse k-space trajectory for efficient RF pulse delivery.
  • To assess the feasibility and performance of the proposed method using Bloch simulations.

Main Methods:

  • A randomly perturbed sparse k-space trajectory was designed by modifying a spiral trajectory.
  • Sparse parallel transmission radiofrequency (RF) pulses were designed based on the optimized trajectory.
  • Bloch simulations were performed using a four-channel coil array to evaluate 90° excitation.
  • Excitation performance was assessed at reduction factors of 1, 2, and 4, comparing against regular spiral trajectories.

Main Results:

  • The proposed sparse parallel transmission technique demonstrated feasibility in Bloch simulations.
  • Quantitative assessment showed comparable or improved excitation profiles compared to standard parallel excitation with regular spiral trajectories.
  • Passband errors were calculated for accurate evaluation of excitation profile accuracy.

Conclusions:

  • The combination of parallel transmission and a sparse spiral k-space trajectory offers an effective strategy for reducing RF transmission time in MRI.
  • The developed method shows promise for accelerating MRI acquisition while maintaining excitation quality.
  • Further optimization of k-space trajectories is crucial for maximizing the benefits of sparse parallel transmission.