Sparse parallel transmission on randomly perturbed spiral k-space trajectory.
Combination of parallel transmission and sparse pulse is able to shorten the excitation by using both the coil sensitivity and sparse k-space, showing improved fast excitation capability over the use of parallel transmission alone. However, to design an optimal k-space trajectory for sparse parallel transmission is a challenging task. In this work, a randomly perturbed sparse k-space trajectory is designed by modifying the path of a spiral trajectory along the sparse k-space data, and the sparse parallel transmission RF pulses are subsequently designed based on this optimal trajectory. This method combines the parallel transmission and sparse spiral k-space trajectory, potentially to further reduce the RF transmission time. Bloch simulation of 90° excitation by using a four channel coil array is performed to demonstrate its feasibility. Excitation performance of the sparse parallel transmission technique at different reduction factors of 1, 2, and 4 is evaluated. For comparison, parallel excitation using regular spiral trajectory is performed. The passband errors of the excitation profiles of each transmission are calculated for quantitative assessment of the proposed excitation method.
1 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.
Yong
Y
Pang
1 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.
Xiaohua
X
Jiang
1 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.
Xiaoliang
X
Zhang
Parallel transmission; RF pulse; k-space trajectory; passband; sparse pulse