Array-Compressed Parallel Transmit Pulse Design

作者：Cao Zhipeng; Yan Xinqiang; Grissom William A^*

来源：Magnetic Resonance in Medicine, 2016, 76(4): 1158-1169.

DOI：10.1002/mrm.26020

• singular value decomposition
• RF pulse design
• selective excitation
• array compression
• parallel transmission
• spokes pulses
• k(T) points pulses
• RF shimming
• tailored excitation
• optimization

Purpose: To design array-compressed parallel transmit radio-frequency (RF) pulses and compare them to pulses designed with existing transmit array compression strategies.
Theory and Methods: Array-compressed parallel RF pulse design is proposed as the joint optimization of a matrix of complex-valued compression weights that relate a full-channel physical array to a reduced-channel virtual array, along with a set of RF pulses for the virtual array. In this way, the physics of the RF pulse application determine the coil combination weights. Array-compressed pulse design algorithms are described for four parallel transmit applications: accelerated two-dimensional spiral excitation, multislice RF shimming, small-tip-angle k(T)-points excitation, and slice-selective spokes refocusing. Array-compressed designs are compared in simulations and an experiment to pulses designed using four existing array compression strategies.
Results: In all cases, array-compressed pulses achieved the lowest root-mean-square excitation error among the array compression approaches. Low errors were generally achieved without increasing root-mean-square RF amplitudes or maximum local 10-gram specific absorption rate. Leave-one-out multisubject shimming simulations demonstrated that array-compressed RF shimming can identify useful fixed coil combination weights that perform well across a population.
Conclusion: Array-compressed pulse design jointly identifies the transmit coil array compression weights and RF pulses that perform best for a specific parallel excitation application.

• 出版日期2016-10