Specific absorption rate benefits of including measured electric field interactions in parallel excitation pulse design
Specific absorption rate benefits of including measured electric field interactions in parallel excitation pulse design
复制标题
DOI：
10.1002/mrm.23004
复制
发表时间：
2012-01-01
影响因子：
3.3
通讯作者：
Zhu, Yudong
中科院分区：
文献类型：
--
作者：
Deniz, Cem Murat;Alon, Leeor;Zhu, Yudong
比吸收率管理和激励保真度是射频脉冲设计的关键方面，用于在1000磁场强度下并行传输。用于多个通道的射频脉冲的设计通常基于正则化最小二乘优化问题的解决方案，对于正则化最小二乘优化问题，通常选择正则化项来控制积分或峰值脉冲波形幅度。与单通道传输不同，并行传输的比吸收率受到与各个传输元件相关联的电场之间的干扰的显著影响，而传统的正则化项没有考虑到这一点。本工作探讨了将实验测量的电场相互作用纳入并行传输脉冲设计后的比吸收率的影响。数值模拟和体模实验的结果表明，当电场相互作用纳入脉冲设计优化时，并行传输过程中的全局比吸收率降低。结果还表明，电场相互作用的知识使得能够在扫描仪上播放之前通过并行射频脉冲对传递到样品或受试者的净功率进行鲁棒预测。Magn Reson Med，2011年。(C)2011 Wiley-Liss，Inc.
Specific absorption rate management and excitation fidelity are key aspects of radiofrequency pulse design for parallel transmission at ultrahigh magnetic field strength. The design of radiofrequency pulses for multiple channels is often based on the solution of regularized least-squares optimization problems for which a regularization term is typically selected to control the integrated or peak pulse waveform amplitude. Unlike single-channel transmission, the specific absorption rate of parallel transmission is significantly influenced by interferences between the electric fields associated with the individual transmission elements, which a conventional regularization term does not take into account. This work explores the effects upon specific absorption rate of incorporating experimentally measurable electric field interactions into parallel transmission pulse design. Results of numerical simulations and phantom experiments show that the global specific absorption rate during parallel transmission decreases when electric field interactions are incorporated into pulse design optimization. The results also show that knowledge of electric field interactions enables robust prediction of the net power delivered to the sample or subject by parallel radiofrequency pulses before they are played out on a scanner. Magn Reson Med, 2011. (C) 2011 Wiley-Liss, Inc.