波谱学杂志 ›› 2018, Vol. 35 ›› Issue (2): 141-149.doi: 10.11938/cjmr20172596

• 研究论文 • 上一篇    下一篇

用于同时多层MRI的选择性射频脉冲的优化设计

卢杉1,2, 常严2, 钱嵩松1, 施波2, 杨晓冬2   

  1. 1. 南京理工大学 电子工程与光电技术学院, 江苏 南京 210094;
    2. 中国科学院苏州生物医学工程技术研究所, 江苏 苏州 215163
  • 收稿日期:2017-09-30 出版日期:2018-06-05 发布日期:2017-12-27
  • 通讯作者: 杨晓冬,Tel:0512-69588133,E-mail:xiaodong.yang@sibet.ac.cn E-mail:xiaodong.yang@sibet.ac.cn
  • 基金资助:
    国家自然科学基金资助项目(11505281,11675254);江苏省社会发展面上项目(BE2017670).

Optimization of Selective Radio Frequency Pulses for Simultaneous Multi-Slice MRI

LU Shan1,2, CHANG Yan2, QIAN Song-song1, SHI Bo2, YANG Xiao-dong2   

  1. 1. College of Electrical Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China;
    2. Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
  • Received:2017-09-30 Online:2018-06-05 Published:2017-12-27

摘要: 近年来,为提高磁共振成像(MRI)信号信噪比(SNR)、缩短成像时间,同时多层成像技术受到了极大的关注.为了实现同时多层的选择性激发,现有的多层成像序列大多使用组合射频(RF)脉冲,该脉冲可包含多个独立的幅值相同相位不同的简单脉冲,由于其采用简单的线性叠加方法,该类脉冲射频功率随脉冲数量呈现平方增长,因而应用受限.针对这一问题,基于自旋动力学和优化控制原理,本文提出了一种针对同时多层MRI的选择性射频脉冲的数值优化方法,该方法充分运用射频脉冲的调控机制,获得优化脉冲,并配合层选梯度,可实现任意层厚、层间距、层数的同时高效选择性激发.最后,通过数字模体的同时多层模拟成像实验验证了优化脉冲的有效性.

关键词: 同时多层成像, 优化控制, 数值优化, 激发轮廓

Abstract: Simultaneous multi-slice magnetic resonance imaging (MRI) has attracted much research interests recently due to its advantages in increasing signal-to-noise ratio (SNR) and decreasing acquisition time. To achieve simultaneous multi-slice excitation, the existing methods used a composite excitation pulse, yielded from the linear combination of radio frequency (RF) pulses with the same amplitude but different phases. The performance of such composite pulse, however, is limited, due to the square relationship between the peak pulse power and slice number. To solve this problem, we proposed a numerical optimization method for multi-slice excitation RF pulse based on both spin dynamics and optimal control theory. Together with slice selection gradient, the optimized pulse achieved selective excitation with arbitrary thickness, distance and number of slices. The performance of the optimized pulse in simultaneous multi-slice MRI was validated by simulation on multimodal imaging-based detailed anatomical (MIDA) digital phantom.

Key words: simultaneous multi-slice MRI, optimal control, numerical optimization, excitation profile

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