Two methods for peak RF power minimization of multiple inversion-band pulses
Two methods for peak RF power minimization of multiple inversion-band pulses
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DOI：
10.1002/mrm.1910370506
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发表时间：
1997-05-01
影响因子：
3.3
通讯作者：
Goelman, G
中科院分区：
文献类型：
--
作者：
Goelman, G
提出了两种新的降低高阶纵向阿达玛编码峰值射频功率的方法，并进行了实验验证。第一种方法利用这样的事实，即在反演过程中参考相位的选择不影响最终的频率响应。在该方法中，不同的单个反相带脉冲被加在一起，每个脉冲具有不同的参考相位。对于适当的相位选择，获得峰值RF功率的最小化。标度律被定义为允许在多种情况下使用给定的相位集。在第二种方法中，将单个反转带脉冲加在一起，每个脉冲在时间上部分移位。这导致峰值功率显著降低，而脉冲长度仅适度增加。实验结果验证了理论分析的正确性，并证明了该方法的频率响应不受峰值功率最小化过程的影响。在新的低峰值射频功率下，可以在任何临床环境下进行8阶（或16阶）的纵向Hadamard编码。
Two novel methods to minimize peak RF power for high order longitudinal Hadamard encoding are described and demonstrated experimentally. The first method uses the fact that the choice of a reference phase in an inversion process does not affect the final frequency response. In this method, the different single inversion-band pulses are added together, each with a different reference phase. For a proper phase choice, minimization of the peak RF power is obtained. Scaling laws are defined allowing the use of a given phase-set in multiple cases. In the second method, single inversion-band pulses are added together, each partially shifted in time. This results in a significant reduction in peak power with only a moderate increase ire pulse length. Theoretical conditions outlining the optimal addition order are defined, Experimental results verify the theoretical conditions and demonstrate that the frequency response is not affected by the peak power minimization process, With the new low peak RF power, longitudinal Hadamard encoding of 8TH (or 16TH) order can be performed in any clinical setting.