Specific absorption rate reduction using nonlinear gradient fields
Specific absorption rate reduction using nonlinear gradient fields
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DOI：
10.1002/mrm.24478
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发表时间：
2013-08-01
影响因子：
3.3
通讯作者：
Atalar, Ergin
中科院分区：
文献类型：
--
作者：
Kopanoglu, Emre;Yilmaz, Ugur;Atalar, Ergin
比吸收率是磁共振成像的主要安全参数之一。成像序列的性能经常受到特定吸收率的限制的阻碍，这些限制在较高的场强下会增加严重性。降低比吸收率的最著名的方法大概是可变速率选择性激发技术，该技术及时修改梯度波形。在这篇文章中，介绍了一种替代方法，使用梯度场与空间的非线性变化，以减少特定的吸收率。示出了这样的梯度场对所需的激励分布和相应的射频脉冲之间的关系的影响。通过三个射频脉冲设计实例，验证了该方法的可行性。最后，将该方法与变速选择激励技术进行了比较和结合。Magn Reson Med 70：537-546，2013. (c)2012 Wiley Periodicals，Inc.
The specific absorption rate is used as one of the main safety parameters in magnetic resonance imaging. The performance of imaging sequences is frequently hampered by the limitations imposed on the specific absorption rate that increase in severity at higher field strengths. The most well-known approach to reducing the specific absorption rate is presumably the variable rate selective excitation technique, which modifies the gradient waveforms in time. In this article, an alternative approach is introduced that uses gradient fields with nonlinear variations in space to reduce the specific absorption rate. The effect of such gradient fields on the relationship between the desired excitation profile and the corresponding radiofrequency pulse is shown. The feasibility of the method is demonstrated using three examples of radiofrequency pulse design. Finally, the proposed method is compared with and combined with the variable rate selective excitation technique. Magn Reson Med 70:537-546, 2013. (c) 2012 Wiley Periodicals, Inc.