Barker G J, Simmons A, Arridge S R, Tofts P S
NMR Research Group, Institute of Neurology, London, UK.
Br J Radiol. 1998 Jan;71(841):59-67. doi: 10.1259/bjr.71.841.9534700.
Inhomogeneity of the transmitted or received B1 field leads to intensity variations in MR images and spatial dependence in apparent concentration in MR spectra. We describe a simple method for investigating such variations. The transmitted B1 field can be measured both in vivo and in vitro which allows investigation of sample dependent effects that can not be measured on phantoms. For homogeneous regions the method also allows the received B1 field to be measured both in vivo and in vitro. Our method uses only a standard spin echo pulse sequence and simple region of interest analysis and should be implementable on any commercial scanner. The method is demonstrated using a variety of transmission and reception radiofrequency coils both in vivo and in vitro.
发射或接收的B1场的不均匀性会导致磁共振图像中的强度变化以及磁共振波谱中表观浓度的空间依赖性。我们描述了一种研究此类变化的简单方法。发射的B1场可在体内和体外进行测量，这使得能够研究无法在模体上测量的样本相关效应。对于均匀区域，该方法还允许在体内和体外测量接收的B1场。我们的方法仅使用标准的自旋回波脉冲序列和简单的感兴趣区域分析，并且应该可以在任何商业扫描仪上实现。该方法在体内和体外使用各种发射和接收射频线圈进行了演示。
