7T与4T对比：头部图像中的射频功率、均匀性及信噪比比较
7T vs. 4T: RF power, homogeneity, and signal-to-noise comparison in head images.
作者信息
Vaughan J T, Garwood M, Collins C M, Liu W, DelaBarre L, Adriany G, Andersen P, Merkle H, Goebel R, Smith M B, Ugurbil K
机构信息
Center for MR Research, Department of Radiology, School of Medicine, University of Minnesota, 2021 Sixth Street SE, Minneapolis, MN 55455, USA.
出版信息
Magn Reson Med. 2001 Jul;46(1):24-30. doi: 10.1002/mrm.1156.
Signal-to-noise ratio (SNR), RF field (B(1)), and RF power requirement for human head imaging were examined at 7T and 4T magnetic field strengths. The variation in B(1) magnitude was nearly twofold higher at 7T than at 4T ( approximately 42% compared to approximately 23%). The power required for a 90 degrees pulse in the center of the head at 7T was approximately twice that at 4T. The SNR averaged over the brain was at least 1.6 times higher at 7T compared to 4T. These experimental results were consistent with calculations performed using a human head model and Maxwell's equations. Magn Reson Med 46:24-30, 2001.
在7T和4T磁场强度下，对用于人体头部成像的信噪比（SNR）、射频场（B(1)）和射频功率要求进行了研究。7T时B(1)幅度的变化比4T时高出近两倍（约42%相比于约23%）。在7T时头部中心产生90度脉冲所需的功率约为4T时的两倍。与4T相比，7T时大脑平均信噪比至少高出1.6倍。这些实验结果与使用人体头部模型和麦克斯韦方程组进行的计算结果一致。《磁共振医学》46:24 - 30，2001年。
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