Quantification of mechanical vibration during diffusion tensor imaging at 3 T
Quantification of mechanical vibration during diffusion tensor imaging at 3 T
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DOI：
10.1016/j.neuroimage.2006.03.004
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发表时间：
2006-08-01
期刊：
影响因子：
5.7
通讯作者：
Joensuu, Raimo
中科院分区：
文献类型：
--
作者：
Hiltunen, Jaana;Hari, Riitta;Joensuu, Raimo
受试者在弥散张量成像（DTI）期间感觉到清晰的机械振动。这些振动可能是由扩散敏感梯度引起的，已经假定在磁共振成像（MRI）扫描仪的所有部分中具有相同的强度和相位，使得它们可以被忽略。然而，我们的测量，从几个部分的MRI扫描仪及其周围环境使用光学激光干涉仪进行，证明了一个不均匀的分布的机械振动的扫描仪。在DT扫描期间，在3 T下，通过将体模定位在头部线圈和/或患者床上的人体受试者中，使用各种扩散加权参数进行测量。振动相关移动是由扩散敏感梯度引起的，最大为0.5 mm，具有脑成像中使用的典型设置。在我们的DTI序列中使用梯度进行涡流补偿，在扩散加权参数B = 1000 s/mm（2）时，振动水平增加了1.5倍或更多，在B = 3000 s/mm（2）时，振动水平增加了3倍或更多。机械振动保持在B的可接受水平
Subjects sense clear mechanical vibrations during diffusion tensor imaging (DTI). These vibrations, likely resulting from diffusion-sensitizing gradients, have been assumed to be of the same strength and phase in all parts of the magnetic resonance imaging (MRI) scanner so that they could be ignored. However, our measurements, carried out from several parts of the MRI scanner and its surroundings using an optical laser-based interferometer, demonstrate an uneven distribution of mechanical vibrations within the scanner. The measurements were performed during DT scanning at 3 T, with various diffusion-weighting parameters, by positioning a phantom in the head coil and/or a human subject on the patient bed. The vibration-related movement was caused by the diffusion-sensitizing gradients and was maximally 0.5 mm with typical settings used in brain imaging. The compensation for eddy currents, done with gradients in our DTI sequence, increased the vibration level by a factor of 1.5 or more with diffusion-weighting parameter b = 1000 s/mm(2) and by a factor of 3 or more with b = 3000 s/mm(2). Mechanical vibrations stayed at an acceptable level with b