Sigmund Eric E, Song Yi-Qiao
Schlumberger-Doll Research, Ridgefield, CT 06877, USA.
Magn Reson Imaging. 2006 Jan;24(1):7-18. doi: 10.1016/j.mri.2005.10.015. Epub 2005 Dec 19.
The standard method of diffusion tensor imaging (DTI) involves one diffusion-sensitizing gradient direction per acquired signal. This paper describes an alternative method in which the entire direction set required for calculating the diffusion tensor is captured in a few scans. In this method, a series of radiofrequency (RF) pulses are applied, resulting in a train of spin echoes. A pattern of applied magnetic field gradients between the RF pulses generates a different diffusion weighting in both magnitude and direction for each echo, resulting in a dataset sufficient to determine the tensor. This significantly reduces the time required for a full DTI scan and potentially allows a tradeoff of this time for image quality. In the present work, this method is demonstrated in an anisotropic diffusion phantom (asparagus).
扩散张量成像(DTI)的标准方法是每个采集信号采用一个扩散敏感梯度方向。本文描述了一种替代方法,通过几次扫描就能获取计算扩散张量所需的完整方向集。在该方法中,施加一系列射频(RF)脉冲,产生一串自旋回波。RF脉冲之间施加的磁场梯度模式为每个回波在大小和方向上产生不同的扩散加权,从而得到足以确定张量的数据集。这显著减少了完整DTI扫描所需的时间,并有可能用此时间换取图像质量的提升。在本研究中,该方法在各向异性扩散模型(芦笋)中得到了验证。