Sotak C H, Li L
Department of Biomedical Engineering, Worcester Polytechnic Institute, Massachusetts 01609.
Magn Reson Med. 1992 Jul;26(1):174-83. doi: 10.1002/mrm.1910260117.
A new magnetic resonance imaging technique for evaluating anisotropic and restricted diffusion effects in a single experiment is described. The method is based on a pulse sequence that simultaneously excites a spin echo (SE) and a stimulated echo (STE) and contains two pairs of diffusion-sensitive gradient pulses. The diffusion attenuation of the SE and STE can be controlled independently by separate adjustment of the parameters associated with each pair of the diffusion-sensitive gradient pulses. This method can be more time efficient than acquiring separate SE and STE images for the same study. Furthermore, the pulse sequence minimizes the effect of motion and instrumental and physiological variations that occur between separate image acquisitions which can give rise to artifactual results when difference imaging is employed. In addition to applications to anisotropic and restricted diffusion, this technique can be used for: (1) simultaneous acquisition of T2-weighted and diffusion-weighted images during cerebral ischemia studies; (2) calculation of diffusion coefficients from a pair of diffusion-weighted images; (3) separating fast and slow diffusion components in a single imaging experiment; and (4) two-dimensional velocity-encoded imaging.
本文描述了一种用于在单个实验中评估各向异性和受限扩散效应的新型磁共振成像技术。该方法基于一个脉冲序列，该序列同时激发自旋回波（SE）和受激回波（STE），并包含两对扩散敏感梯度脉冲。通过分别调整与每对扩散敏感梯度脉冲相关的参数，可以独立控制SE和STE的扩散衰减。与为同一研究获取单独的SE和STE图像相比，该方法可以更节省时间。此外，该脉冲序列将单独图像采集之间发生的运动、仪器和生理变化的影响降至最低，当采用差异成像时，这些变化可能会产生伪影结果。除了应用于各向异性和受限扩散外，该技术还可用于：（1）在脑缺血研究期间同时采集T2加权和扩散加权图像；（2）从一对扩散加权图像计算扩散系数；（3）在单个成像实验中分离快速和慢速扩散成分；以及（4）二维速度编码成像。
