Parrish T, Hu X
Department of Radiology, University of Minnesota, Minneapolis.
Magn Reson Med. 1994 Nov;32(5):652-7. doi: 10.1002/mrm.1910320515.
The T2 contrast in images obtained with driven equilibrium (90degreesx-180degreesx-90degreesx) prepared ultrafast gradient-echo sequence is compromised by the longitudinal magnetization build-up after the second 90degreesx pulse, which does not carry T2 information. This paper describes a new T2 contrast preparation technique for ultrafast gradient-echo sequence that suppresses the signal arising from the build-up. By dephasing in the preparation and rephasing in the acquisition of the gradient echoes, the new technique eliminates signals that are not dictated by the T2 contrast in a driven-equilibrium approach. Consequently, it generates an image that is essentially T2-weighted. Phantom and in vivo experiments were conducted to validate the technique and to demonstrate its clinical utility. These studies indicate that the technique works properly and can be used for in vivo studies.
采用驱动平衡（90°x - 180°x - 90°x）准备的超快梯度回波序列所获得图像中的T2对比度，会因第二个90°x脉冲后纵向磁化强度的积累而受损，该积累不携带T2信息。本文描述了一种用于超快梯度回波序列的新型T2对比度准备技术，该技术可抑制由积累产生的信号。通过在梯度回波的准备阶段进行去相和在采集阶段进行重相，新技术消除了在驱动平衡方法中不由T2对比度决定的信号。因此，它生成的图像本质上是T2加权的。进行了体模和体内实验以验证该技术并证明其临床实用性。这些研究表明该技术运行正常，可用于体内研究。
