Olt Silvia, Schmitt Peter, Fidler Florian, Haase Axel, Jakob Peter M
Physikalisches Institut, EP5, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
MAGMA. 2002 Nov;15(1-3):45-51. doi: 10.1007/BF02693843.
In this study, a new strategy for slow flow imaging is proposed. The basic idea is to generate flow contrast on a microscopic level below the spatial resolution of an imaging experiment. Since a microscopic spin tagging scheme is used, this concept is called MiST (Microscopic Spin Tagging). MiST is not a single specific measurement sequence, but rather a new flow sensitive preparation concept which is highly flexible and can be carried out in many ways. The common principle in all possible realizations of MiST is a periodic tagging of magnetization in thin planes (100-200 microm) within the imaging voxels by means of spatially selective RF-pulses. Therefore, flow sensitivity occurs via inflow of fresh spins on a microscopic scale. With this approach, short evolution times are sufficient to introduce inflow contrast and a spatial dependence of inflow times is avoided. The flow sensitive preparation and image orientation are also not connected as they are in conventional time-of-flight techniques. Another powerful feature of MiST is that it can be designed as a non-subtraction method, which results in no signal from stationary spins. Here we present a first realization of the MiST concept and its validation in quantitative flow measurements to demonstrate the feasibility of the proposed preparation concept.
在本研究中，提出了一种用于慢流成像的新策略。其基本思想是在成像实验的空间分辨率以下的微观层面上生成流动对比。由于使用了微观自旋标记方案，这一概念被称为MiST（微观自旋标记）。MiST不是一个单一的特定测量序列，而是一种高度灵活且可以通过多种方式实现的新的流动敏感准备概念。MiST所有可能实现方式的共同原理是通过空间选择性射频脉冲对成像体素内薄平面（100 - 200微米）中的磁化进行周期性标记。因此，流动敏感性通过微观尺度上新鲜自旋的流入而产生。通过这种方法，短的演化时间足以引入流入对比，并且避免了流入时间的空间依赖性。流动敏感准备和图像取向也不像传统飞行时间技术那样相互关联。MiST的另一个强大特性是它可以被设计为一种非减法方法，这使得静止自旋不产生信号。在此，我们展示了MiST概念的首次实现及其在定量流动测量中的验证，以证明所提出的准备概念的可行性。
