Norris David G
FC Donders Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands.
Magn Reson Med. 2007 Oct;58(4):643-9. doi: 10.1002/mrm.21339.
This work describes a novel method for rapid acquisition with relaxation enhancement (RARE)/fast spin-echo (FSE) imaging that removes the constraint of compliance with the Carr-Purcell-Meiboom-Gill (CPMG) condition. In a multiecho sequence, echoes with either odd or even parities are acquired. The refocusing angles are chosen using a recursive algorithm, so that the signal amplitude satisfies a predetermined modulation function. In the examples given in this article an exponential decay to a plateau is used. At each echo the echo parity that gives the desired signal amplitude for the minimum refocusing angle is selected. It is further shown that in the presence of an initial magnetization having an arbitrary phase distribution, the complex conjugate of the signal of one echo parity has to be taken and its k-space coordinates reversed. T(2) (*)-weighted images are presented and initial applications to diffusion-weighted imaging (DWI) and functional imaging shown.
这项工作描述了一种用于快速采集并带有弛豫增强（RARE）/快速自旋回波（FSE）成像的新方法，该方法消除了符合 Carr-Purcell-Meiboom-Gill（CPMG）条件的限制。在多回波序列中，采集奇数或偶数奇偶性的回波。使用递归算法选择重聚焦角度，以使信号幅度满足预定的调制函数。在本文给出的示例中，使用到一个平稳期的指数衰减。在每个回波处，选择能给出最小重聚焦角度所需信号幅度的回波奇偶性。进一步表明，在存在具有任意相位分布的初始磁化的情况下，必须获取一个回波奇偶性信号的复共轭，并反转其 k 空间坐标。展示了 T(2)*加权图像以及在扩散加权成像（DWI）和功能成像方面的初步应用。
