Busse Reed F, Brau Anja C S, Vu Anthony, Michelich Charles R, Bayram Ersin, Kijowski Richard, Reeder Scott B, Rowley Howard A
GE Healthcare, MR Applied Science Lab, Madison, Wisconsin 53717, USA.
Magn Reson Med. 2008 Sep;60(3):640-9. doi: 10.1002/mrm.21680.
Recent advances have reduced scan time in three-dimensional fast spin echo (3D-FSE) imaging, including very long echo trains through refocusing flip angle (FA) modulation and 2D-accelerated parallel imaging. This work describes a method to modulate refocusing FAs that produces sharp point spread functions (PSFs) from very long echo trains while exercising direct control over minimum, center-k-space, and maximum FAs in order to accommodate the presence of flow and motion, SNR requirements, and RF power limits. Additionally, a new method for ordering views to map signal modulation from the echo train into k(y)-k(z) space that enables nonrectangular k-space grids and autocalibrating 2D-accelerated parallel imaging is presented. With long echo trains and fewer echoes required to encode large matrices, large volumes with high in- and through-plane resolution matrices may be acquired with scan times of 3-6 min, as demonstrated for volumetric brain, knee, and kidney imaging.
近期的进展缩短了三维快速自旋回波（3D-FSE）成像的扫描时间，包括通过重聚焦翻转角（FA）调制和二维加速并行成像实现的非常长的回波链。本文描述了一种调制重聚焦FA的方法，该方法能从非常长的回波链中产生锐利的点扩散函数（PSF），同时可直接控制最小、中心k空间和最大FA，以适应血流和运动的存在、信噪比要求以及射频功率限制。此外，还提出了一种新的视图排序方法，用于将回波链中的信号调制映射到k(y)-k(z)空间，从而实现非矩形k空间网格和自动校准二维加速并行成像。如在脑部、膝盖和肾脏的容积成像中所示，使用长回波链且编码大矩阵所需的回波较少，可在3至6分钟的扫描时间内获取具有高平面内和平面分辨率矩阵的大容积图像。
