Lucas MRS/I Center, Department of Radiology, Stanford University, Stanford, California 94305-5488, USA.
Magn Reson Med. 2009 Dec;62(6):1629-40. doi: 10.1002/mrm.22122.
Readout segmentation (RS-EPI) has been suggested as a promising variant to echo-planar imaging (EPI) for high-resolution imaging, particularly when combined with parallel imaging. This work details some of the technical aspects of diffusion-weighted (DW)-RS-EPI, outlining a set of reconstruction methods and imaging parameters that can both minimize the scan time and afford high-resolution diffusion imaging with reduced distortions. These methods include an efficient generalized autocalibrating partially parallel acquisition (GRAPPA) calibration for DW-RS-EPI data without scan time penalty, together with a variant for the phase correction of partial Fourier RS-EPI data. In addition, the role of pulsatile and rigid-body brain motion in DW-RS-EPI was assessed. Corrupt DW-RS-EPI data arising from pulsatile nonlinear brain motion had a prevalence of approximately 7% and were robustly identified via k-space entropy metrics. For DW-RS-EPI data corrupted by rigid-body motion, we showed that no blind overlap was required. The robustness of RS-EPI toward phase errors and motion, together with its minimized distortions compared with EPI, enables the acquisition of exquisite 3 T DW images with matrix sizes close to 512(2).
读出分割（RS-EPI）已被提议作为一种有前途的变体来替代回波平面成像（EPI），用于高分辨率成像，特别是与并行成像相结合时。这项工作详细介绍了扩散加权（DW）-RS-EPI 的一些技术方面，概述了一组重建方法和成像参数，这些方法既可以最小化扫描时间，又可以在减少失真的情况下提供高分辨率的扩散成像。这些方法包括一种用于 DW-RS-EPI 数据的高效广义自校准部分并行采集（GRAPPA）校准，而不会增加扫描时间，以及一种用于部分傅里叶 RS-EPI 数据的相位校正的变体。此外，还评估了脉动和刚体脑运动在 DW-RS-EPI 中的作用。大约有 7%的 DW-RS-EPI 数据因脉动非线性脑运动而受到污染，通过 k 空间熵度量可以可靠地识别。对于因刚体运动而受到污染的 DW-RS-EPI 数据，我们表明不需要盲目重叠。RS-EPI 对相位误差和运动的稳健性，以及与 EPI 相比的最小化失真，使其能够采集到具有接近 512(2) 矩阵大小的精致的 3 T DW 图像。
