McNab Jennifer A, Gallichan Daniel, Miller Karla L
Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, University of Oxford, Oxford, UK.
Magn Reson Med. 2010 Jan;63(1):235-42. doi: 10.1002/mrm.22183.
While most diffusion-weighted imaging (DWI) is acquired using single-shot diffusion-weighted spin-echo echo-planar imaging, steady-state DWI is an alternative method with the potential to achieve higher-resolution images with less distortion. Steady-state DWI is, however, best suited to a segmented three-dimensional acquisition and thus requires three-dimensional navigation to fully correct for motion artifacts. In this paper, a method for three-dimensional motion-corrected steady-state DWI is presented. The method uses a unique acquisition and reconstruction scheme named trajectory using radially batched internal navigator echoes (TURBINE). Steady-state DWI with TURBINE uses slab-selection and a short echo-planar imaging (EPI) readout each pulse repetition time. Successive EPI readouts are rotated about the phase-encode axis. For image reconstruction, batches of cardiac-synchronized readouts are used to form three-dimensional navigators from a fully sampled central k-space cylinder. In vivo steady-state DWI with TURBINE is demonstrated in human brain. Motion artifacts are corrected using refocusing reconstruction and TURBINE images prove less distorted compared to two-dimensional single-shot diffusion-weighted-spin-EPI.
虽然大多数扩散加权成像（DWI）是使用单次激发扩散加权自旋回波平面回波成像来采集的，但稳态DWI是一种替代方法，有潜力获得更高分辨率且失真更小的图像。然而，稳态DWI最适合分段三维采集，因此需要三维导航来完全校正运动伪影。本文提出了一种用于三维运动校正稳态DWI的方法。该方法使用一种独特的采集和重建方案，称为使用径向分批内部导航回波的轨迹（TURBINE）。采用TURBINE的稳态DWI在每个脉冲重复时间使用层面选择和短平面回波成像（EPI）读出。连续的EPI读出围绕相位编码轴旋转。对于图像重建，使用成批的心脏同步读出从完全采样的中心k空间圆柱体形成三维导航器。在人脑上展示了采用TURBINE的体内稳态DWI。使用重聚焦重建校正运动伪影，与二维单次激发扩散加权自旋EPI相比，TURBINE图像的失真更小。
