Avram Alexandru V, Guidon Arnaud, Truong Trong-Kha, Liu Chunlei, Song Allen W
Section on Tissue Biophysics and Biomimetics, NICHD, National Institutes of Health, Bethesda, Maryland, USA.
Magn Reson Med. 2014 Mar;71(3):1044-53. doi: 10.1002/mrm.24767.
To present a novel technique for high-resolution stimulated echo diffusion tensor imaging with self-navigated interleaved spirals readout trajectories that can inherently and dynamically correct for image artifacts due to spatial and temporal variations in the static magnetic field (B0) resulting from eddy currents, tissue susceptibilities, subject/physiological motion, and hardware instabilities.
The Hahn spin echo formed by the first two 90° radiofrequency pulses is balanced to consecutively acquire two additional images with different echo times and generate an inherent field map, while the diffusion-prepared stimulated echo signal remains unaffected. For every diffusion-encoding direction, an intrinsically registered field map is estimated dynamically and used to effectively and inherently correct for off-resonance artifacts in the reconstruction of the corresponding diffusion-weighted image.
After correction with the dynamically acquired field maps, local blurring artifacts are specifically removed from individual stimulated echo diffusion-weighted images and the estimated diffusion tensors have significantly improved spatial accuracy and larger fractional anisotropy.
Combined with the self-navigated interleaved spirals acquisition scheme, our new method provides an integrated high-resolution short-echo time diffusion tensor imaging solution with inherent and dynamic correction for both motion-induced phase errors and off-resonance effects.
介绍一种用于高分辨率刺激回波扩散张量成像的新技术，该技术采用自导航交错螺旋读出轨迹，能够固有地、动态地校正由于涡流、组织磁化率、受试者/生理运动和硬件不稳定性导致的静磁场（B0）的空间和时间变化所引起的图像伪影。
由前两个90°射频脉冲形成的哈恩自旋回波被平衡，以连续获取具有不同回波时间的另外两幅图像并生成固有场图，而扩散准备的刺激回波信号不受影响。对于每个扩散编码方向，动态估计一个固有配准的场图，并用于在相应扩散加权图像的重建中有效且固有地校正失谐伪影。
在用动态获取的场图进行校正后，局部模糊伪影从各个刺激回波扩散加权图像中被专门去除，并且估计的扩散张量具有显著提高的空间准确性和更大的分数各向异性。
结合自导航交错螺旋采集方案，我们的新方法提供了一种集成的高分辨率短回波时间扩散张量成像解决方案，能够固有地、动态地校正运动引起的相位误差和失谐效应。
