Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.
Magn Reson Med. 2018 Apr;79(4):2046-2056. doi: 10.1002/mrm.26877. Epub 2017 Aug 24.
To develop a method of tracking active NMR markers that requires no alterations of common imaging sequences and can be used for prospective motion correction (PMC) in brain MRI.
Localization of NMR markers is achieved by acquiring short signal snippets in rapid succession and evaluating them jointly. To spatially encode the markers, snippets are timed such that signal phase is accrued during sequence intervals with suitably diverse gradient actuation. For motion tracking and PMC in brain imaging, the markers are mounted on a lightweight headset. PMC is then demonstrated with high-resolution T *- and T -weighted imaging sequences in the presence of instructed as well as residual unintentional head motion.
With both unaltered sequences, motion tracking was achieved with precisions on the order of 10 µm and 0.01° and temporal resolution of 48 and 39 ms, respectively. On this basis, PMC improved image quality significantly throughout.
The proposed approach permits high-precision motion tracking and PMC with standard imaging sequences. It does so without altering sequence design and thus overcomes a key hindrance to routine motion tracking with NMR markers. Magn Reson Med 79:2046-2057, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
开发一种无需改变常见成像序列即可跟踪主动 NMR 标记的方法，并且可用于脑 MRI 的前瞻性运动校正（PMC）。
通过快速连续采集短信号片段并联合评估来实现 NMR 标记的定位。为了对标记进行空间编码，将片段定时，使得在具有适当不同梯度激励的序列间隔期间累积信号相位。对于脑成像中的运动跟踪和 PMC，将标记安装在轻便的耳机上。然后，在存在指令性和残留非故意头部运动的情况下，用高分辨率 T *和 T 加权成像序列演示 PMC。
使用未经修改的序列，运动跟踪的精度分别约为 10 µm 和 0.01°，时间分辨率分别为 48 和 39 ms。在此基础上，整体上显著改善了 PMC 的图像质量。
所提出的方法允许使用标准成像序列进行高精度的运动跟踪和 PMC。它无需改变序列设计，从而克服了使用 NMR 标记进行常规运动跟踪的关键障碍。磁共振医学 79:2046-2057, 2018。© 2017 国际磁共振学会。
