Johnson Patricia M, Liu Junmin, Wade Trevor, Tavallaei Mohammad Ali, Drangova Maria
Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
Magn Reson Imaging. 2016 Nov;34(9):1274-1282. doi: 10.1016/j.mri.2016.06.006. Epub 2016 Jul 20.
To develop and evaluate a rapid spherical navigator echo (SNAV) motion correction technique, then apply it for retrospective correction of brain images.
The pre-rotated, template matching SNAV method (preRot-SNAV) was developed in combination with a novel hybrid baseline strategy, which includes acquired and interpolated templates. Specifically, the SNAV templates are only rotated around X- and Y-axis; for each rotated SNAV, simulated baseline templates that mimic object rotation about the Z-axis were interpolated. The new method was first evaluated with phantom experiments. Then, a customized SNAV-interleaved gradient echo sequence was used to image three volunteers performing directed head motion. The SNAV motion measurements were used to retrospectively correct the brain images. Experiments were performed using a 3.0T whole-body MRI scanner and both single and 8-channel head coils.
Phantom rotations and translations measured using the hybrid baselines agreed to within 0.9° and 1mm compared to those measured with the original preRot-SNAV method. Retrospective motion correction of in vivo images using the hybrid preRot-SNAV effectively corrected for head rotation up to 4° and 4mm.
The presented hybrid approach enables the acquisition of pre-rotated baseline templates in as little as 2.5s, and results in accurate measurement of rotations and translations. Retrospective 3D motion correction successfully reduced motion artifacts in vivo.
开发并评估一种快速球面导航回波（SNAV）运动校正技术，然后将其应用于脑部图像的回顾性校正。
结合一种新型混合基线策略开发了预旋转模板匹配SNAV方法（preRot-SNAV），该策略包括采集的模板和插值模板。具体而言，SNAV模板仅绕X轴和Y轴旋转；对于每个旋转的SNAV，插值模拟绕Z轴旋转的物体的基线模板。首先通过体模实验评估新方法。然后，使用定制的SNAV交错梯度回波序列对三名进行定向头部运动的志愿者进行成像。SNAV运动测量用于回顾性校正脑部图像。实验使用3.0T全身MRI扫描仪以及单通道和8通道头部线圈进行。
与使用原始preRot-SNAV方法测量的结果相比，使用混合基线测量的体模旋转和平移在0.9°和1mm范围内一致。使用混合preRot-SNAV对体内图像进行回顾性运动校正可有效校正高达4°和4mm的头部旋转。
所提出的混合方法能够在短短2.5秒内采集预旋转基线模板，并能准确测量旋转和平移。回顾性3D运动校正在体内成功减少了运动伪影。
