Simultaneous Motion and Distortion Correction Using Dual-Echo Diffusion-Weighted MRI.
Simultaneous Motion and Distortion Correction Using Dual-Echo Diffusion-Weighted MRI.
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DOI：
10.1111/jon.12708
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发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
Warfield SK
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文献类型：
--
作者：
Afacan O;Hoge WS;Wallace TE;Gholipour A;Kurugol S;Warfield SK
由大的姿态变化引起的几何失真降低了运动测量的准确性，并且干扰了生成无伪影信息的能力。我们的目标是开发一种算法和脉冲序列，以实现运动补偿、几何失真补偿的扩散加权MRI，并评估其在校正由大而频繁的头部运动引起的场不均匀性和位置变化方面的功效。在两个独立的实验中，在5名志愿者中评价了双回波平面成像（EPI）与翻转相位编码失真校正技术，并与静态场图失真校正进行了比较。在第一个实验中，双回波EPI图像采集在两个头部位置，旨在引起一个大的字段不均匀性的变化。在每个位置采集一个场标测图和一个无失真结构图像，以评估双回波EPI生成可靠场标测图的能力，并在两个位置进行几何失真校正。在第二个实验中，志愿者被要求在扩散扫描期间移动到多个随机位置。使用双回波校正和切片到体积（SVR）配准算法重建图像。将SVR运动估计的准确性与外部测量的地面实况运动参数进行比较。我们的研究结果表明，双回波EPI可以产生切片级的字段地图与参考金标准方法产生的字段地图的质量相当。我们还表明，切片级失真校正提高了SVR算法的准确性，因为在不同方向采集的切片具有不同程度的失真，这可能会在配准过程中产生误差。双回波采集与blip-reversed相位编码可以用来生成切片级失真免费的图像，这是运动鲁棒切片体积配准的关键。失真校正的图像不仅导致更好的运动估计，它们还使得能够进行更准确的最终扩散图像重建。
Geometric distortions resulting from large pose changes reduce the accuracy of motion measurements and interfere with the ability to generate artifact free information. Our goal is to develop an algorithm and pulse sequence to enable motion-compensated, geometric distortion compensated diffusion-weighted MRI, and to evaluate its efficacy in correcting for the field inhomogeneity and position changes, induced by large and frequent head motions. Dual echo planar imaging (EPI) with a blip-reversed phase encoding distortion correction technique was evaluated in 5 volunteers in two separate experiments and compared with static field map distortion correction. In the first experiment, dual-echo EPI images were acquired in two head positions designed to induce a large field inhomogeneity change. A field map and a distortion-free structural image were acquired at each position to assess the ability of dual-echo EPI to generate reliable field maps and enable geometric distortion correction in both positions. In the second experiment, volunteers were asked to move to multiple random positions during a diffusion scan. Images were reconstructed using the dual-echo correction and a slice-to-volume (SVR) registration algorithm. The accuracy of SVR motion estimates were compared to externally measured ground truth motion parameters. Our results show that dual-echo EPI can produce slice-level field maps with comparable quality to field maps generated by the reference gold standard method. We also show that slice-level distortion correction improves the accuracy of SVR algorithms as slices acquired at different orientations have different levels of distortion, which can create errors in the registration process. Dual-echo acquisitions with blip-reversed phase encoding can be used to generate slice-level distortion free images, which is critical for motion-robust slice to volume registration. The distortion corrected images not only result in better motion estimates, they also enable a more accurate final diffusion image reconstruction.
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