Phase unwrapping in 4D MR flow with a 4D single-step laplacian algorithm
Phase unwrapping in 4D MR flow with a 4D single-step laplacian algorithm
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DOI：
10.1002/jmri.25045
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发表时间：
2016-04-01
影响因子：
4.4
通讯作者：
Wieben, Oliver
中科院分区：
文献类型：
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作者：
Loecher, Michael;Schrauben, Eric;Wieben, Oliver
PurposeTo介绍和演示的方法展开4D流数据，利用连续性约束在所有四个可用dimensions.Materials和MethodsA拉普拉斯为基础的算法展开相位数据展开展开沿着除了所有三个空间维度的时间维度。在不同血管直径和速度编码（V-enc）值下对模拟血流进行了测试。该算法还在5名志愿者的主动脉中进行了测试，使用V-enc= 80 cm/s和40 cm/s采集的包裹数据。视觉测量解缠绕性能，并与无相位缠绕的高V-enc参考进行比较。10例主动脉缩窄与临床V-enc值和较低的V-enc重建进行了纠正和评分的盲评0-3 scale.ResultsSimulated数据完全展开最临床相关水平的速度混叠使用所提出的方法。对于中度缠绕的情况（V-enc= 80 cm/s，峰值速度=约160 cm/s），主动脉中的体内数据完全展开，而对于更显著混叠的数据集（V-enc= 40 cm/s），残留混叠仍然存在。在评分方面有所改善（临床和低V-enc数据集的平均得分分别提高了1.1和2.2），由患者队列中的盲审者进行标准和低V-enc重建。和无参数的单-用于展开4D流数据的步进方法被示出对于用于最常见的速度混叠的临床发生是有效的。J. Magn. Reson.影像学2016;43：833-842
PurposeTo introduce and demonstrate a method for unwrapping 4D flow data by utilizing continuity constraints in all four available dimensions.Materials and MethodsA Laplacian-based algorithm for unwrapping phase data was expanded to unwrap along the temporal dimension in addition to all three spatial dimensions. The method was tested on simulated blood flow under varying vessel diameters and velocity encoding (V-enc) values. The algorithm was also tested in the aorta of five volunteers, with wrapped data acquired with V-enc=80cm/s and 40cm/s. Unwrapping performance was measured visually and in comparison to a high V-enc reference free of phase wrapping. Ten patients with aortic coarctations with clinical V-enc values and lower-V-enc reconstructions were corrected and scored by blinded reviewers on a 0-3 scale.ResultsSimulated data were completely unwrapped for most clinically relevant levels of velocity aliasing using the proposed method. In vivo data in the aorta were completely unwrapped for cases of moderate wrapping (V-enc=80cm/s, peak velocities=approximate to 160cm/s), while residual aliasing remained for the more considerably aliased datasets (V-enc=40cm/s). Improvements were seen in scoring (mean score improved by 1.1 and 2.2 for clinical and low-V-enc datasets, respectively) by the blinded reviewers in the patient cohort for both standard and low-V-enc reconstructions.ConclusionA computationally fast, fully automated, easy to use, and parameter-free single-step method for unwrapping 4D flow data is shown to be effective for use in most common clinical occurrences of velocity aliasing. J. Magn. Reson. Imaging 2016;43:833-842