INTRODUCTION Time-resolved three-dimensional phase contrast MRI (4D flow) of aortic blood flow requires acceleration to reduce scan time. Two established techniques for highly accelerated 4D flow MRI are k-t principal component analysis (k-t PCA) and compressed sensing (CS), which employ either regular or random k-space undersampling. The goal of this study was to gain insights into the quantitative differences between k-t PCA- and CS-derived aortic blood flow, especially for high temporal resolution CS 4D flow MRI. METHODS The scan protocol consisted of both k-t PCA and CS accelerated 4D flow MRI, as well as a 2D flow reference scan through the ascending aorta acquired in 15 subjects. 4D flow scans were accelerated with factor R = 8. For CS accelerated scans, we used a pseudo-spiral Cartesian sampling scheme, which could additionally be reconstructed at higher temporal resolution, resulting in R = 13. 4D flow data were compared with the 2D flow scan in terms of flow, peak flow and stroke volume. A 3D peak systolic voxel-wise velocity and wall shear stress (WSS) comparison between k-t PCA and CS 4D flow was also performed. RESULTS The mean difference in flow/peak flow/stroke volume between the 2D flow scan and the 4D flow CS with R = 8 and R = 13 was 4.2%/9.1%/3.0% and 5.3%/7.1%/1.9%, respectively, whereas for k-t PCA with R = 8 the difference was 9.7%/25.8%/10.4%. In the voxel-by-voxel 4D flow comparison we found 13.6% and 3.5% lower velocity and WSS values of k-t PCA compared with CS with R = 8, and 15.9% and 5.5% lower velocity and WSS values of k-t PCA compared with CS with R = 13. CONCLUSION Pseudo-spiral accelerated 4D flow acquisitions in combination with CS reconstruction provides a flexible choice of temporal resolution. We showed that our proposed strategy achieves better agreement in flow values with 2D reference scans compared with using k-t PCA accelerated acquisitions.

中文翻译：

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伪螺旋采样和压缩感知重建在加速主动脉4D流MRI中提供了时间分辨率的灵活性：与kt主成分分析的比较。

引言主动脉血流的时间分辨三维相衬MRI（4D血流）需要加速以减少扫描时间。kt主成分分析（kt PCA）和压缩传感（CS）是两种用于高度加速4D流MRI的成熟技术，它们采用常规或随机k空间欠采样技术。这项研究的目的是深入了解kt PCA和CS衍生的主动脉血流量之间的定量差异，特别是对于高时间分辨率CS 4D流量MRI。方法扫描方案包括kt PCA和CS加速4D流MRI，以及通过15位受试者获得的升主动脉的2D流参考扫描。使用因子R = 8加速了4D流扫描。对于CS加速扫描，我们使用了伪螺旋笛卡尔采样方案，可以另外以更高的时间分辨率进行重建，从而导致R =13。将4D流量数据与2D流量扫描进行了流量，峰值流量和行程量的比较。还进行了kt PCA和CS 4D血流之间的3D峰值收缩体素速度和壁切应力（WSS）比较。结果在R = 8和R = 13的情况下，2D流量扫描和4D流量CS之间的流量/峰值流量/冲程量的平均差分别为4.2％/ 9.1％/ 3.0％和5.3％/ 7.1％/ 1.9％ ，而对于R = 8的kt PCA，差异为9.7％/ 25.8％/ 10.4％。在逐像素4D流动比较中，我们发现与CS相比，kt PCA的速度和WSS值分别降低了13.6％和3.5％，与CS相比，kt PCA的速度和WSS值分别降低了15.9％和5.5％ R = 13。结论伪螺旋加速4D流采集与CS重建相结合，可以灵活地选择时间分辨率。我们表明，与使用kt PCA加速采集相比，我们提出的策略在2D参考扫描中实现了更好的流量值一致性。