Model-Based Reconstruction for Real-Time Phase-Contrast Flow MRI: Improved Spatiotemporal Accuracy
Model-Based Reconstruction for Real-Time Phase-Contrast Flow MRI: Improved Spatiotemporal Accuracy
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DOI：
10.1002/mrm.26192
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发表时间：
2017-03-01
影响因子：
3.3
通讯作者：
Frahm, Jens
中科院分区：
文献类型：
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作者：
Tan, Zhengguo;Roeloffs, Volkert;Frahm, Jens
目的：开发一种基于模型的实时相位对比流磁共振成像技术，与利用两幅不同流量编码的独立重建图像的相位差的方法相比，具有更高的时空精度。方法：该方法联合计算由高欠采样径向闪光获得的每对流量补偿和流量编码的数据集的共同图像、相位对比图和一组线圈灵敏度。每幅图像5个和7个径向辐条的实时采集分别导致每个相位对比图的测量时间分别为25.6ms和35.7ms。相位对比流磁共振成像的信号模型需要求解一个非线性逆问题，该逆问题通过迭代正则化的高斯-牛顿法来完成。讨论了正则化和缩放化方面的问题。结果：在所有条件下，与先前开发的实时Flow MRI方法相比，该方法能够得到定量准确的相位对比图(即血流速度图)，提高了空间锐度，降低了相位噪声，减少了条纹伪影。结论：这种基于模型的重建技术有望成为临床实时Flow MRI的一种新工具。(C)2016国际医学磁共振学会
Purpose: To develop a model-based reconstruction technique for real-time phase-contrast flow MRI with improved spatiotemporal accuracy in comparison to methods using phase differences of two separately reconstructed images with differential flow encodings.Methods: The proposed method jointly computes a common image, a phase-contrast map, and a set of coil sensitivities from every pair of flow-compensated and flow-encoded datasets obtained by highly undersampled radial FLASH. Real-time acquisitions with five and seven radial spokes per image resulted in 25.6 and 35.7 ms measuring time per phase-contrast map, respectively. The signal model for phase-contrast flow MRI requires the solution of a nonlinear inverse problem, which is accomplished by an iteratively regularized Gauss-Newton method. Aspects of regularization and scaling are discussed. The model-based reconstruction was validated for a numerical and experimental flow phantom and applied to real-time phase-contrast MRI of the human aorta for 10 healthy subjects and 2 patients.Results: Under all conditions, and compared with a previously developed real-time flow MRI method, the proposed method yields quantitatively accurate phase-contrast maps (i.e., flow velocities) with improved spatial acuity, reduced phase noise and reduced streaking artifacts.Conclusion: This novel model-based reconstruction technique may become a new tool for clinical flow MRI in real time. (C) 2016 International Society for Magnetic Resonance in Medicine