Improvements in Spiral MR Imaging

描述(由申请人提供)：使用最先进的1.5T磁共振系统，建议项目的主要目标是通过减少成像时间、提高对运动伪影的免疫力和改进非共振(和化学位移)重建来显著改进螺旋MRI，从而实现新的和/或改进的心脏、大脑和身体成像应用。其具体目的是：(1)通过并行成像方法和高加速下的重建(如SENSE、GRAPPA、共轭梯度)，有效地减少螺旋MRI的采集时间，从而提高螺旋MR运动伪影的免疫力；(2)开发与传统频率分段方法相比具有更高性能和更少计算时间的新的快速偏离共振校正技术，(3)创建稳健的螺旋脂肪/水分离方法，其防止偏离共振模糊，并提供优于空间频谱技术的性能和缩短的采集时间，以及(4)开发基于最小化时间、混叠能量、流动敏感性、偏离共振模糊和/或其他图像质量测量的帕累托最优/(-空间轨迹设计方法。 我们的项目将表明，使用新的螺旋采集、新的后处理方法和新的轨迹设计技术，使用/(-空间和/或图像数据)可以减少成像时间，并显著改善心脏、大脑和腹部的成像。初步结果表明，通过并行成像显著提高运动免疫力是可能的。在探索重建算法、加速量和可靠性方面的改进仍有重要工作要做。采用分块区域校正法可以减少非共振计算负担。例如，在性能和速度方面的进一步改进将探索使用区域信息来控制计算块大小。与常用的空间谱方法相比，我们的脂肪抑制方法将使扫描时间减少2-4倍，性能优越；我们探索了2pt和3pt螺旋Dixon方法(在相同的扫描时间下)的效率/稳健性。与传统的直线或螺旋方法相比，这些方法本身就可以改善腹部和心脏的成像。独特的是，我们先进的非直线轨迹设计方法是将非共振、运动和卡帕空间采样密度效应之间的相互关系正式地链接到图像域伪影，从而使得独特的波形参数化和形式优化能够创建比传统设计更好的轨迹(从而产生更好的图像)。我们相信，这些目标的成功实现将大大改善螺旋磁共振，从而更好地利用这一重要的磁共振方法。

DESCRIPTION (provided by applicant): Using a state-of-the-art 1.5T MR system, the main goal of the proposed project is to create significant im- provements in spiral MRI via novel techniques that reduce imaging time, improve immunity to motion artifact, and improve off-resonance (and chemical shift) reconstruction so that new and/or improved cardiac, brain and body imaging applications will be enabled. The specific aims are to: (1) improve spiral MR motion artifact immunity by developing efficient reductions in spiral MRI acquisition time through parallel imaging methods and reconstruction (e.g., SENSE, GRAPPA, conjugate gradient) at high acceleration; (2) develop new rapid off-resonance correction techniques with improved performance and reduced computation time when compared to conventional frequency segmented methods, (3) create robust spiral fat/water separation methods that prevent off-resonance blurring and provide superior performance and reduced acquisition time when compared to spatial spectral techniques, and, (4) develop methodologies for Pareto-optimal /(-space trajectory design based on minimizing time, aliasing energy, flow sensitivity, off-resonance blurring and/or other image quality measurements. Our project will show that use of new spiral acquisition, new post-processing methods and new trajectory de- sign techniques using/(-space and/or image data can reduce imaging time and significantly improve cardiac, brain and abdominal imaging. Preliminary results show that significant improvements in motion immunity through parallel imaging are possible. Significant work remains to explore improvements in reconstruction algorithms, amount of acceleration, and reliability. Off-resonance computational burden can be reduced by using a block re- gional correction method. For example, further improvements in performance and speed will explore use of re- gional information to control the computational block size. Our fat suppression methods will give rise to reductions in scan time by up to a factor of 2-4X with superior performance as compared to commonly used spatial spectral approaches; the efficiency/robustness of 2pt and 3pt Spiral Dixon methods (at equal scan time) are explored. These alone will enable improved abdominal and cardiac imaging when compared to conventional rectilinear or spiral methods. Uniquely, our advanced non-rectilinear trajectory, design method is that the inter-relationship be- tween off-resonance, motion and kappa-space sampling density effects are formally linked to image domain artifacts, thereby enabling unique waveform parameterizations and formal optimization to create superior trajectories (and hence better images) than those designed conventionally. We believe successful attainment of these aims will give rise to significant improvements in spiral MR and hence greater utilization of this important MR method.