Improvements in Spiral MR Imaging

描述（由申请人提供）：使用最先进的1.5T MR系统，申报项目的主要目标是通过新技术对螺旋MRI进行重大改进，这些新技术可缩短成像时间，提高对运动伪影的免疫力，并改善非共振（和化学位移）重建，从而实现新的和/或改进的心脏、大脑和身体成像应用。具体目标是：（1）通过并行成像方法和重建（例如，SENSE、GRAPPA、共轭梯度）;（2）开发新的快速非共振校正技术，与传统的频率分段方法相比，该技术具有改进的性能和减少的计算时间，（3）创建鲁棒的螺旋脂肪/水分离方法，该方法防止非共振模糊，并且与空间谱技术相比，提供上级性能和减少的采集时间，以及，（4）基于最小化时间、混叠能量、流动灵敏度、非共振模糊和/或其他图像质量测量，开发用于帕累托最优/空间轨迹设计的方法。 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、大脑和腹部成像。初步结果表明，通过并行成像的运动免疫显着改善是可能的。重要的工作仍然是探索重建算法，加速量和可靠性的改进。采用分块区域修正方法可以减少非共振计算量。例如，性能和速度的进一步改进将探索使用区域信息来控制计算块大小。与常用的空间光谱方法相比，我们的脂肪抑制方法将使扫描时间减少2- 4倍，具有上级性能;探索了2 pt和3 pt螺旋狄克逊方法（在相同的扫描时间）的效率/鲁棒性。与传统的直线或螺旋方法相比，这些单独的方法将能够改善腹部和心脏成像。独特的是，我们先进的非直线轨迹设计方法是，非共振、运动和kappa空间采样密度效应之间的相互关系被正式地链接到图像域伪影，从而实现独特的波形参数化和正式优化，以创建比传统设计的轨迹更好的上级轨迹（并因此创建更好的图像）。我们相信，成功实现这些目标将导致显着改善螺旋MR，因此更大的利用这一重要的MR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.