Multidimensional motion correction in MRI

MRI 中的多维运动校正

• 批准号: RGPIN-2016-05835
• 负责人: Drangova, Maria
• 金额: $ 2.99万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688310
• 关键词: Multidimensional; motion; correction; MRI

BACKGROUND: The availability of high field strength magnetic resonance imaging (MRI) scanners is driving resolution to higher levels. However subject motion can often negate the benefits of increasing field strength by blurring images or introducing artifacts. Degradation in image quality is a result of the motion itself and the change in local magnetic field uniformity resulting from the motion. Therefore methods for rapid measurement of motion in six-degrees of freedom (DoF) and rapid generation of a magnetic field (B0) map, which can be used for active shimming, are required.***An approach to detect bulk motion is the navigator-echo method, which measures motion from the MR signal acquired in k-space. The geometric features of a navigator k-space trajectory and the motion extraction algorithms are two key aspects in developing navigator-based techniques. We have developed acquisition and computational algorithms to determine motion in 6 DoF using a spherical navigator (SNAV) rapidly, by registering the navigator data acquired at the moved position with navigator templates collected at a reference position.***For real time shimming following the detection of large motion, a need exists for rapid methods to measure the local magnetic field in 3D. At high field strength such measurements are often difficult because of numerous wraps of the phase images used to generate the field map. We have developed robust and computationally efficient phase unwrapping and B0 mapping methods, enabling accurate and rapid B0 mapping.***OBJECTIVE: We propose to develop efficient and robust implementations of our SNAV technique to provide 6 DoF motion determination during MR imaging at high field strengths along with real time shimming. Technical developments and experimental evaluation will focus on combining the novel navigator technique with real time field mapping to compensate for involuntary and physiological motions at 3T and 7T.***APPROACH: The program will focus on:*** Optimization of the accelerated SNAV trajectories *** Implementation of real-time B0 field mapping technique *** Modeling of the changes of B0 for different head motions and incorporating these models, along with the real time maps, into an active shimming algorithm*** Integration of the novel shimming and motion correction techniques within ultra-high resolution pulse sequences for brain imaging and optimization of timing parameters to allow on-the fly motion correction*** Optimization of analysis techniques to minimize processing time, while expanding the range of motion that can be tracked*** Evaluation in purpose-built dynamic models***SIGNIFICANCE: The success of this work will lead to the ability to monitor and correct for 6 DoF motion in real time using an MR-based technique, while also performing active shimming based on the motion measurements made. The proposed technical developments promises to have immediate impact on MR imaging.**

背景：高场强磁共振成像（MRI）扫描仪的可用性正在推动分辨率向更高水平发展。然而，被摄体的运动往往会通过模糊图像或引入伪影来抵消增加场强的好处。图像质量的下降是运动本身和运动引起的局部磁场均匀性变化的结果。因此，需要快速测量六自由度（DoF）运动和快速生成可用于主动摆振的磁场（B0）图的方法。***探测大块运动的一种方法是导航回波法，它从k空间获得的MR信号中测量运动。导航器k空间轨迹的几何特征和运动提取算法是发展基于导航器技术的两个关键方面。我们开发了采集和计算算法，通过将在移动位置获取的导航器数据与在参考位置收集的导航器模板进行注册，使用球形导航器（SNAV）快速确定6自由度的运动。***对于大运动检测后的实时振荡，需要在3D中快速测量局部磁场的方法。在高场强的情况下，这种测量通常是困难的，因为用于生成场图的相位图像有许多层。我们开发了鲁棒和计算效率高的相位展开和B0映射方法，实现了准确和快速的B0映射。***目的：我们建议开发高效且稳健的SNAV技术，在高场强和实时振荡的MR成像过程中提供6自由度运动确定。技术开发和实验评估将集中于将新型导航技术与实时现场测绘相结合，以补偿3T和7T时的非自愿和生理运动。* * *的方法:该计划将重点关注：***加速SNAV轨迹的优化***实时B0场测绘技术的实现***不同头部运动的B0变化建模并结合这些模型，以及实时地图；***在超高分辨率脑成像脉冲序列中集成了新颖的游动和运动校正技术，并优化了定时参数，以允许动态运动校正***优化了分析技术，以最大限度地减少处理时间，同时扩大了可跟踪的运动范围***专用动态模型评估***意义：这项工作的成功将导致使用基于核磁共振的技术实时监测和纠正6自由度运动的能力，同时还可以根据所做的运动测量执行主动游动。拟议的技术发展有望对磁共振成像产生直接影响