Alex M. Cerjanic, Alexa M. Diano, Curtis L. Johnson
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引用次数: 0
Abstract
Purpose
To introduce a novel sequence for achieving fast, whole-brain MR elastography data through the introduction of a magnetization preparation block for motion encoding along with rapid imaging readouts.
Theory and Methods
We implemented MRE motion encoding in a magnetization preparation pulse sequence block, where spins are excited, motion encoded, and then stored longitudinally. This magnetization is accessed through a train of rapid gradient echoes and encoded with a 3D stack-of-spirals trajectory. Spoilers are included to crush unprepared magnetization and avoid image artifacts. We demonstrate the feasibility of the proposed method in capturing MRE displacement data for estimating mechanical properties and accelerating scan times.
Results
We measured stability of phase across gradient echo readouts in the readout train after magnetization preparation. Additionally, we obtained displacement fields with high OSS-SNR with retrospective sampling and differences in average stiffness properties (NRMSE) of 3.6% () and 7.7% () between retrospectively undersampled and fully sampled data. Prospective undersampling showed highly similar multiscale similarity measures and global property differences between 1.0% to 3.5% with one outlier of 8.1% between the proposed method and reference EPI scans.
Conclusion
Magnetization preparation for MRE is feasible and can accelerate brain MRE scans, producing high-quality mechanical property maps at 2.5 mm isotropic resolution in 1 min 20 s.
目的:介绍一种新的序列,通过引入用于运动编码的磁化准备块以及快速成像读数来实现快速的全脑磁共振弹性成像数据。理论和方法:我们在磁化制备脉冲序列块中实现了MRE运动编码,其中自旋被激发,运动编码,然后纵向存储。这种磁化是通过一列快速梯度回波来实现的,并通过三维螺旋轨迹进行编码。扰流片包括粉碎未准备磁化和避免图像伪影。我们证明了所提出的方法在捕获MRE位移数据以估计机械性能和加速扫描时间方面的可行性。结果:我们测量了磁化后读出序列中相位跨梯度回波读出的稳定性。此外,我们通过回顾性采样获得了具有高oss -信噪比的位移场,平均刚度特性(NRMSE)差异为3.6% ( R x y = 2 $$ {R}_{xy}=2 $$ ) and 7.7% ( R x y = 4 $$ {R}_{xy}=4 $$ ) between retrospectively undersampled and fully sampled data. Prospective undersampling showed highly similar multiscale similarity measures and global property differences between 1.0% to 3.5% with one outlier of 8.1% between the proposed method and reference EPI scans.Conclusion: Magnetization preparation for MRE is feasible and can accelerate brain MRE scans, producing high-quality mechanical property maps at 2.5 mm isotropic resolution in 1 min 20 s.
期刊介绍:
Magnetic Resonance in Medicine (Magn Reson Med) is an international journal devoted to the publication of original investigations concerned with all aspects of the development and use of nuclear magnetic resonance and electron paramagnetic resonance techniques for medical applications. Reports of original investigations in the areas of mathematics, computing, engineering, physics, biophysics, chemistry, biochemistry, and physiology directly relevant to magnetic resonance will be accepted, as well as methodology-oriented clinical studies.