Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota.
Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota.
Magn Reson Med. 2018 Dec;80(6):2573-2585. doi: 10.1002/mrm.27347. Epub 2018 May 17.
To introduce newly developed MR elastography (MRE)-based dual-saturation imaging and dual-sensitivity motion encoding schemes to directly measure in vivo skull-brain motion, and to study the skull-brain coupling in volunteers with these approaches.
Six volunteers were scanned with a high-performance compact 3T-MRI scanner. The skull-brain MRE images were obtained with a dual-saturation imaging where the skull and brain motion were acquired with fat- and water-suppression scans, respectively. A dual-sensitivity motion encoding scheme was applied to estimate the heavily wrapped phase in skull by the simultaneous acquisition of both low- and high-sensitivity phase during a single MRE exam. The low-sensitivity phase was used to guide unwrapping of the high-sensitivity phase. The amplitude and temporal phase delay of the rigid-body motion between the skull and brain was measured, and the skull-brain interface was visualized by slip interface imaging (SII).
Both skull and brain motion can be successfully acquired and unwrapped. The skull-brain motion analysis demonstrated the motion transmission from the skull to the brain is attenuated in amplitude and delayed. However, this attenuation (%) and delay (rad) were considerably greater with rotation (59 ± 7%, 0.68 ± 0.14 rad) than with translation (92 ± 5%, 0.04 ± 0.02 rad). With SII the skull-brain slip interface was not completely evident, and the slip pattern was spatially heterogeneous.
This study provides a framework for acquiring in vivo voxel-based skull and brain displacement using MRE that can be used to characterize the skull-brain coupling system for understanding of mechanical brain protection mechanisms, which has potential to facilitate risk management for future injury.
介绍新开发的基于磁共振弹性成像（MRE）的双饱和成像和双敏感运动编码方案，以直接测量活体颅骨-脑运动，并通过这些方法研究志愿者中的颅骨-脑耦合。
对 6 名志愿者使用高性能紧凑型 3T-MRI 扫描仪进行扫描。颅骨-脑 MRE 图像是通过双饱和成像获得的，其中颅骨和脑运动分别通过脂肪和水抑制扫描获得。应用双敏感运动编码方案，在单次 MRE 检查中同时采集低和高灵敏度相位，估计颅骨中的重包裹相位。低灵敏度相位用于引导高灵敏度相位解包裹。测量颅骨和脑之间刚体运动的幅度和时相延迟，并通过滑动界面成像（SII）可视化颅骨-脑界面。
成功获取并解包裹了颅骨和脑运动。颅骨-脑运动分析表明，颅骨向脑的运动传递在幅度和延迟上均减弱。然而，与平移（59±7%，0.04±0.02 弧度）相比，旋转（59±7%，0.68±0.14 弧度）的衰减和延迟更为显著。SII 显示颅骨-脑滑动界面不完全明显，滑动模式具有空间异质性。
本研究提供了一种使用 MRE 获得活体体素颅骨和脑位移的框架，可用于描述颅骨-脑耦合系统，以了解机械性脑保护机制，这有可能促进未来损伤的风险管理。
