Pahlavian Soroush Heidari, Oshinski John, Zhong Xiaodong, Loth Francis, Amini Rouzbeh
Department of Mechanical Engineering, Conquer Chiari Research Center, The University of Akron, 264 Wolf Ledges Parkway 1st floor, RM 211b, Akron, OH 44325 e-mail: .
Radiology & Imaging Sciences and Biomedical Engineering, Emory University School of Medicine, 1364 Clifton Road NE, Atlanta, GA 30322 e-mail: .
J Biomech Eng. 2018 Aug 1;140(8). doi: 10.1115/1.4040227.
Intrinsic cardiac-induced deformation of brain tissue is thought to be important in the pathophysiology of various neurological disorders. In this study, we evaluated the feasibility of utilizing displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) to quantify two-dimensional (2D) neural tissue strain using cardiac-driven brain pulsations. We examined eight adult healthy volunteers with an electrocardiogram-gated spiral DENSE sequence performed at the midsagittal plane on a 3 Tesla MRI scanner. Displacement, pixel-wise trajectories, and principal strains were determined in seven regions of interest (ROI): the brain stem, cerebellum, corpus callosum, and four cerebral lobes. Quantification of small neural tissue motion and strain along with their spatial and temporal variations in different brain regions was found to be feasible using DENSE. The medial and inferior brain structures (brain stem, cerebellum, and corpus callosum) had significantly larger motion and strain compared to structures located more peripherally. The brain stem had the largest peak mean displacement (PMD) (187 ± 50 μm, mean ± SD). The largest mean principal strains in compression and extension were observed in the brain stem (0.38 ± 0.08%) and the corpus callosum (0.37 ± 0.08%), respectively. Measured values in percent strain were altered by as much as 0.1 between repeated scans. This study showed that DENSE can quantify regional variations in brain tissue motion and strain and has the potential to be utilized as a tool to evaluate the changes in brain tissue dynamics resulting from alterations in biomechanical stresses and tissue properties.
心脏内在因素引起的脑组织变形被认为在各种神经疾病的病理生理学中起着重要作用。在本研究中，我们评估了利用刺激回波位移编码（DENSE）磁共振成像（MRI），通过心脏驱动的脑搏动来量化二维（2D）神经组织应变的可行性。我们使用3特斯拉MRI扫描仪在矢状中平面上对8名成年健康志愿者进行了心电图门控螺旋DENSE序列检查。在七个感兴趣区域（ROI）中确定了位移、逐像素轨迹和主应变：脑干、小脑、胼胝体以及四个脑叶。结果发现，使用DENSE对不同脑区的小神经组织运动和应变及其时空变化进行量化是可行的。与位于更外围的结构相比，内侧和下部脑结构（脑干、小脑和胼胝体）具有明显更大的运动和应变。脑干的峰值平均位移（PMD）最大（187±50μm，平均值±标准差）。压缩和拉伸时最大的平均主应变分别出现在脑干（0.38±0.08%）和胼胝体（0.37±0.08%）。在重复扫描之间，应变百分比的测量值变化高达0.1。本研究表明，DENSE可以量化脑组织运动和应变的区域差异，并且有可能被用作评估生物力学应力和组织特性改变所导致的脑组织动力学变化的工具。
