Wu Dan, Reisinger Dominik, Xu Jiadi, Fatemi S Ali, van Zijl Peter C M, Mori Susumu, Zhang Jiangyang
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Division of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD, USA.
Neuroimage. 2014 May 1;91:12-20. doi: 10.1016/j.neuroimage.2014.01.014. Epub 2014 Jan 17.
High-resolution diffusion MRI (dMRI) is useful for resolving complex microstructures in the mouse brain, but technically challenging for in vivo studies due to the long scan time. In this study, selective excitation and a three-dimensional fast imaging sequence were used to achieve in vivo high-resolution dMRI of the mouse brain at 11.7Tesla. By reducing the field of view using spatially selective radio frequency pulses, we were able to focus on targeted brain structures and acquire high angular resolution diffusion imaging (HARDI) data at an isotropic resolution of 0.1mm and 30 diffusion encoding directions in approximately 1h. We investigated the complex tissue microstructures of the mouse hippocampus, cerebellum, and several cortical areas using this localized dMRI approach, and compared the results with histological sections stained with several axonal and dendritic markers. In the mouse visual cortex, the results showed predominately radially arranged structures in an outer layer and tangentially arranged structures in an inner layer, similar to observations from postmortem human brain specimens.
高分辨率扩散磁共振成像（dMRI）有助于解析小鼠大脑中的复杂微观结构，但由于扫描时间长，在体内研究中存在技术挑战。在本研究中，采用选择性激发和三维快速成像序列，在11.7特斯拉磁场下实现了小鼠大脑的体内高分辨率dMRI。通过使用空间选择性射频脉冲缩小视野，我们能够聚焦于目标脑结构，并在约1小时内以0.1毫米的各向同性分辨率和30个扩散编码方向获取高角分辨率扩散成像（HARDI）数据。我们使用这种局部dMRI方法研究了小鼠海马体、小脑和几个皮质区域的复杂组织微观结构，并将结果与用几种轴突和树突标记物染色的组织学切片进行了比较。在小鼠视觉皮层中，结果显示外层主要是径向排列的结构，内层是切向排列的结构，这与死后人类脑标本的观察结果相似。
