Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
J Cereb Blood Flow Metab. 2013 Jun;33(6):819-25. doi: 10.1038/jcbfm.2013.20. Epub 2013 Feb 13.
This paper describes a novel optical method for label-free quantitative imaging of cerebral blood flow (CBF) and intracellular motility (IM) in the rodent cerebral cortex. This method is based on a technique that integrates dynamic light scattering (DLS) and optical coherence tomography (OCT), named DLS-OCT. The technique measures both the axial and transverse velocities of CBF, whereas conventional Doppler OCT measures only the axial one. In addition, the technique produces a three-dimensional map of the diffusion coefficient quantifying nontranslational motions. In the DLS-OCT diffusion map, we observed high-diffusion spots, whose locations highly correspond to neuronal cell bodies and whose diffusion coefficient agreed with that of the motion of intracellular organelles reported in vitro in the literature. Therefore, the present method has enabled, for the first time to our knowledge, label-free imaging of the diffusion-like motion of intracellular organelles in vivo. As an example application, we used the method to monitor CBF and IM during a brief ischemic stroke, where we observed an induced persistent reduction in IM despite the recovery of CBF after stroke. This result supports that the IM measured in this study represent the cellular energy metabolism-related active motion of intracellular organelles rather than free diffusion of intracellular macromolecules.
本文描述了一种新颖的光学方法，用于对啮齿动物大脑皮层中的脑血流 (CBF) 和细胞内运动 (IM) 进行无标记定量成像。该方法基于一种集成动态光散射 (DLS) 和光相干断层扫描 (OCT) 的技术，称为 DLS-OCT。该技术可测量 CBF 的轴向和横向速度，而传统的多普勒 OCT 仅测量轴向速度。此外，该技术产生了一个扩散系数的三维图谱，量化了非平移运动。在 DLS-OCT 扩散图谱中，我们观察到了高扩散点，其位置与神经元细胞体高度对应，其扩散系数与文献中体外报道的细胞内细胞器的运动一致。因此，本方法首次实现了对细胞内细胞器的扩散样运动的无标记体内成像。作为一个示例应用，我们使用该方法在短暂的缺血性中风期间监测 CBF 和 IM，我们观察到中风后尽管 CBF 恢复，但 IM 持续减少。这一结果支持了本研究中测量的 IM 代表细胞内细胞器与细胞能量代谢相关的主动运动，而不是细胞内大分子的自由扩散。
