Division of Regenerative Medicine, The Jikei University School of Medicine, 3-25-8, Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.
Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Saitama, Japan.
Sci Rep. 2024 Nov 6;14(1):26901. doi: 10.1038/s41598-024-78246-0.
Ex vivo studies of the brain are often employed as experimental systems in neuroscience. In general, brains for ex vivo MRI studies are usually fixed with paraformaldehyde to preserve molecular structure and prevent tissue destruction during long-term storage. As a result, fixing brain tissue causes microstructural changes and a decrease in brain volume. Therefore, the purpose of this study was to investigate the regional effect of brain volume and microstructural changes on the restricted diffusion of water molecules in the common marmoset brain using in vivo and ex vivo brains from the same individual. We used 9.4T magnetic resonance imaging and also compared the T2-weighted images and diffusion-weighted imaging (DWI) data between in vivo and ex vivo brains to investigate changes in brain volume and diffusion of water molecules in 12 common marmosets. We compared fractional anisotropy, mean diffusivity, AD (axial diffusivity), and radial diffusivity values in white matter and gray matter between in vivo and ex vivo brains. We observed that AD showed the strongest correlation with regional volume changes in gray matter. The results showed a strong correlation between AD and changes in brain volume. By comparing the in vivo and ex vivo brains of the same individual, we identified significant correlations between the local effects of perfusion fixation on microstructural and volumetric changes of the brain and alterations in the restricted diffusion of water molecules within the brain. These findings provide valuable insights into the complex relationships between tissue fixation, brain structure, and water diffusion properties in the marmoset brain.
离体研究经常被用作神经科学的实验系统。一般来说，用于离体 MRI 研究的大脑通常用多聚甲醛固定，以在长期储存过程中保存分子结构和防止组织破坏。然而，固定脑组织会导致微观结构的变化和脑体积的减少。因此，本研究的目的是使用来自同一个体的体内和离体大脑来研究水的受限扩散在常见狨猴脑中的脑体积和微观结构变化的区域效应。我们使用了 9.4T 磁共振成像，并比较了体内和离体大脑的 T2 加权图像和弥散加权成像 (DWI) 数据，以研究 12 只常见狨猴脑体积和水分子扩散的变化。我们比较了白质和灰质中各向异性分数、平均弥散度、AD（轴向弥散度）和径向弥散度值。我们观察到 AD 与灰质的区域体积变化相关性最强。结果表明 AD 与脑体积变化之间存在很强的相关性。通过比较同一个体的体内和离体大脑，我们确定了灌注固定对大脑微观结构和体积变化以及脑内水分子受限扩散改变的局部影响之间的显著相关性。这些发现为理解狨猴脑组织固定、脑结构和水扩散特性之间的复杂关系提供了有价值的见解。
