Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy. It is frequently associated with abnormal MRI findings, which are caused by underlying cellular, structural, and chemical changes at the micro-scale. In the current study, it is investigated to which extent these alterations correspond to imaging features detected by high resolution magnetic resonance imaging in the intrahippocampal kainate mouse model of MTLE. Fixed hippocampal and whole-brain sections of mouse brain tissue from nine animals under physiological and chronically epileptic conditions were examined using structural and diffusion-weighted MRI. Microstructural details were investigated based on a direct comparison with immunohistochemical analyses of the same specimen. Within the hippocampal formation, diffusion streamlines could be visualized corresponding to dendrites of CA1 pyramidal cells and granule cells, as well as mossy fibers and Schaffer collaterals. Statistically significant changes in diffusivities, fractional anisotropy, and diffusion orientations could be detected in tissue samples from chronically epileptic animals compared to healthy controls, corresponding to microstructural alterations (degeneration of pyramidal cells, dispersion of the granule cell layer, and sprouting of mossy fibers). The diffusion parameters were significantly correlated with histologically determined cell densities. These findings demonstrate that high-resolution diffusion-weighted MRI can resolve subtle microstructural changes in epileptic hippocampal tissue corresponding to histopathological features in MTLE.

中文翻译：

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弥散加权磁共振显微镜在内侧颞叶癫痫小鼠模型中的组织学相关性

内侧颞叶癫痫 (MTLE) 是最常见的局灶性癫痫类型。它经常与异常的 MRI 结果有关，这些异常是由微观尺度的潜在细胞、结构和化学变化引起的。在当前的研究中，研究了这些改变在多大程度上与 MTLE 海马内海人酸小鼠模型中高分辨率磁共振成像检测到的成像特征相对应。使用结构和扩散加权 MRI 检查了生理和慢性癫痫条件下 9 只动物的小鼠脑组织的固定海马和全脑切片。基于与同一标本的免疫组织化学分析的直接比较，研究了微观结构细节。在海马结构内，可以看到与 CA1 锥体细胞和颗粒细胞的树突以及苔藓纤维和 Schaffer 侧枝相对应的扩散流线。与健康对照相比，慢性癫痫动物的组织样本中可以检测到扩散率、分数各向异性和扩散方向的统计学显着变化，对应于微观结构的改变（锥体细胞的退化、颗粒细胞层的分散和苔藓纤维的发芽） . 扩散参数与组织学确定的细胞密度显着相关。这些发现表明，高分辨率弥散加权 MRI 可以解决癫痫海马组织中与 MTLE 组织病理学特征相对应的细微微观结构变化。