Diffusion tensor imaging (DTI) is widely used to evaluate microstructural variations in brain tissue. In particular, fractional anisotropy (FA), reflecting the magnitude and orientation of anisotropic water diffusion, allows us to detect pathological events in white matter. An ex vivo DTI study coupled with histological assessment is an efficient strategy to evaluate the myelination process, i.e. demyelination and remyelination. The relationship between DTI values and myelin content or the individual cellular components such as oligodendrocytes, microglia, and astrocytes during both processes of demyelination and remyelination are not well-understood. To address this issue, we employed a cuprizone-inducible demyelination mouse model. Demyelination can be induced in this model during cuprizone exposure and termination of cuprizone exposure induces remyelination. We fed the mice cuprizone-containing chow for 4 weeks and then normal chow for an additional 4 weeks. The ex vivo DTI was performed to evaluate the white matter profiles observed by FA, mean diffusivity (MD), and radial diffusivity (RD) at both demyelinating and remyelinating time points, and then we evaluated histological properties at the same time points. The results indicated a gradual FA decrease during the cuprizone treatment (0, 2, 3, 4 weeks). A lower peak was seen at 1 week after the normal chow was resumed, with recovery to baseline at 2 and 4 weeks. MD and RD showed an opposing pattern to that of FA. These DTI values were positively or negatively correlated with myelin content regardless of the status of the white matter. The RD value was more sensitive to myelination status than FA and MD. We have clarified the temporal changes in the DTI values coupled with histological properties over both the demyelination and remyelination processes.

扩散张量成像（DTI）被广泛用于评估脑组织的微结构变化。特别地，分数各向异性（FA）反映了各向异性水扩散的幅度和方向，使我们能够检测白质中的病理事件。一个体外DTI研究与组织学评估相结合是评估髓鞘形成过程（即脱髓鞘和再髓鞘）的有效策略。在脱髓鞘和再髓鞘化的两个过程中，DTI值与髓磷脂含量或单个细胞成分（如少突胶质细胞，小胶质细胞和星形胶质细胞）之间的关系尚不清楚。为了解决这个问题，我们采用了铜氮酮诱导的脱髓鞘小鼠模型。在铜吡酮暴露期间可以在该模型中诱导脱髓鞘，并且终止铜卓酮暴露诱导髓鞘再生。我们给小鼠喂食含铜酮的食物4周，然后再给正常食物喂4周。在体外进行DTI评估脱髓鞘和再髓鞘时间点的FA，平均扩散率（MD）和径向扩散率（RD）观察到的白质分布，然后评估同一时间点的组织学性质。结果表明在铜酮治疗期间（0、2、3、4周）FA逐渐降低。恢复正常饮食后第1周出现一个较低的峰值，并在第2周和第4周恢复到基线。MD和RD显示出与FA相反的模式。这些DTI值与髓磷脂含量呈正相关或负相关，而与白质的状态无关。RD值比FA和MD对髓鞘形成状态更敏感。我们已经阐明了脱髓鞘和髓鞘再生过程中DTI值的时间变化以及组织学性质。