扩散张量成像导出量对扩散时间依赖关系的实验研究

目的研究扩散张量导出量与扩散时间的关系。方法保持扩散敏感梯度磁场强度不变，使用8个不同的扩散时间对11名被试者进行扩散张量成像扫描得到脑部的各向异性与各向同性信息，计算出各个感兴趣区的平均扩散率与各向异性分数后进行比较。结果不同扩散时间对应的平均扩散率有显著性差异（P〈0．05），而各向异性分数无显著性差异（P〉0．05）。结论扩散时间对扩散张量成像导出量中的各向异性分数无影响，对平均扩散率有影响。原因是细胞内外水分子扩散性质不同。

Experimental Study on Dependence of Diffusion Tensor-derived Parameters upon Diffusion Time

Objective To investigate the relationship between diffusion time and diffusion tensor-derived parameters. Method Diffusion tensor data sets were obtained from 11 healthy volunteers using 8 different levels of diffusion time while keeping the diffusion sensitive gradient magnetic field strength fixed. Diffusion tensor-derived parameters with variant diffusion time for six regions of interest were calculated and compared. Result There was statistically significant difference in mean diffusivity (MD) of variant diffusion time (P<0.05), but fractional anisotropy (FA) were diffusion time independent (P>0.05). Conclusion There is no diffusion time dependent in FA, but MD are diffusion time dependent. The reason may be attributed to the difference of the diffusion properties between the intra- and extra-cellular water molecules.