| 温清清,童海洋,杨鸿毅.扩散时间对离体小鼠脑拉伸指数模型和分数阶微积分模型DWI参数的影响[J].中国医学影像技术,2018,34(12):1761~1766 |
| 扩散时间对离体小鼠脑拉伸指数模型和分数阶微积分模型DWI参数的影响 |
| Impacts of diffusion time on DWI parameters of stretched-exponential model and fractional order calculus model in mice brains in vitro |
| 投稿时间：2018-04-13 修订日期：2018-08-31 |
| DOI：10.13929/j.1003-3289.201804068 |
| 中文关键词: 扩散磁共振成像 扩散时间 分数阶微积分模型 拉伸指数模型 |
| 英文关键词:Diffusion magnetic resonance imaging Diffusion time Fractional order calculus model Stretched-exponential model |
| 基金项目:合肥物质科学研究院专项基金（YZJJ201702）。 |
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| 中文摘要: |
| 目的 探讨扩散时间对小鼠离体脑拉伸指数模型和分数阶微积分（FC）模型DWI参数的影响。方法 采用9.4T MR对6只正常小鼠离体脑行DWI，随机分为2组，分别行EPI序列DWI，扩散时间为10、16、22、28、34 ms；FSE序列DWI，扩散时间为12、18、25和33 ms。在Matlab平台上采用Levenberg-Marquardt算法拟合计算拉伸指数模型和FC模型参数，获得离体脑灰质和白质的DWI参数，包括拉伸指数模型扩散系数（DDC）、不均匀性指数（α）和FC模型扩散系数（D）、复杂性参数（β）、空间常数（μ）；分析DWI参数与扩散时间的关系。结果 EPI和FSE序列DWI中，小鼠离体脑灰质和白质DDC和D均随扩散时间增大而减小，α和β均略增大，μ增大明显。结论 小鼠离体脑中，拉伸指数模型和FC模型DWI参数与扩散时间的变化关系基本一致。观察生物组织中水分子扩散时，除考虑微观障碍物的影响，还需考虑各种膜结构的渗透作用。 |
| 英文摘要: |
| Objective To investigate the impacts of diffusion time on DWI parameters derived from stretched-exponential model and fractional order calculus (FC) model in mice brains in vitro. Methods Totally 6 normal mice brains were used for in vitro DWI on 9.4T MR scanner, which were randomly divided into 2 groups. Diffusion time of EPI-DWI was 10, 16, 22, 28 and 34 ms, while of FSE-DWI was 12, 18, 25 and 33 ms, respectively. A Levenberg-Marquardt nonlinear algorithm in Matlab was used to fit the parameters of stretched-exponential model and FC model. DWI parameters of gray matter and white matter in vitro mice brains were obtained, including the distributed diffusion coefficient (DDC), heterogeneity index (α) from stretched-exponential model and diffusion coefficient (D), complexity index (β), a spatial parameter (μ) from FC model. The relationship between DWI parameters and diffusion time was analyzed. Results On EPI-DWI and FSE-DWI, DDC and D in gray matter and white matter of mice brains in vitro decreased with the increase of diffusion time, while α and β slightly increased and μ significantly increased. Conclusion For in vitro mice brains, the relationship between DWI parameters and diffusion time of stretched-exponential model and FC model is basically the same. In the study of water molecular diffusion in tissues, the permeation of membranes should be considered in addition to the impacts of microscopic barriers. |
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