Is the "biexponential diffusion" bilexponential?
Is the "biexponential diffusion" bilexponential?
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DOI：
10.1002/mrm.21164
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发表时间：
2007-03-01
影响因子：
3.3
通讯作者：
Il'yasov, Kamil A.
中科院分区：
文献类型：
--
作者：
Kiselev, Valerij G.;Il'yasov, Kamil A.
来自大脑的扩散加权信号，S，偏离了对b因子的单指数依赖。这种性质通常被称为双指数扩散，因为相应的模型很好地拟合了数据。这项研究的目的是检验在各向同性扩散加权b=2.5ms/mum(2)的均匀体素中使用双指数模型的必要性。将该模型与In S在b中的幂函数展开进行了比较，后者起源于扩散加权信号的基本性质，但在大b处发散。在灰质中，缺乏统计上显著的双指数扩散证据。在项b(2)之后终止的累积量展开用更少的可调参数同样很好地描述了数据。对于部分脑脊液体积的体素，双指数模型更可取。
Diffusion-weighted signal from the brain, S, deviates from monoexponential dependence on the b-factor. This property is often referred to as biexponential diffusion, since the corresponding model fits data well. The aim of this study is to examine the necessity of using the biexponential model in homogeneous voxels under isotropic diffusion weighting up to b = 2.5 ms/mu m(2). The model is compared to the cumulant expansion of In S in a power series in b, which takes its origin in fundamental properties of the diffusion-weighted signal, but diverges at large b. The absence of statistically significant evidences for the biexponential diffusion is demonstrated in gray matter. The cumulant expansion terminated after the term b(2) describes data equally well with fewer adjustable parameters. The biexponential model is preferable in voxels with a partial volume of CSF.