Precision and accuracy of diffusion kurtosis estimation and the influence of b-value selection.
Precision and accuracy of diffusion kurtosis estimation and the influence of b-value selection.
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DOI：
10.1002/nbm.3777
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发表时间：
2017-11
影响因子：
2.9
通讯作者：
Jespersen SN
中科院分区：
文献类型：
--
作者：
Chuhutin A;Hansen B;Jespersen SN
扩散峰度成像（DKI）是扩散张量成像的扩展，可解释主要的非高斯扩散效应。在DKI研究中，使用了各种不同的梯度强度（b值），已知这会影响估计的扩散率和峰度参数。因此，有必要评估作为b值函数的估计参数的准确度和精密度。这项工作检查的峰度张量（MKT）相对于地面真理的平均值的估计误差，使用模拟的基础上的生物物理模型的灰色（GM）和白色（WM）的问题。模型参数来自于在离体大鼠脑和在体人脑中获得的密集采样的实验数据。此外，MKT的变异性进行了研究，使用实验数据。流行的拟合协议的实施和调查。结果表明，所有采用的拟合协议的净相对误差和误差的标准偏差的最大b值的强烈依赖。发现具有最小MKT估计误差和误差标准差的b值的选择取决于协议类型和组织。发现利用两项累积量展开（DKI）的方案在b值小于1 ms/μm2时在GM中实现最小误差，而在WM中发现约2.5 ms/μm2的最大b值是最佳的。协议，包括额外的高阶项的累积展开被发现提供更高的精度更常用的b值制度在GM，但与WM的较高的错误。在多个体素上平均，对于最佳b值选择，观察到WM和GM的净平均误差约为15%。这些结果表明，当使用DKI生成的指标进行微观结构建模时，以及当比较使用不同拟合技术和b值获得的结果时，应谨慎。
Diffusion kurtosis imaging (DKI) is an extension of diffusion tensor imaging that accounts for leading non-Gaussian diffusion effects. In DKI studies, a wide range of different gradient strengths (b-values) is used, which is known to affect the estimated diffusivity and kurtosis parameters. Hence there is a need to assess the accuracy and precision of the estimated parameters as a function of b-value. This work examines the error in the estimation of mean of the kurtosis tensor (MKT) with respect to the ground truth, using simulations based on a biophysical model for both gray (GM) and white (WM) matter. Model parameters are derived from densely sampled experimental data acquired in ex vivo rat brain and in vivo human brain. Additionally, the variability of MKT is studied using the experimental data. Prevalent fitting protocols are implemented and investigated. The results show strong dependence on the maximum b-value of both net relative error and standard deviation of error for all of the employed fitting protocols. The choice of b-values with minimum MKT estimation error and standard deviation of error was found to depend on the protocol type and the tissue. Protocols that utilize two terms of the cumulant expansion (DKI) were found to achieve minimum error in GM at b-values less than 1 ms/μm2, whereas maximal b-values of about 2.5 ms/μm2 were found to be optimal in WM. Protocols including additional higher order terms of the cumulant expansion were found to provide higher accuracy for the more commonly used b-value regime in GM, but were associated with higher error in WM. Averaged over multiple voxels, a net average error of around 15% for both WM and GM was observed for the optimal b-value choice. These results suggest caution when using DKI generated metrics for microstructural modeling and when comparing results obtained using different fitting techniques and b-values.
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影响因子：
2.9
作者：
Jensen, Jens H.;Helpern, Joseph A.
通讯作者：
Helpern, Joseph A.
DOI：
10.1006/jmrb.1994.1037
发表时间：
1994-03-01
期刊：
JOURNAL OF MAGNETIC RESONANCE SERIES B
影响因子：
--
作者：
BASSER, PJ;MATTIELLO, J;LEBIHAN, D
通讯作者：
LEBIHAN, D
影响因子：
2.5
作者：
Gong, Nan-Jie;Wong, Chun-Sing;Chu, Yiu-Ching
通讯作者：
Chu, Yiu-Ching
影响因子：
8.3
作者：
Cheung JS;Wang E;Lo EH;Sun PZ
通讯作者：
Sun PZ
影响因子：
3.7
作者：
Delgado y Palacios R;Verhoye M;Henningsen K;Wiborg O;Van der Linden A
通讯作者：
Van der Linden A