B-value dependence of DTI quantitation and sensitivity in detecting neural tissue changes
B-value dependence of DTI quantitation and sensitivity in detecting neural tissue changes
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DOI：
10.1016/j.neuroimage.2009.10.022
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发表时间：
2010-02-01
期刊：
影响因子：
5.7
通讯作者：
Wu, Ed X.
中科院分区：
文献类型：
--
作者：
Hui, Edward S.;Cheung, Matthew M.;Wu, Ed X.
最近，利用磁共振扩散张量成像(DTI)来表征白质在复杂生物组织微结构中的扩散不是一个自由或高斯过程，而是受到阻碍和限制，从而与传统DTI中扩散加权信号以单指数方式衰减的基本假设相矛盾。然而，在常规研究和临床环境中，DTI仍然是迄今为止在常规研究和临床环境中评估DTI指标的b值相关性和评估其在检测神经组织变化中的敏感性的最快和最稳健的方法。21和120具有不同的b值(0.5-2.5ms/mum(2))和30个梯度方向的分析结果表明，在白色和灰质中，平均扩散系数和方向扩散系数均随b值的增大而一致地减小。轴向弥散系数监测脑成熟的敏感性一般随b值降低而降低，而径向弥散系数增加的灵敏度一般随b值变化较小，但与年龄和组织类型有关。分析还表明，b值对FA检测特定组织改变的敏感性有影响。这些实验结果证实了b值对定量DTI在监测神经组织改变中的关键作用。他们建议，在常规DTI采集中，b值的选择可以优化以检测神经组织的变化，但应取决于特定的组织类型及其变化或目标病理，在解释DTI指数时必须谨慎。(C)2009 Elsevier Inc.保留所有权利。
Recently, remarkable success has been demonstrated in using MR diffusion tensor imaging (DTI) to characterize white matter Water diffusion in complex biological tissue microstructure is not a free or Gaussian process but is hindered and restricted, thus contradicting the basic assumption in conventional DTI that diffusion weighted signal decays with b-value in a monoexponential manner Nevertheless, DTI by far is still the fastest and most robust protocol in routine research and clinical settings To assess the b-value dependence of DTI indices and evaluate their sensitivities in detecting neural tissues changes, in vivo DTI data acquired from rat brains at postnatal day 13, 21 and 120 with different b-values (0 5-2.5 ms/mu m(2)) and 30 gradient directions were analyzed Results showed that the mean and directional diffusivities consistently decreased with b-value in both white and gray matters. The sensitivity of axial diffusivity in monitoring brain maturation generally decreased with b-value whereas that of radial diffusivity increased FA generally varied less with b-value but in a manner dependent of the age and tissue type. Analysis also revealed that the FA sensitivity in detecting specific tissue changes was affected by b-value These experimental findings confirmed the crucial effect of b-value on quantitative DTI in monitoring neural tissue alterations. They suggested that the choice of b-value in conventional DTI acquisition can be optimized for detecting neural tissue changes but shall depend on the specific tissue type and its changes or pathologies targeted, and caution must he taken in interpreting DTI indices. (C) 2009 Elsevier Inc. All rights reserved.