Department of Radiology, New York University School of Medicine, 660 First Avenue, New York, NY 10016-3295, USA.
J Magn Reson. 2011 Jun;210(2):233-7. doi: 10.1016/j.jmr.2011.03.012. Epub 2011 Mar 17.
Hardware constraints typically require the use of extended gradient pulse durations for clinical applications of diffusion-weighted magnetic resonance imaging (DW-MRI), which can potentially influence the estimation of diffusion metrics. Prior studies have examined this effect for the apparent diffusion coefficient. This study employs a two-compartment exchange model in order to assess the gradient pulse duration sensitivity of the apparent diffusional kurtosis (ADK), a quantitative index of diffusional non-Gaussianity. An analytic expression is derived and numerically evaluated for parameter ranges relevant to DW-MRI of brain. It is found that the ADK differs from the true diffusional kurtosis by at most a few percent. This suggests that ADK estimates for brain may be robust with respect to changes in pulse gradient duration.
硬件限制通常需要在扩散加权磁共振成像（DW-MRI）的临床应用中使用扩展的梯度脉冲持续时间，这可能会影响扩散度量的估计。先前的研究已经检查了这种对表观扩散系数的影响。本研究采用双室交换模型来评估表观扩散峰度（ADK）的梯度脉冲持续时间敏感性，ADK 是扩散非高斯性的定量指标。推导了一个解析表达式，并针对与大脑 DW-MRI 相关的参数范围进行了数值评估。结果发现，ADK 与真实扩散峰度的差异最多不超过几个百分点。这表明大脑的 ADK 估计值可能对脉冲梯度持续时间的变化具有鲁棒性。
