Convergence and Parameter Choice for Monte-Carlo Simulations of Diffusion MRI
Convergence and Parameter Choice for Monte-Carlo Simulations of Diffusion MRI
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DOI：
10.1109/tmi.2009.2015756
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发表时间：
2009-09-01
影响因子：
10.6
通讯作者：
Alexander, Daniel C.
中科院分区：
文献类型：
--
作者：
Hall, Matt G.;Alexander, Daniel C.
本文介绍了一个通用的和灵活的蒙特-卡罗扩散自旋模拟框架，产生逼真的合成数据的扩散磁共振成像。在文献中类似的系统只考虑简单的基板和他们的作者不考虑收敛性和参数优化。我们将展示如何运行复杂的不规则衬底内的蒙特-卡罗模拟。我们比较的蒙特-卡罗模拟的结果，限制扩散的分析模型，以评估所产生的结果的精度和准确性。在给定的运行时间内，我们通过权衡更新次数来获得旋转和更新的最佳组合，从而优化合成数据的精度和准确性。进一步的实验证明了该系统使用的组织环境，目前的分析模型不能捕捉。该组织模型包括肿胀、邻接和变形。由于邻接圆柱体的影响，在细胞外空间中的溶胀诱导的限制导致与分析模型的预测大的偏差，该分析模型没有捕获这些影响。这种肿胀诱导的限制可能是解释急性缺血性卒中后观察到的表观扩散常数变化的重要机制。
This paper describes a general and flexible Monte-Carlo simulation framework for diffusing spins that generates realistic synthetic data for diffusion magnetic resonance imaging. Similar systems in the literature consider only simple substrates and their authors do not consider convergence and parameter optimization. We show how to run Monte-Carlo simulations within complex irregular substrates. We compare the results of the Monte-Carlo simulation to an analytical model of restricted diffusion to assess precision and accuracy of the generated results. We obtain an optimal combination of spins and updates for a given run time by trading off number of updates in favor of number of spins such that precision and accuracy of sythesized data are both optimized. Further experiments demonstrate the system using a tissue environment that current analytic models cannot capture. This tissue model incorporates swelling, abutting, and deformation. Swelling-induced restriction in the extracellular space due to the effects of abutting cylinders leads to large departures from the predictions of the analytical model, which does not capture these effects. This swelling-induced restriction may be an important mechanism in explaining the changes in apparent diffusion constant observed in the aftermath of acute ischemic stroke.