■连续波功能近红外光谱技术已被证明是一种有价值的工具,用于以非侵入性和廉价的方式评估人脑中的血液动力学活动。然而,当前的大多数处理/分析方法都假定磁头是均匀介质,因此,不要适当地纠正来自头皮的信号。可以通过在人体头部的分层模型中考虑光传播来减少这种影响。作为蒙特卡洛(MC)模拟为此目的的黄金标准。然而,这意味着大量的计算时间和苛刻的硬件能力。
■在这项工作中,我们研究了用分析多层模型代替均质模型和MC模拟的可行性,以这种方式结合,前者的实施速度和简单性,后者的鲁棒性和准确性。
■氧合血红蛋白和脱氧血红蛋白(HbO和HbR,分别)在基于磁共振成像(MRI)的人体头部网格模型的两个不同层中提出了浓度变化,然后通过(i)典型的均匀重建和(ii)理论分层重建来检索这些变化。
■结果表明,在分层模型中使用光传播的分析模型优于使用传统齐次重建算法获得的结果,为两者提供更准确的结果,外和脑组织。我们还将分析分层重建与基于MC的重建进行了比较,达到类似的精确度,尤其是在灰质层中,但速度更快(在4到5个数量级之间)。
■我们已经成功开发,已实施,并验证了一种检索人脑发色团浓度变化的方法,结合简单性和速度的传统齐次重建算法的鲁棒性和准确性更类似于由MC模拟提供。
UNASSIGNED: Continuous-wave functional near-infrared spectroscopy has proved to be a valuable tool for assessing hemodynamic activity in the human brain in a non-invasively and inexpensive way. However, most of the current processing/analysis methods assume the head is a homogeneous medium, and hence do not appropriately correct for the signal coming from the scalp. This effect can be reduced by considering light propagation in a layered model of the human head, being the Monte Carlo (MC) simulations the gold standard to this end. However, this implies large computation times and demanding hardware capabilities.
UNASSIGNED: In this work, we study the feasibility of replacing the homogeneous model and the MC simulations by means of analytical multilayered models, combining in this way, the speed and simplicity of implementation of the former with the robustness and accuracy of the latter.
UNASSIGNED: Oxy- and deoxyhemoglobin (HbO and HbR, respectively) concentration changes were proposed in two different layers of a magnetic resonance imaging (MRI)-based meshed model of the human head, and then these changes were retrieved by means of (i) a typical homogeneous reconstruction and (ii) a theoretical layered reconstruction.
UNASSIGNED: Results suggest that the use of analytical models of light propagation in layered models outperforms the results obtained using traditional homogeneous reconstruction algorithms, providing much more accurate results for both, the extra- and the cerebral tissues. We also compare the analytical layered reconstruction with MC-based reconstructions, achieving similar degrees of accuracy, especially in the gray matter layer, but much faster (between 4 and 5 orders of magnitude).
UNASSIGNED: We have successfully developed, implemented, and validated a method for retrieving chromophore concentration changes in the human brain, combining the simplicity and speed of the traditional homogeneous reconstruction algorithms with robustness and accuracy much more similar to those provided by MC simulations.