School of Electrical Engineering and Automation, Harbin Institute of Technology, No. 92 West Da-zhi Street, Nangang District, Harbin, People's Republic of China.
Physiol Meas. 2012 Jun;33(6):925-42. doi: 10.1088/0967-3334/33/6/925. Epub 2012 May 3.
The non-invasive measurement of cerebral functional haemodynamics using near-infrared spectroscopy (NIRS) instruments is often affected by physiological interference. The suppression of this interference is crucial for reliable recovery of brain activity measurements because it can significantly affect the signal quality. In this study, we present a recursive least-squares (RLS) algorithm for adaptive filtering to reduce the magnitude of the physiological interference component. To evaluate it, we implemented Monte Carlo simulations based on a five-layer slab model of a human adult head with a multidistance source-detector arrangement, of a short pair and a long pair, for NIRS measurement. We derived measurements by adopting different interoptode distances, which is relevant to the process of optimizing the NIRS probe configuration. Both RLS and least mean squares (LMS) algorithms were used to attempt the removal of physiological interference. The results suggest that the RLS algorithm is more capable of minimizing the effect of physiological interference due to its advantages of faster convergence and smaller mean squared error (MSE). The influence of superficial layer thickness on the performance of the RLS algorithm was also investigated. We found that the near-detector position is an important variable in minimizing the MSE and a short source-detector separation less than 9 mm is robust to superficial layer thickness variation.
利用近红外光谱（NIRS）仪器对脑功能血流的无创测量常常受到生理干扰的影响。抑制这种干扰对于可靠地恢复脑活动测量至关重要，因为它会显著影响信号质量。在这项研究中，我们提出了一种递归最小二乘法（RLS）算法，用于自适应滤波以减小生理干扰分量的幅度。为了进行评估，我们基于一个具有多距离源-探测器排列的成人头部的五层平板模型，实施了蒙特卡罗模拟，用于 NIRS 测量。我们采用不同的光极间距离进行测量，这与优化 NIRS 探头配置的过程有关。RLS 和最小均方（LMS）算法都被用于尝试去除生理干扰。结果表明，由于 RLS 算法具有更快的收敛速度和更小的均方误差（MSE），因此更能最小化生理干扰的影响。还研究了浅层厚度对 RLS 算法性能的影响。我们发现，近探测器位置是最小化 MSE 的重要变量，并且源-探测器之间的短距离分离小于 9mm 对浅层厚度变化具有鲁棒性。
