Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Canada.
Physics Department and PERFORM center, Concordia University, Montreal, Canada.
J Neurosci Methods. 2018 Nov 1;309:91-108. doi: 10.1016/j.jneumeth.2018.08.006. Epub 2018 Aug 11.
Application of functional Near InfraRed Spectroscopy (fNIRS) in neurology is still limited as a good optical coupling and optimized optode coverage of specific brain regions remains challenging, notably for prolonged monitoring.
We propose to evaluate a new procedure allowing accurate investigation of specific brain regions. The procedure consists in: (i) A priori maximization of spatial sensitivity of fNIRS measurements targeting specific brain regions, while reducing the number of applied optodes in order to decrease installation time and improve subject comfort. (ii) Utilization of a 3D neuronavigation device and usage of collodion to glue optodes on the scalp, ensuring good optical contact for prolonged investigations. (iii) Local reconstruction of the hemodynamic activity along the cortical surface using inverse modelling.
Using realistic simulations, we demonstrated that maps derived from optimal montage acquisitions showed, after reconstruction, spatial resolution only slightly lower to that of ultra high density montages while significantly reducing the number of optodes. The optimal montages provided overall good quantitative accuracy especially at the peak of the spatially reconstructed map. We also evaluated real motor responses in two healthy subjects and obtained reproducible motor responses over different sessions.
We are among the first to propose a mathematical optimization strategy, allowing high sensitivity measurements.
Our results support that using personalized optimal montages should allow to conduct accurate fNIRS studies in clinical settings and realistic lifestyle conditions.
功能近红外光谱（fNIRS）在神经病学中的应用仍然有限，因为良好的光耦合和特定脑区的优化光探头覆盖仍然具有挑战性，尤其是在长时间监测方面。
我们提出了一种新的方法来评估可以准确研究特定脑区的程序。该程序包括：（i）针对特定脑区，通过预先最大化 fNIRS 测量的空间灵敏度，同时减少应用光探头的数量，以减少安装时间并提高被试者舒适度。（ii）利用 3D 神经导航设备和使用胶浆将光探头粘贴在头皮上，以确保长时间的良好光学接触。（iii）使用逆模型来局部重建皮层表面的血流动力学活动。
使用现实模拟，我们证明了从最优采集模式获得的图谱在重建后，空间分辨率仅略低于超高密度采集模式，同时显著减少了光探头的数量。最优采集模式总体上提供了良好的定量准确性，尤其是在空间重建图谱的峰值处。我们还在两名健康受试者中评估了真实的运动反应，并在不同的实验中获得了可重复的运动反应。
我们是第一个提出允许高灵敏度测量的数学优化策略的人之一。
我们的结果支持使用个性化的最优采集模式应该可以在临床环境和现实生活条件下进行准确的 fNIRS 研究。
