Significance: Cerebral blood flow is an important biomarker of brain health and function as it regulates the delivery of oxygen and substrates to tissue and the removal of metabolic waste products. Moreover, blood flow changes in specific areas of the brain are correlated with neuronal activity in those areas. Diffuse correlation spectroscopy (DCS) is a promising noninvasive optical technique for monitoring cerebral blood flow and for measuring cortex functional activation tasks. However, the current state-of-the-art DCS adoption is hindered by a trade-off between sensitivity to the cortex and signal-to-noise ratio (SNR). Aim: We aim to develop a scalable method that increases the sensitivity of DCS instruments. Approach: We report on a multispeckle DCS (mDCS) approach that is based on a 1024-pixel single-photon avalanche diode (SPAD) camera. Our approach is scalable to >100,000 independent speckle measurements since large-pixel-count SPAD cameras are becoming available, owing to the investments in LiDAR technology for automotive and augmented reality applications. Results: We demonstrated a 32-fold increase in SNR with respect to traditional single-speckle DCS. Conclusion: A mDCS system that is based on a SPAD camera serves as a scalable method toward high-sensitivity DCS measurements, thus enabling both high sensitivity to the cortex and high SNR.

中文翻译：

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高灵敏度多斑点扩散相关光谱

意义：脑血流是大脑健康和功能的重要生物标志物，因为它调节氧气和底物向组织的输送以及代谢废物的清除。此外，大脑特定区域的血流变化与这些区域的神经元活动相关。漫射相关光谱法（DCS）是一种有前途的无创光学技术，可用于监测脑血流量和测量皮质功能激活任务。但是，由于对皮层的敏感性与信噪比（SNR）之间的权衡，阻碍了当前最新的DCS的采用。目的：我们旨在开发一种可扩展的方法，以提高DCS仪器的灵敏度。方法：我们报告了一种基于1024像素单光子雪崩二极管（SPAD）相机的多斑点DCS（mDCS）方法。由于对汽车和增强现实应用的LiDAR技术进行了投资，由于大像素数SPAD相机的问世，我们的方法可扩展至超过100,000个独立的散斑测量。结果：相对于传统的单斑点DCS，我们证明了SNR的32倍增长。结论：基于SPAD摄像机的mDCS系统可作为可扩展方法用于高灵敏度DCS测量，从而实现对皮层的高灵敏度和高SNR。