Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
Bar-Ilan University, Tel Aviv District, Ramat Gan, Israel.
Sci Rep. 2023 May 31;13(1):8803. doi: 10.1038/s41598-023-36074-8.
Diffuse correlation spectroscopy (DCS) is an optical technique that can be used to characterize blood flow in tissue. The measurement of cerebral hemodynamics has arisen as a promising use case for DCS, though traditional implementations of DCS exhibit suboptimal signal-to-noise ratio (SNR) and cerebral sensitivity to make robust measurements of cerebral blood flow in adults. In this work, we present long wavelength, interferometric DCS (LW-iDCS), which combines the use of a longer illumination wavelength (1064 nm), multi-speckle, and interferometric detection, to improve both cerebral sensitivity and SNR. Through direct comparison with long wavelength DCS based on superconducting nanowire single photon detectors, we demonstrate an approximate 5× improvement in SNR over a single channel of LW-DCS in the measured blood flow signals in human subjects. We show equivalence of extracted blood flow between LW-DCS and LW-iDCS, and demonstrate the feasibility of LW-iDCS measured at 100 Hz at a source-detector separation of 3.5 cm. This improvement in performance has the potential to enable robust measurement of cerebral hemodynamics and unlock novel use cases for diffuse correlation spectroscopy.
漫反射相关光谱学（DCS）是一种可用于组织血流特征分析的光学技术。DCS 在脑血流测量方面的应用具有很大的潜力，尽管传统的 DCS 实现方式存在信噪比（SNR）和脑灵敏度不理想的问题，难以对成年人的脑血流进行稳健的测量。在这项工作中，我们提出了长波长干涉 DCS（LW-iDCS），它结合了长波长（1064nm）照明、多散斑和干涉检测的使用，以提高脑灵敏度和 SNR。通过与基于超导纳米线单光子探测器的长波长 DCS 的直接比较，我们在人体血流信号的测量中证明了 LW-DCS 单通道 SNR 提高了约 5 倍。我们展示了 LW-DCS 和 LW-iDCS 之间提取的血流的等效性，并证明了在 3.5cm 的源-探测器分离距离处以 100Hz 测量 LW-iDCS 的可行性。这种性能的提高有望实现脑血流的稳健测量，并为漫反射相关光谱学开拓新的应用案例。
