Diffuse correlation spectroscopy measurements of blood flow using 1064 nm light.
Diffuse correlation spectroscopy measurements of blood flow using 1064 nm light.
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DOI：
10.1117/1.jbo.25.9.097003
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发表时间：
2020-09
影响因子：
3.5
通讯作者：
Franceschini MA
中科院分区：
文献类型：
--
作者：
Carp S;Tamborini D;Mazumder D;Wu KC;Robinson M;Stephens K;Shatrovoy O;Lue N;Ozana N;Blackwell M;Franceschini MA
重要性：扩散相关光谱（DCS）是一种成熟的光学模式，其通过量化由移动红细胞的动态散射产生的时间光强度波动来实现对深部组织中的血流的无创测量。与近红外光谱相比，DCS由于需要使用小的检测孔径来保持散斑对比度而受到有限的信噪比（SNR）的阻碍。然而，DCS是一种动态光散射技术，不依赖于血红蛋白对比度;因此，由于各种生物物理和调节因素，使用较长波长（）进行DCS测量具有显著的SNR优势。目的：我们通过模拟和实验演示，对在1064 nm与典型的765至850 nm波长下运行DCS的优势和挑战进行了定量评估。方法：我们评估光子预算，深度灵敏度，和SNR检测血流变化，使用数值模拟。我们讨论了连续波（CW）和时域（TD）DCS的硬件考虑1064 nm操作。我们报告的概念验证测量组织样幻影和健康的成年志愿者。结果如下：由于增加的光子计数和较慢的自相关衰减，与通常使用的波长范围（765至850 nm）的DCS测量相比，1064 nm处的DCS对深部组织提供了更高的固有灵敏度。这些优势进行了探讨，使用模拟和证明使用幻影和体内测量。我们展示了第一个高速（心脏脉动分辨），高信噪比测量在大的源检测器分离（3厘米）CW-DCS和TD-DCS的后期时间门（1纳秒）。结论：1064 nm的DCS在监测深部组织血流的能力上实现了飞跃，在提高成人脑血流监测的可靠性方面尤其有用。
Significance: Diffuse correlation spectroscopy (DCS) is an established optical modality that enables noninvasive measurements of blood flow in deep tissue by quantifying the temporal light intensity fluctuations generated by dynamic scattering of moving red blood cells. Compared with near-infrared spectroscopy, DCS is hampered by a limited signal-to-noise ratio (SNR) due to the need to use small detection apertures to preserve speckle contrast. However, DCS is a dynamic light scattering technique and does not rely on hemoglobin contrast; thus, there are significant SNR advantages to using longer wavelengths () for the DCS measurement due to a variety of biophysical and regulatory factors. Aim: We offer a quantitative assessment of the benefits and challenges of operating DCS at 1064 nm versus the typical 765 to 850 nm wavelength through simulations and experimental demonstrations. Approach: We evaluate the photon budget, depth sensitivity, and SNR for detecting blood flow changes using numerical simulations. We discuss continuous wave (CW) and time-domain (TD) DCS hardware considerations for 1064 nm operation. We report proof-of-concept measurements in tissue-like phantoms and healthy adult volunteers. Results: DCS at 1064 nm offers higher intrinsic sensitivity to deep tissue compared with DCS measurements at the typically used wavelength range (765 to 850 nm) due to increased photon counts and a slower autocorrelation decay. These advantages are explored using simulations and are demonstrated using phantom and in vivo measurements. We show the first high-speed (cardiac pulsation-resolved), high-SNR measurements at large source–detector separation (3 cm) for CW-DCS and late temporal gates (1 ns) for TD-DCS. Conclusions: DCS at 1064 nm offers a leap forward in the ability to monitor deep tissue blood flow and could be especially useful in increasing the reliability of cerebral blood flow monitoring in adults.