Transmissive detection laser speckle imaging for blood flow monitoring in thick tissues

a, Transmission detection laser speckle contrast imaging (TR-LSCI) system diagram. b, Diagram of a conventional reflection detection LSCI system. c, Comparison of TR-LSCI and conventional LSCI for skin / subcutaneous blood flow mapping in different parts of the mouse body. In (c), it is clear that TR-LSCI has excellent image quality for each body part, especially the thick part. d, TR-LSCI for dynamic blood flow monitoring of mouse hind limbs after injection of acetylcholine (drug that dilates blood vessels). TR-LSCI was able to distinguish individual cutaneous blood vessels. The plot in (d) shows the dynamics of the femoral vein and the branches of the femoral vein. This indicates that the blood flow velocity in the branches of the femoral vein responded more strongly but recovered faster than in the femoral vein. e, Comparison of TR-LSCI and conventional LSCI for subcutaneous blood flow mapping of different parts of the human hand. As shown in (e), blood flow in individual blood vessels could be solved by TR-LSCI, but could not be distinguished by conventional LSCI. f, conventional LSCI and TR-LSCI for human hand reactive hyperemia experiments. Surface perfusion was monitored using conventional LSCI and TR-LSCI was used to monitor blood flow in deep vessels. The histogram in (f) shows the dynamics of superficial perfusion and deep blood flow. The results suggested that blood flow in larger vessels was more affected by pressure and recovered more slowly after the pressure was released. Credits: Dong-Yu Li, Qing Xia, Ting-Ting Yu, Jing-Tan Zhu, Dan Zhu
Blood flow velocity is an important parameter that reflects vascular function. Abnormal vascular function is closely associated with the development and development of many diseases such as diabetes, arteriosclerosis and thrombosis. Therefore, flow velocity monitoring is not only an important research subject, but also an important clinical indicator.

Laser Speckle Contrast Imaging (LSCI) is a wide-field, non-invasive imaging technique that is temporal and Spatial resolution Based on the analysis of the optical signal after scattering and random interference, it obtains velocity information of scattered particles. Living tissue (for example, Red blood cells ). Widely used for research on vascular function. However, traditional windowless models operate in reflection detection mode, so they can barely detect deep signals. Therefore, the strength of the upper static speckle is much higher than the strength of the dynamic speckle signal of the deep blood vessels of the target, resulting in a lower signal-to-background ratio (SBR).

In a new paper published in Optical science and application Dan Zhu’s group at the Briton Chance Biomedical Photonics Center, Wuhan Optoelectronics Institute, China China University of Technology, has significantly enhanced the imaging capabilities of laser speckle imaging in thick tissues by changing the detection method of laser speckle imaging. Improved to. With the permeation detection method, the dynamic speckle signal from the vascular layer is stronger than the static speckle information from the upper tissue layer, improving the SBR for thick tissue blood flow detection.

In previous studies, conventional reflex detection LSCI was able to obtain high resolution images of the […]

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