Transmissive-detected laser speckle contrast imaging for blood flow monitoring in thick tissue: from Monte Carlo simulation to experimental demonstration

• Published in: Light, science & applications Vol. 10; no. 1; p. 241
• Main Authors: Li, Dong-Yu, Xia, Qing, Yu, Ting-Ting, Zhu, Jing-Tan, Zhu, Dan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.12.2021; Springer Nature B.V; Nature Publishing Group
• Subjects: 639/624/1107/510; 639/624/1111/55; Applied and Technical Physics; Atomic; Blood flow; Classical and Continuum Physics; Lasers; Molecular; Monte Carlo simulation; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Spatial discrimination
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-021-00682-8

Laser speckle contrast imaging (LSCI) is a powerful tool to monitor blood flow distribution and has been widely used in studies of microcirculation, both for animal and clinical applications. Conventionally, LSCI usually works on reflective-detected mode. However, it could provide promising temporal and spatial resolution for in vivo applications only with the assistance of various tissue windows, otherwise, the overlarge superficial static speckle would extremely limit its contrast and resolution. Here, we systematically investigated the capability of transmissive-detected LSCI (TR-LSCI) for blood flow monitoring in thick tissue. Using Monte Carlo simulation, we theoretically compared the performance of transmissive and reflective detection. It was found that the reflective-detected mode was better when the target layer was at the very surface, but the imaging quality would rapidly decrease with imaging depth, while the transmissive-detected mode could obtain a much stronger signal-to-background ratio (SBR) for thick tissue. We further proved by tissue phantom, animal, and human experiments that in a certain thickness of tissue, TR-LSCI showed remarkably better performance for thick-tissue imaging, and the imaging quality would be further improved if the use of longer wavelengths of near-infrared light. Therefore, both theoretical and experimental results demonstrate that TR-LSCI is capable of obtaining thick-tissue blood flow information and holds great potential in the field of microcirculation research. The performance of novel transmissive-detected LSCI was systematically demonstrated through simulation and experiments. With such a simple system, individual vessel-resolution blood flow mapping and monitoring were realized on human hand.