Abstract：Objective: Blood vessels and their corresponding blood microcirculation are closely related to life activities. Different blood flow and microcirculation in the organism often correspond to different physiological and pathological conditions. The main function of microcirculation system mainly by the arteries, capillaries and microvascular and other small blood vessels (<150 μm) composition, is to provide nutrients and oxygen for the organization at the same time, the removal of carbon dioxide and other metabolic waste. Clinical medicine, by monitoring the changes in blood flow can be achieved on diabetes, hypertension, foot ulcers, atherosclerosis, Alzheimer's disease and tumor diseases such as early diagnosis or follow-up. Therefore, monitoring blood flow in blood vessels is not only important for studying the functional and disease mechanisms of biological tissues, but also one of the important methods for the clinical diagnosis and the evaluation of diseases.Changes in skin blood flow has been a hotspot in microcirculation research. At present, the commonly used method on studying the microcirculation of blood flow changes in spatial resolution is not high enough or need to add exogenous markers, with the passage of time, the marker content will gradually reduce the impact of follow-up measurement accuracy. This study aims to investigate the application and characteristics of laser speckle imaging (LSI) in the infrared microcirculation. Methods: Firstly, prepare a complete set of infrared therapy instrument model and recruit 10 volunteers,and then using the laser speckle imaging system to monitor 10 healthy volunteers (keep hand not moving during measurement) through the infrared therapy instrument heating with the microcirculation changes in the surface of the blood flow velocity and blood flow in real time changes. Results: Infrared thermotherapy methods lead to skin microcirculation (blood flow and vasomotor), skin temperature and body temperature increased significantly. From the laser speckle image can be seen in 10 volunteers compared with the normal state of the hand, infrared stimulation after the image of the red area increased, that is, blood flow has significantly increased. Conclusion: With far infrared effect on the skin, most of the energy can be absorbed by the skin energy into heat, causing skin temperature rise, stimulating the skin heat receptors, through the thalamus reflex, the vascular smooth muscle relaxation, blood vessels, and blood circulation to speed up. On the other hand, due to thermal effects, causing the release of vasoactive substances, decreased vascular tension, shallow arteries, shallow capillaries and superficial vein dilation, blood circulation improved. Through the laser speckle imaging technology can be effectively monitored under the influence of infrared therapy instrument under the microcirculation of blood flow changes. Laser speckle imaging has achieved real-time monitoring of vascular structure and function due to the advantages of high temporal resolution and large field imaging. However, since the imaging depth of the laser speckle imaging system is affected by the penetration depth of the excitation light in human tissue limit, the current laser speckle imaging is limited to the surface of the blood vessels and blood flow imaging. Therefore, how to deepen the blood vessel flow imaging is an important future direction of the development.
. [J]. 中国生物医学工程学报(英文版）, 2017, 26(3): 108-113.
HONG Yun-long. Application of Laser Speckle Imaging in Infrared Radiation Microcirculation. Chinese Journal of Biomedical Engineering, 2017, 26(3): 108-113.
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