A comparative study between laser speckle contrast imaging in transmission and reflection modes by adaptive window space direction contrast algorithm

Blood flow visualization is of paramount importance in diagnosing and treating vascular diseases. Laser speckle contrast imaging (LSCI) is a widely utilized technique for visualizing blood flow. However, Reflect-laser speckle contrast imaging (R-LSCI) systems are limited in their imaging depth and primarily suitable for shallow blood flow imaging. In this study, we conducted a comparative analysis of Transmissive-laser speckle contrast imaging (T-LSCI) and R-LSCI using four spatial domain imaging methods: spatial contrast (sK), adaptive window contrast (awK), space-directional contrast (sdK), and adaptive window space direction contrast (awsdK), for deep blood flow imaging. Experimental results show that T-LSCI is superior to R-LSCI in imaging deep blood flow within a certain thickness of tissue. T-LSCI can be used for continuous non-invasive blood flow monitoring. Particularly, the utilization of the awsdK method in T-LSCI substantially improves the visualization of deep blood flow and enhances the ability to monitor blood flow variations.