Interpreting ICT: from Blood flow to Vascular Network


The inverse correlation time (ICT) is a key quantity in laser speckle contrast imaging (LSCI) measurement. Traditionally, ICT is mainly regarded as a metric of blood flow, such as speed, perfusion, and so on. However, we highlight that ICT not only contains important information about blood flow, but also reflects the structural impact of vascular network. In the past, ICT has been found to be correlated with vessel diameter. Here, we further report that ICT exhibits a differentiated sensitivity to blood flow contingent upon vessel orientation. Specifically, ICT is more sensitive to blood flow speed changes in vessels descending from or arising to the tissue surface, compared with those extending in the surface. Those findings shift our understanding of ICT from pure blood flow to more onto the structural impact of vascular network. We also develop theories to facilitate the study of vascular network’s impact on ICT.