Robust laser speckle contrast images suitable for blood vessel visualization

Abstract

Laser speckle contrast imaging (LSCI) is an optical technique capable for blood flow analyzing based on local speckle contrast. In general, a CCD camera combined with a simple optical arrangement allows to obtain blood flow information. Unfortunately, there are important limitations in the case of deep blood vessels (about 300μm). In this case, it is difficult to obtain blood vessel information since speckle patterns inside the images are sparse. In this work, we propose an iterative spatiotemporal anisotropic filtering approach which, aims to improve the performance under deep vessels images. This approach consists in two different filters combined with an iterative behavior and a post processing step. First, a temporal filter computes the contrast gradient (K) for all pixels within the input image. Then, contrast directions are computed. Finally, a spatiotemporal filter analyzes the blood flow behavior based on the contrast directions. Experimental results are encouraging, the proposed approach improves the performance under deep vessels, compared with previous work. Furthermore, these results (which were obtained at different samples) demonstrated that it is possible to improve the global performance by using an iterative behavior.