Motion correction of laser speckle imaging of blood flow by simultaneous imaging of tissue structure and non-rigid registration

Laser speckle contrast imaging (LSCI) has been widely used for mapping blood flow. LSCI is well known to be highly sensitive to movement artifacts. Previous studies attempted to register the global misalignment by using raw speckle images and rigid registration algorithm. However, it is difficult to correct the local non-rigid motion only by using granular raw speckle images, especially in the tissue dominated by small blood vessels. Here, we propose a method of imaging the tissue structure and its laser speckle simultaneously by a colour camera combined with a non-rigid registration algorithm to improve the motion correction of speckle imaging. The results of animal experiments show that this method significantly reduces the influence of non-rigid, spatially non-uniform motion on the estimation of blood flow, and improves the visualization of blood vessels in moving tissue, which can help to promote the practical application of LSCI technology.