Imaging of blood flow and blood concentration change in a frame rate using laser speckle: Methods for image analysis

We have proposed so far the method for imaging of blood flow and blood concentration change using laser speckle patterns at two wavelengths. In the method, blood flow was imaged at a frame rate of the imaging device used. The image quality was, however, deteriorated owing to the effects of random noises. Moreover, in imaging of blood concentration change, temporal averaging of speckle patterns, which was indispensable for speckle reduction, deteriorated the temporal resolution. In this paper, analysis of spatio-temporal differentiation of speckle patterns was first investigated to improve the image quality in imaging of blood flow. Use of median filtering for speckle patterns was secondly investigated to improve the temporal resolution in imaging of blood concentration change. Experiments were conducted for an anesthetized rat to confirm the feasibility of the present techniques.