Research On Speckle Contrast Related Factors In Laser Speckle Imaging

Monitoring cerebral blood flow (CBF) and blood vessel is important to understand the mechanisms of neurovascular coupling and regulation in normal and disease brain. However, conventional methods used to measure blood flow suffer from the low spatial resolution and temporal resolution or the injection of exogenous substances. Laser speckle contrast imaging (LASCI) technique is a non-scanning image technique, resulting measurements of the regional blood flow with high spatial and temporal resolution. And thus this method is popular in nowadays.In this thesis, LASCI was studied from two aspects. Firstly, the LASCI was researched, including factors affecting spatial contrast imaging and the relationship between temporal contrast and spatial contrast. Secondly, temporal contrast imaging of cerebral blood flow through the intact skull of rat was demonstrated.Theories of laser speckle spatial contrast imaging (LSSCI) and image processing method were discussed in this thesis. Sensitivity of blood flow measurement decreased with velocity. The absorption coefficient and intensity influenced the measurement of blood flow.In the thesis the relations of spatial contrast and temporal contrast were deduced. A laser speckle imaging system was built for high interference light illumination and stability. The model experiments were prepared for researching the relation of velocity and contrast. Imaging CBF with harmless method is an aim of researchers. Existing methods have the defects of damage to cerebrum or low resolution. Thus this thesis demonstrated that the temporal contrast imaging could be used to monitoring CBF through intact rat skull. Model experiments and animal experiments were provided to test the method.User interface of laser speckle image processing is a data processing and analysis tool for biological and medical researchers. Thus, software named SpecUI was developed.