Skull Optical Clearing For Trancranial Microvasculature And Blood Flow Imaging

Monitoring and manipulation of cortical vasculature in vivo is integrant for studying the morphology and physiology microcirculation. Modern optical imaging method and sophisticated labeling technology make it possible for visualization of both cerebrovascular structural and functional architecture with high temporal-spatial resolution. In order to overcome the high scattering properties of skull which is above the cortex, craniotomy was performed. Unfortunately, the craniotomy yet has limitations. Optical clearing method is hopeful to solve the high scattering properties of the turbid skull. However, the current optical clearing method is mainly focus on the soft tissue which has no effect for the skull. How to develop a new effective skull optical clearing method to reduce the high scattering coefficient of skull, how to build a transparent skull window which is suitable for cortical imaging in vivo is need to be study. In this work, an innovative skull optical clearing solution has been proposed which can make the skull transparent in tens of minutes. The efficiency of the skull optical clearing method has been evaluated comprehensively. Both cerebrovascular structural and functional architecture were obtained based on the method:1) Theoretical and experimental study of screening effective skull optical clearing agents:Based on the analysis of composition and structure characteristics of the skull, high effective skull optical clearing agents were screened due to the combination of optical clearing theory and other theoretical analysis method for each component of the skull. Combined with the physical and chemical enhancement methods, implementation programs of the skull optical clearing technique was proposed.2) Quantitative evaluation of skull optical clearing efficacy:In order to investigate the efficiency of the proposed skull optical clearing technique quantitatively, in vitro experiments were designed to evaluate the efficacy including the divergence of beam spot, transmittance, scattering coefficient of skull, the performance of fluorescent imaging and the stability of fluorescent samples before and after the treatment.3) Cortical blood flow imaging based on skull optical technique:the combination of the skull optical technique and laser speckle contrast imaging system was used for mapping cortical blood flow and vasculature with high temporal-spatial resolution. The dynamic response of cerebral blood flow to durgs was monitored real time in vivo. Quantitative investigate was made to evaluate the improvement of the imaging performance. The results showed that the resolution, contrast, and sensitivity were greatly improved.4) Cortical vasculature imaging based on skull optical technique:the optical, acoustic and photoacoustic imaging performance were evaluated by modeling experiments in vitro before and after skull optical clearing treatment. the combination of the skull optical technique and photoacoustic imaging microscopy was used to obtain the architecture of cortex blood vessels in deep tissue in vivo. Quantitative investigate was made to evaluate the improvement of the imaging performance. The results showed that the signal level can be effectively elevated, and the artifacts induced by the skull can be depressed.The proposed skull optical clearing method can achieve the visualization of both cerebrovascular structural and functional architecture with high temporal-spatial resolution without craniotomy. It provides a simple and effective method for observation and manipulation of cortical vasculature real time in vivo, which will generate a significant contribution to brain research.