In-vivo Imaging Of Zebrafish Based On Functional Optical Coherence Tomography

As an important animal model,zebrafish has high similarity with human from the genetic to the organ and has important research value in the fields of development,pathology,and toxicology.In-vivo imaging of zebrafish is important for long-term monitoring of the dynamic changes for different organs.Developing a label-free,highresolution in-vivo optical method for zebrafish imaging with a large field of view and large imaging depth has significant practical value.Optical coherence tomography(OCT)can obtain high-resolution,label-free,large-field,three-dimensional images for the sample in real time.In recent years,OCT has been combined with other technologies for more specific functional information inside the sample,which further extends the function of OCT.In this thesis,a high-resolution polarization-sensitive OCT(PS-OCT)system was built,and an OCT Angiography(OCTA)method suitable for PS-OCT was developed.Comprehensive and detailed in-vivo functional imaging studies were carried out for the muscles,skin and brain of zebrafish at the juvenile and adult stages.The work content and research results are as follows:1.A high-resolution PS-OCT system was built,whose axial and lateral resolutions are3.4 ?m and 8 ?m,respectively.A variety of polarization parameters can be obtained,including accumulative retardation,accumulative optic axis,degree of polarization uniformity,local retardation,and local optic axis.2.A circulatory anesthesia system with a peristaltic pump and catheter was designed and built,which was suitable for zebrafish in-vivo imaging.Different clamping elements for different imaging positions were designed.3.An OCTA algorithm for PS-OCT was developed.Combining the dual-channel signals from PS-OCT,a new OCTA algorithm was developed based on the splitspectrum amplitude-decorrelation angiography(SSADA)method.The study demonstrated that the average intensity projection of OCTA was the best display method for zebrafish vascular information.4.Based on the PS-OCT system,an in-vivo imaging study for zebrafish muscle was carried out.The lateral,dorsal and ventral sides of zebrafish were scanned with a large field of view,and three-dimensional images of the zebrafish muscle were achieved.The structure and polarization information of various muscles were analyzed.Based on the degree of polarization uniformity(DOPU)threshold,the zebrafish muscles in the PS-OCT image were extracted.In addition,based on different polarization images,zebrafish muscle types and fiber orientation were identified,and the symmetry of zebrafish ventral and dorsal muscle was discovered.Based on the in-vivo imaging result of zebrafish muscle wounds,injured and normal muscle regions were distinguished.This study proved that PS-OCT has the feasibility of in-vivo imaging for zebrafish muscle and application value in muscle development and pathological analysis.5.Based on PS-OCT and OCTA,a multi-functional in-vivo imaging study of zebrafish skin was carried out,which realized the synchronous monitoring of adult zebrafish skin tissue and blood vessels.The structure,polarization characteristics,and vascular distribution of juvenile and adult zebrafish skin were analyzed and compared.Based on PS-OCT and OCTA images,skin,bone and different pigments can be effectively distinguished,and the spatial relationship between vessels and scale matrix can be displayed.The in-vivo monitoring for the healing process of zebrafish skin wounds revealed the recovery mechanism of zebrafish skin wounds.This study proved that PS-OCT and OCTA have the feasibility of in-vivo imaging for zebrafish skin and the application value in pigment distribution and skin wound monitoring.6.Based on PS-OCT and OCTA,a multi-functional in-vivo imaging study of zebrafish brain and skull was carried out,and the polarization imaging for the adult zebrafish brain and the label-free imaging for the head vasculature were realized.After the skull removal,the polarization results of the brain were analyzed and demonstrated that polarization characteristics of the zebrafish brain are similar to those of the human brain.The results of in-vivo imaging for the zebrafish brain and skull proved that different areas of the brain have different pigment driving abilities.The skull and skull sutures were identified,and the distribution of the vasculature of the zebrafish head was displayed.The results of in-vivo monitoring for zebrafish skull and brain wounds revealed the recovery mechanism of zebrafish skull and brain wounds.This study proved that PS-OCT and OCTA have the feasibility of in-vivo imaging for zebrafish brain and skull and the application value of pigment-driven and skull injury research.In conclusion,PS-OCT and OCTA were combined for in-vivo zebrafish muscles,skin and brain imaging.The PS-OCT system and the zebrafish in-vivo imaging anesthesia system were constructed.An OCTA algorithm suitable for PS-OCT was developed.Plenty of studies have been carried out on the image acquisition,calculation,and analysis for the structure,polarization,and vasculature of different tissues and organs in zebrafish.This researches in the thesis extend in vivo zebrafish optical imaging from the zebrafish larva stage(less than 15 days)to the juvenile and adult stage,providing a new technical method for digging more information of zebrafish.