Quantifying collagen-based biological tissues using Fourier-transform-second-harmonic generation imaging

The purpose of this thesis is to report the generalization of Fourier transform-second-harmonic generation (FT-SHG) imaging to quantify the arrangement of collagen fibers in biological tissues in 3D. Collagen is the primary structural protein in the human body. Depending on the spatial arrangement of collagen fibers, collagen-based biological tissues can have a wide range of functions and mechanical properties. In addition, many biological tissues consist of 3D hierarchical structures made of collagen. Therefore, a 3D quantitative imaging technique with high specificity to collagen fibers will be a valuable tool for diagnostic and medical purposes. Recently, we have generalized FT-SHG to 3D by utilizing the 3D imaging capability of SHG microscopy and combining that with 3D spatial Fourier analysis to quantify collagen fiber organization. Via 3D FT-SHG, quantitative metrics such as orientation isotropy and preferred orientation can be extracted readily from SHG images. This thesis is going to demonstrate the utility of 3D FT-SHG by apply it to three different biological tissues: porcine tendon, porcine sclera, and rat cervix