Investigation of the spectroscopic optical coherence tomography technique for tissue analysis

Optical coherence tomography (OCT), a low coherence interferometric imaging technique, is a potentially useful tool for disease diagnosis and biological process monitoring. Spectral analysis of the OCT signals can yield additional information on the properties of scatterers in the sample, allowing tissue analysis and functional imaging to be performed. The objective of this work is to investigate the use of the spectroscopic OCT (SOCT) technique for biomedical applications. A systematic study was first carried out to determine an optimal metric for quantifying scatterer sizes using an improved SOCT analysis method. The proposed metric is then applied to the SOCT imaging of human palatine tonsil epithelial tissues for the purpose of cellular differentiation in disease management. In two tissue regeneration applications, the monitoring of stem cell seeded healing flexor tendons and fibroblast seeded silk fibroin scaffolds over time demonstrates the potential use of the SOCT method for observing cellular growth and quantifying cells of interest. An 840 nm wavelength Fourier-Domain OCT (FD-OCT) imaging system was designed, built and characterized in this thesis. The FD-OCT system is first used to investigate the optical-biomechanical characteristics of normal and injured flexor tendons under load. OCT images reveal vertical and horizontal banding caused by different optical phenomena in the flexor tendons. Images of tendons under mechanical loading show the gradual disappearance of vertical bands caused by the collagen fibers straightening during stress. Microtears, which are not visible to the naked eye, were also observed within the tendon after the maximum load was removed. The results demonstrate that the OCT modality is suitable for the non-invasive monitoring of tendon biomechanical properties and is potentially useful for assessing the quality of suture repair techniques.DOCTOR OF PHILOSOPHY (EEE