Optical coherence tomography imaging of collagenous tissue microstructure

Abstract

The engineering of new biomaterials requires an in-depth understanding of the structure and function of the native tissues. Optical coherence tomography (OCT) is a non-destructive technique that allows the visualization of the microstructure of biological tissues. The aim of this study was to determine if OCT could be used to identify geometric properties of tendons such as crimp pattern. Freshly harvested tendon tissue was imaged with OCT during the application of incremental axial strain. Loads were simultaneously recorded during imaging. Results revealed that birefringent banding perpendicular to the collagen fiber axis could be visualized and measured. This crimp banding disappeared at a very low strain. Birefringent banding parallel to the collagen fiber axis was also seen and it was observed that the number of parallel bands increased as strain increased. Stress-strain data was calculated and found to lie within the expected range. These results indicate that OCT may prove to be a useful tool for the non-destructive analysis of tissue microstructure.

A novel microstructural approach in tendon viscoelastic modelling at the fibrillar level

“…The relations between the mechanical characteristics in tendons and their fibrillar structure have been investigated by Fraztl et al (1997). The stress-strain curve starts with a toe region where the vertical crimp banding disappears (Hansen et al, 2000), indicating the straightening of crimped collagen fibrils (Hansen et al, 2002). For strains beyond 3%, molecular links occur by thermal activation and bring to an increase of stiffness, typical of the heel region.…”

Investigation of the spectroscopic optical coherence tomography technique for tissue analysis

“…By contrast, the horizontal bands in the OCT images are found to shift when the polarization of the incident light is varied. This is in good agreement with previous studies[111,162] and indicates that the horizontal bands are induced by collagen birefringence. As the light polarization states in the reference and sample arms of the OCT system are unknown, the actual phase retardation in the birefringent regions of the sample revealed in the OCT images were not extracted in this work.…”

“…In early tendon imaging, conventional OCT has been used to study the optical characteristics of tendons [144][145]162]. Vertical and horizontal banding patterns were observed from TD-OCT images of sheep tendons [162]. The horizontal bands in the OCT images were observed to be polarization-dependent and they were attributed to collagen birefringence due to the crimp of the fibril.…”

Biomechanical Behavior of Atherosclerotic Plaque

“…The mechanical response of collagen is often modeled using tendon, since tendon is predominantly composed of collagen fibers aligned in a single direction. Several studies have attempted to visualize collagen structure and load response using tendon specimens (Hansen et al 2000;Hansen et al 2002;Puxkandl et al 2002;Krahn et al 2006;Fata et al 2013). These studies have employed confocal microscopy, X-ray diffraction, and other imaging techniques to visualize the collagen structure.…”