Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

Abstract

Abstract. We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury.

In vivooptical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

“…Complete mathematical analysis of each dataset was performed. 32,33,38 In summary, birefringent tissue regions were detected in PS-OCT by depth-dependent changes in the cumulative phase retardation experienced by different polarization states of the reflected light. With an increase in tissue birefringence, more rapid changes in both phase retardation and polarization state will be detected.…”

“…This graph displays data averaged over the entire imaged volume. After allowing for the thickness of the epineurium in the first few microns, 33 the initial slope of this graph indicated by the red line (0.4328 deg ∕μm) provides a quantifiable measurement of birefringence. Figure 3(d) is an image of the corresponding histological section.…”

“…Similar technology has been previously used with success for the assessment of birefringence changes in skin following thermal damage due to denaturation of dermal collagen 32 as well as for determining the structural features in rat sciatic nerve. 33 In this animal study, we evaluate the ability of PS-OCT to assess the microenvironment of the normal and injured peripheral nerves following nerve crush injury and nerve transection.…”

Polarization sensitive optical coherence tomography – a review [Invited]

“…20, demonstrating the reduced birefringence in tumor tissue. PS-OCT could also find an application in the study of the regeneration of nerves after injury or to visualize nerves intraoperatively during e.g., prostatectomy, due to the contrast PS-OCT images provide over structural intensity images for nerves due to their birefringent properties [171][172][173].…”

Polarization Sensitive Optical Coherence Tomography: A Review of Technology and Applications

“…Improved delineation of the sciatic nerve boundaries to muscle and adipose tissues as well as quantitative birefringence measurements were enabled by the additional polarization contrast [224]. In an experimental nerve crush model, decreasing birefringence was observed in parallel to a loss of myelination (Figure 12a-d) [225].…”