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

Abstract

Abstract. Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitiveoptical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve microenvironment through measurements of birefringence after applying a nerve crush injury in a rat model. Initial loss of function and subsequent recovery were demonstrated by calculating the sciatic function index (SFI). We found that the PS-OCT phase retardation slope, which is proportional to birefringence, increased monotonically with the SFI. Additionally, histomorphometric analysis of the myelin thickness and g-ratio shows that the PS-OCT slope is a good indicator of myelin health and recovery after injury. These results demonstrate that PS-OCT is capable of providing nondestructive and quantitative assessment of nerve health after injury and shows promise for continued use both clinically and experimentally in neuroscience.

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].…”

Uncovering the biology of myelin with optical imaging of the live brain

“…OCM is a technique that capitalizes on the variation in scattering of near-infrared light between different cellular structures and tissues in order to extract contrast (Huang et al, 1991). This imaging technique has been used extensively for label-free imaging of retinal structure (Hee et al, 1995) but has also been shown to be able to extract images of myelin in the brain (Ben Arous et al, 2011;Henry et al, 2015;Yamanaka, Teranishi, Kawagoe, & Nishizawa, 2016). Similar to OCM's dependence on differential tissue scattering, THG microscopy is a nonlinear imaging approach that generates a signal at lipid-water interfaces due to nonlinear coherent scattering (Weigelin, Bakker, & Friedl, 2016).…”

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]. The prostatic nerves-indiscernible from surrounding tissue by standard, intensity based OCT-were identified in prostates of rats and humans, thereby indicating the feasibility of PS-OCT as a method for intrasurgical imaging [226].…”