Assessing the progression of systemic sclerosis by monitoring the tissue optic axis using PS-OCT.

The clinical assessment of fibrosis is critical to the diagnosis and management of patients with systemic sclerosis. Current clinical standards for patient assessment is to use skin fibrosis as an indicator of organ involvement, though this approach is highly subjective and relies on manual palpation. The development of a new method for accurately quantifying collagen content may therefore significantly improve the accuracy of the traditional skin score in patients with systemic sclerosis and may additionally aid in the monitoring of anti-fibrotic therapies in clinical practice. Polarization-sensitive optical coherence tomography (PS-OCT) is a high-speed volumetric imaging modality that can be used to assess birefringent tissues including collagen. In this work we demonstrate a novel computational approach using PS-OCT for the assessment of fibrosis. This approach, based on the measured distribution of optic axis values associated with a given volume of collagen orientation, characterizes fibrotic changes independently from the depth of the region of interest in the tissue. This approach has the potential to accurately quantify collagen content and orientation faster and more robustly compared to traditional PS-OCT metrics. We investigate the viability of this approach for assessing the development of fibrosis in a bleomycin induced skin fibrosis mouse model.