Structured light imaging mesoscopy: application to skin changes in scleroderma

SignificanceScleroderma is a chronic, autoimmune disorder, characterized by the fibrosis of skin and internal organs. The extent of skin fibrosis is a good predictor of disease severity and mortality. Structured light imaging mesoscopy (SLIM) is a noncontact and label-free imaging technique that requires minimal postprocessing and no inverse model. SLIM may provide improved disease diagnosis and monitoring of scleroderma.AimWe aim to evaluate SLIM as a new optical method to assess skin involvement in scleroderma.ApproachSLIM measurements were collected from 25 scleroderma patients and 18 healthy controls across a range of spatial frequencies and wavelengths to find the optimal imaging parameters across skin tones. Monte Carlo simulations were conducted on a multilayer skin model that mimicked known biological changes in scleroderma.ResultsClinical data and simulations show that optimal spatial frequency (fx) and spectral (λ) imaging parameters for scleroderma monitoring lie in the range of fx=0.15 to 0.2 mm−1 and λ=811 to 851 nm, irrespective of subject skin tone. SLIM measurements taken with these parameters provided discrimination of scleroderma from healthy skin with an area under the curve of ≥0.87. We hypothesize that these changes correspond to changes in dermal collagen.ConclusionsSLIM can be used as a quantitative and objective method to assess skin involvement in scleroderma. The optimal imaging parameters target the relevant depths of the skin, making it sensitive to biological changes in scleroderma.