Assessing spatial frequency domain imaging as an objective quantification of longitudinal skin changes in scleroderma

PROJECT SUMMARY/ABSTRACT Systemic sclerosis (SSc) is an autoimmune connective tissue disease, with a 10-year mortality of 40%, the highest of all autoimmune diseases. Painful, itchy skin tightening is an early feature, and can have a major impact on quality of life and daily living. Clinically, quantification of skin fibrosis in SSc is performed using the modified Rodnan skin score (mRSS), which involves pinching of the skin in several body areas. mRSS is subjective, has high inter-rater variability, and may not be sensitive enough to detect small but clinically meaningful changes. Clinical trials using mRSS as an outcome measure have failed, leading to a lack of skin-directed FDA-approved therapies. The overall goal of our research is to solve this unmet clinical need, by delivering an outcome measure for monitoring SSc skin disease that is both objective, sensitive, and reliable. Spatial frequency domain imaging (SFDI) is a low cost, objective and noninvasive method that can rapidly measure a large tissue area (> 10 x 10 cm) with penetration depths of 1-5 mm. Results from our prior study suggest that SFDI could accurately quantify skin changes in SSc, and can even detect sub-clinical skin changes, with an inter-observer variability that outperforms that of mRSS. Preliminary results show strong correlation between longitudinal changes in SFDI with changes in mRSS scores in individual patients. The specific aims of this proposal will prospectively evaluate the ability of SFDI in tracking disease change over time in individual SSc patients. Over a 12-month period, we will track changes in disease activity by measuring SFDI at specific time points. We will then compare its performance with established clinical skin outcome measures and PROs in Aim 1, and with other noninvasive skin metrics and histology disease markers in Aim 2. Successful completion of these aims will help further validate SFDI as an objective and sensitive skin outcome measure both for disease management and for future use in SSc clinical trials.