Systemic sclerosis, also known as scleroderma, causes fibrosis that runs deep through the layers of the skin. Clinicians typically grade it with the modified Rodnan Skin Score, a manual pinch-and-feel exam that varies with physician skill. Biopsies provide more objective data, but they are invasive and cannot be done frequently enough to catch subtle changes.
Spatial frequency domain imaging (SFDI) offers a different approach. It uses ordinary visible light to probe the optical properties of skin, making it noninvasive and radiation-free. In a study published in Lancet Rheumatology, researchers at Boston University tested SFDI in 49 scleroderma patients and 25 healthy controls. The imaging parameters—diffuse reflectance and reduced scattering coefficient—correlated with Rodnan scores (r ranging from -0.38 to -0.48) and with fibrosis seen in biopsies (r ranging from -0.34 to -0.52). Both parameters were significantly lower in patients than in controls, even when Rodnan scores did not differ.
The research team also followed participants for up to four years, scanning every three to six months. Changes in SFDI parameters correlated with changes in Rodnan scores, suggesting the technology could track disease progression over time. Still, the authors caution that the longitudinal sample was modest and regression to the mean may have influenced the change-score analyses. They recommend larger, more diverse prospective studies and better handheld device designs before SFDI is ready for routine clinical use.