Sidestream Dark Field (SDF) imaging of oral microcirculation in the assessment of systemic sclerosis

Introduction Systemic sclerosis (SSc) is a systemic disease characterised by abnormalities in small blood vessels, skin and organ fibrosis. It is assessed using generalised skin thickening scores, autoantibodies and nailfold capillaroscopy. Sidestream Dark Field imaging (SDF) is a non-invasive imaging tool that assesses microcirculation. This study aims to investigate the potential of using SDF as a diagnostic tool in SSc. Method: Oral microcirculation of 20 patients with SSc was compared to 20 age and gender matched controls using SDF imaging. Sublingual, buccal and incisor regions of the mouth were examined. All volunteers were female averaging 48.0 (24-64) years old. Vasculature was assessed by calculating the De Backer score and Functional Capillary Density (FCD) on an imaging software. Results: At all regions of the mouth, SSc patients had a significantly lower De Backer score compared to controls (SSc 3.484 +/- 0.1361/mm vs Control 5.184 +/- 0.1896/mm, unpaired t-test p < 0.0001). The SSc patients showed significantly lower FCDs compared to controls at all areas as well (SSc 19.65 +/- 0.9445% vs Control 29.45 +/- 1.681%, unpaired t-test, p < 0.0001). The incisor regions had significantly higher De Backer and FCD scores than buccal and sublingual regions in both control and SSc patients (one way anova, p < 0.05). De Backer/FCD scores showed significant correlation against Rodnan Skin Scores in patients with SSc (Pearson correlation, p < 0.05). Conclusions: SSc patients showed decreased oral vasculature compared to controls. SDF imaging has shown the ability to be a useful diagnostic tool in the assessment of SSc.