By using our dual-modality system enabling simultaneous real-time ultrasound (US) and photoacoustic (PA) imaging of human peripheral joints, we explored the potential contribution of PA imaging modality to rheumatology clinic. By performing PA imaging at a single laser wavelength, the spatially distributed hemoglobin content reflecting the hyperemia in synovial tissue in metacarpophalangeal (MCP) joints of 16 patients were imaged, and compared to the results from 16 healthy controls. In addition, by performing PA imaging at two laser wavelengths, the spatially distributed hemoglobin oxygenation reflecting the hypoxia in inflammatory joints of 10 patients were imaged, and compared to the results from 10 healthy controls. The statistical analyses of the PA imaging results demonstrated significant differences (p < 0.001) in quantified hemoglobin content and oxygenation between the unequivocally arthritic joints and the normal joints. Increased hyperemia and increased hypoxia, two important physiological biomarkers of synovitis reflecting the increased metabolic demand and the relatively inadequate oxygen delivery in affected synovium, can both be objectively and non-invasively evaluated by PA imaging. The proposed dual-modality system has the potential of providing additional diagnostic information over the traditional US imaging approaches and introducing novel imaging biomarkers for diagnosis and treatment evaluation of inflammatory arthritis.

No abstract

Objective Systemic sclerosis (SSc) is a multisystem disease with heterogeneity in presentation and prognosis. An international collaboration to develop new SSc subset criteria is underway. Our objectives were to identify systems of SSc subset classification and synthesize novel concepts to inform development of new criteria. Methods Medline, Cochrane MEDLINE, CINAHL, EMBASE and Web of Science were searched from their inceptions to December 2019 for studies related to SSc sub-classification, limited to humans without language or sample size restrictions. Results Of 5686 citations, 102 articles reported original data on SSc subsets. Subset classification systems relied on extent of skin involvement and/or scleroderma-specific autoantibodies (n=61), nailfold capillary patterns (n=29), molecular, genomic and cellular patterns (n=12). While some systems of subset classification confer prognostic value for clinical phenotype, severity, and mortality; only subsetting by gene expression signatures in tissue samples has been associated with response to therapy. Conclusion Subsetting on extent of skin involvement remains important. Novel disease attributes including SSc-specific autoantibodies, nailfold capillary patterns and tissue gene expression signatures have been proposed as innovative means of SSc subsetting.

No abstract