Hyperspectral imaging in systemic sclerosis-associated Raynaud phenomenon

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background/purpose</jats:title><jats:p>Lack of robust, feasible, and quantitative outcomes impedes Raynaud phenomenon (RP) clinical trials in systemic sclerosis (SSc) patients. Hyperspectral imaging (HSI) non-invasively measures oxygenated and deoxygenated hemoglobin (oxyHb and deoxyHb) concentrations and oxygen saturation (O<jats:sub>2</jats:sub>sat) in the skin and depicts data as oxygenation heatmaps. This study explored the potential role of HSI in quantifying SSc-RP disease severity and activity.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Patients with SSc-RP (<jats:italic>n</jats:italic>= 13) and healthy control participants (HC;<jats:italic>n</jats:italic>= 12) were prospectively recruited in the clinic setting. Using a hand-held camera, bilateral hand HSI (HyperMed™, Waltham, MA) was performed in a temperature-controlled room (22 °C). OxyHb, deoxyHb, and O<jats:sub>2</jats:sub>sat values were calculated for 78-mm<jats:sup>2</jats:sup>regions of interest for the ventral fingertips and palm (for normalization). Subjects underwent a cold provocation challenge (gloved hand submersion in 15 °C water bath for 1 min), and repeated HSI was performed at 0, 10, and 20 min. Patients completed two patient-reported outcome (PRO) instruments: the Raynaud Condition Score (RCS) and the Cochin Hand Function Scale (CHFS) for symptom burden assessment. Statistical analyses were performed using the Mann-Whitney<jats:italic>U</jats:italic>test and a mixed effects model (Stata, College Station, TX).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Ninety-two percent of participants were women in their 40s. For SSc-RP patients, 69% had limited cutaneous SSc, the mean ± SD SSc duration was 11 ± 5 years, and 38% had prior digital ulcers—none currently. Baseline deoxyHb was higher, and O<jats:sub>2</jats:sub>sat was lower, in SSc patients versus HC (<jats:italic>p</jats:italic>< 0.05). SSc patients had a greater decline in oxyHb and O<jats:sub>2</jats:sub>sat from baseline to time 0 (after cold challenge) with distinct rewarming oxyHb, O<jats:sub>2</jats:sub>sat, and deoxyHb trajectories versus HCs (<jats:italic>p</jats:italic>< 0.01). There were no significant correlations between oxyHb, deoxyHb, and O<jats:sub>2</jats:sub>sat level changes following cold challenge and RCS or CHFS scores.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Hyperspectral imaging is a feasible approach for SSc-RP quantification in the clinic setting. The RCS and CHFS values did not correlate with HSI parameters. Our data suggest that HSI technology for the assessment of SSc-RP at baseline and in response to cold provocation is a potential quantitative measure for SSc-RP severity and activity, though longitudinal studies that assess sensitivity to change are needed.</jats:p></jats:sec>