Background Optical coherence tomography (OCT) has been recently shown to be a novel quantitative reliable tool to assess skin involvement in Systemic Sclerosis (SSc) (1). However the sensitivity to change over-time has not been evaluated.
Objectives The present study aimed to compare skin assessment by OCT over-time in patients with SSc.
Methods We performed 52 OCT scans of dorsal forearms on 26 sites of analysis from 17 SSc patients (9 with diffuse, 8 with limited subset according to Le Roy et al; F/M =15:2; mean disease duration at baseline ± SD =6±4.5 years) at 0 and 24 months. Clinical skin involvement was assessed using the modified Rodnan skin score (mRss). Minimum and Maximum Optical Density (Min and Max OD) of the mean-A scans were calculated employing Matlab software as previously described (1). Comparison of the mRss at the site of analysis and Min and Max OD at the 2 time-points was performed by two-tailed paired t-test employing GraphPrism software.
Results Fourteen sites of analysis with local mRss=0 did not change over 24 months. Accordingly, both Min and Max OD showed only an average +2.98% and -0.05% change, respectively (p>0.05). By contrast, at 6 sites of analysis mRss improved by 2 points (three sites with local score “2” improved to “0”, three sites with local score of “3” improved to “1”). At these sites Min OD showed an average increase of 23.92% (p=0.0084) and Max OD of 25.13% (p=0.008). At 4 sites of analysis mRss improved by 1 point (two sites with local score “3” improved to “2”, one site with local score of “2” improved to “1”, one site with local score of “1” improved to “0”). At these sites Min OD and Max OD showed no significant improvement (Min OD of 1.93% and Max OD of 8.15%; p>0.05 for both). Furthermore, both Min and Max OD showed a trend towards a decrease (-3.54%, -5.41% respectively) at the 2 sites of analysis with worsening mRSS (one point increase).
Conclusions Although a low number of observations, this preliminary study provides the first evidence suggesting that OCT of the skin is sensitive to change over time and is consistent with mRss. The lack of improvement of OCT findings at sites with a mRSS of 1 deserves further evaluation to determine whether this is associated with poor accuracy of mRSS or room for improvement in OCT analysis. Studies including a larger number of patients and sites of analysis with different grades of skin involvement and improvement/deterioration of clinical score are needed for more definitive validation.
Abignano G, Aydin SZ, Castillo-Gallego C et al. Virtual Skin biopsy by Optical Coherence Tomography: the first quantitative imaging biomarker for Scleroderma. Ann Rheum Dis 2013;72:1845-51.
Disclosure of Interest G. Abignano: None declared, L.-A. Bissell: None declared, J. Britton: None declared, G. Lettieri: None declared, D. Woods Employee of: Michelson Diagnostics, M. Buch: None declared, D. McGonagle: None declared, P. Emery: None declared, F. Del Galdo: None declared