Abstract
Background
The modified Rodnan skin score (mRSS) is the current gold standard for skin assessment in systemic sclerosis (SSc) both in clinical trials and practice. Several studies have reported that skin high frequency ultrasound (HFUS) and, more recently, optical coherence tomography (OCT) are able to reflect the severity of the skin disease in SSc. Aim of the study was to compare OCT and HFUS in the assessment of skin involvement in SSc.
Methods
Dorsal forearm skin of consecutive diffuse cutaneous SSc (dcSSc) patients and matched-healthy controls (HC) were scanned using OCT and HFUS by investigators blinded to the clinical details using Vivosight scanner (1 assessor) and Esaote MyLab70 equipped with a 22 MHZ probe (2 assessors) respectively. Minimum Optical Density (MinOD), Maximum OD (MaxOD) and OD at 300 micron-depth (OD300) (OCT) and skin thickness (HFUS) were measured. Clinical involvement was assessed by a blinded operator using the mRSS and results were cross matched with imaging data. Statistical analysis was performed using GraphPad Prism software V.7.0.
Results
A total of 88 OCT images and 176 HFUS images were obtained from 22 dcSSc patients [20 Female, mean age 49 (±11) years, 12 with < 5 years disease duration) and 22 HC (20 Female, mean age 50.7 (±6.7) years]. All OCT measures (MinOD, MaxOD and OD300) were significantly lower in SSc patients than in HC (p = 0.011, p < 0.0001, p < 0.0001 respectively). HFUS showed a lower performance in discriminating SSc skin vs HC compared to OCT (overall AUC 0.6 vs 0.72, 0.8 and 0.89 for MinOD, MaxOD and OD300 respectively). Nevertheless, mean HFUS skin thickness significantly correlated with mRSS at site of analysis (r = 0.47, p = 0.0013) and showed overall excellent interobserver reliability between assessors (ICC >0.8). Importantly, MaxOD and OD300 negatively correlated with HFUS skin thickness (r=-0.32, p = 0.035; r=-0.31, p = 0.039).
Conclusion
OCT of the skin has been previously validated against skin biopsy in SSc. Our results validate HFUS against OCT and indicate that HFUS of the skin is a reliable measure of skin involvement. Further, here we show that HFUS and OCT outperform each other in measuring different aspects of skin involvement in SSc and they offer complementary surrogate outcome measures of disease.
Disclosures
D. Temiz Karadag None. G. Lettieri None. V. Picerno None. O. Gundogdu None. M. Padula None. G.A. Mennillo None. A.A. Padula None. F. Del Galdo None. S. D'Angelo None. G. Abignano None.
Comparison of very-high-frequency ultrasound and spectral-domain optical coherence tomography corneal and epithelial thickness maps