Background/Purpose: Virtual skin biopsy by Optical Coherence Tomography (OCT) has been proposed as quantitative outcome measure of fibrosis in Systemic Sclerosis (SSc). Dynamic OCT (D-OCT) is a newly developed technology that allows quantification of blood flow in vivo during OCT scans. Here we aimed to determine the validity of skin D-OCT as outcome measure of the skin microvascular disease, employing as comparator nailfold video-capillaroscopy (NVC) capillary patterns in SSc patients, and as clinical gold standard the presence of digital ulcers (DU).

Methods: One hundred and four subjects were enrolled in this study in 2 independent cohorts. In cohort 1 (Criterion Validity), 40 SSc patients fulfilling the ACR/EULAR 2013 criteria with different NVC pattern (10 for each normal/non- specific, early, active, ad late NVC pattern) and 10 healthy volunteers (HV), underwent nailfold D-OCT. In cohort 2 (Face/Content Validity) 36 SSc patients with (18) or without (18) DU and 18 patients with Raynaud’s phenomenon (RP) and SSc specific ANA, who did not fulfill ACR/EULAR 2013 criteria (SRP group) underwent D-OCT of index and middle fingers on the proximal phalanx. Microvascular flow (MVF) was analyzed using the proprietary software from Michelson Diagnostics Ltd.

Results:

Nailfold D-OCT allowed visualization of the corresponding SSc patterns seen at NVC. Furthermore, within D-OCT images, MVF measurements were significantly different between HV and SSc patients with any specific capillary pattern (0.16±0.02 vs 0.10±0.01,p=0.0028) and between SSc patients without and with specific capillary pattern (0.14±0.01 vs 0.10±0.01,p=0.02). Concordantly, MVF was significantly lower in patients displaying capillary loss as main feature compared with those with remarkable angiogenesis (p=0.03). Skin D-OCT showed a median MVF significantly different among the 3 groups: 0.134 (DU) vs 0.153 (no DU) vs 0.167 (SRP) (p<0.0001), and in the DU vs no DU (p<0.001) or vs SRP (p<0.001). Further, DU patients on Sildenafil (n=6) had a significantly higher MVF than DU patients on no Sildenafil (p<0.01).

Conclusion: MVF assessed by D-OCT shows face/content and criterion validity as biomarker of skin microvascular disease in SSc. Future longitudinal studies are needed to evaluate its sensitivity to change over time.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/microvascular-flow-assessed-by-dynamic-optical-coherence-tomography-first-non-invasive-quantitative-outcome-measure-of-microvascular-disease-in-systemic-sclerosis/