Background/Purpose: Systemic sclerosis (SSc) is a chronic connective tissue disease, characterized by the early occurrence of vasculopathy [1], easily detected by nailfold videocapillaroscopy (NVC) [2]. Newly-developed Doppler techniques enable the sampling of slow vascular flows and the extrapolation of spectral parameters in both arterioles and capillaries, thanks to specific motion-suppression algorithms that isolate and eliminate clutters [3]. Aim of the study was to investigate the peripheral vascular bed of SSc patients at the level of their fingers, using ultra-high frequency ultrasounds (US 33-9 MHz), looking for any correlations with NVC scleroderma patterns [4].

Methods: Fingers of both hands of 33 SSc patients and 34 healthy controls (CNT) were evaluated with an ultra-high frequency US machine, equipped with 33-9 MHz (frequency band for Doppler imaging, 10-18 MHz) and 18-5 MHz (frequency band for Doppler imaging, 5-11 MHz) transducers. Proximal Resistive Index (PRI) and Peak Systolic Velocity (PSV) were calculated at the level of the second interdigital artery; moreover, the Distal Resistive Index (DRI) was calculated performing Doppler spectral analysis at the level of the nailfold arteriole of the third finger. The nailfold blood flow was initially investigated in a longitudinal plane, placing the 33-9 MHz probe on the dorsal side of the middle and distal phalanxes of the third fingers. NVC examination was performed no more than a month earlier US evaluation to detect scleroderma patterns (“early” – 4 patients, “active” – 14 patients, “late” – 8 patients, “like” – 7 patients).

Results: SSc patients showed a significantly slower PSV (8.38±3 cm/s vs 11.14±4.5 cm/s, p=0.005) and a higher DRI (0.65±0.14 vs 0.57±0.11, p=0.01) than CNT. No differences were found between PRI values of SSc patients and CNT (0.76±0.11 vs 0.73±0.12, p=0.35). The NVC subgroup analysis did not show any significant difference, when different scleroderma patterns (“early”, “active”, “late” and “like”) were correlated to PRI, DRI and PSV of SSc patients.

Conclusion: The spectral Doppler analysis of the blood flow of digital small arterioles and capillaries, using ultra-high frequency US transducers, allow to investigate the anomalies of microvasculature of SSc patients. Of note, these alterations could be missed when Doppler examination is performed using lower Doppler frequencies and/or at a more proximal level.

NVC seems to provide different information than high-resolution US and the association of the two techniques could represent an important evolution in the study of SSc microcirculation.

References: 1. Cutolo M et al. Expert Rev Clin Immunol. 2019;15:753-764. 2. Cutolo M et al. Nat Rev Rheumatol. 2021;17:665-677. 3. Schioppo T et al. Microvasc Res. 2019;122:125-130. 4. Smith V et al. Autoimmun Rev. 2019;18:102394.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/blood-flow-assessment-of-digital-arterioles-and-capillaries-in-systemic-sclerosis-patients-using-ultra-high-resolution-doppler-ultrasounds/