Ultra-high frequency ultrasound for digital arteries: improving the characterization of vasculopathy in systemic sclerosis

Objectives: To provide a full characterization of proper palmar digital arteries (PPDA) in systemic sclerosis (SSc) with ultra-high frequency ultrasound (UHFUS), and to investigate possible relationships between digital macroangiopathy and microangiopathy. Methods: SSc patients without active digital ulcers and healthy controls (HC) were enrolled. Each subject underwent UHFUS 70 MHz evaluation of PPDA from II to V fingers bilaterally, searching for vessel occlusion and measuring the thickness of the three arterial layers and the systolic-diastolic excursion range. Microcirculation was investigated with capillaroscopy and laser speckle contrast analysis (LASCA). Results: Forty-six SSc patients (87% female, mean age 55.5 years) and 15 HC comparable for age and sex were enrolled. UHFUS in SSc revealed the occlusion of 124 (16.8%) PPDA, whereas in HC they were all patent. Considering a finger with at least one PPDA occluded as ultrasonographically pathological, 67.4% patients presented ≥1 pathological fingers. All three arterial layers were significantly thicker and excursion range significantly reduced in SSc than in HC (p<0.001 for all). Seventy-three percent of fingers previously affected by digital ulcers, were ultrasonographically pathological. Disease duration was directly correlated to the thickness of all three arterial layers. No significant correlations emerged between capillaroscopy or LASCA findings and UHFUS features. Conclusion: UHFUS allows the characterization of vasculopathic involvement of PPDA in SSc, also showing subclinical vasculopathy. The lack of correlations between UHFUS and capillaroscopy or LASCA likely mirrors non-overlapping vasculopathic processes. UHFUS evaluation of PPDA emerges as complementary to microcirculation assessment for a more accurate and complete characterization of SSc vasculopathy.