Background Microvascular damage plays a critical role in the initiation and perpetuation of systemic sclerosis (SSc). A comprehensive approach should investigate both superficial and deep layers of peripheral microcirculation. In addition to nailfold videocapillaroscopy (NVC), a well-established technique to evaluate outer skin layer vessels, power Doppler ultrasound (PDUS) has been recently used to study microcirculation in the inner levels [1].

Objectives To study the severity of microvascular involvement in patients with SSc by using both NVC to measure capillary density (outer layer at the nailfold area) and PDUS to detect perfusion (deeper layers at the nailfold and pulp area).

Methods 100 SSc consecutive patients fulfilling the 2013 EULAR classification criteria were enrolled. PDUS was performed at the 3rd and 4th finger of the dominant hand after exclusion of ulnar artery occlusion (UAO). In case of UAO non-dominant hand was examined. Ultrasound investigation was performed with Esaote MyLab 70 XVG by means of linear array transducer (10–22 MHz). Power Doppler settings were standardized (Doppler frequency 14.3 MHz, Gain 55%, PRF 750 Hz). PDUS measurements included sagittal scan of nailbed and fingertip qualitatively graded from 1 (no signal) to 4 (marked hyperemia) [2], and resistivity index (RI) of ulnar and radial proper digital arteries. Capillary density (number/mm) was calculated by NVC with magnification 200X performed on two images of the same digits examined by PDUS.

Results 100 SSc patients, 87 (87%) women, 86 (86%) limited cutaneous SSc, median age 62.2 years old, median disease duration 8 years were evaluated. 7 (7%) patients had UAO. Concordance between fingertip and nailbed perfusion as assessed by PDUS is reported in Table 1.

Concordance between fingertip and nailbed perfusion as assessed by PDUS is equal to 0.7398. The lower 97.5% confidence interval limit is 0.6433.

Association between capillary density, and fingertip and nailbed perfusion as assessed by PDUS is shown in Table 2.

Conclusions To our knowledge, this is the first study to correlate NVC and PDUS finding in SSc patients. Fingertip and nailbed PDUS grade concordance was found to be satisfactory. The mean capillary density tends to be greater with respect to grade 1. This is particularly evident comparing grade 4 and grade 1. As such, these two imaging techniques provide different and potentially complementary information on SSc-related peripheral microvascular involvement. There is potential clinical utility in these observations that has yet to be unlocked fully.

References

1. Lescoat A et al. Arthritis Care Res. 2016;Epub ahead of print.

2. Newman JS et al. Radiology. 1996,198:582–584.

References

Disclosure of Interest None declared