Applicability of shear wave elastography for the evaluation of skin strain in systemic sclerosis

Abstract

The assessment of skin fibrosis is vital for the diagnosis and monitoring of treatment in the systemic sclerosis (SSc)-a severe autoimmune disease. The elastography is a technique of skin fibrosis assessment through the evaluation of skin strain. We compared the efficacy of the shear wave elastography (SWE) and commonly used modified Rodnan skin score (RSS) in skin fibrosis assessment in SSc. The study included 40 SSc patients and 28 healthy individuals, with the exclusion of individuals with other skin/autoimmune diseases. Skin thickness using RSS and skin strain using SWE were assessed in the same 20 body localizations. Subjects' informed consent and the bioethics committee approval were obtained. Elastographic skin strain correlated positively with both partial and overall RSS values, with strong positive correlation (r ≥ 0.75) for hands and fingers localizations in particular. In SSc patients with normal RSS values, the elastographic strain was significantly higher than in healthy controls. Elastographic strain of fingers' skin evaluated in SWE is highly accurate for distinguishing SSc patients (sensitivity 0.897-0.923, specificity 0.929-0.964, positive predictive value 0.946-0.973, negative predictive value 0.867-0.900). ESW results are substantially more reproducible than those of RSS examination (intraclass correlation coefficients: 0.987 vs. 0.941). The shear wave elastography is more reproducible and has higher sensitivity than RSS in the evaluation of skin condition in SSc, especially in case of changes non-detectable on physical evaluation, indicating it might become a useful tool in SSc diagnosis.

How to perform high ultrasound examination of skin involvement among patients with systemic sclerosis – proposition of a unified protocol

“…Studies suggest that skin thickness (ST) measured with a US-based modality can replace mRSS examination [1,[9][10][11][12]. This is mainly because of the positive correlation between skin stiffness and the mRSS in these studies [1,11,[13][14][15][16][17][18][19].…”

“…Skin involvement assessed with the mRSS correlates with skin stiffness and thickness. According to personal experience and analyzed studies the authors suggest the use of ultrasound-based techniques, in particular high-frequency ultrasound and shear-wave elastography [9,10,13,14,[17][18][19][20].…”

“…As many authors have already suggested, HFU allows one to measure dermal thickness and obtain comprehensive imaging of skin layers [9,10,13,14,[17][18][19][20]. According to Sobolewski et al [10] and Flower et al [19] the HFU technique can distinguish skin layers through examination of ST, SWE and echogenicity. Some studies suggest that whole-body mRSS tended to correlate more closely to the finger or hand skin SE than ST among patients with SSc [20].…”

“…Currently, ultrasound (US)-based techniques of skin imaging are being introduced as a potential tool to replace mRSS [8]. The following methods have been evaluated over the course of the last ten years and considered as tools for skin assessment in SSc: ultrasound elastography, shear-wave elastography (SWE), high-frequency ultrasonography (HFU), acoustic radiation force impulse (ARFI) imaging and magnetic resonance imaging (MRI) [9][10][11][12].…”

The Updated Role of Ultrasound in Assessing Dermatological Manifestations in Systemic Sclerosis

“…Indeed, numerous studies have reported on skin stiffness based on manual compression 38,39,54,55 and shear-wave elastography. 44,[56][57][58][59][60][61] Most of these studies reported a significantly higher shear-wave velocity value in SSc patients than in controls, at almost all the Rodnan skin sites (Table 3). Interestingly, four of these studies observed a significantly higher skin stiffness in clinically uninvolved skin, ie, with an mRSS score of 0, in SSc than in healthy controls.…”