OP0037 Evaluation of skin involvement in systemic sclerosis patients by using two ultrasound transducers with different frequency

Abstract

BackgroundThe modified Rodnan skin score (mRSS) is the validated method to evaluate the extension of skin involvement in systemic sclerosis (SSc) and to distinguish between patients with limited cutaneous skin involvement (lcSSc, skin involvement is confined to the extremities) or diffuse (dcSSc) (1,2). Recently several studies have demonstrated that skin high frequency ultrasound (US) is a valid and reproducible technique to measure dermal thickness (DT) in patients with SSc (3–6).ObjectivesTo compare the values of DT obtained by two ultrasound transducers with different frequency (18 MHz and 22 MHz) in evaluating the DT in lcSSc patients and healthy controls.MethodsThirty-seven lcSSc patients (mean age 62±13SD years, mean disease duration 5±5SD years) and 37 healthy controls (CNT) sex and age matched were enrolled after informed consent. Both US transducers of 18 and 22 MHz (Esaote, Genova) were used to evaluate DT in the seventeen areas of the skin (zygoma, fingers, dorsum of hands, forearms, arms, chest, abdomen, thighs, legs, feet) of SSc patients where Rodnan skin score (mRSS) is usually assessed. Skin US was also performed in the same seventeen areas of CNT, looking for DT differences in comparison with lcSSc patients. Statistical analysis was carried out by non parametric tests.ResultsDT evaluated with the 22 MHz probe was found significantly higher in all body areas in comparison with the 18 MHz transducer, both in lcSSc patients (p<0.01) and in CNT (p=0.05). The median difference of DT values between the two probes was of 0.11 millimetres in lcSSc patients (minimum 0.0023, maximum 0.28 mm) and 0.01 millimetres in CNT (minimum 0.0029, maximum 0.03 mm). Of interest, in lcSSc DT evaluated by 18 MHz transducer was recognized significantly higher (p<0.001) also in four out of six skin areas where the mRSS was found normal (score=0) (upper-arms, chest and abdomen), with exclusion of thighs (p=0.08), in contrast with the classification of lcSSc. However, by using the 22 MHz transducer a statistically significantly higher median DT was showed in all skin areas, included thighs (p<0.01). Finally, a positive statistically significant correlation was observed between the two transducers in the evaluation of DT (p<0.0001), as well as between both probes and mRSS (p<0.0001 for both).ConclusionsThis study suggests that subclinical dermal involvement may be detectable by skin high frequency US already in patients with limited cutaneous SSc. This study confirms that DT can be better assessed in SSc patients by using a 22 MHz US probe, and suggests that DT might be underestimated by using US probes of lower frequency (18 MHz). However, the DT values obtained using both probes resulted significantly correlated together and with the mRSS.References Clements PJ, et al. Arthritis Rheum 2000;43:2445–54.Moore TL, et al. Rheumatology 2003;42:1559–63.Sulli A, et al. Ann Rheum Dis. 2014;73:247–51.Czirják L, et al. Ann Rheum Dis. 2007;66:966–9.Hesselstrand R, et al. Rheumatology 2008;47:84–7.Kaloudi O, et al. AnnRheum Dis.2010;69:...

High-frequency Ultrasound Assessment of Systemic Sclerosis Skin Involvement: Intraobserver Repeatability and Relationship With Clinician Assessment and Dermal Collagen Content

“…We have demonstrated that changes in SSc skin quality can be detected by ultrasound when either clinically or objectively of normal thickness. Previous studies have demonstrated similar findings with skin thickness [3,29,32]; although we are the first to demonstrate such abnormalities using dermal echogenicity and SWE. There are two likely explanations for the disparity between detection of skin pathology by ultrasound and mRSS.…”

“…This is further reflected by previous reports of increased inter-observer variability in HFUS dermal thickness measurement at the finger compared to other anatomical sites [18]. It has been suggested that higher frequencies of HFUS may provide better skin assessment than those in the lower end of the 'high frequency' range and particularly that they may have better sensitivity to identifying proximal skin thickening in lcSSc [32]. Whilst this seems logical, there are few studies to affirm it and therefore further studies are required to determine the optimum frequency for this application whilst balancing against the limited accessibility of very high frequency machines (>50MHz).…”