Preliminary Study On The Quantitative Assessment Of Skin Affected By Systemic Scleroderma With 20 MHz High-frequency Ultrasound And Real-time Shear Wave Elastography

Objective:To explore the value of 20 HMz high-frequency ultrasound and real-time shear wave elastography(SWE)in assessing the affected skin of patients with systemic scleroderma(SSc),and to find an objective,quantitative,simple and feasible evaluation method for the clinical assessment of skin thickness and hardness in patients with SSc.Methods:We select 23 patients with systemic scleroderma(SSc group)who were admitted and treated in the rheumatology and immunology department and dermatology department of our hospital from July 2019 to December 2020,and 23 normal healthy people were selected as the control group.Both the control group and SSc patients underwent real-time shear wave elastography to measure skin elasticity and conventional ultrasound to measure its thickness.Quantitative parameters included maximum(Emax),minimum(Emin),mean(Emean)and dispersion(SD).Each part needs to be measured three times,averaged and recorded.The measurement sites include bilateral proximal fingertip joints,bilateral metacarpophalangeal joints,bilateral back of the hands,bilateral forearms,bilateral upper arms,bilateral thighs and bilateral calves.Compare the age,gender,skin elasticity and thickness of the SSc group and the control group,use the ROC curve to evaluate the best cut-off value of the Young’s modulus and thickness of the control group and the SSc group,and evaluate the diagnostic efficiency of the ROC curve.Result:1.Comparison between the left and right sides of the control group:(1)Thickness comparison: The bilateral thickness difference of all parts is not statistically significant(P>0.05).(2)Comparison of Young modulus values: There was no statistical difference in the results of the bilateral Young modulus values of all parts(P>0.05).It indicates that the thickness and elasticity of the left and right skin of healthy people in the normal group are symmetrical.2.Comparison between the left and right sides of the SSc group:(1)Thickness comparison: The bilateral thickness difference of all parts is not statistically significant(P>0.05).(2)Comparison of Young modulus values: There was no statistical difference in the results of the bilateral Young modulus values of all parts(P>0.05).It suggests that the left and right skin of SSc are affected symmetrically.3.Comparison between the SSc group and the control group:(1)Thickness comparison: The skin thickness of all parts measured is statistically significant compared with the control group(P<0.05).(2)Comparison of Young modulus: The values of Young modulus Emean,Emax,and Emin of all parts measured are statistically significant compared with those of the control group(P<0.05),except for the SD value of the back of the hand and the thigh.In addition to statistical significance(P>0.05),other parts of SD are also statistically significant(P<0.05).4.Comparison of proximal interphalangeal joint and metacarpophalangeal joint in SSc group:(1)Thickness comparison:The skin thickness of proximal interphalangeal joint was statistically significant compared with metacarpophalangeal joint(P<0.05).(2)Comparison of Young’s modulus: The Young’s modulus of the proximal interphalangeal joint was statistically significant compared with that of the metacarpophalangeal joint(P<0.05).5.ROC curve analysis:(1)ROC curve analysis of the thickness of each part: the proximal fingertip joints,metacarpophalangeal joints and the proximal fingertip joints of the back of the hand,the metacarpophalangeal joints and the back of the hand correspond to 0.977,0.953 and 0.953 respectively.0.795,the sensitivity was89.1%,87.0%,and 76.1%,and the specificity was 100%,95.7%,and 73.9%,respectively.The diagnostic efficiency of other parts is poor(AUC<0.7).(2)The ROC curve analysis of Young’s modulus value showed that the proximal interphalangeal joint AUC was the largest,Emean,Emin,Emax and SD were 0.999,0.999,0.992,0.954,respectively.Conclusion:1.High-frequency ultrasound and SWE can sensitively display SSc skin changes.2.Regarding the skin changes of SSc,regardless of the application of high-frequency conventional ultrasound or the application of SWE technology,the diagnostic efficiency of the proximal interphalangeal joint is the best.3.Compared with high-frequency ultrasound,Emean and Emin of SWE are more effective in diagnosing SSc skin lesions.