Quantitative assessment of scleroderma using ultrasound surface wave elastography

Skin stiffening is an early biomarker of many systemic fibrotic disorders. The Modified Rodnan Skin Score (MRSS) is considered the gold standard measurement in clinical studies of systemic sclerosis (SSc). However, the MRSS is a palpation method. We have developed a noninvasive ultrasound surface wave elastography (USWE) technique for measuring skin elastic properties. The purpose of this paper is to demonstrate the clinical use of USWE for assessing patients with SSc. In USWE, a low intensity 0.1 second harmonic vibration is generated on the skin of a subject using a handheld vibrator. An ultrasound probe is aligned with the indenter of the vibrator to measure the generated surface wave propagation on the skin. In a prospective clinical study, we measure both skin and lung on patients with SSc and interstitial lung disease (ILD). Significant differences in wave speed between SSc patients and healthy subjects were found. For example, the surface wave speed of the skin is 1.83 +/- 0.04 m/s at 100 Hz, 2.33 +/- 0.25 m/s at 150 Hz, and 3.04 +/- 0.37 m/s at 200 Hz for a healthy subject, and the surface wave speed of the skin is 2.82 +/- 0.31 m/s at 100 Hz, 3.60 +/- 0.38 m/s at 150 Hz, and 5.36 +/- 0.55 m/s at 200 Hz for an age matched SSc patient in the same location. USWE is a noninvasive technique for generating and measuring surface wave propagation on the skin. USWE can provide objective measurement of skin elastic properties in various regions of the body, which may be useful for assessing the status and potentially the progression of SSc.