Saavedra Ana Cecilia, Arroyo Junior, Zvietcovich Fernando, Lavarello Roberto J, Castaneda Benjamin
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:3456-3459. doi: 10.1109/EMBC.2018.8512935.
Skin elastic properties change during a cutaneous disorder or in the aging process. Deep knowledge of skin layers helps monitoring and diagnosing structural changes. High frequency ultrasound (HF-US) has been recently introduced to diagnose and evaluate some dermatological disorders in the clinical practice. US elastography adds elasticity information of the analyzed tissue. In particular, harmonic elastography estimates the speed of shear waves produced by external vibration sources, in order to relate the shear wave speed to the Young's modulus. In the epidermis and dermis layers, shear waves are not generated; in contrast, surface acoustic waves (SAWs) exist as they propagate in the top of the tissue. This study uses crawling wave sonoelastography for the estimation of SAWs in human thigh dermis in vivo. Experiments were performed in ten volunteers in the range of 200 - 500 Hz. As other studies suggest, SAW speed needs to be compensated to reach shear wave speed, for calculating the Young's modulus. Thus, the SAW speed estimated was corrected when it propagates in solidUS gel interface. Specifically, the elasticity modulus found was $18.35 \pm 1.04$ KPa for a vibration frequency of 200 Hz. Results suggest that the elasticity modulus can be estimated in vivo using crawling wave HF-US for skin application and shows potential for future application in skin disorders.
皮肤弹性特性在皮肤疾病或衰老过程中会发生变化。深入了解皮肤各层有助于监测和诊断结构变化。高频超声（HF-US）最近已被引入临床实践，用于诊断和评估一些皮肤病。超声弹性成像可提供被分析组织的弹性信息。特别是，谐波弹性成像可估计由外部振动源产生的剪切波速度，以便将剪切波速度与杨氏模量相关联。在表皮和真皮层中，不会产生剪切波；相反，表面声波（SAW）在组织顶部传播时存在。本研究使用爬行波超声弹性成像在体内估计人大腿真皮中的表面声波。在10名志愿者身上进行了频率范围为200 - 500 Hz的实验。正如其他研究表明的那样，为了计算杨氏模量，表面声波速度需要进行补偿以达到剪切波速度。因此，当表面声波在固体 - 超声凝胶界面传播时，对估计的表面声波速度进行了校正。具体而言，对于200 Hz的振动频率，发现的弹性模量为$18.35 \pm 1.04$千帕。结果表明，使用爬行波高频超声在体内估计皮肤的弹性模量具有可行性，并且在未来皮肤疾病的应用中显示出潜力。
