Reproducibility analysis on shear wave elastography (SWE)-based quantitative assessment for skin elasticity

Shear Wave Elastography (SWE) is an objective and non-invasive method widely used to quantify the tissue solidity. However, there are concerns about the accuracy of the skin SWE results due to the low signal-to-noise ratio (SNR) caused by subcutaneous fat, muscle and bone. This article analyzed the reproducibility of the result for skin SWE and therefore evaluated the availability of SME for skin elasticity involved diseases. Thirty volunteers (mean age: 37 ± 12 years) were selected. SWE were taken on the skin of abdomen and the middle tibia in order to assess the impact of fat, muscle and bone on SWE results. Skin in the area of anterior and lateral tibia marked with seven parallel lines, and each line indicated an identical thickness of the subcutaneous fat from 1-7 mm. Intra-class correlation coefficients (ICC) were used to evaluate the intra-observer and inter-observer reproducibility. The solidity of abdominal skin showed soft and small individual differences (12.4 ± 2.7 kPa), whereas high shear moduli (25-48 kPa) were observed in the skin above tibia and tibialis anterior muscle. When the subcutaneous fat was thicker than 3 mm (≥3), we obtained excellent intra-observer reproducibility (ICC range 0.78-0.98) and inter-observer reproducibility (ICC range 0.75-0.98). The thickness of subcutaneous fat could affect the reproducibility of skin SWE. The further study on skin SWE standardization should be taken.