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

Abstract

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.

Ultrasound Elastography Images in Vascular Anomalies

“…It is a descriptive series and without a quantitative objective, at least with the current techniques. Previous studies show wide application of UE in liver fibrosis, breast lesions, prostate cancer, and muscle properties …”

“…Previous studies show wide application of UE in liver fibrosis, breast lesions, prostate cancer, and muscle properties. 4 However, there are arguments about the reproducibility and standardization of UE for skin detection. In particular, when UE is used to evaluate cutaneous lesions, the probe and the skin are too close, and some subcutaneous tissues may cause a stronger signal to override the signal of skin detection, ultimately resulting in a low signal-to-noise ratio.…”

Ultrasonographic elastography in the evaluation of normal and pathological skin – a review

“…To the best of our knowledge, except for a few studies [13,17,20,21], elastographic parameters of normal skin have not been studied to date, and no published reference values for skin strain have been identified thus far. Moreover, most previous cutaneous elastography studies were relatively small observational studies or analyses of case series.…”

“…Skin, with an average thickness of only 1 mm, is composed of three layers with different elasticity: the epidermis, the papillary dermis and the reticular dermis with its adjacent subcutaneous tissue. The low thickness and considerable structural heterogeneity of the skin may significantly hinder selection of a representative ROI for elastographic examination [13,17].…”

“…Their close proximity to the skin may result in a decrease in the signal-to-noise ratio and lower reproducibility of elastographic parameters. Recently, also the thickness of subcutaneous fat has been identified as a significant contributor to lower repeatability and reproducibility of elastographic measurements [13].…”