Elastography reference values of facial skin elasticity

Introduction
With an introduction of new ultrasonographic transducers, skin elastography may find an application in dermatology and aesthetic medicine enabling direct evaluation of various pathological or natural processes.

Aim
To verify which elastographic technique, strain elastography (SE) or shear wave elastography (SWE), is a better candidate for the reference method of facial skin elasticity examination and to determine normal ranges for elastographic parameters in various facial regions.

Material and methods
The study included 71 female volunteers (age: 40–67 years, mean: 52 ±7.5 years). All participants were subjected to SE and SWE of the skin in five anatomical regions: the forehead, suborbital regions, cheeks, nasolabial folds and chin. Reference ranges for elastographic parameters were defined as 95% confidence intervals and ±2 standard deviations and estimated by means of ROC analysis.

Results
Shear wave elastography parameters, but not SE indices, showed strong inverse correlations with the patient age. No significant correlations were found between SE and SWE parameters of the facial skin. In contrast to SWE, no significant correlations were observed between bilateral SE parameters. Based on these findings, SWE was chosen as the reference method to determine age-specific normative values for the elasticity of the facial skin. Reference and cut-off values of SWE parameters were defined for three age groups.

Conclusions
Shear wave elastography is suitable for the determination of elastographic parameters of normal facial skin, and can be used to determine reference ranges thereof. Elasticity of the facial skin decreases considerably with age, and this factor should be considered during determination of reference values for the elastographic parameters.