In vivo high frequency ultrasound assessment of skin elasticity

A new instrument for noninvasive assessment of skin elasticity is reported. The instrument consists of a combination of a computer controlled mechanical system which can stretch the skin with a resolution of 1 micron and a 40 MHz ultrasound biomicroscope (UBM) which images the stretching process. Stress, biomicroscopic images and radio frequency data are recorded at various levels of strain in the skin. Specifically, forearm skin from 10 subjects were analyzed to an aggregate strain of 40% in 8 steps. UBM images show a significant increase in dermal greyscale levels for increasing strain. The increase of signal strength with strain is due to the decrease of ultrasound attenuation and increase of backscatter with strain as previously reported. Strain effects on Young's modulus in skin and stress relaxation process are also presented in detail.