In vivo characterization of human fingertip and forearm skin using attenuation of high frequency ultrasound

Attenuation of high frequency ultrasound (10-55 MHz) by skin layers and subcutaneous fat was studied in vivo using 16 normal subjects aged 19 to 34. Attenuation values at several frequencies were obtained by computing the slope of spectra vs. depth (dB/mm). Diffraction effects were eliminated using axial translation of the focal zone within the tissue. Data were collected from three sites in the body: fingertip, dorsal side of forearm near the wrist, and dorsal side of forearm near the elbow. At 25 MHz, significant differences in attenuation were found between dermis at the fingertip and the two forearm regions (9.5±2.5 vs. 2.7±2.6 and 1.8±2.1 dB/mm, Mean±SD among the subjects). The corresponding mean attenuation coefficients were 0.32, 0.21 and 0.20 dB/mm/MHz respectively. Significant differences were not found between the dermis and fat at the forearm regions. These results are expected to aid future studies on quantitative characterization of skin tissues using high frequency ultrasound