“…US at frequencies below 100 MHz is now commonly used in medical practice [ 3 ], and the >100 MHz probes are constantly being designed [ 4 ]. Improving spatial resolution of acquired images, the higher frequency of the US probe enables clear visualization of superficial structures such as the fat layer, the muscle layer, blood vessels, hair follicles, and skin appendages [ 2 , 5 , 6 , 7 ]. HFUS is used for healthy skin analysis, where skin thickness is inversely proportional to age, and due to increased collagen production connected with aging, echogenicity tends to increase too [ 2 ].…”