Evaluation of the safety and efficacy of home-use micro-focused ultrasound: a preclinical study

Abstract

Background: The demand for home-use micro-focused ultrasound (MFU) devices for dermatologic uses like facial skin tightening and treating forms of skin laxity is increasing. However, the procedures used to evaluate such devices remain underdeveloped.Methods: We performed simulations on ex vivo porcine tissues to calculate the thermal coagulation point (TCP) area corresponding to the applied energy levels. Surface and intradermal temperature distributions posttreatment on porcine dorsal skin were assessed during MFU. Subsequently, we evaluated the safety and effectiveness of the MFU device in vivo after single or repeated treatments. MFU energy was delivered in vivo to porcine skin at 7 MHz and 12 W to a penetration depth of 3.0 mm under different experimental settings. Tissue samples were obtained immediately after treatment and 14 days later and subjected to histological analysis.Results: TCPs were distinctly observed in ex vivo tissues after MFU. Energy-dependent micro-coagulation zones were small at ~1 mm3. The temperature escalation was linearly proportional to the number of treatments. Notably, MFU treatment promoted collagen and elastin deposition in vivo and induced neocollagenesis in the mid and deep reticular dermis and neoelastogenesis in the deep reticular dermis.Conclusion: The novel MFU energy regimen used in this study was effective in our animal model, and the energy settings used may mitigate unwanted side effects. Our results show that a home-use MFU device that provides uniform TCP and precise treatment can be safely applied to the face and effectively tightens skin.