Characterization of Nonthermal Focused Ultrasound for Noninvasive Selective Fat Cell Disruption (Lysis): Technical and Preclinical Assessment

Abstract

There has been a lack of published bench and preclinical data supporting the safety and effectiveness of a noninvasive, nonthermal, focused ultrasound technology for body contouring. A series of experiments were conducted with a transcutaneous focused ultrasound device (UltraShape Contour I; UltraShape Inc., Yoqneam, Israel): (1) three-dimensional acoustic field distribution was measured by hydrophone in a water bath; (2) the real-time two-dimensional acoustic field was assessed using optical visualization by a Schlieren system; (3) three-dimensional and Schlieren results were compared in tissue-mimicking gel phantoms and in frozen specimens of porcine subcutaneous fat; and (4) a porcine in vivo preclinical model was used to test safety, selectivity, and efficacy by histological staining of excised skin and subcutaneous fat specimens. Real-time imaging of acoustic field distribution obtained by the Schlieren system, as well as real-time ultrasound visualization, produced stable cavitation both in water and in the gel phantoms. The area where the effect was visible corresponded to the focal area of energy delivered by the system transducer, as measured by the hydrophone. Histologically stained specimens of skin and subcutaneous fat that were excised from porcine studies (n = 14) following treatments (n = 31) demonstrated fat cell lysis and no observable cellular destruction of adjacent blood vessels, nerves, and connective tissue. No epidermal or dermal changes were observed clinically or histologically. The delivery of noninvasive focused ultrasonic energy has been validated and supported by the basic and preclinical data presented. Future studies will investigate various treatment regimens for improved body-contouring results.