Successful treatment of submental fat using a non‐focused pulsed ultrasound

The prevalence of non‐invasive aesthetic treatments is increasing, with patients demanding easier, safer, and more effective non‐invasive cosmetic procedures. Submental fat is usually addressed using liposuction, which is associated with significant adverse events and a long recovery. Although newer, non‐invasive submental fat treatments are gaining popularity, they are often complex, require frequent injections, or have adverse side effects.

posing adipocytes to ultrasonic vibrations and high thermal energy, reducing the amount of adipose tissue by altering adipocyte permeability. 13 This technology precisely heats subcutaneous adipose tissue without affecting the epidermis, dermis, or subcutaneous muscles and nerves. 14 Unlike focused ultrasound, 15 non-focused ultrasound does not induce necrosis of adipocytes but only disrupts the cellular membrane without causing cell death. 13,14 Furthermore, high-intensity focused ultrasound (HIFU) is often accompanied by side effects such as pain, discomfort, and bruising. 16 Non-focused ultrasound is well tolerated and is not associated with any adverse events. 17 Vacuum-assisted acoustic wave technology was previously found to be effective, safe, and painless for circumference reduction of the abdominal region. 18 Here, we present preliminary results using the same technology with a smaller handle on the submental fat of 14 female patients.

| Patients
This is a retrospective evaluation of 20 female patients aged 36 to 65 (average 49.4 years). Inclusion criteria were a body mass index (BMI) between 18.5 and 30. Exclusion criteria were somatic pain, heart disease, pregnancy, nursing, thrombophlebitis, plastic medical components, metal prosthesis, heart pacemaker, renal failure, any malignancy in the past 5 years, use of systemic anti-coagulants, and active infection/disease or psoriasis in the area of treatment. All patients signed an informed consent form.

| Treatment
Treatments were conducted weekly using a non-focused ultrasound with a 40 mm bell-shaped sonotrode (MiniWave, Alma PrimeX, Alma Lasers, Figure 1) with mineral oil used between the applicator and the skin. The device delivers 100 kHz concentric acoustic-guided waves with an intensity of up to 3 W/cm 2 in a continuous or pulsed fashion. Treatments were focused on the submental area, in which an automated current control allows resonance matching between applicator and skin. The conical cavity acts as a resonator and enhances the acoustic waves. The center of the applicator creates a vacuum, allowing improved contact with the skin and reduces energy loss during treatments. An intermittent 10 Hz vibration promotes mechanical disturbance through soft shockwaves. Piezo-elements produce longitudinal ultrasound waves that are amplified and emitted from the inner cavity and where the contact of the skin is at its greatest. In the central area, the plate emits predominantly longitudinal waves (producing heating of the skin), while in the peripheral zone (edges of the plate), the emitted transverse waves result in a mechanical effect.
The impulse feature (10/20 s on/off) changes the energy delivery from continuous mode to pulses resulting in soft shockwaves at the beginning of every pulse. The power level was set at 5-8. Throughout the treatment, skin temperature was monitored to avoid a temperature above 43°C. Patients underwent a total of three 15-min weekly treatments. Post-treatment instructions included avoiding strenuous activity and exposure to extreme temperature for 48 h.

| Outcome
Improvement was measured three months after the final treatment by patient satisfaction questionnaires and independent F I G U R E 1 MiniWave 40 mm bell-shaped sonotrode. The vacuum-assisted treatment parameters were power level 5-8, Impulse frequency 10 Hz, Impulse cycle (on/off) 10/20 s, 15-min weekly sessions.
dermatologists' blinded evaluations. Pictures were standardized using the same camera (Canon EOS 2000D) fixed at an 18 mm zoom on a fixed tripod with fixed illumination (GodoxML60, two flash LEDs). All patients were positioned at the same distance from the camera. Two physicians scored results according to the Clinician-Reported Submental Fat Rating Scale (CR-SMFRS). 19 Using the CR-SMFR scale, physicians assessed submental fat (SMF) on a 5-point scale (1 = absent, no localized SMF evident, to 5 = extreme, extreme submental convexity). Paired Student t-test was used to test the significance of measurement improvement. Patient satisfaction was recorded using a 5-point scale ((1) very satisfied, (2) somewhat satisfied, (3) neutral, (4) somewhat dissatisfied, and (5) very dissatisfied). 20

| RE SULTS
This study included 20 female patients, ages 36 to 65 (mean age 49.4), which were treated every week for a total of 3 treatments (Table 1). Improvement in submental fat was assessed three months after the final treatment using questionnaires for the patients and physicians. Of the 20 patients, six were unable to return for the 3month visit due to the lockdowns as a consequence of the coronavirus disease 2019 (COVID-19) outbreak, leaving 14 patients who completed the treatments and attended the photography visits to support physicians' assessments. Two blinded dermatologists rated each patient using the Clinician-Reported Submental Fat Rating Scale (CR-SMFRS). 19 The CR-SMFR scale rates submental fat on a 5-point scale with 1 = absent and 5 = extreme. Both physicians rated a significant improvement in 100% of patients (paired T-Test, p < 0.001, Table 1). Of note, in 12 out of the 14 patients, the physicians scored identically both before and after the treatment. Self-evaluation of the 14 patients on a 1 to 5 satisfaction scale averaged 2.14, indicating that most patients were somewhat satisfied. Examples of patient outcomes are presented in Figures 2-4. No adverse events were recorded, except a few cases of mild erythema, which spontaneously resolved within 30 min.

| DISCUSS ION
According to a 2020 statistics report published by the American Society of Plastic Surgeons, 15.6 million cosmetic procedures were conducted in the United States alone, out of which 13.2 were noninvasive. 1 Patients are demanding easier, safer, and more effective non-invasive cosmetic procedures. Indeed, the non-invasive aesthetic treatment global market is currently assessed at $54B.
Submental fat can be particularly challenging to treat without cosmetic intervention because it is often resistant to general measures TA B L E 1 Demographics, physician ratings, and patient satisfaction of study participants. for weight loss, often remaining even after significant weight loss.

Patient number and initials
Furthermore, skin elasticity and the presence of submental fat are attributed to a combination of weight, genetics, and age. Until recently, liposuction was the primary treatment used for submental fat deposits, but it is invasive, expensive, and has a long recovery time.
Newer therapies include cryolipolysis, 4 deoxycholic acid injection, 5 radiofrequency, 11 or combinations thereof. 6 Successful non-invasive reduction of adipose tissue by ultrasound technology has been widely reported and is associated with significantly fewer adverse events than liposuction and cryolipolysis. [21][22][23] Although high-intensity focused ultrasound (HIFU) has historically been used, 22 non-focused ultrasound has been shown to reduce fat in animal models 24 and human subjects 18 and affects subcutaneous adipose tissue without destroying the epidermis, dermis, or subcutaneous muscles and nerves. 14 Furthermore, HIFU has been associated with significant side effects, including edema, erythema, dysesthesia, and ecchymosis, 25,26 none of which have been observed using low-energy ultrasound.
Here, we showed the successful use of non-focused pulsed ultrasound on submental fat. This non-invasive method has several advantages over the current techniques used to treat submental fat in terms of treatment complexity, compared to deoxycholic acid injection, which requires up to 70 monthly injections, and adverse events compared to liposuction and cryolipolysis. Both physicians and patients saw improvement after only three weekly, 15-min treatments. Therefore, non-focused ultrasound treatment provides a novel, safe, and effective treatment for submental fat.

AUTH O R CO NTR I B UTI O N
MS and TS contributed to the design and implementation of the study, the analysis of the results, and the writing of the manuscript.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.

E TH I C S S TATEM ENT
All participants gave written informed consent to participate in the study.
F I G U R E 2 Before (A) and 3 months after (B) images of patient AR-4.
F I G U R E 3 Before (A) and 3 months after (B) images of patient OG-11.
F I G U R E 4 Before (A) and 3 months after (B) images of patient ZG-16.