Plastic surgery is sometimes considered the gold standard for facial rejuvenation and body contouring. However, many non-invasive options for facial rejuvenation are increasing in popularity, and are fast becoming part of the arsenal of the aesthetic practitioner. Non-invasive methods are cheaper and quicker to perform, with minimal down-time and fewer complications as compared with surgical procedures.

High intensity focused ultrasound (HIFU) is one of these new, non-invasive methods of facial rejuvenation, which uses ultrasound waves to achieve adipose tissue destruction, and therefore a reduction in fat. This technology was first described by White at al. in 2007, and was further developed and applied for facial rejuvenation, body contouring and reshaping (White et al., 2007). These devices work by creating negative acoustic pressure (cavitation) within the adipose cells and by heat transformation of acoustic energy, which results in denaturation and coagulation of proteins at temperatures higher than 43°C (Shalom et al., 2013). At temperatures above 80°C, coagulative necrosis can be observed within the targeted cells only, and without any damage to the surrounding tissues (Tadisina et al., 2013; Gupta et al., 2018).

A HIFU technology aesthetic device is a non-invasive fat reduction system that targets all four layers of the skin: the epidermis, dermis, subcutaneous fat, and superficial muscular aponeurotic system (SMAS). The devices use cartridges, designed to converge ultrasound at a specific skin layer depth. It targets adipose tissue by using high-intensity ultrasound energy, causing thermal coagulation to fat cells. The device uses focused ultrasound cartridge depths of 8 mm and 13 mm. The energy penetrates through the skin and destroys the adipose tissue, releasing triglycerides. During the treatment, the destroyed cells send out chemotactic signals and draw macrophages to the treated area. Macrophage cells engulf and clean away adipose cells following the body’s normal metabolism process. The controlled thermal effect results in a change to the physiology of the skin, resulting in immediate contraction and stimulation of collagen and elastin as part of the healing process. The elimination of waste products and healing takes approximately 8-12 weeks, and gradually reduces the thickness of the fat layer.

Patient selection

Every patient who is suitable for HIFU treatment must be assessed prior to treatment with a HIFU device. All patients need to disclose a full medical history, as well as current medications. In addition to this, the reason for seeking treatment must be identified. If identified as suitable candidates, patients should be counseled regarding the fat reduction treatment, realistic outcomes from the use of HIFU devices, and the results they should expect. Previous treatments, including the areas treated and outcomes delivered, should also be discussed.

Treatment takes up to 60 minutes to be completed. A patch test must be performed on the area prior to treatment in order to check the patient’s reaction to the thermal treatment. Before and after photos must also be taken to enable comparison. The practitioner must weigh the patient and take measurements of the area to be treated before the session. The practitioner must ensure that the patient will commit to follow the pre- and post-care advice.

One treatment session is sufficient for most areas. However, depending on the thickness of the fat layer or levels of patient satisfaction with the initial results, the procedure may be repeated in the same area. The maximum results are visible within 8-12 weeks. After completing the first treatment, a 12-week gap is mandatory before undergoing another HIFU session.

Rx Vitamin A must not be used 3 days before HIFU treatment, and Roaaccutane use must be discontinued 6 months before HIFU treatment.

Suitable areas for HIFU treatment

Areas suitable for treatment with HIFU include:
• Face
• Neck
• Abdomen
• Flanks
• Hips
• Thighs
• Upper arms

Practitioners should avoid treating any area with less than 1 cm of subcutaneous tissue when using an 8.0 mm cartridge, and 1.5 cm when using a 13.0 mm cartridge.

Other areas to avoid include:
• Belly button
• Any area with a hernia
• Bony areas
• Groin area
• Any area with metallic implants
• Breast tissue
• Major blood vessels
• Thyroid cartilage and gland
• Trachea

Side effects of HIFU treatment

There are several potential side effects of HIFU treatment, and these will vary across patients, depending on the patient’s skin type and sensitivity.

Potential side effects may include:
• Erythema (redness): the treatment area may exhibit erythema immediately following treatment
• Oedema (swelling): the treated area may exhibit mild oedema following treatment. This typically resolves within a few days of treatment
• Pain: momentary discomfort may be experienced during the procedure while energy is being deposited. Post-procedure discomfort or tenderness to the touch is also possible
• Bruising: mild bruising, which is caused by damage to soft tissue blood vessels, may occur occasionally and typically resolves within few days of treatment
• Nerve effects: transient local muscle weakness may result after treatment due to inflammation of a motor nerve or transient numbness may result after treatment due to inflammation of a sensory nerve
• Nerve effects: transient pain, paraesthesia and/or tingling may be experienced. No permanent injuries to facial nerves have been reported
• Scarring: the possibility for scar formation (which may respond to medical care) may exist if incorrect technique is used
• Skin sensitivity: the duration of skin sensitivity will vary between patients and is dependent on skin type and general sensitivity of the skin.

HIFU treatment is safe after undergoing other cosmetic treatments, including:
• 6 months after thread lift procedure
• 1 week after superficial peel and microdermabrasion
• 2 weeks after botulinum toxin A and water based dermal fillers
• 6 weeks after oil-based dermal filler and medium or deep chemical peels.

Aftercare advice

Each patient should be given an aftercare advice sheet upon completion of this procedure. They should be advised that if they are concerned about any potential side effects, they can return to the clinic for a free consultation. At this stage, treatment can be assessed in order to achieve the desired outcome.

Patients are advised not to exercise, to avoid hot baths, and not to massage the area for 5-7 days post-treatment. It is important not to use sunbeds or sunbathe during the healing process (up to 8 weeks). Patients should be advised to use moisturizer if the skin gets dry, and to apply SPF 50 daily. Follow-up appointments are recommended at 8- and 12-weeks post-treatment. Patients are also advised to not consume alcohol 24 hours before and after treatment, and to not have laser or intense pulsed light (IPL) treatments 1 month before and after treatment.

Contraindications

Contraindications for HIFU treatment include:
• Pregnancy, recent pregnancy or breast feeding
• Metal prosthesis or implants
• Anticoagulant and regular anti-inflammatory medication
• Skin thinning medication
• Heart conditions including pacemakers
• History of cancer