Due to the fact that ultrasound returns as an echo when directed at solid objects, diagnostic ultrasound or ultrasound has been used in medicine for many years. The properties of ultrasound also make it possible to focus it, like a beam of light, with high precision.

At frequencies 1 – 7 MHz ultrasound can be focused very sharply. If, however, ultrasound is directed to body tissues, and the power of the ultrasound source is high enough, the temperature in the concentration zone will increase to more than 60оС, which will lead to coagulation of tissue proteins. This ultrasound is called High Intensity Focused Ultrasound (HIFU). An important feature of high-intensity focused ultrasound is that damage to the target point, located a few millimeters below the skin surface, is not accompanied by damage to the tissue above and below the target point. High-intensity focused ultrasound has become an important tool in the treatment of serious medical conditions such as tumors.

Superficial musculoaponeurotic system of the face

podtyazhka-kozhi-mikrofokusirovannym-ultrazvukomInterconnected fiber network attached to the periosteum or connected to the facial muscles. The morphology of SMAS type 1 is typical of the frontal, parotid, zygomatic and infraorbital regions, as well as the lateral nasolabial fold, and is more susceptible to the effects of aging. The morphology of SMAS type 2 (upper and lower lip) is a network of interconnected collagen and elastin fibers, as well as muscle fibers.

The impact of microfocused ultrasound on the superficial musculoaponeurotic system of the face

Heat damage is known to cause collagen shrinkage. However, prior to the use of microfocused ultrasound in cosmetic dermatology, such exposure was limited to the use of surface heating by means of lasers. By adjusting the ultrasound frequency, depth of focus, output power and duration of exposure, the temperature in the dermal layer can be briefly raised to 60

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C, which leads to the formation of a separate zone of thermal coagulation. Such small volumes (˂1mm2) of coagulated tissue are possible due to the relatively short and precise exposure to microfocused ultrasound. When exposed to microfocused ultrasound on the superficial musculoaponeurotic system of the face, a small but constant reduction in collagen occurs, while the coda and intermediate tissues are not affected.

Microfocused Ultrasound with Imaging System (MFU-V)

To date, only one non-invasive aesthetic procedure using microfocused ultrasound with an imaging system has been approved by the US Food and Drug Administration (FDA) – Ulthera System, Ulthera, Inc., Mesa, Arizona.

podtyazhka-kozhi-mikrofokusirovannym-ultrazvukomThe device has an Ulthera DeepSEE transducer that allows ultrasonic imaging of target tissues up to 8mm below the skin surface. The transducer provides proper adhesion to the skin, the required depth of exposure and no effect on non-target tissue (eg, bone). Among the frequency converters / depth of focus – 4MHz/4.5mm, 7MHz/4.5mm, 7MHz/3.0mm, 10MHz/1.5mm and 7MHz/3.0mm. Each transducer ensures the penetration of the beam of microfocused ultrasound to the selected depth of focus, where the tissue is heated up to ˃60

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С in the heat damage zone 1 – 1.5 mm2 and the collagen is thermally coagulated. Description of the process of using MFU-V systems for skin tightening

The choice of transducer depends on the anatomical area to be treated. For example, areas with thinner skin, such as the neck and periorbital region, are treated using superficial, eyebrows and temples – superficial and deeper, and cheeks and subchin skin – the deepest transducers 4 MHz / 4.5 mm, followed by processing with a surface transducer. The use of double depth transducers may improve the results of the procedure.

The ultrasound gel is applied to the skin and the transducer is placed on the target area so that its entire surface is evenly in contact with the skin surface. This uniform contact can be achieved by using the imaging function to obtain an ultrasound image of the target area. Then the specialist manually draws several lines 25mm long (in the target area) at a distance of 2 – 3 mm apart. The total number of lines in the processed area depends on the size of this area and the selected protocol. The manufacturer provides guidelines for the procedure, including transducer selection and recommended treatment patterns for various areas of the face.

Warnings

The most serious potential complication of this procedure is motor nerve palsy. Areas at highest risk:

temporal part of the trigeminal nerve;
  • marginal mandibular nerve.
    • Such complications can be prevented by avoiding treatment directly over the maxillary or facial nerves. Due to the lack of sales glasses to protect the eyes from ultrasonic energy, the procedure inside the orbital ridge is prohibited. The thyroid gland must also be marked prior to the procedure to avoid exposure to ultrasound energy in this area.

Contraindications for using MFU-V systems  

open wounds or injuries;
  • severe or cystic acne:
  • presence of active implants (pacemakers and defibrillators);
  • presence of metal implants in the treated area;
  • pregnancy;
  • Illnesses and medications that can interfere with wound healing.

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