What it means for a patient
- Focused ultrasound can heat the SMAS, a deep facial layer, without cutting the skin.
- This study was done in cadavers. It shows the heat reached the SMAS, not that living patients look tighter.
- Tissue shrinkage in cadavers does not tell you how much lift you would see or how long it lasts.
- Ask for results in living patients before choosing a device over surgery.
Why this paper matters
It showed in cadavers that intense ultrasound can target the SMAS at a set depth and spare the skin. The authors present the SMAS as a new target for noninvasive facial rejuvenation.
Overview
The SMAS is a deep layer of the face beneath the skin and fat. The authors tested whether intense ultrasound delivered through the skin could heat the SMAS alone, without harming the layers above and below. They used 6 unfixed human cadaver specimens and examined the treated tissue under the microscope.
Findings
- 6 unfixed human cadaver specimens.
- The device's ultrasound imaging was used to see and target the SMAS.
- 2 handpieces; 202 exposure lines on both sides in several facial regions; energy 0.5 to 8.0 J.
- Tissue was examined by eye and under the microscope with a viability stain.
- Reproducible thermal injury zones formed selectively in the SMAS at depths up to 7.8 mm.
- Surrounding tissue, including the epidermis, was spared.
- Higher energy and denser exposure lines produced more tissue shrinkage.
- The authors state focused heating of SMAS collagen to cause shrinkage had not been reported before.
Terms
- SMAS: the layer of muscle and fibrous tissue under the facial skin and fat.
- Intense ultrasound (IUS): focused sound energy that heats tissue at a set depth.
- Thermal injury zone (TIZ): a small area of tissue heated enough to be damaged on purpose.
- Collagen denaturation: heat-induced change in collagen that makes it shrink.
- Epidermis: the outer layer of the skin.
- Unfixed cadaver: a donor body not preserved with chemicals.
- Viability stain: a dye that shows which tissue is alive or damaged.