Integration of Thermal Imaging With Subsurface Radiofrequency Thermistor Heating for the Purpose of Skin Tightening and Contour Improvement: A Retrospective Review of Clinical Efficacy
December 2014 | Volume 13 | Issue 12 | Original Article | 1485 | Copyright © December 2014
Douglas J. Key MD
Key Laser Institute, the Center for Regenerative Cosmetic Medicine, Portland, OR
INTRODUCTION: Radiofrequency has remained a staple procedure for the treatment of skin laxity as therapeutic heat thresholds effectively
promote collagen remodeling. Nevertheless, comprehensive skin tightening involves both dermal and hypodermal collagen
remodeling. However, transcutaneous radiofrequency is unable to deliver consistent and measurable temperatures to the hypodermal
layers. Herein, we evaluated a newly emerging approach that provides precise and controlled subdermal heating is thermistor-controlled
subdermal skin tightening (ThermiTight) using a percutaneous radiofrequency treatment probe.
METHODS: A retrospective analysis of 35 patients was completed on patients having undergone ThermiTight for submental skin
tightening. Treated sites included under-chin and under-chin and jowls. The ThermiTight probe temperature was set between 50 to
60oC and was maintained using the thermistor integrated electrode. The probe was guided at a deliberate pace, treating a surface
area of 3.0 cm2 every two minutes. The clinical endpoint was an epidermal temperature of 42oC. Two blinded reviewers assessed
photographs taken at baseline and 30 days post-procedure. They were randomly presented with a photograph and asked to rate the
photograph using a 4.0 skin laxity scale.
RESULTS: The combined mean change comparing baseline and post-procedure skin laxity scores was -0.78, which was statistically significant (Table 2; P
<0.0001). Each blinded reviewer correctly categorized photographs as either being “baseline” or “post-procedure” 89% of the time. No adverse events were reported.
DISCUSSION: These data demonstrate the safety and efficacy of the ThermiTIght procedure for the treatment of skin laxity. J Drugs Dermatol
A burgeoning non-invasive treatment for skin laxity is
transcutaneous thermogenesis – achieved using ultrasound,
radiofrequency, or light. These approaches
use heat to promote neocollagenesis, denaturation of collagen
cross-links, activation of wound healing pathways, contraction
of collagen, and increase in collagen fibril size.1-3 However, for transcutaneous treatments, their effect is limited
to dermal collagenous tissue.4 This is a critical limitation as
the dermis and the deeper hypodermis combine to create an
interwoven network of collagenous tissue that involves the
papillary and reticular layers of the dermis, fibrous septum
with fat, and the underlying structure of fascia layers.4,5 For
example, the fibrous septum reinforces skin elasticity by anchoring
the dermis to deep fascia.5 Dermal and subdermal
tissues, together, contribute to the skin’s quality and durability.
Accordingly, improvement in the overall quality of lax
skin would require concurrent remodeling of both dermal and
deeper hypodermal collagenous tissue.
Heat-induced collagen remodeling requires disruption of intraand
inter-molecular forces, which occurs within a well-defined
temperature range. Therefore, maintaining a temperature within
this range requires accurate temperature monitoring and
regulation. The inability to monitor subdermal temperatures represents
another chief limitation of transcutaneous therapy. The
only measureable temperature value is the epidermis. Accordingly,
epidermal temperatures approaching the burn threshold
generally designate the treatment endpoint. However, the
temperature threshold for burns in the epidermis is lower than
the temperature threshold required for collagen remodeling.
Therefore, stopping treatment because epidermal temperature
thresholds were reached may imprudently shorten the treatment
and prevent subdermal temperatures from reaching therapeutic
temperatures. Without a means to monitor or regulate subdermal
temperatures during a transcutaneous treatment, there is
much uncertainty concerning treatment optimization.
A newly emerging approach that provides precise and controlled
subdermal heating is thermistor-controlled subdermal
skin tightening (ThermiTight). This approach uses a percutaneous
treatment probe to administer radiofrequency directly to
dermal and subdermal tissue. Subdermal temperatures are