Philadelphia: A three-dimensional imaging technique often used in the automotive
and aerospace industries for accurate measurement may be useful to
measure the efficacy of injectable wrinkle reducers such as Botox and
Dysport, according to new research from the Perelman School of Medicine at the University of Pennsylvania. The procedure, called three-dimensional speckle tracking photogrammetry, is described in the May issue of Plastic and Reconstructive Surgery.
Authors say it has the potential to measure the efficacy of several
treatments for which these types of injections are used, not only for
cosmetic purposes but also to reduce facial paralysis arising from
stroke and Bell’s palsy.
Photogrammetry is the use of photography to measure distances
between objects. Using the new technique, researchers can measure
dynamic facial wrinkles and their subsequent reduction following
injection. Results are presented as a color-coded heat map. By
comparing before- and after-treatment heat maps of patients, physicians
can objectively evaluate wrinkle reduction and such other variables
such as optimal dosage for obtaining maximum aesthetic benefit.
“There is a growing body of evidence that injectable fillers for
both cosmetic and reconstructive purposes can have significant
psychological benefits,” said senior author Ivona Percec, MD, PhD, director of Basic Science Research and associate director of Cosmetic Surgery in the division of Plastic Surgery at Penn.
“With more people turning to this procedure, it is important to have
evidence-based ways of improving cosmetic and reconstructive surgical
results.” Current attempts at measuring wrinkle reduction mostly rely
on static photographs and subjective visual assessments.
Injectable fillers reduce or eliminate wrinkles by relaxing the
muscles responsible for their development. After treatment, the muscles
gradually become less active, allowing the overlying skin to appear
smoother.
In the new study, the Penn team evaluated fourteen subjects using a
dual camera system and three-dimensional optical analysis. White
foundation and black speckle makeup were randomly applied to each
patient before and two weeks after injection of 20 units of filler in
the area between the eyebrows. Movement of the speckles was tracked by
the digital camera for analysis. Wrinkles in treated areas were
analyzed, resulting in before- and after-treatment heat maps. In the
pre-treatment heat map light blue represented wrinkles. Two weeks after
treatment, the light blue had been largely replaced with light green
and yellow. These new colors were representative of decreased skin
compression or wrinkling.
In addition to color changes that signal improvement, the system
allows precise measurement of wrinkle reduction. In the study,
horizontal compression or wrinkling in the treated area decreased from
9.11 percent to 2.60 percent and from 4.83 percent to 0.83 percent in
the forehead following injection. Average vertical stretch (another
form of wrinkling) of the area during brow furrowing decreased from
2.51 percent to 1.15 percent, and average vertical stretch in the
forehead decreased from 6.73 percent to 1.67 percent.
Application of the technique raises the possibility of objectively
answering several open questions in cosmetic medicine. For example, in
the United States there are currently two other approved formulations
for reducing wrinkles. Objective evidence of which formulation provided
maximum wrinkle reduction could guide physician and consumer choice in
individual cases.
Controversy also exists regarding preparation, dilution, and dosing
efficacy of a given toxin, as well as how soon to expect results and
how long the results last. Previous investigations of questions such as
these largely used static photography with subjective, although
validated, scoring scales; these scoring methods could be replaced by
three-dimensional speckle tracking photogrammetry. In addition,
different dose efficacy in various populations (such as male versus
female patients from various age groups) could be determined.
“As new therapies and expanded applications become available for
antiaging and the treatment of neuromuscular disorders, this method may
make it possible to quantify clinical efficacy and establish precise
therapeutic regimens,” Percec said. “Though future studies will need to
explore the use of digital image correlation in larger groups, our
results are the first to show the modality can be applied to study a
range of challenges in plastic surgery.”
Other Penn co-authors are Anthony J. Wilson, MD; Bianca C. Chin, MD; Vivian M. Hsu, MD; and Michael N. Mirzabeigi, MD.