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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
Date: 15-Nov-08
Mistral™- A New Light and Heat Energy (LHE®)
System for Multiple Aesthetic and Dermatological
Applications
Dr. Rothman Julia; Mr. Raif Joshua.
Radiancy Clinical Department, Hod Hasharon , Israel .
.
Abstract
Light-based systems have made significant inroads into the field of dermatology and aesthetics, becoming
the standard treatment tools for a wide range of applications. Various lasers and non-laser light devices
are currently approved and clinically applied for indications such as hair removal, photo rejuvenation,
vascular and pigmented lesions, tattoo removal, leg veins, acne and psoriasis. In most of these
applications, light energy is transformed to thermal energy in the absorbing chromophore. LHE
technology combines the application of light energy with an additional source of direct heat energy. This
paper describes Radiancy's new Light and Heat Energy (LHE) system, Mistral, and summarizes the latest
clinical results using this unique technology.
clinical application.
Introduction
Light-based systems have, over the past 20 years,
made significant inroads into the field of
dermatology and aesthetics. The range of systems
offered, as well as the range of clinical
applications for which they are being used, is
constantly and rapidly expanding. Most of these
systems are based on the theory of Selective
Photothermolysis, first published by Anderson &
Parrish in 1983 (1). This theory defines the
optimal wavelength and pulse duration required to
achieve a desired effect on dermatological lesions
with minimal effect to surrounding tissue. Based
on this theory, products such as the pulsed dye
laser (PDL) and Q switched Ruby laser were
developed and became widely used by
dermatologists for the treatment of port-winestains, pigmented lesions and tattoo removal.
While clinically effective for a wide range of
dermatological applications, varying today from
leg veins to hair removal, lasers are
monochromatic, emitting a single wavelength.
Therefore, different laser systems are required for
different clinical applications. To overcome this
limitation, Intense Pulsed Light (IPL) systems
were introduced in the mid 90’s. These systems
emit a broad spectral range of wavelengths, which
can be filtered to optimize the desired clinical
effect. A single IPL system can be used for
several different dermatological applications by
changing filters and pulse durations. Current IPL
systems usually come standard with several lightemitting “heads”, each optimized for a different
© 2008 by Radiancy
Light and Heat Energy (LHE)
LHE was born from the theory of Selective
Photothermolysis itself. As the name implies, this
theory deals with selective destruction (lysis) of
human tissue by heat (thermo) generated by
absorption of light (photo). While lasers and IPL
devices use only light to generate heat, thus
requiring high light fluences, LHE technology
uses a combination of lower fluence light with
direct heat to safely and efficiently implement the
concepts of Selective Photothermolysis in a wide
range of clinical applications. This streamlined
the design and production and took non-laser,
light-based dermatological phototherapy one-step
further towards affordability by a much wider
base of physicians and aesthetics providers.
The Mistral System
The Mistral LHE system by Radiancy is a
compact, tabletop device that utilizes low fluence
flash lamps, which emit light of 350-1200 nm.
The treatment heads direct both light and heat
towards a particularly large aperture. The aperture
defines an effective treatment area of up to 18.5
cm2. Small area adaptors, which reduce the spot
size down to 4.2 cm2, may be fitted over the
aperture for situations where smaller treatment
areas are required. Mistral emits light fluences of
up to 15 J/cm2 at repetition rates of 2-4 seconds
in between pulses.
A range of eight treatment heads is offered
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
with the Mistral for different clinical applications
and different patient skin types. These differ in
both the spectral and temporal characteristics of
the light output, in order to maximize clinical
efficacy and assure patient safety. Contrary to
previously available LHE systems, the Mistral
emits a rapid train of pulses with intervals
optimized for different clinical situations.
initial system settings are based on
manufacturer’s recommendations or user’s
experience, for a particular patient’s skin type,
hair color, coarseness and density. These settings
are then confirmed or modified through a series of
test spots conducted preferably 24-48 hours
before treatment. Optimal settings are judged by
the thermal effect on the hair, by surrounding
perifollicular erythema and by the lack of any
adverse side effects such as marked erythema in
the shape of the aperture or blistering. For full
hair reduction results, multiple treatments are
performed on each site at intervals of 3-weeks to
3 months, depending on hair regrowth. Up to 10
treatment sessions may be required for maximum
hair reduction. If regrown hair becomes thinner
and lighter treatment parameters will have to be
increased in order to reach the desired clinical
endpoint.
LHE hair removal studies with long-term followup have been conducted and published. Adatto (2)
studied 21 patients of skin type II & III with dark,
coarse hair mainly on the back or chest for males
and the bikini/axilla area for females. Average
clinical percentage of hair reduction at 3-6 months
after the last treatment session was 58% for males
and 73% for females. As expected, the anatomical
sites treated on females respond better than those
treated on males and require, on average, fewer
sessions (5.53 vs. 7.5).
Side effects were all minor, transient, and
included erythema for up to two days and few
crusted areas where hair was very dark and
coarse. These crusts fell off within a few days
with no dyspigmentation of the skin.
LHE hair removal on patients with skin type I-IV
is typically conducted with the regular hair
removal treatment head which emits a spectrum
of 400-1200nm. For darker skin types a longer
wavelength, sensitive skin, treatment head is
available. Sadick & Krespi (3) studied the
efficacy and safety of this treatment head on 26
subjects with Fitzpatrick skin types V & VI. Fifty
seven (57) sites were treated once and were
followed up for 3 months. Average hair clearance
of 41.7% was found at the 6 week follow-up visit
and an average of 35.5% clearance was found at
the 12-week follow-up. Besides mild and transient
edema in two patients and erythema in eleven
patients, one patient had a burn which resulted in
crusting and hypopigmentation while another four
patients developed hyper or hypopigmentation. At
the 12-week follow-up all cases of
Fig 1- The Mistral LHE® System
LHE Hair Removal
The dual light and heat energy (LHE) concept for
hair removal is based on the fact that follicle
damage can be more efficiently achieved by
combining the effects of selective light absorption
in follicular melanin with direct conduction of
heat through the hair shaft down to the follicle.
Light energy absorption occurs in epidermal
melanin as well as in hair melanin; however the
temporal characteristics of these mechanisms are
quite different. The epidermis, being a thin layer
with a greater surface to mass ratio than the hair
follicle, possesses a low thermal relaxation time
in the range of 3-7 msec. The hair follicle, in
contrast, has a longer thermal relaxation time in
the order of 30-100 msec. For hair removal the
Mistral utilizes this difference by emitting the
light in a special pulse algorithm that allows the
epidermis to dissipate its absorbed energy while
the follicle retains the light energy and transform
it to the required increase in follicle temperature.
Following the light pulse, the Mistral delivers a
heat pulse to both the epidermis and the hair shaft.
This combined light and heat energy achieves
follicular necrosis while sparing surrounding skin
from adverse effect
.
As with any laser or IPL hair removal treatment,
© 2008 by Radiancy
Date: 15-Nov-08
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
hypopigmentation were resolved while the
hyperpigmentation cases were still present but
reduced to a mild form. Hydroquinone cream was
prescribed for these cases.
Date: 15-Nov-08
average improvement of 62.5% (3 on a scale of 4)
was achieved. For patients with primary
indication of vascular lesions, an average
improvement of 45.2% (2.3 out of 4) was
Baseline
1 month after 3Tx
Fig 2- LHE® Hair Removal Z.G.33y, ST II
obtained. Clinical improvement was also seen in
skin texture but was difficult to quantify. All
patients had transient erythema after each
treatment, which resolved within 2-12 hours.
Pigmented lesions darkened a few minutes after
the treatment and exfoliated within a few days.
Superficial crusting was the most common side
effect occurring in almost 30% of the patients.
Only one patient experienced transient
hypopigmentation while another patient (skin type
IV) experienced hyperpigmentation, which lasted
2 months and disappeared following treatment
with hydroquinone 4% cream. Three patients had
blistering but no permanent scarring occurred.
Morel (6) reported on twenty patients treated for
photo rejuvenation with LHE. For sun damage
pigmentation the average number of treatment
sessions was 2.5 (range 1 to 4) and follow-up was
up to 6 months. There were no significant adverse
effects. All patients experienced temporary
erythema and immediate darkening of pigmented
spots. Superficial crusting resolved within 7-10
days. Two patients had partial blistering.
Lightening
of of
pigmented
lesions was observed
End
Tx
after the first treatment session and improved with
further treatments. While objective evaluation of
wrinkle improvement was not possible, patients
did experience an improvement in skin texture
and skin tone .
LHE Photorejuvenation
Photo rejuvenation is a non-invasive, no
downtime technique for the treatment of
photodamaged, aged skin. Using a broad
spectrum of wavelengths in addition to direct
heat, LHE technology can eliminate pigmented
sun damage and small, visible, blood vessels,
while simultaneously initiating neo-collagenesis
as a result of a mild thermal insult to dermal
collagen.
Adatto & Lima (4) studied LHE photo
rejuvenation on 16 female subjects representing
23 locations which included face, neck, chest and
hands with varying degrees of photodamage.
Results were assessed by comparing digital
photographs of patients taken before and after
treatment. Reduction in skin pigmentation was
2.85 on a scale of 4. Improvement in vascular
l e s i o ns wa s 2 o n a s c al e of 4. Cl i ni c al
improvement in skin texture was difficult to
quantify although diminution of fine wrinkles was
evident and neo-collagenesis was demonstrated in
skin biopsy specimens. No scarring, hyper or
hypo-pigmentation was observed
.
BL
In a multicenter study (5) 99 patients, mostly
females, of Fitzpatrick skin types I-V and mean
age 52.4 years were treated for photorejuvenation.
In most of these patients (65.5%) solar lentigines
was the primary indication. For these patients an
© 2008 by Radiancy
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
Date: 15-Nov-08
1 month after 1Tx
Baseline
Fig 3- LHE® Sun Spot treatment .32y, ST II
1 month after 1Tx
Baseline
Fig 4- LHE® Skin Texture treatment .29y, ST III
evaluate the safety and effectiveness of LHE for
the treatment of mild to severe inflammatory acne
vulgaris (8). The study included three phases:
control period, treatment period and follow-up
period. The patients served as their own control
by foregoing any method of treatment for a period
of 4 weeks. After completion of the control
period, the patients were treated twice a week for
a period of 4 weeks. Follow-up for safety and
effectiveness evaluations were performed
following each one of the treatments and 4 weeks
following the last treatment.
Patients with mild to severe acne were enrolled in
the study but only pustules and papules (inflamed
lesions) were assessed for efficacy evaluation.
LHE Acne Treatment
The Mistral Acne treatment head emits a 35 msec
pulse of 430-1100 nm at an optical fluence of 315 J/cm². This combined light and heat energy
pulse utilizes several photo thermal principles,
which are known to have a positive effect in the
treatment of inflammatory acne. The emitted light
wavelengths accommodate well for photo
excitation of endogenous porphyrins produced by
P. acne bacteria and for the coagulation of blood
vessels that surround the acne lesions while the
pulse of heat contributes to anti-inflammatory
reactions and sooths the painful lesions associated
with acne. The additional heat also speeds up the
reaction time and intensifies the basic chemical
process associated with the release of singlet
oxygen from the photo-excited porphyrins (7).
© 2008 by Radiancy
Before treatment, the area was thoroughly
cleaned and dried Based upon a pre-treatment
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
test, the highest power level that showed no side
effects was used for treatment. After covering the
entire area, the clinicians waited 5 minutes to
allow the skin to cool down, and repeated the
procedure one more time
.
In total, in 75% of the treated areas, 50% or
greater reduction in inflamed lesions was
recorded following the treatment regimen, while
no such improvement was achieved following the
control period. Following the follow-up phase, a
mean reduction of 60.2% was achieved as
compared to an increase of 32.4% measured after
the control phase
.
Erythema was the only side effect reported and in
al l cas es , i t was mi ni mal and t r ansi ent.
Patients are spared the risks associated with
exposure to antibiotic acne medications.
Zimmerman's (9) experience with LHE for the
treatment of mild to moderate acne confirms these
published results. In a group of eleven patients
(age 13 to 27, 6 females 5 males) he documented
the number of non-inflamed and the number of
inflamed acne lesions over a 4-week treatment
period. On average, non-inflamed lesion clearance
of 58.4% and inflamed lesion clearance of 76.5%
were observed. On all eleven patients, an
inflamed lesion clearance of at least 50% was
obtained. Side effects were minimal and included
mild erythema in three patients and mild crusting
in one. Overall, patient satisfaction with these
results was high
.
Baseline
Date: 15-Nov-08
the skin and maintaining the psoriatic plaque.
Selective photothermolysis of the dermal
vasculature using a 585nm pulsed dye laser (PDL)
has been demonstrated and has been cleared by
the FDA. LHE is potentially a more effective
treatment for psoriasis since in addition to green
and yellow light for the coagulation of the
psoriatic capillaries, this non-laser system also
emits a pulse of heat, which reduces swelling and
inflammation and relieves itching
.
An intra-patient controlled study on the use of
LHE for the treatment of mild to moderate
psoriasis has been published (10). In this study,
13 patients received two therapy regimens on
similar psoriatic lesions or on two sides of the
same lesion. One regimen included ten biweekly
LHE treatments combined with daily application
of 20% salicylic acid while the second, control
regimen, included daily salicylic acid only.
Efficacy of the treatment was assessed using the
Psoriasis Severity Index (PSI) calculated from the
investigator’s overall assessment of the plaque’s
erythema, scaling and induration. PSI was
evaluated at baseline, at every other treatment
visit and at two follow-up visits conducted 1 and
5 weeks following the last treatment visit. In most
cases, a fluence level of 8.6 J/cm² was found to be
the most effective and safest treatment parameter.
Of the 11 patients who completed the treatment
regimen, only one had a poor response (12.5%
reduction in global PSI). Ten of the patients
2 months after 8 bi-weekly Tx
Fig 5- LHE® Acne Clearance
(91%) had a 50% or above reduction in their PSI
s cor e whil e s i x (55%) had a si gni fi cant
improvement of 70% reduction or above. In
contrast, on the control sites average global PSI
score was reduced by only7.4%. Side effects
included erythema, in all cases, which resolved
LHE Psoriasis Treatment
In psoriasis, the earliest observable electron
microscopic changes are in the dermal papillary
vasculature. These vessels have been implicated
as participating in the pathogenesis of the disease
by facilitating the access of activated T cells to
© 2008 by Radiancy
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
within 24-48 hours and six cases of burns, which
resolved, following appropriate remedy, within 2
days to 2 weeks. The clinical results obtained with
the LHE system in this study were remarkably
similar to those previously reported with the
pulsed dye laser.
Zimmerman (9) studied a group of 29 patients (17
males, 12 females) in which individual plaque
psoriasis lesions from 3x2 cm. to 14x12 cm. were
designated for treatment. Lesions were located on
the elbow, knee, foot, belly, forearm and thigh.
Lesions underwent an average of 9.8 treatment
sessions (range 6-16). In each visit scaling,
erythema and induration were assessed on a 0-4
scale and an SEI score was documented. At the
end of treatments, average SEI score reduction
was 60.3%. Clearance of 50% or above was
achieved in 24 of the 29 treated lesions (83%).
Size and shape of the treated lesions remained
unchanged. Treatment fluence was in the range of
6-7 J/cm2 . Higher fluences may be even more
effective but are too uncomfortable for the
patients
.
Baseline
Date: 15-Nov-08
which 5-Aminolevulinic acid (ALA) is topically
applied to the area for 30 minutes before LHE
activation. Gold (11) reported on the use of this
technique on twenty patients with moderate to
severe acne lesions. Patients received one
treatment per week for 4 weeks. Five patients
were lost to follow-up and three did not respond.
Of the remaining twelve patients, reduction in
acne lesions was 71.8% 12 weeks after final
treatment. Gaboriau (12) also reported on the use
of LHE PDT for the treatment of actinic keratosis,
Bowen's disease and photoaging-related skin
changes in situations where the condition is more
severe and the patient is willing to be out of the
sun and bright light for 48 hours.
In summary
The Light and Heat Energy (LHE) based Mistral
is a compact, simple to operate and cost-effective
system which is applicable for a wide range of
dermatological and aesthetic applications. These
include hair removal, elimination of superficial
pigmented lesions and superficial vascular
lesions, photo rejuvenation of sun damaged, aged
skin and phototherapy of acne and psoriasis
lesions. Use of this system for the treatment of
keloid scars has also been reported (12,13)
resulting in softening and some flattening of the
scar as well as marked diminution of the
erythema. These different applications are
afforded by attaching different handpiece
assemblies to the same basic system. The
operation of the system is extremely simple,
treatment is fast due to the large spot size and
high repetition rate, and patients usually
experience only mild discomfort with no
convalescence downtime.
References
1. A n d e r s o n R R , P a r i s h J A : S e l e c t i v e
Photothermolysis: precise microsurgery by
selective absorption of pulsed radiation. Science
1983, Apr 29;220(4596):524-7.
5 days after 1Tx
2. Adatto MA: Hair removal with a combined
light/heat-based photo-epilation system: a 6month follow-up. J. Cosmetic & Laser Ther
2003;5:163-167.
Fig 6- LHE® Psoriasis Care
LHE Photodynamic Therapy
To enhance the photodynamic reaction in acne
phototherapy and potentially treat moderate to
severe inflammatory acne, some investigators
have began to use an exogenous form of PDT in
© 2008 by Radiancy
3.Sadick NS, Krespi MD: Hair Removal for
Fitzpatrick Skin Types V and VI Using Light
and Heat Energy Technology. J. Drugs in
Dermatology, Sept 2006, Vol 5, No 8, pp 724-6.
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Mistral™- A New Light and Heat Energy (LHE ) System for Multiple Aesthetic and Dermatological Applications
4. Adatto MA, Lima HRB : Photorejuvenation
with a New Light/Heat-Based Energy Device:
A Preliminary Study. Cosmetic Dermatology,
Jan 2005, Vol 18 No 1, pp 53-63.
5. Adatto MA et al : Results of Non-Ablative
Photorejuvenation with a New Device Using
Light and Heat Energy (LHE®): A MultiCenter Study. ASLMS poster presentation,
April 2004.
BL
6. Morel J-L,: Technologie LHE™ (Energie
Lumineuse et Thermique)- Une approche
originale du rajeunissement non ablative cutane.
AFME Bulletin Trimestriel Nov 2004.
7. Elman M, Lask G: The role of pulsed light and
heat energy (LHE) in acne clearance. J.
Cosmetic Laser Ther. 2004 Jun;6(2):91-5.
8. Gregory AN, et al: A Study on the Use of a
Novel Light and Heat Energy System to Treat
Acne Vulgaris. Cosmetic Dermatology Vol. 17
No. 5 May 2004.
9. Zimmerman J.: Dermatologische Indikationen
fur die Behandlung mit Kombinierter Licht-und
Warmeenergie (LHE Light Heat Energy).
Asthetische Dermatologie 3/2005.
10. Leviav A, Wolf R, Vilan A: Treatment of
psoriasis with light and heat energy (LHE): a
preliminary study. Dermatology Online J. 2004
Oct 15;10(2):4.
11. Gold MH et al : The Use of a Novel Intense
Pulsed Light and Heat Source and ALA-PDT in
the Treatment of Moderate to Severe
Inflammatory Acne Vulgaris. J Drug Dermatol
2004; 3(6): S15-S16.
12. Gaboriau HP: Skin Rejuvenation with the
SkinStation. Cosmetic Dermatology, Oct 2006,
Vol 19 No 10, pp 642-647
.
13. L e v e n b e r g A . : T r e a t m e n t o f a
Mediastinoscopy-Induced Keloid with a Pulsed
Light and Heat Energy Device. Cosmetic
Dermatology, July 2004, Vol 17 No 7 pp 445-7.
© 2008 by Radiancy
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Date: 15-Nov-08