Histologic evaluation of the pulsed Nd:YAG laser for laser lipolysis

Histological findings in adipocytes when cellulite is treated with a variable-emission radiofrequency system

Cellulite is a disorder of the subcutaneous fat layer and the overlying superficial skin. Recently, radiofrequency (RF) has been proposed as an effective treatment of cellulite; however, the mechanism through which the absorbed electrical energy acts on the tissue is still not fully clear. This study reports on the histological findings from biopsies taken immediately after a single RF treatment session, on cellulite located in the buttocks, with a novel technology called automatic multi-frequency and low impedance (AMFLI) RF. Tissue samples were stained with either haematoxylin and eosin (H&E), so that we could study the morphological findings, or with oil red O, to enable us to identify lipid deposits. The histological findings observed in biopsies taken after a single RF treatment showed changes in shape, size, and lipid content, as well as in cytoplasmic and nuclear morphology. After RF treatment adipocytes were more polyhedric, with irregular, degenerated membranes, with less or no lipid content and apoptotic changes. We postulate that RF treatment on cellulite produces a decrease in lipid content of cells as well as changes in the adipocyte membrane which will lead to cell rupture and the death and extrusion of lipid content out of the cell. Further studies are needed to characterise the nature of the extra-cellular lipid material that we have demonstrated with the oil red O stain in our biopsies.

Lasers and optical technologies in facial plastic surgery

Lasers and optical technologies play a significant role in aesthetic and reconstructive surgery. The unique ability of optical technologies to target specific structures and layers in tissues to effect chemical, mechanical, or thermal changes makes them a powerful tool in cutaneous rejuvenation, hair removal, fat removal, and treatment of vascular lesions such as port-wine stains, among many other procedures. With the development of adjunct techniques such as epidermal cooling, lasers and optical technologies have become more versatile and safe. The constant improvement of existing applications and the emergence of novel applications such as photodynamic therapy, nanoparticles, spectroscopy, and noninvasive imaging continue to revolutionize aesthetic medicine by offering a minimally invasive alternative to traditional surgery. In the future, therapies will be based on individualized, maximum, safe radiant exposure to deliver optimal dosimetry. Lasers and optical technologies are headed toward safer, easier, more quantifiable, and more individualized therapy.

Lipolysis using a 980-nm diode laser: a retrospective analysis of 534 procedures

BACKGROUND

The safety and efficacy of the 980-nm diode laser for laser lipolysis were evaluated in different body areas.

METHODS

From June 2005 to June 2007, 334 subjects underwent laser lipolysis. The treatment was performed using a 980-nm diode laser (OSYRIS, Hellemmes, France). After tumescent anesthesia, a 1-mm-diameter microcannula housing a 600-mum optical fiber was inserted into the subcutaneous fat. The cannula was moved back and forth in a predetermined manner to get a homogeneous distribution of energy at the treated area. Laser settings (power and cumulative energy) were selected in relation to individual body areas: 6 W (chin, arm, knee), 10 W (abdomen, back), and 15 W (thigh, hips, buttock). Patient satisfaction was evaluated and side effects were recorded. The laser energy counter incrementally counted the energy used; then the cumulative energy used for each treatment was recorded. Ultrasound imaging was used to control tumescent anesthesia infiltration, cannula position prior to laser emission,and postoperative fat liquefaction.

RESULTS

Five hundred thirty-four (534) laser lipolysis procedures were performed on 334 patients. Different areas were treated: hips (197), inner thighs (86), abdomen (86), knees (61), flanks (57), buttocks (28), chin (22), arms (18), back (4). Mean cumulative energy was area-dependent, ranging from a minimum of 2200 J (knee) to a maximum of 51,000 J (abdomen). Contour correction and skin retraction were observed almost immediately in most patients. There was no scarring, infection, burns, hypopigmentation, bruising, swelling, or edema. Ecchymoses were observed in almost all patients but resolved in under 1 week for 322 patients. Patient satisfaction was very high. Because laser lipolysis is an outpatient procedure, patients were able to resume normal daily activities after 24 h. Ultrasound imaging confirmed that the thermal effect generated by the laser results in melting and rupture of the collagenous and subdermal bands.

CONCLUSION

This clinical study demonstrates that the removal of small volumes of fat with concurrent subdermal tissue contraction can be performed safely and effectively using a 980-nm diode laser. Additional benefits include excellent patient tolerance and quick recovery time. This study also confirms that enough accumulated energy must be delivered to achieve sufficient lipolysis throughout different fat layers.

New advances in liposuction technology

Although suction-assisted liposuction under tumescent anesthesia remains the traditional method for body sculpting, newer technologies promise to increase efficiency, decrease surgeon fatigue, and minimize complication. Power-, ultrasound-, and laser-assisted devices are ideal in large volume cases and in areas of fibrous tissues as an adjunct to traditional liposuction. Although skepticism remains chemical lipolysis, more commonly termed mesotherapy or lipodissolve may be an alternative to surgical treatment of localized fat. This article reviews the recent advancements in the field of liposuction and the current literature which support their use.

Mathematical modeling of laser lipolysis

Background and Objectives

Liposuction continues to be one of the most popular procedures performed in cosmetic surgery. As the public's demand for body contouring continues, laser lipolysis has been proposed to improve results, minimize risk, optimize patient comfort, and reduce the recovery period. Mathematical modeling of laser lipolysis could provide a better understanding of the laser lipolysis process and could determine the optimal dosage as a function of fat volume to be removed.

Study design/Materials and Methods

An Optical-Thermal-Damage Model was formulated using finite-element modeling software (Femlab 3.1, Comsol Inc). The general model simulated light distribution using the diffusion approximation of the transport theory, temperature rise using the bioheat equation and laser-induced injury using the Arrhenius damage model. Biological tissue was represented by two homogenous regions (dermis and fat layer) with a nonlinear air-tissue boundary condition including free convection.

Video recordings were used to gain a better understanding of the back and forth movement of the cannula during laser lipolysis in order to consider them in our mathematical model. Infrared video recordings were also performed in order to compare the actual surface temperatures to our calculations. The reduction in fat volume was determined as a function of the total applied energy and subsequently compared to clinical data reported in the literature.

Results

In patients, when using cooled tumescent anesthesia, 1064 nm Nd:YAG laser or 980 nm diode laser: (6 W, back and forth motion: 100 mm/s) give similar skin surface temperature (max: 41°C). These measurements are in accordance with those obtained by mathematical modeling performed with a 1 mm cannula inserted inside the hypodermis layer at 0.8 cm below the surface. Similarly, the fat volume reduction observed in patients at 6-month follow up can be determined by mathematical modeling. This fat reduction depends on the applied energy, typically 5 cm³ for 3000 J. At last, skin retraction was observed in patients at 6-month follow up. This observation can be easily explained by mathematical modeling showing that the temperature increase inside the lower dermis is sufficient (48–50°C) to induce skin tightening

Discussion and Conclusion

Laser lipolysis can be described by a theoretical model. Fat volume reduction observed in patients is in accordance with model calculations. Due to heat diffusion, temperature elevation is also produced inside the lower reticular dermis. This interesting observation can explain remodeling of the collagenous tissue, with clinically evident skin tightening.

In conclusion, while the heat generated by interstitial laser irradiation provides stimulate lipolysis of the fat cells, the collagen and elastin are also stimulated resulting in a tightening in the skin. This mathematical model should serve as a useful tool to simulate and better understand the mechanism of action of the laser lipolysis

The new laser liposuction for men

Laser-assisted lipolysis with a medium-pulsed 1064-nanometer neodymium-doped yttrium aluminum garnet (Nd:YAG) system is a new FDA-approved method of removing localized areas of fat with the added benefit of skin tightening. This new method is particularly useful in treating the lower abdomen and submental areas where skin laxity may occur after the removal of adipose tissue. In addition, decreased bruising and scrotal edema after treating men is possible with use of the tumescent technique and the added benefit of coagulation produced by the laser. Experience in treating men with this modality is reviewed.

A Prospective, Randomized, Double-Blind, Controlled Clinical Trial Comparing Laser-Assisted Lipoplasty with Suction-Assisted Lipoplasty

BACKGROUND

The authors randomized and prospectively analyzed their clinical experience with the use of internal neodymium:yttrium-aluminum-garnet low-level laser-assisted lipoplasty compared with suction-assisted lipoplasty.

METHODS

Suction-assisted lipoplasty was generated through a SmartLipo machine and delivered into the subcutaneous tissues through 2-mm solid optical probes. Ipsilateral suction-assisted lipoplasty and contralateral laser-assisted lipoplasty were performed on one or more comparable topographic areas of the body in the same patient. Laser-assisted lipoplasty and suction-assisted lipoplasty sides of 25 patients were compared with preoperative and postoperative photographs at 3 to 5 days, 12 to 15 days, and 6 to 11 months. Statistical analysis considered surgeon and patient satisfaction, time used in the procedures, learning curves, lipocrits, operative technique, postoperative pain, edema, ecchymosis, time of recovery, body mass index, DNA proteins, free fatty acids, and cytologic patterns of post-laser-assisted lipoplasty and suction-assisted lipoplasty adipocyte architecture. Photographs were sent to the patients (blinded to the operated sides) and two plastic surgeons unfamiliar with the cases for evaluation of results.

RESULTS

All patients completed the preestablished follow-ups. No complications were observed. Less pain, lower lipocrits, higher triglycerides, and DNA cellular membrane traces were detected in the laser-assisted lipoplasty sides. All other considerations studied showed no differences with either technique in the three periods of the follow-up controls. Cytologic studies showed more damage of the adipocytes in the laser-assisted lipoplasty sides.

CONCLUSIONS

No major clinical differences for suction-assisted lipoplasty versus laser-assisted lipoplasty were found. Higher concentrations of free-fatty acids after laser-assisted lipoplasty must alert us to possible hepatic and renal toxicity.

Submental Nd:Yag laser-assisted liposuction

BACKGROUND

Liposuction of the neck is currently one of the most common cosmetic surgical procedures. In the present study, the author describes his experience with neck and jowl laser-assisted liposuction.

STUDY DESIGN/MATERIALS AND METHODS

In this procedure, submental lipodystrophy is treated with an Nd:YAG laser, at a 1,064 nm wavelength. Over a 5-year-period, 82 subjects were treated using 6-W power, 40-Hz frequency, 150-mJ energy, and 100-microsecond pulse width parameters. Histology was performed on fatty tissue samples.

RESULTS

Submental laser-assisted liposuction resulted in significant cosmetic improvement. Histology revealed a rupture of the adipocyte membrane as well as collagen coagulation and channels along the fatty tissue. Additionally, small blood vessels were coagulated. An adequate skin contraction was observed with an improvement of the cervicofacial region.

CONCLUSIONS

The Nd:YAG laser is a useful tool for the treatment of local lipodistrophy. The laser proved to be effective for cellular lysis and collagen neoformation.