Non invasive options for adipose removal are few. The best studied non invasive treatment is focused ultrasound.
A significant barrier to non invasive treatments is the issue of fat localization after treatment. Adipose tissue stores triglycerides.
The Nd:YAG laser has been used alone or in combination with suction liposuction. SmartLipo™ (Cynosure, USA), a 300 um and 1,064 nm fiber encased in a micro-cannula, is an example of this type of device.
Devices for Removal of Adipose Tissue
While the demand for non-invasive removal is high, the effective means to do so is more limited. There are few laser or light based treatments for the removal of adipose tissue, and all currently available laser or light based options are invasive. The Nd:YAG laser has been used invasively, with or without liposuction, to remove adipose tissue. A low level 635 nm laser has also been combined with liposuction to remove adipose tissue. CO2 laser has been used, in direct contact with adipose tissue to destroy it.1 This section will review the light and laser based treatments for adipose tissue (Table 1). In addition, ultrasound approaches will be discussed as well.13
Table 1
Laser and light treatment for adipose tissue
Technology | Example | Evidence in peer reviewed journal |
|---|---|---|
1,064 nm Nd:YAG laser | SmartLipo™ (Cynosure® Inc.; Westford, MA) | Prospective, double blind, controlled trial of 25 patients and 110 treatments.2 Patients served as their own control with suction lipoplasty on one half and laser-assisted lipoplasty on the other with a 2 mm and 1,064 nm Nd:YAG laser fiber follow by suction with a 3 mm cannula. Two blinded investigators evaluated photographs and found no difference between the groups. Postoperative pain was higher in the suction-assisted side versus the laser-assisted side at the first follow up visit only. Lipocrit (volume of red blood cells in the aspirated material) was lower on the laser-assisted side, a statistically significant difference. Histologic analysis showed more disruption of architecture on the laser-assisted side. Seventeen samples of infranatant were evaluated, and ten were found to have elevated triglycerides. These ten cases were laser-assisted cases. Statistical significance was not tested. It is unclear if the remaining seven cases were laser-assisted cases. |
FDA approved | Double blind study of 15 patients who received laser assisted liposuction on one side and standard liposuction on the other.3 A 600 um Nd:YAG fiber in a 4 or 6 mm cannula at 40 W with a pulse duration of 0.2 s was used in combination with suction. In those patients who received both modalities, there was no difference in paresthesias or skin irregularities, and there was no scarring, infection, or hypopigmentation. Post operative pain seemed to be slightly less on the laser treated side. Lipocrit values did not show any trend. Laser assisted liposuction was not found to be more beneficial than standard liposuction. | |
Review of 1,734 patients who received treatment with a 1,064 nm laser delivered through a 300 μm fiber in a 1 mm microcannula.4 Fat was drained with negative pressure. Cosmetic results were similar to traditional liposuction. | ||
Randomized, controlled study of 30 female patients with focal areas of fat less than 100 cm3 on the arm, submental area, thigh, and abdomen.5 Ten received laser lipolysis with a 1,064 nm Nd:YAG laser with a 300 um fiber encased in a 1 mm microcannula. The procedure was not followed by suction. These patients had MRI pre and post procedure. Ten received and nine completed laser lipolysis followed by a biweekly treatment with the Tri-active system. Ten patients served as controls. Patients who received laser lipolysis reported an improvement of 37% at 3 months. An average 17% reduction in fat volume (p < 0.01) was seen on MRI. Bruising and swelling were present in four and seven patients, respectively. Two patients had tingling that resolved, two had hyperpigmentation, four had tenderness, and one had a subcutaneous nodule that resolved. | ||
Report of 245 patients who received laser assisted liposuction with a 1,064 nm laser in a 1 mm cannula followed by aspiration with a 3 mm cannula.6 Laser assisted liposuction was more time intensive, but less traumatic. There was no control group in this study, and statistical significance was not tested. | ||
Report of 82 patients who received laser assisted liposuction in the submental region with a 1,064 nm laser in a 1 mm cannula at 150 mJ with a 100 ms pulse.7 Suction followed treatment in most cases. Biopsies were taken immediately following the procedure and 40 days following the procedure. On biopsy, coagulation of the blood vessels in the fat, adipocyte rupture, laser channels, “reorganization” of the reticular dermis, and coagulation of the collagen septa were seen. The author felt that the clinical result was similar to traditional liposuction. There was no control group in this study, and statistical significance did not appear to be tested. | ||
Report of one patient who received laser assisted liposuction with a 1,064 nm laser at 150 mJ followed by suction.8 The purpose of this study was to understand histologic response to laser. The patient received conventional liposuction on one flank and laser assisted liposuction on the other flank. In the superior portion of the laser assisted side, she received a total energy of 3,000 J and 1,000 J in the inferior. Fat was sampled from all three areas. A control sample was obtained from an abdominoplasty obtained from the same patient. The average adipocyte diameter was found to be 73.48, 84.54, 95.69, and 82.63 from the control, conventional, 1,000 J site, and the 3,000 J site respectively. Standard deviations were reported. The standard deviation of the control site overlapped with the laser treated side. Statistical significance was not tested. The authors suggest that the laser treatment resulted in a larger adipocyte size due to alteration of the cell membrane that allows transport of extracellular material to the intracellular space. Ultimately, the treatment yielded adipocyte lysis or necrosis, explaining the larger diameter of the adipocyte at the 1,000 J rather than the 3,000 J site. | ||
External 635 nm low level laser | Erchonia 3LT™ Lasers (Erchonia Medical, Inc.; McKinney, TX) | Study of 12 tissue samples.9 Twelve tissue samples from 12 female subjects were exposed to the 635 nm laser for 0, 4, and 6 min with and without infusion of tumescent solution. After 4 min and tumescence or 6 min and no tumescence, adipocytes lost their round shape and fat spread to the intercellular space on scanning electron and transmission electron microscopy. After 6 min and tumescence, fat was completely removed from cells. A control portion of the sample, not exposed to laser or tumescence, was not noted to have changes in fat architecture. |
FDA approved | Report of 700 cases.10 635 nm diode laser applied to abdomen and thighs for 6 min and 10–12 min to back, sides, and axilla followed by liposuction. There was no control group and no statistical evaluation. Ninety-five percent of patients were satisfied with results. Asymmetry developed in 3% of procedures, hyperpigmentation in 0.1% of procedures, and fluid collections or seromas in 40% of patients. Two patients developed cellulitis. | |
Placebo controlled, randomized, blinded study of low level laser followed by liposuction in 72 subjects.11 635 nm 14 mW dual diode laser used to treat 36 test subjects. A sham device was used to treat 36 subjects in the placebo group. One investigator was blinded. One investigator was not blinded. Subjects treated with laser were found to have less discomfort and swelling (both statistically significant) post operatively. Investigators found that fat extraction was easier after laser (statistically significant). | ||
Three human patients and two Yucatan pigs were treated with a 635 nm 10 mW laser.12 Humans were treated with low level laser therapy. Biopsies were done to compare areas that were treated with and without low level laser. No adipocyte differences between irradiated and non irradiated sites were seen. Pigs were treated with ultrasound-assisted lipoplasty, suction lipoplasty, and low lever laser plus suction lipoplasty. Adipocytes were destroyed after ultrasound-assisted lipoplasty, but not suction lipoplasty or low level laser lipoplasty. |
Non invasive options for adipose removal are few. The best studied non invasive treatment is focused ultrasound. Selective photothermolysis of adipose tissue has been reported at 1210 and 1720 nm wavelengths and may offer another non invasive option for treatment of adipose tissue, but a clinical device is not yet available.14
A significant barrier to non invasive treatments is the issue of fat localization after treatment. Adipose tissue stores triglycerides. Unlike cholesterol, which can be excreted, triglycerides are not excreted by the body; rather, they are metabolized for energy, stored, or used for such molecules as plasma lipoproteins.15 Thus, the removal of large deposits of subcutaneous fat may yield redistribution to other sites in the body. Since increased visceral fat has been linked to increased cardiovascular disease, non invasive therapies should be approached cautiously, and their use may be limited to treatment of small deposits of fat.16
Focused Ultrasound
The Ultrashape™ System (Ultrashape Ltd, Israel), a focused ultrasound system, represents the only currently available non invasive device to destroy adipose tissue. This system delivers focused ultrasound waves at a precise depth to mechanically destroy adipose tissue and has been shown to decrease fat deposits with few side effects in one to three treatments.17 ’ 18 Eighty-five percent of the fat reduction occurs in the first 14 days, so response to treatment can be assessed rapidly.18 The procedure is quite lengthy, requiring topical anesthesia prior to treatment and a procedure time of 60–120 min.18
In a study of 30 patients, after three treatments, a statistically significant decrease of 2.3 cm in local deposits was found.17 These patients maintained constant weight during the treatment period. In a larger prospective trial of 164 subjects with 27 controls, subjects were treated once on the abdomen, thighs, or flanks.18 At 3 month follow up, a statistically significant mean reduction of 1.9 cm was reported, in the setting of weight maintenance, compared to baseline, control group, and internal control for patients treated on the thigh. Liver ultrasound at 14–28 days and serial laboratory evaluations showed no “clinically significant” treatment associated changes, with no elevations in serum lipids or lipoproteins. No systemic adverse effects were noted, and cutaneous adverse effects were rare and included a tingling sensation, erythema, purpura, and blisters. Ninety-two percent of patients reported minimal to no discomfort after 90 min of topical anesthesia.
1,064 nm Laser with and without Liposuction
The Nd:YAG laser has been used alone or in combination with suction liposuction. SmartLipo™ (Cynosure, USA), a 300 um fiber encased in a micro-cannula, is an example of this type of device. The cannula is inserted subcutaneously to destroy lipid membranes and release lipids. Adipocytes appear to swell at lower energies and lyse at higher energies.8 The laser heat also coagulates collagen fibers. This process is termed “laser lipolysis.”19 It is worth noting that the term “lipolysis” appears to be misused in this context. Strictly speaking, “lipolysis” is defined not as destruction of the adipocyte membrane, but rather as shrinkage of the fat cell due to the use of lipid for energy at the cellular level.
The Nd:YAG laser has been extensively studied, and these reports are described in Table 1.2–8 There appears to be minimal cosmetic advantage to this procedure compared with traditional liposuction, although patients may have less post operative pain with laser-assisted lipoplasty. The procedure may be helpful for the surgeon, requiring less effort, particularly in difficult to treat areas,4 but it can be more time consuming.6
An illustrative example is a prospective, double blind, controlled trial of 25 patients and 110 areas of treatment with patients serving as their own control with suction lipoplasty on one half and laser-assisted lipoplasty on the other with a 2 mm and 1,064 nm Nd:YAG laser fiber follow by suction with a 3 mm cannula.2 No clinical difference in cosmetic result was found, although postoperative pain was higher in the suction-assisted side versus the laser-assisted side at the first follow up visit only.
Without liposuction, the Nd:YAG may have a role in the removal of local deposits of fat. The use of a 1,064 nm Nd:YAG laser with a 300 um fiber encased in a 1 mm microcannula, without combining it with liposuction was studied in a randomized study of 30 female patients with focal areas of fat less than 100 cm3 on the arm, submental area, thigh, and abdomen.5 An average 17% reduction in fat volume (p < 0.01) was seen on MRI. Bruising, swelling, and tenderness were seen, and uncommonly, transient tingling, hyperpigmentation, and a subcutaneous nodule were reported. As with non invasive approaches, use of this device without liposuction may be best suited to small collections of fat.
635 nm Laser and Liposuction
Neira has combined low level 635 nm laser and liposuction in a technique labeled the “Neira 4 L technique”.10 Patients are irradiated with a low-level 635 nm laser after tumescent anesthesia. Following irradiation, removal of fat is accomplished with a cannula or other technique. Neira postulates that low level laser creates a pore in the adipocyte membrane, causing leakage of lipid into the interstitial space.20 He studied 12 patients and found that after 6 min of low level laser, fat was completely removed from the cell.9 He has reported a change in the consistency of fat with MRI evaluation.21
In contrast, another study did not find a histologic change in treated and untreated adipocytes, raising questions about the efficacy of the treatment.12 Histologic analysis of the effects of low-level laser of adipose tissue in rats found enlargement and fusion of the brown, but not yellow fatty tissue.22
Neira reported a case series of 700 patients of whom 95% were satisfied with results.10 A well designed randomized, controlled, blinded study found a statistically significant decrease in pain and swelling post operatively after treatment with low level laser.11 Investigators reported a greater ease of fat extraction after low level laser therapy, also statistically significant. Based on these studies, low level therapy may influence healing, but the histologic effects and the effect on cosmesis remain unclear.
External Ultrasound and Liposuction
External ultrasound and liposuction have been combined to remove adipose tissue.23–25 External ultrasound is theorized to relax the bonds between cells, affecting the septa, enhancing skin contraction after liposuction and allowing for the use of thin cannulas.26 Fat cells can be used for grafting.27 The typical procedure involves application of a 2–3 W/cm ultrasound device for 5–15 min.
Several studies have found external ultrasound to be beneficial,27–30 although one double blind study casts doubt on the utility of this procedure.31 In most of the studies, there appears to be a slight advantage of the ultrasound assisted approach in terms of physician fatigue (50–70% preferred the ultrasound treated side). Patients had less bruising (40–70% of patients), swelling (40–70% of patients), and discomfort (50–80% of patients) on the ultrasound treated side.28–30 The cosmetic result appears to be similar.28–30 One of the studies reported increased skin retraction of 30% on the side treated with ultrasound.29 These studies were randomized and controlled, but statistical significance was not tested. The surgeon was blinded in one of the trials.28 The number of patients in these studies ranged from 10 to 30. Adverse effects including erythema, mild warmth, burns, blisters, and seroma were reported during the procedure.24 ’ 26 ’ 27 ’ 30
A larger study of 59 patients comparing external ultrasound assisted to standard liposuction also reported that patients had less bruising and discomfort.27 A faster recovery time was reported, but patients receiving external ultrasound were given different instructions about reduction of physical activity, leading to a potential bias in recovery time. Skin shrinkage as evidenced by a smoothness of the skin was apparent on the ultrasound side at 30 days and on the standard liposuction side at 6 months; however, this smoothness was not quantitatively defined and no statistical evaluation was done.
These studies contrast with a double blinded study of 19 patients who served as their own control to evaluate external ultrasound-assisted liposuction.31 The treatment side received ultrasound at 2–3 W/cm2 for 10 min and the control side received 0.2–0.3 W/cm2. Fat was sampled in two patients. There was no difference between resistance to removal and the rate of fat removal in 14 of 19 patients. Patients assessed the treatment as well, and only 4 of 19 reported a better operative and post operative course with external ultrasound. Statistical significance was tested for physician and patient assessments, and no benefit to using external ultrasound with liposuction was found. Histologic evaluation showed no difference between the experimental and control side. Although the study was limited by the small number of patients, the double blind, controlled framework provides strong support that the use of external ultrasound may not yield significant benefit.
Internal Ultrasound and Liposuction
Liposuction in combination with internal ultrasound was pioneered by Zocchi.32 Several studies reported large series of patients treated with ultrasound assisted lipoplasty,33–37 and the purported benefits of this technology include less blood loss, less surgeon fatigue, and improved skin retraction.38 ’ 39 Ultrasound assisted liposuction has been found to be more selective for adipocyte removal; however, this selectivity may not yield superior results.34 In studies that compare standard versus ultrasound-assisted lipoplasty, the ultrasound-assisted approach has not had better cosmetic outcome.34 ’ 36 ’ 40 It may be that ultrasound-assisted lipoplasty is better for certain indications such as fibrous areas.41
A well designed study of 63 patients who received both traditional and ultrasound-assisted lipoplasty provides an example.36 Patients were blinded to the procedure in this trial. In addition to the evaluations by patient and surgeon, an independent panel evaluated ten randomly selective patients. Ultrasound-assisted lipoplasty was not found to be superior to traditional lipoplasty with no difference in sensory, pigment change, surface irregularity, skin contraction, bruising, or swelling. Similarly, a randomized, controlled study of ultrasound-assisted liposuction compared with traditional liposuction in 28 patients found no significant difference in cosmetic result and adverse effects.40 Physicians reported less fatigue.
Skin necrosis, burn, fat necrosis and fibrosis, sensory alteration, infection, lower limb edema, and seromas have been reported.33–35 ’ 40–43 Skin necrosis is a particularly concerning adverse effect. It is thought to be due to destruction of deep dermal vessels despite higher perfusion with ultrasound-assisted liposuction compared with suction liposuction.44 ’ 45 Postoperative sensory changes occur in both traditional and ultrasound-assisted liposuction; immediately after surgery, these changes may be more prominent in those patients treated with ultrasound.46 ’ 47 Surgeon experience and surgical technique may play a role in ultrasound assisted complications.33
With respect to invasive options for fat removal, internal or external ultrasound and laser assisted lipoplasty appear to offer minimal advantages over traditional lipoplasty. Nearly all blinded and controlled studies have failed to show improved cosmetic outcome with these devices. The Ultrashape™, an ultrasound based technology, is the only non invasive option currently available. Other non invasive options on the horizon may involve utilization of the 1,210 nm or 1,720 nm wavelength to destroy adipose tissue. However, it is clear that there is no panacea: non invasive removal of adipose tissue comes with an additional set of concerns and should be approached cautiously and systematically.
