Lasers in Surgery and Medicine

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Online ISSN: 1096-9101
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Article
To evaluate MR-thermometry using fast MR sequences for laser induced interstitial thermotherapy (LITT) at 0.2 and 1.5 T systems. In-vitro experiments were performed using Agarose gel mixture and lobes of porcine liver. MR-thermometry was performed by means of longitudinal relaxation time (T1) and proton resonance frequency shift (PRF) methods under acquisition of amplitude and phase shift images. Four different sequences were used for T1 thermometry: A gradient-echo (GRE), a True Fast Imaging with Steady Precession (TRUFI), a Saturation Recovery Turbo-FLASH (SRTF), and an Inversion Recovery Turbo-FLASH (IRTF) sequence (FLASH-Fast Low Angle Shot). PRF was measured with four sequences: Two fast-spoiled GRE sequences (one as WIP sequence), a Turbo-FLASH (TFL) sequence (WIP sequence), and a multiecho-TrueFISP sequence. Temperature was controlled and verified using a fiber-optic Luxtron device. The temperature was correlated with the MR measurement. All sequences showed a good linear correlation R(2) = 0.97-0.99 between the measured temperature and the MR-thermometry measurements. The only exception was the TRUFI sequence in the Agarose phantom that showed a non-linear calibration curve R(2) = 0.39-0.67. At 1.5 T, the Agarose experiments revealed similar temperature accuracies of 4-6°C for all sequences excluding TRUFI. During experiments with the liver, the PRF sequences showed better performance than the T1, with accuracies of 5-12°C, contrary to the T1 sequences at 14-18°C. The accuracy of the Siemens PRF-FLASH sequence was 5.1°C. At 0.2 T, the Agarose experiments provided the highest accuracy of 3.3°C for PRF measurement. At the liver experiments the T1 sequences SRTF and FLASH revealed the best accuracies at 6.4 and 7.0°C. The accuracy and speed of MR temperature measurements are sufficient for controlling the temperature-based tumor destruction. For 0.2 T systems SRTF and FLASH sequences are recommended. For 1.5 T systems SRTF and FLASH are the most accurate.
 
Article
Background and objectives: It is desirable to minimize peripheral thermal damage during laser irradiation, since thermal damage to collagen and mineral compromises the bond strength to restorative materials in dentin and inhibits healing and osteointegration in bone. There were two primary objectives of this study. The first objective was to measure the degree of thermal damage peripheral to incisions in dentin produced with lasers resonant to the specific absorption bands of water, collagen, and hydroxyapatite with varying pulse duration using polarized-light microscopy (PLM). The second objective was to use synchrotron radiation infrared spectromicroscopy (SR-FTIR) to identify the specific chemical nature of the optical changes observed under PLM in the respective zones of thermal damage peripheral to the laser incisions. Study design/materials and methods: Precise incisions were produced in 3 x 3 mm2 blocks of human dentin using CO2 (9.6 microm), Er:YSGG (2.79 microm), and Nd:YAG (355 nm) lasers with and without a computer controlled water-spray. Optical coherence tomography (OCT) was used to obtain optical cross-sections of each incision to determine the rate of ablation. The peripheral thermal damage zone around each incision was analyzed using PLM and SR-FTIR. Results: Thermally induced chemical changes to both mineral and the collagen matrix were observed with SR-FTIR with a 10 microm spatial resolution and those changes were correlated with optical changes observed with PLM. Minimal (<10 microm) thermal damage was observed for pulse durations less than the thermal relaxation time (Tr) of the deposited laser energy, with and without applied water at 9.6 microm and with only applied water at 2.79 microm. For pulse durations greater than Tr, greater peripheral thermal damage was observed for both IR laser wavelengths with and without the water-spray. There was minimal thermal damage for 355 nm laser pulses less than Tr with and without applied water; however, extensive mechanical damage (cracks) was observed. Conclusions: High resolution SR-FTIR is well suited for characterization of the chemical changes that occur due to thermal damage peripheral to laser incisions in proteinaceous hard tissues. Sub-microsecond pulsed IR lasers resonant with water and mineral absorption bands ablate dentin efficiently with minimal thermal damage. Similar laser parameters are expected to apply to the ablation of alveolar bone.
 
Article
To evaluate the ability of monitoring laser induced temperature changes in an open, interventional 0.5 T magnet, adopting fast T1-weighted sequences. A fast gradient echo- (FGRE) and a fast spoiled gradient echo-sequence (FSPGR), both enabling an image update every 2.5 s, were investigated for their ability to visualize laser tissue effects at 5 Watt. Laser induced temperature was fluorooptically measured and correlated with signal intensity (SI) changes depicted by magnetic resonance imaging (MRI). MRI-lesions were compared with macroscopic findings. SI changes on FGRE images appeared as early as 15 s following the onset of laser application and were significantly more pronounced than those seen on FSPGR images (p < .0001). A correlation of r = 0.94 (FGRE) and r = 0.92 (FSPGR) between temperature and SI loss was established. Owing to a steeper slope, the FGRE sequence was considered more sensitive to temperature changes. The areas of macroscopic tissue change correlated with those of SI loss, but lesion size was generally underestimated by MRI. Laser monitoring is possible with rapid image updates in a midfield (0.5 T) interventional MRI environment using fast gradient echo sequence designs.
 
Article
Background and objectives: The conventional pulsed-dye laser (wavelength 585 nm, pulse duration 0.5 milliseconds) is seen as the standard treatment for port wine stains (PWS). Using the pulsed-dye laser at wavelengths of 590, 595, and 600 nm and at varying pulse durations of 1.5-40 milliseconds is one of the newest developments in the field, the therapeutic value of which has been examined in only a few studies. Treatment of PWS with short- and long-pulse dye lasers. Comparison of two wavelengths (585 nm vs. 595 nm) and two pulse durations (0.5 milliseconds vs. 20 milliseconds). Study design/materials and methods: Fifteen patients with untreated PWS were included in a randomized prospective study with three different laser settings. Patients underwent one treatment session. The following treatment parameters were chosen at a uniform spot size of 7 mm: (1) 585 nm/0.5 milliseconds/5.5 J/cm(2), (2) 595 nm/0.5 milliseconds/5.5 J/cm(2), and (3) 595 nm/20 milliseconds/13 J/cm(2). The clearance as well as side effects was evaluated. All treatments were performed with cold air-cooling. Follow-up took place immediately, 2 days and 4 weeks after the treatment. The PWS was assigned a clearance score (CS) from 1 to 4 (1 = poor to 4 = excellent). Results: Descriptively, 585 nm/0.5 milliseconds generated the best average CS of 2.7, followed by 595 nm/20 milliseconds (2.5) and 595 nm/0.5 milliseconds (1.6)); statistically, there is no difference between the CS of 585 nm/0.5 milliseconds and 595 nm/20 milliseconds. The best lightening rates overall were achieved in purple PWS (CS = 3.5) versus red (CS = 2.5) and pink (CS = 2.0). Purple PWS responded best to 585 nm/0.5 milliseconds; red and pink PWS yielded similar results with 585 nm/0.5 milliseconds and 595 nm/20 milliseconds. The setting, 595 nm/0.5 milliseconds was clearly not as effective as the other laser settings. Purpura, pain, and crusting were most commonly reported after treatments with 585 nm/0.5 milliseconds (93%/93%/33%), closely followed by treatments at 595 nm/20 milliseconds (86%/93%/20%). The settings 595 nm/0.5 milliseconds yielded the lowest rate of adverse effects (67%/60%/0%). Hypopigmentation only occurred in one case (585 nm/0.5 milliseconds), and there were no reports of hyperpigmentation or scarring. Conclusions: With respect to treating PWS, the conventional pulsed-dye laser set to 585 nm/0.5 milliseconds yields a significantly greater clearance rate than it does at a setting of 595 nm (with the same pulse duration, fluence, and spot size), although the former also entails the highest spectrum of adverse effects. In this study, purple PWS treated at these parameters showed the best results. In dealing with pink PWS, the results were similar to those of the conventional pulsed-dye laser when the pulse duration was increased to 20 milliseconds and fluence was increased. As a rule, the clearance rate corresponded to the extent of the postoperative purpura.
 
Article
Stellate ganglion blocks are an effective but invasive treatment of upper extremity pain. Linearly polarized red and near-infrared (IR) light is promoted as a safe alternative to this procedure, but its effects are poorly established. This study was designed to assess the physiological effects of this latter approach and to quantitate its benefits in people with upper extremity pain due to Complex Regional Pain Syndrome I (CRPS I, RSD). This was a two-part study. In the first phase, six adults (ages 18-60) with normal neurological examinations underwent transcutaneous irradiation of their right stellate ganglion with linearly polarized 0.6-1.6 microm light (0.92 W, 88.3 J). Phase two consisted of a double-blinded evaluation of active and placebo radiation in 12 subjects (ages 18-72) of which 6 had upper extremity CRPS I and 6 served as "normal" controls. Skin temperature, heart rate (HR), sudomotor function, and vasomotor tone were monitored before, during, and for 30 minutes following irradiation. Analgesic and sensory effects were assessed over the same period as well as 1 and 2 weeks later. Three of six subjects with CRPS I and no control subjects experienced a sensation of warmth following active irradiation (P = 0.025). Two of the CRPS I subjects reported a >50% pain reduction. However, four noted minimal or no change and improvement did not reach statistical significance for the group as a whole. No statistically significant changes in autonomic function were noted. There were no adverse consequences. Irradiation is well tolerated. There is a suggestion in this small study that treatment is beneficial and that its benefits are not dependent on changes in sympathetic tone. Further evaluation is warranted.
 
Article
Using an optically shielded fiber optic laser catheter, the amount of gas produced when firing an argon ion laser into 0.9% saline solution or blood alone and into atheromatous aorta in either a blood or 0.9% saline medium was quantitated. Energies from 0.25 to 4 joules (J) were used at powers of 2, 5, and 8 W. We found that total volume of gas produced is small not only at equilibrium (0.3 +/- 0.1 microliter/J when firing in blood alone and also when ablating aorta in blood or saline media) but also at peak (2.5 +/- 0.2 microliters/J firing in blood alone and 1.0 +/- 0.1 microliter/J or 0.9 +/- 0.1 microliter/J when ablating aorta in saline or blood, respectively). Because these volumes are small, a clinically significant event from a gas embolus is unlikely during intravascular laser ablation of atheromatous plaque in the energy and power range studied. No gas was quantitated when firing the argon ion laser into 0.9% saline solution alone. The peak gas volume when firing in blood alone was significantly greater than that produced in the other chamber environments. This is thought to be due to increased absorption of argon laser light by hemoglobin. The gas volumes produced by lasing aorta in 0.9% saline or blood were not statistically different.
 
Article
The extent of thermal injury during laser prostatectomy is dependent on the light distribution in laser-irradiated tissue. As tissue is irradiated, the optical properties change as a function of temperature due to an alteration of molecular and cellular structure. The purpose of the present study was to determine how the exposure of both fresh and previously frozen canine prostate tissue to elevated temperatures affects the optical properties. Optical properties were measured by using a double integrating sphere spectrophotometer with an inverse adding-doubling algorithm. Measurements were made at two wavelengths (1,064 nm and 633 nm) on samples heated in a waterbath in 5 degree-10 degree increments for 10 min through a 50 degrees C temperature range. Upon coagulation, the absorption coefficient of fresh tissue decreased from the baseline measurement for both wavelengths (0.027 +/- 0.003 to 0.019 +/- 0.002 for lambda = 1,064 nm; 0.073 +/- 0.007 to 0.061 +/- 0.006 for lambda = 633 nm). However, the scattering coefficient increased sharply from the baseline measurement following coagulation (3.06 +/- 0.26 to 6.05 +/- 0.29 for lambda = 1,064 nm; 4.89 +/- 0.23 to 7.22 +/- 0.30 for lambda = 633 nm). Thermal coagulation occurred during exposure to temperatures between 60 degrees C and 70 degrees C. Data obtained in this study indicate that thermal coagulation of tissue alters the optical properties. The extent to which these changes occur was found to be dependent on wavelength and freshness of tissue. These results are significant because they suggest how thermally induced changes in the optical properties may limit the depth of light penetration in tissue thus compromising treatment.
 
Article
Laser-assisted lipolysis has been suggested to augment traditional liposculpture by improving skin laxity and providing hemostasis. Previous studies have reported improved hemostasis and smoother post-operative appearance with the 1,064 Nd:YAG laser-assisted lipolysis system. Three separate pilot studies were performed. In the first study, both arms were treated with tumescent liposculpture. One arm was randomized to treatment with a subcutaneous 1,064 nm Nd:YAG laser. The second study treated multiple sites with half of the area randomized to receive the 1,064 nm versus the 1,320 nm system followed by aspiration at equal power. The third study treated patients using a combined 1,064/1,320 nm multiplex laser system at multiple sites. The endpoint of laser treatment was determined by an external skin surface temperature of 40 degrees C. In all three studies, photographs were compared at 1 week, 1 month, and 3 months post-operatively. In the first study, no significant improvement over tumescent liposculpture alone was noted using the 10 W, 1,064 nm laser. The second study showed no difference using the 10 W, 1,320 nm versus the 10 W, 1,064 nm laser-assisted lipolysis system. Finally, the multiplex 1,064/1,320 nm system appeared to show improvement in skin laxity and fat reduction. Complications included intra-operative thermal burns in 2 of 20 patients using the multiplex system. No complications were noted using the 1,064 or 1,320 nm 10 W systems. Laser-assisted lipolysis provides an innovative way to address the problem of skin laxity and fat reduction. Clinical results increased dramatically with the combined 1,064/1,320 nm multiplex system. However, caution should be used when exceeding external skin temperatures of 40 degrees C to avoid unwanted thermal burns. Future studies comparing the end temperature and wavelengths independently may help to conclusively delineate the optimal system.
 
Article
Many current parameters to ablate vascular beds using 1,064 nm lasers are based on high-energy settings and often fail to consider vessel diameter and/or pulse width. This study attempts to define the minimal effective dosage (MED) of energy and pulse width for specific vessel diameters in an animal model. 1,064 nm Nd: YAG was used in 15 Sprague-Dawley rats. Bilateral extended dorsolateral skin flaps were elevated and vessel diameters from 0.1 to 1 mm were identified. Pulse widths (PW) in a range of 15-60 milliseconds and fluences between 70-110 J/cm2 with contact cooling at 5 degrees C (Celsius) were utilized. Results were determined clinically and histologically. Ideal pulse width and MED for each vessel diameter were determined using a 6 mm spot size. Histology showed early hemostasis and subsequent thrombosis, which are consistent with clinical findings. This model allows in vivo monitoring of vessel ablation. Optimal pulse width and MED levels versus vessel diameter determined in this animal model provide a useful algorithm that may allow for more effective treatment of vascular targets utilizing the 1,064 nm Nd:YAG laser.
 
Article
Millisecond pulsed 1,064 nm Nd:YAG lasers have been developed for the treatment of leg telangiectasias. To date there have been very few side by side comparison studies of laser versus the gold standard sclerotherapy in treating small leg veins. This study aims to compare a long pulsed Nd:YAG laser with contact cooling to sclerotherapy for treating small diameter leg telangiectasias by evaluating objective and subjective clinical effects. Fourteen patients were selected with leg telangiectasias ranging from 0.5 to 2 mm at four comparable sites. One site was treated with long pulsed Nd:YAG alone, the second received sclerotherapy alone, the third laser then sclerotherapy, and the last one sclerotherapy then laser. The patients were followed up at 3 months after the last treatment. Photographs were taken pre-operatively and at 3 months after the last session. They were used for objective and comparative analysis. Statistical analysis was performed using Friedman's test controlling for subject. Improvement was tabulated from the photographic assessment on an improvement scale from 0 (no change) to 4 (greater than 75% clearing). There were clinical improvements in the laser group than sclerotherapy without statistical significance. Side effects were minimal and included hyperpigmentation. This pilot study demonstrates that the Smartepil LS long pulse Nd:YAG 1,064 nm laser can yield results similar to sclerotherapy in the treatment of small leg telangiectasias. Combination of both methods could increase response to treatment.
 
Article
Improvements in the physical signs of photoaging can be achieved by non-invasive laser resurfacing procedures. To evaluate the effectiveness and safety of the Nd:YAG 1,064 nm and KTP 532 nm lasers for non-invasive skin rejuvenation. Subjects requesting non-invasive skin rejuvenation underwent two treatments with the 532 nm laser to one side of the face and with both lasers to the other side, followed by three treatments with the 1,064 nm laser to both sides. Skin characteristics were evaluated before, during, and up to 4 months after treatment. A >25% improvement in overall skin condition was observed for >30% of subjects at the 1 month follow-up and >40% of subjects at the 4 month follow-up. The greatest improvements were observed for visual dryness, roughness, and uneven pigmentation. No adverse events were reported. There was a trend for greater improvement in patients who received more 1,064 nm treatments but this was not statistically significant. The 532 nm KTP and 1,064 nm Nd: YAG lasers can be effectively and safely used for non-invasive skin rejuvenation.
 
Article
The long pulse 1,064-nm Nd:YAG laser is used clinically to decrease rhytid formation. The dermal level at which this change occurs has not been established. This study attempts to answer these questions using a porcine skin model. Non-randomized prospective experimental trial involving the domestic piglet treated serially with the long pulse 1,064-nm Nd:YAG laser. Collagen formation occurred at the level of the reticular dermis. After one laser treatment, a significant level of collagen formation was induced in the reticular dermis compared to controls. The greatest gain was observed after four laser treatments. Energy levels of 20, 30, 40, and 50 J/cm2 were evaluated. Although not statistically significant, 30 J/cm2 had the greatest effect on collagen formation. However, at 50 J/cm2, marked ablative changes to the epidermis were observed. The long pulse 1,064-nm Nd:YAG laser induces collagen formation in the reticular dermis in porcine skin.
 
Article
Laser-assisted lipolysis with a medium pulsed 1,064 nm Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) system has been used since FDA approval in October 2006 [1]. Since then, this technology has been advanced to include an additional wavelength (1,320 nm) and an accelerometer designed to improve efficacy and safety. (1) Evaluate the efficacy and safety of a sequentially firing 1,064 and 1,320 nm Nd:YAG laser device for lipolysis. (2) Evaluate the skin tightening effect by photographic documentation and skin measurements. (3) Assess new collagen formation by histologic and scanning electron microscopic studies. Twenty subjects with unwanted local adiposities and skin laxity were enrolled. An Nd:YAG laser with sequentially firing wavelengths of 1,064/1,320 nm was used to treat localized areas of body adiposities. Digital photographs were taken before and after treatment, blinded independent observers graded improvement utilizing a percentile evaluation scale and subjects performed self-assessments. Five of the 20 subjects had the following tests performed: (1) Placement of 4 cmx4 cm square India Ink tattoos for measurement of skin tightening, (2) histology and electron microscopy, (3) biopsies prior to the procedure, 3 days and 1 month after the procedure to determine the presence of new collagen markers. Results showed reduction in localized adiposities with no adverse events from use of this device. Independent observers found 76-100% improvement in adiposities in 85% of subjects and 51-75% improvement in 15% of subjects. Of the subset of five patients, India Ink tattoo maps demonstrated an 18% decrease in surface area indicating a significant skin tightening effect. Histology by H&E, Methylene blue stains, and electron microscopy indicated new collagen formation compared to baseline. The 1,064 nm Nd:YAG and 1,320 nm Nd:YAG sequentially firing device with an accelerometer appears to be an effective and safe treatment for localized adiposities with the additional benefit of skin tightening.
 
Article
Advancements in laser treatment of leg veins necessitate concurrent investigations in topical anesthesia to minimize treatment-related pain. To evaluate the efficacy of the S-Caine Peel for providing topical anesthesia after a 60-minute application. A randomized, double-blinded, placebo-controlled trial was performed in two centers. Sixty patients received S-Caine Peel and placebo vehicle on different treatment sites for 60 minutes prior to laser treatment of leg veins using a 1,064 nm long-pulsed Nd:YAG laser. Patients rated their level of pain using a visual analog scale. Adequacy of anesthesia and expressed pain at each site were rated by the investigator. The mean visual analog scale (VAS) was 27 mm for active sites compared to 43 mm for placebo (P < 0.001). Improved pain relief was noted for 67% of active versus 30% of placebo sites (P < 0.001). Anesthesia was judged adequate by the investigator for 55% of active compared with 12% of placebo sites (P < 0.001). The S-Caine Peel is safe and effective when applied for 60 minutes prior to laser therapy of leg veins.
 
Article
The aim was to investigate the bactericidal effect of the 1,064 nm Nd:YAG laser on Staphylococcus epidermidis. S. epidermidis was inoculated on agar plates and then exposed to pulsed laser light in three different modes: with an uninterrupted train of pulses, or with two different repeated cycles of fractionated trains of pulses. The agar temperature was measured directly after uninterrupted radiation. A bacterial growth inhibition area of 0.3 cm(2) and maximum temperature of approximately 80 degrees C was observed after uninterrupted radiation at 2,000 J cm(-2). The corresponding figures after an exposure of 5,000 J cm(-2) were 0.9 cm(2) and 100 degrees C, respectively. No bacterial inhibition was observed after exposure to repeated cycles of 20 seconds of radiation followed by 60 seconds of rest. The antimicrobial effect of the 1,064 nm Nd:YAG laser light is caused by a photothermal rather than a photochemical effect.
 
Article
Background: The use of lasers to treat atrophic scarring conditions in darker skin types presents a significant challenge to laser practitioners. Current treatment modalities, including deep dermal peels; ablative; non-ablative; and fractional laser resurfacing and surgical techniques, are limited in skin types IV through VI due to increased risks of hyper- and hypo-pigmentation. This is especially true when attempting to treat large areas of acne scarring. This study investigates the treatment of atrophic scarring with a non-ablative sub-millisecond-pulsed 1,064 nm Nd:YAG laser in darker skin types. Objective: To evaluate the safety and efficacy of a sub-millisecond 1,064 nm Nd:YAG laser for the treatment of atrophic scarring in Fitzpatrick skin types III-VI through retrospective photographic analysis. Methods: A retrospective analysis was conducted of all patients (n = 22) who received sub-millisecond Nd:YAG laser treatments for atrophic scarring over a 6-month period. Patients had Fitzpatrick skin types III-VI and were treated for the indication of atrophic scarring using the fluence of 14-16 J/cm(2) , pulse duration of 300-500 microseconds and repetition rate of 5-7 Hz. An average of six treatments was performed on each patient approximately 3 weeks apart and the mean follow-up time after the final treatment was 9 months (range of 3-10 months). Blinded photographic assessments were performed by three independent physicians using photos unlabeled for before and after and arranged in non-chronological order. Reviewers were asked to determine before and after photos and the degree of improvement in scarring, textural change, and post-inflammatory hyper-pigmentation (PIH) secondary to the acne or scarring condition. Degree of improvement was graded using a four-point scale: 0 = <25%, 1 = 25-50%, 2 = 51-75%, 3 = 76-100%. Results: Based on blinded photo assessments by three independent reviewers, clinically and statistically significant median improvement of 2 in scarring, 2.3 in texture, and 2 in pigment were observed (one-sample Wilcoxon signed rank test, P < 0.001). Reviewers were highly consistent (inter-reviewer reliability) in identification of before and after photos (kappa of 0.88). Conclusions: Preliminary data collected in this retrospective study suggest that sub-millisecond 1,064 nm Nd:YAG laser treatment is a safe and effective treatment for atrophic scarring in patients with darker skin types, delivering clinically and statistically significant results with reduced risk of pigment complications and patient discomfort.
 
Article
Basal cell carcinomas (BCCs) have supporting vasculature that serves as a target for vascular selective lasers. The objective of this study was to determine the effect of repeated treatment with a combined 585 nm pulsed dye laser (PDL) and 1,064 nm Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser on BCCs of superficial and nodular subtypes of varying diameters. Ten subjects with 13 biopsy-proven BCCs received four combined PDL and Nd:YAG at treatments 2-4 week intervals. None of the BCCs met the criteria for Mohs micrographic surgery. The tumor and 4 mm of peripheral skin were treated using standardized parameters delivered with a 7 mm spot with 10% overlap. The treated area was excised and evaluated histologically for residual tumor. The primary study endpoint was histologic clearance of tumor. The secondary study endpoint was blinded investigator assessment of clinical endpoint and adverse effects. Approximately half of all tumors showed a complete response to four combined PDL and Nd:YAG treatments (n = 7/12, 58%). When stratified by size, 75% of all tumors <1 cm in diameter (n = 6/8) showed complete response. Tumor histologic types among the complete responders included superficial and nodular BCCs. All subjects with incompletely responding BCCs were on various forms of anticoagulation, which we hypothesize, may inhibit laser-mediated thrombosis necessary for the clinical effect. Blinded investigator assessment suggests that biopsy related erythema improves with subsequent laser treatments. Combined PDL and Nd:YAG laser is an effective means of reducing tumor burden in patients with BCC and may be a promising, emerging alternative therapy. Factors influencing treatment response includes the concomitant use of anticoagulation. Further studies are needed to investigate and optimize the utility of this treatment protocol. Lasers Surg. Med. © 2013 Wiley Periodicals, Inc.
 
Article
Recently developed laser lipolysis systems have been disappointing because they require more time to remove the same amount of fat than other liposuction methods. A new Nd:YAG laser has been introduced that uses the 1,444 nm wavelength, better absorbed by fat. This study consisted of two protocols. The first protocol was an in vivo minipig model. Four 10x10 cm(2) areas were treated on the back of the first minipig. Using the same total energy and power settings (5,000 J, 8 W), both the 1,064 nm and 1,444 nm lasers were used to irradiate the two cephalic areas. The two caudal areas were irradiated with both lasers, using the maximum power settings (12 W with the 1,064 nm laser, 8 W with the 1,444 nm laser). Another minipig was administered a preoperative injection of tumescent solution and treated with the same condition. Measurements of fat volume with computed tomography and histologic exams were conducted. The second experiment involved in vitro human fat. Equal amounts of human fat, harvested by liposuction, were put into test tubes and irradiated with 1,064 nm and 1,444 nm lasers. Oil production was measured from each test tube. A marked reduction in fat volume and more oil vacuoles and giant cells in histology were identified with the 1,444 nm wavelength compared to the 1,064 nm wavelength. Human fat in the in vitro experiments also revealed more oil production following the use of the 1,444 nm laser. The 1,444 nm Nd:YAG laser showed a greater lipolytic effect compared to the 1,064 nm Nd:YAG laser in in vivo minipig and in vitro human fat experiments. To achieve a full understanding of the effects of 1,444 nm Nd:YAG laser lipolysis on the human body, in vivo experimentation will be necessary.
 
Article
Laser radiation (1,210 nm) has been previously shown to be capable of selective photothermolysis of adipose tissue in vitro when applied non-invasively. The objective of this pilot study was to evaluate the in vivo effects of this laser in human subjects. Twenty-four adult subjects were exposed non-invasively on the abdomen to a 1,210 nm laser at fluences of 70, 80, and 90 J/cm(2), with a 10 mm spot size, 5 seconds pre-cooling, and 3 seconds exposure duration delivered with parallel contact cooling. There was an impairment of the skin-cooling device during the study. Exposure and control sites were biopsied at either 1-3 days or 4-7 weeks. Tissue was processed for nitroblue tetrazolium chloride (NBTC) staining, a marker for thermal damage, and hematoxylin and eosin (H&E) staining. Laser exposures were painful, requiring local anesthesia in most subjects, but otherwise well tolerated. At 1-3 days after exposure, there was a fluence-dependent loss of NBTC staining in the fat and dermis. In 2 of 14 subjects (2 of 42 exposure sites) evaluated at 1-3 days after exposure, epidermal damage was noted within a small portion of the test site, likely due to impaired contact cooling. At 4-7 weeks, lipomembranous changes of the fat were seen in 89% of test sites and 33% of control sites. This in vivo study shows histologic evidence of laser-induced damage of fat. With further development, this might become a useful treatment for disorders involving the fat and/or lower dermis.
 
Article
The high transparency of dental enamel in the near-IR (NIR) light at 1,310-nm can be exploited for imaging dental caries without the use of ionizing radiation (X-rays). We present the results of the first in vivo imaging study in which NIR images were acquired of approximal contact surfaces. NIR imaging hand-pieces were developed and attached to a compact InGaAs focal plane array and subsequently used to acquire in vivo NIR images of 33 caries lesions on 18 test subjects. The carious lesions were discernible on bitewing radiographs, but were not visible upon clinical examination. NIR images were acquired in vivo from three directions and the majority of lesions examined were too small to require restoration, based on accepted bitewing radiograph criteria. All but one of the 33 lesions examined were successfully imaged from at least one direction. This first in vivo study of imaging at the 1,310-nm wavelength region shows that NIR imaging has great potential as a screening tool for the detection of approximal lesions without the use of ionizing radiation.
 
Article
Advantages of a new 1,318 nm Nd:YAG laser based on multiple lung metastasectomies are shown. Ninety-three percent of 328 patients with metastases (8/patient, range 1-124) had precision laser resections (lobectomy-rate reduced to 7%); this laser delivers 20 kW/cm(2) 1,318 nm power densities with 400 microm fibers, and a focussing handpiece. Absorption in water is tenfold higher. Between 1/1996 and 12/2003 in 328 patients (164 males/females, 61 years) 3,267 nodules were removed. Pathologic examination revealed 2,546 metastases (range 3-80 mm) from kidney (n = 112), colorectal (n = 91), and breast cancers (n = 35). In 85% of patients where the complete resection was achieved the 5-year survival was 41%. For remaining 15% (incomplete resection) the 5-year survival was 7%. Five-year survival for patients with 10 (and more) metastases was 28%, for patients with 20 (and more) was 26%. No 30-day mortality was observed. This new laser system facilitates any kind of parenchymal lung resection in lobe-sparing manner and in case of complete resection improves significantly the survival.
 
Energy Deposition Parameters for the Nd:YAG, Nd:YAP, and KTP Laser
Temperature profiles induced in the same test spots as above using the KTP laser (λ = 532 nm). Temperature values are scaled to radiant exposure value of H0 = 10 J/cm2.
Depth z50, up to which 50% of the absorbed laser energy was deposited at either anatomic location. Average values for each laser under consideration (see the legend) and their standard deviations (bars) are determined from three measurements performed on each test site in every volunteer.
Temperature profiles as measured in shoulder of volunteer LV upon irradiation with the Nd:YAP (solid line) and Nd:YAG laser (dashed), scaled up to reach the same epidermal temperature rise of 40°C. Note the corresponding radiant exposure values in the legend.
Article
Background and objectives: Nd:YAP laser emitting at 1,342 nm appears promising for nonablative skin rejuvenation treatment, based on favorable absorption properties of water and melanin in this part of the spectrum. A quantitative determination of energy deposition characteristics of Nd:YAP in normal human skin should enable design of a safe and effective treatment protocol for future human studies. Study design: Energy deposition profile of a prototype Nd:YAP laser was determined using pulsed photothermal radiometry. This technique involves time-resolved measurement of mid-infrared emission from a sample after pulsed laser irradiation. The laser-induced temperature depth profile is reconstructed from the radiometric transients using a custom optimization algorithm, developed and tested earlier in our group. Measurements were performed on the extremities of four healthy volunteers at low radiant exposure (2.8 J/cm(2) ). For the purpose of comparison, energy deposition characteristics of commercial Nd:YAG and KTP lasers (at 1,064 and 532 nm, respectively), were also determined at the same test sites. Results: On average, the Nd:YAP laser deposits 50% of the absorbed energy within the top 0.36 mm of skin and 90% within 0.86 mm, which is significantly shallower than the Nd:YAG laser. The ratio between the dermal versus epidermal heating is more favorable and shows a smaller inter- and intra-patient variance as compared to both Nd:YAG and KTP laser. Conclusions: Energy deposition characteristics of the 1,342 nm Nd:YAP laser are very suitable for controlled heating of the upper dermis, as required for nonablative skin rejuvenation. The risks of overheating the epidermis or subcutis should be significantly reduced in comparison with the 1,064 nm Nd:YAG laser.
 
Article
Striae distensae are dermal scars with flattening and atrophy of the epidermis. Successful treatment of these stretch marks has been disappointing. The non-ablative 1,450-nm diode laser has been shown to improve atrophic scars and may be expected to improve striae. As yet, no study has been published to document the effects of this laser on striae. Our aim is to evaluate the efficacy of the 1,450-nm diode laser in the treatment of striae rubra and striae alba in Asian patients with skin types 4-6. Striae on one half of the body in 11 patients were treated with the 1,450-nm diode laser with cryogen cooling spray with the other half serving as a control. The following parameters were used: 6 mm spot size and dynamic cooling device (DCD) for 40 milliseconds to protect the epidermis. Patients were randomly assigned to receive either 4, 8, or 12 J/cm2. A total of three treatments were given at 6-week intervals. The following sites were treated: abdomen, arms, back, buttocks, and thighs. Two patients had striae rubra and nine striae alba. Clinical photographs were taken before and after each treatment and analysis was undertaken through photographic evaluation by non-treating physicians. At 2 months after the last treatment, no patients showed any noticeable improvement in the striae on the treated side compared to baseline and to the control areas. Side effects were limited to transient erythema and postinflammatory hyperpigmentation (PIH), which occurred in seven (64%) patients. The non-ablative 1,450-nm diode laser is not useful in the treatment of striae in patients with skin types 4, 5, and 6.
 
Article
Laser treatment using a 1,450 nm diode laser has been shown to improve acne and acne scarring. Its widespread adoption in younger populations has been significantly limited by discomfort. A new double-pass protocol reduced pain, but doubled treatment time. A new laser with a fourfold larger area treatment beam was developed to decrease treatment time and improve efficacy. Thirteen subjects with active papular acne were enrolled in the study. Subjects were treated 4 times at monthly intervals using an average fluence of 7.8 J/cm(2), a 12 mm spot and an average dynamic cooling device setting of 42.2, treating the entire face with 2 laser passes. Acne counts, Allen-Smith acne grades and standardized digital photography were performed 2 months following the final treatment, and compared to pre-treatment counts and photographs. Improvement in 11 subjects completing treatment evaluated by physician observers comparing pre- and post-treatment photographs was rated as none to mild improvement in three subjects, moderate improvement in six subjects, and marked improvement in two subjects. Allen Smith acne scores decreased from 2.7 pre-treatment to 2.0 post-treatment, and lesion counts decreased from an average of 34.4 pre-treatment to 16.1, 2 months post-treatment. Pain ratings on a 1 (min) to 10 (max) scale averaged 4.9 (range 1-10). All subjects rated their skin as less oily at the follow-up period. Low-energy, double pass 1,450 nm laser treatment with a larger 12 mm-diameter spot size effectively reduces acne counts 2 months post-treatment.
 
Article
Laser treatment using a 1,450 nm diode laser has been shown to improve acne and acne scarring. Its widespread adoption in younger populations has been significantly limited by discomfort. Six subjects with active papular acne were treated in a pilot study to determine parameters for a split-face, double-pass, low-energy protocol of 1,450 nm laser treatment. Sides of the face were randomized to receive single-pass, high-energy treatment (13-14 J/cm(2)), or double-pass, low energy treatment (8-11 J/cm(2)), for a total of four treatments delivered at monthly intervals. Acne counts and standardized, digital photograph were performed 2 months following the final treatment, and compared to pre-treatment counts and photographs. Improvement was evaluated comparing pre- and post-treatment photos and averaged 2.5 for the high-energy, single-pass side and 2.3 for the low-energy, double-pass side, using a 0 (worse) to 4 (max improvement) scale. Acne counts were reduced 78% on the high-energy, single-pass side and 67% on the low-energy, double-pass side. Pain ratings on a 1 (min) to 10 (max) scale averaged 5.6 (range 1-9) for the high-energy, single-pass side and 1.3 (range 1-2) for the low-energy, double-pass side. Low-energy, double-pass 1,450 nm laser treatment effectively reduces acne counts 2 months post-treatment, and dramatically reduces the pain associated with treatment. The treatment parameters used in this study have eliminated the need for anesthetic cream in daily practice.
 
Article
A laser with a wavelength in the mid-IR range targeting the depth in skin where sebaceous glands are located in combination with cryogen spray cooling was evaluated for treatment of acne. In this non-ablative treatment, the laser energy heats the dermal volume encompassing sebaceous glands whereas the cold cryogen spray preserves the epidermis from thermal damage. Monte Carlo simulations and heat transfer calculations were performed to optimize the heating and cooling parameters. A variety of heating and cooling parameters were tested in an in vivo rabbit ear study to evaluate the histological effect of the device on sebaceous glands and skin. Similar experiments were performed on ex vivo human skin. A clinical study for the treatment of acne on backs of human males was also conducted. Monte Carlo simulations and heat transfer calculations resulted in a thermal damage profile that showed epidermal preservation and peak damage in the upper dermis where sebaceous glands are located. Ex vivo human skin histology confirmed the damage profile qualitatively. In vivo rabbit ear histology studies indicated short-term thermal alteration of sebaceous glands with epidermal preservation. In the human clinical study on the back, a statistically significant reduction in lesion count on the treated side compared to the control side was seen (p < 0.001). Side effects were transient and few. The studies reported here demonstrate the feasibility of treating acne using a photothermal approach with a mid-IR laser and cryogen cooling.
 
Article
The 1,450-nm Smoothbeam Laser is a diode laser equipped with a cryogen cooling spray. Primary objectives were to evaluate the effects of this non-ablative laser on Apligraf (bioengineered skin-substitute) and to document its use as a model for non-ablative procedures. We also measured the effects of laser fluence levels on collagen and elastin expression. Three sheets of Apligraf were used for this study. Each received six separate laser applications at 4J, 6J, 8J, 10 J, 12J, and 14J. The sheets were then incubated with 10% CO(2) at 37 degrees C and samples were collected and analyzed 3 days later, using RT-PCR and immunofluorescent staining. Collagen III expressions significantly increased in both mRNA and protein levels at approximately 12 J. There appears to be a threshold effect where there is very little increased collagen III mRNA and protein expression until the laser fluence reaches around 12J.
 
Article
Nonablative resurfacing has proven its efficacy in vascular and pigmented lesions, while its capacity of substantial wrinkle reduction is still discussed controversially. We present the treatment results of a 1,450 nm diode laser for facial rhytides. Thirty facial regions were treated with a 1,450 nm diode laser. Pre- and post treatment pictures were compared by the treating physician and two blinded observers. Even if mild improvement was rated in up to 35% of the post treatment pictures, a discrepancy shows up in the assessments of the three observers, presenting almost no congruency in the rating of improvement. Our study failed to provide convincing data on the efficacy of nonablative treatment of rhytides with the 1,450 nm diode laser. In this respect, we challenge objective judgment in the assessment of subtle changes in nonablative wrinkle reduction.
 
Article
Over the last several years, several light-based systems have been employed for the treatment of acne vulgaris. The 1,450-nm diode laser has been shown to improve acne, and this has been suggested to be due to effects on sebaceous glands. However, an effect on sebum production has not been demonstrated. The objective of this study was to evaluate if the 1,450-nm diode laser indeed reduces sebum production. Eight patients with a history of acne were recruited and treated with the 1,450-nm diode laser on the right side of the nose over a 6-week period, for a total of three treatments. Sebum production was quantified using the Sebutape method. The number of sebum-producing follicles was reduced by 8.5 and 16.7% at weeks 4 and 6, respectively (P<0.05). A significant reduction in total collected sebum (-18%) was observed at week 6. This data suggests that the clinical effectiveness of the 1,450-nm diode laser may be based, at least in part, on its effects on sebaceous glands, with subsequent reduction in sebum production.
 
Article
The 585-nm pulsed-dye laser and the 1,450-nm diode laser have been found effective for the treatment of mild-to-moderate inflammatory facial acne. This study was designed to evaluate the efficacy and safety of the combined treatment with the 595-nm pulsed-dye laser and the 1,450-nm diode laser for inflammatory facial acne. Fifteen patients with inflammatory facial acne were treated with a combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser. Patients' subjective response to treatment was evaluated regarding improvement in acne, acne scarring, oiliness, and redness of the skin. All patients had reductions in acne lesion counts. Mean lesion counts decreased 52% (P < 0.01), 63% (P < 0.01), and 84% (P < 0.01) after one, two, and three treatments, respectively. Patients described moderate-to-marked improvement in acne, acne scarring, and post-inflammatory erythema. Adverse effects were limited to mild, transient erythema. The combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser is safe and effective for the treatment of inflammatory facial acne, acne scarring, and post-inflammatory erythema.
 
Article
The need for reduction of post-tonsillectomy hemorrhage has led to promotion of tonsillotomy techniques for tonsil tissue reduction in obstructive tonsillar hypertrophy. This trial compares ablative tissue effects using 1,470 nm diode laser and carbon dioxide laser for tonsillotomy in an intraindividual design. 21 children aged 3-13 years (mean age 6.3 years) underwent laser tonsillotomy for obstructive tonsillar hypertrophy in this double blind, prospective, randomized, clinical feasibility trial. In each of the blinded patients, tonsillotomy was performed using fiber guided 1,470 nm diode laser (contact mode, 15 W power) on the one side and carbon dioxide laser (12 W power) on the other side. An independent, blinded physician documented clinical presentation and patients' symptoms preoperatively and on Days 1, 3, 7, 14, and 21 post-operatively using standardized questionnaire including VAS for each side separately. The mean duration of operative treatment was 2.7 min using 1,470 nm laser and 4.9 min using carbon dioxide laser respectively. Intraoperative bleeding and the frequency of bipolar forceps use for intraoperative bleeding control was significantly less using 1,470 nm diode laser system. There was no difference in post-operative pain scores between the carbon dioxide laser treated and the 1,470 nm fiber guided diode laser treated side. No infections, hemorrhages or other complications occurred in the course of the 3 weeks post-operative period. A fiber-guided 1,470 nm diode laser system offers an efficient and safe method for tonsillotomy as treatment of obstructive tonsillar hypertrophy. Compared to our standard practice (carbon dioxide laser), 1,470 nm laser application provides comparable tissue ablation effects with less intraoperative bleeding and shorter operation time.
 
Article
Various laser systems have been used for volume reduction of hyperplastic nasal turbinates. For endonasal application, fiber controlled diode lasers are preferred over conventional laser systems for reasons of cost and practicability. This study compares coagulative tissue effects using λ = 1,470 nm and λ = 940 nm lasers in treatment of hyperplastic inferior nasal turbinates in an intraindividual manner. Twenty patients underwent laser coagulation for hyperplastic inferior nasal turbinates in this prospective, randomized, double-blind, clinical feasibility trial. In each case, one nasal cavity was treated using 1,470 nm laser (4-5 W power), the other one with 940 nm laser (12 W power), endoscopically controlled in noncontact mode. Clinical presentation and patients symptoms were documented preoperatively and on day 1, 3, 7, 14, and 21 postoperatively using rhinomanometry, standardized questionnaires including SNOT 20 GAV (German adapted version), and separate endoscopic examination, respectively. No infections, hemorrhages, or other complications occurred intra- or postoperatively. The mean operation time was significantly shorter using the 1,470 nm diode laser as compared to the 940 nm laser. There was a significant reduction of nasal obstruction on day 21 postoperatively compared to the preoperative condition on both sides regardless of the laser system used. Evaluation of the SNOT-Scores as assessed before and 3 weeks after surgery showed significant subjective improvements. 1,470 nm diode laser system offers an efficient method for tissue reduction in hyperplasia of inferior nasal turbinate. Compared with our standard practice (940 nm diode laser), 1,470 nm diode laser application provides an equivalent tissue reduction in shorter operation time using less total energy and a comparable relief of nasal obstruction postoperatively.
 
Article
Scarring is a major source of morbidity in patients with burns. Burn scars are difficult to treat and are among the worst scars seen in clinical medicine. Fractional laser resurfacing is a promising treatment option because of its unique wound healing response and depth of penetration. To evaluate the efficacy of nonablative fractional resurfacing as a therapeutic option for extensive cutaneous scarring in burn patients. Prospective, single-arm, pilot study. Ten subjects with second and third degree burn scars were treated with five nonablative fractional resurfacing treatments given at 4-week intervals. Three independent investigators evaluated subject outcomes at 3 months post-treatment (primary outcome); patients also provided subjective assessments of improvement (secondary outcome). Nonablative fractional resurfacing resulted in overall improvement in 90% of subjects, as determined by independent investigators; improvements were moderate to excellent in 60%. Ninety percent of subjects had improved skin texture, 80% had improved dyschromia, and 80% had improved hypertrophy/atrophy. Patients' self-reports also revealed moderate to excellent improvements (on average) in burn scar area, and significant improvements in self-esteem at 3 months post-treatment (P = 0.03). Small sample size and lack of control group. Fractional resurfacing is a promising new treatment modality for burn scars. We should continue to identify novel approaches and management strategies for the spectrum of diverse burn scars so that we can better treat this patient population.
 
Article
There are a wide variety of fractional resurfacing devices that are available and it is important to understand the tissue effect of different devices at different parameters to ensure a well-controlled treatment. Thus, we have chosen to characterize and compare two different fractional laser devices, the Fraxel SR750 and SR1500 (re:store) (Solta Medical, Hayward, CA). While the SR750 has a fixed focus spot diameter, the SR1500 features an internally controlled zoom optic allowing for an adjustable spot size. Exposures were performed in vitro on human skin samples at 37 degrees C. The exposures were performed for the SR750 at pulse energies between 6 and 40 mJ at 125 MTZ/cm(2) with up to 20 passes, and for the SR1500 between 6 and 100 mJ, at Treatment Level 7 and 8 passes. The skin samples then were processed for serial frozen sectioning, stained with Nitro-Blue-Tetrazolium-Chloride (NBTC) and lesion depth and width was determined. Mean lesion depth was significantly greater for lesions treated with the SR1500 laser compared to the SR750 at pulse energies of 6, 10, 30, and 40 mJ (P<0.001) with a borderline difference at 20 mJ. Mean lesion width was comparable for energies up to 20 mJ and relatively increased for the SR1500 for higher energies. The depth-to-width ratio (DWR) was in general higher for the SR1500, reaching significance at 6, 10, and 40 mJ. We have characterized the lesion depth and width for the for two different Fractional Photothermolysis devices (SR750 vs. SR1500). The device with the adjustable spot size (SR1500 or Fraxel re:store) provides generally deeper lesions at the same energy level. It remains to be shown whether increased lesion depth improves efficacy for certain clinical applications.
 
Article
Fractional technology has changed the dermatologists view in how to treat acne scars in ethnic skin as a result of its favorable safety profile. To evaluate the safety and efficacy of non-ablative fractional (NAF) 1,550 nm and ablative fractional (AF) CO(2) Lasers in the treatment of acne scars in ethnic skin. In this retrospective analysis patients with acne scars who were treated with NAF 1,550 nm or AF CO(2) lasers from January 2008 until July 2009 were included. Evaluation was made through comparing pre- and post-photographs and physician global assessment. Patients' satisfaction rate was also recorded. Assessment of improvement was based on a quartile grading scale. Bleaching creams and oral antibiotics were routinely given after each session. Adverse effects were recorded. Follow up visits were scheduled at weeks 1 and 4 of each session and 12 weeks post-last session. A total of 82 patients were recruited in the study. Forty-five patients treated with NAF 1,550 nm laser and 37 patients with AF CO(2) laser. Skin phototype was mainly type IV (III-V). An overall patient satisfaction was 71% for NAF 1,550 nm laser group and 65% for AF CO(2) laser group. Thirty-five percent and 37% of patients attained more than 50% improvement with NAF 1,550 nm and AF CO(2) lasers, respectively. Patients treated with NAF 1,550 nm laser had less down time. Transient post-inflammatory hyperpigmentation (PIH) was noted in 17% of patients treated with NAF 1,550 nm laser compared to 14% with AF CO(2) . Both NAF 1,550 nm and AF CO(2) lasers are effective in treating acne scars in ethnic skin with good patient satisfaction rate and high safety profile. PIH decreased with routine use of prophylactic bleaching creams. Fractional laser resurfacing open a wide horizon for treating acne scars in ethnic skin.
 
Article
Wavelengths near ∼1,720 nm are of interest for targeting fat/lipid-rich tissues due to the high absorption coefficient of human fat and low water scattering and absorption. In this study, a 1,708 nm laser was built and shown to selectively target fat/lipid adjacent to porcine heart and dermis and then used to damage dermal sebaceous glands in human skin. STUDY DESIGN AND MATERIALS: An all-fiber 1,708 nm laser with ∼4 W maximum power was designed and built. Selectivity for targeting fat/lipid was studied by exposing porcine heart and skin tissue cross-sections to the 1,708 nm laser. Human skin treatments to damage sebaceous glands were performed both with and without cold window cooling. Histochemical evaluation on the frozen sections was performed using methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. Histochemical analysis of porcine tissue cross-sections showed that 1,708 nm laser can selectively damage pericardial fat(heart) and subcutaneous fat(skin) with little to no damage to the myocardium and the dermis, respectively. In human skin, histochemical evaluation without contact cooling showed damage to both epidermis and dermis. With cooling, epidermis was spared and damage was observed in dermis extending ∼0.4-1.65 mm from the skin surface at an average laser fluence of ∼80 J/cm(2). Selective damage of sebaceous glands was suggested but not definitively demonstrated. We have developed an all-fiber 1,708 nm laser capable of damaging majority of the sebaceous glands in the dermis and thus may have potential applications in the treatment of conditions such as acne vulgaris whose pathophysiology involves disorders of sebaceous glands.
 
Article
We are currently working with a novel class of photoactivated 4-amino substituted 1,8-naphthalimide compounds for tissue bonding. With promising results in other tissues, we are pursuing potential vascular applications. This study focused on determining the appropriate compound formulation(s), concentration, and exposure times to optimize penetration of the heterogeneous arterial wall. Segments of atheromatous rabbit carotid artery were immersed in hydrophilic or lipophilic forms of the compound, then frozen, cryosectioned, and examined by confocal microscopy. The hydrophilic compound exhibited preferential localization within the intima and media and limited presence in the adventitia. Conversely, the lipophilic compound concentrated in the intima and adventitia with virtual exclusion from the media. Exposure to both forms resulted in complete penetration of the arterial wall. These results extend our knowledge and permit a more practical approach to potential vascular applications using these photoactivated compounds for tissue bonding.
 
Article
The holmium:YAG laser is currently the most common laser lithotripter. However, recent experimental studies have demonstrated that the thulium fiber laser is also capable of vaporizing urinary stones. The high-temperature water absorption coefficient for the thulium wavelength (mu(a) = 160 cm(-1) at lambda = 1,908 nm) is significantly higher than for the holmium wavelength (mu(a) = 28 cm(-1) at lambda = 2,120 nm). We hypothesize that this should translate into more efficient laser lithotripsy using the thulium fiber laser. This study directly compares stone vaporization rates for holmium and thulium fiber lasers. Holmium laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 microseconds pulse duration was delivered through a 100-microm-core silica fiber to human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Thulium fiber laser radiation pulsed at 10 Hz with 70 mJ pulse energy and 1-millisecond pulse duration was also delivered through a 100-microm fiber for the same sets of 10 stones each. For the same number of pulses and total energy (126 J) delivered to each stone, the mass loss averaged 2.4+/-0.6 mg (UA) and 0.7+/-0.2 mg (COM) for the holmium laser and 12.6+/-2.5 mg (UA) and 6.8+/-1.7 (COM) for the thulium fiber laser. UA and COM stone vaporization rates for the thulium fiber laser averaged 5-10 times higher than for the holmium laser at 70 mJ pulse energies. With further development, the thulium fiber laser may represent an alternative to the conventional holmium laser for more efficient laser lithotripsy.
 
Article
Melasma is a common acquired symmetrical hyperpigmentation that is often recurrent and refractory. To investigate the efficacy and safety of a single administration of high-density fractional thulium fiber laser (1,927 nm) for the treatment of refractory melasma in 20 patients. A retrospective chart and photographs review of 20 women (Fitzpatrick skin type II–IV) with clinical diagnosis of melasma treated with the 1,927-nm fractionated thulium laser at 10 or 20 mJ/cm2, with 60–70% surface area coverage. Four investigators independently evaluated Melasma Area Severity Index (MASI) scores before, 4 weeks, 3–6 months, and 6–12 months after treatment. Mean MASI scores decreased dramatically from 13.2 ± 5.4 before treatment to 8.5 ± 3.5 at 4 weeks after laser treatment (P = 0.004). Patient assessment revealed that 12 of the 20 subjects had more than 50% clearance of their melasma. Recurrence was reported by 7 out of 15 patients who were successfully followed-up (mean 10.2 months). Two patients developed postinflammatory hyperpigmentation that subsided with topical bleaching after 3 months. High-density coverage fractional 1,927-nm thulium laser proved to be safe and effective for melasma with long-term remission. Lasers Surg. Med. 45: 95–101, 2013.
 
Article
The beneficial deep homogeneous coagulation of neodymium (Nd):YAG laser radiation at 1.06 microns owing to low absorption and high scattering in tissue has been documented widely. For another Nd:YAG laser wavelength at 1.32 microns the absorption coefficient of water and saline is approximately ten times higher than at 1.06 microns. This results in more efficient energy conversion into heat in tissue at 1.32 microns. The extinction coefficient in blood at 1.32 microns is only one-third of that at 1.06 microns. We would expect this to result in less heat dissipation by blood and deeper penetration in tissue at 1.32 microns. Nevertheless, at this wavelength scattering also contributes to an effective, uniform distribution of the laser light in the tissue. Animal experiments have been done to examine the effect of wavelength, irradiation time, and beam geometry on tissue damage and to assess its possible clinical uses. The results imply that the 1.32 microns wavelength will produce further indications for the use of the Nd:YAG laser in surgery.
 
Article
Although laser angioplasty has been demonstrated to be effective for the treatment of long, complex coronary arterial atherosclerotic stenoses, there is an associated risk of acute arterial spasm, dissection, and perforation as well as a significant restenosis rate. It has been postulated that the use of lasers emitting at wavelengths designed for radiation absorption by water would decrease local tissue trauma. We have examined the use of a Nd:YAG laser designed to emit at 1.44 microns, an absorption peak for water, and compared the results of laser ablation at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths. Nd:YAG laser angioplasty was performed in the abdominal aorta of White Leghorn roosters. Acute and chronic vascular trauma was assessed by contrast angiography and histological analysis. There was a significant decrease in early mortality with 1.44 microns laser ablation. This decreased mortality after 1.44 microns ablation was associated with a decrease in vascular spasm, perforation, and thermal damage. Atherosclerotic plaque development at follow up was decreased with 1.44 microns ablation but this was not significant. 1.44 microns laser ablation decreases early vascular trauma and mortality and may decrease subsequent atherosclerotic plaque development.
 
Article
Evaluation of the efficacy, on 1–2 mm blue leg telangiectasia, of a 1,064 nm Nd:YAG laser emitting in a non uniform pulse sequence calculated to consider Met-Hb formation during laser irradiation of a blood vessel. A 1,064 nm Nd:YAG laser (Quantel Medical, Athos, France) was used in a non uniform pulse sequence mode, fluences: 300–360 J/cm2 spot: 2 mm, + 5°C contact cooling. The clinical evaluation was performed on 11 female patients, average age: 43 (25–57) years, phototype I–VI. All subjects were previously examined with Doppler ultrasound. A treatment site (6 × 4 cm) was selected on each patient. The topography of the vessels network was reported on a tracing plastic frame before each session and 6 weeks after the last one. These frames were digitized and the number of vessels was determined using the Digitized Tracing Frames Technique. Side effects were noted before and after every treatment, and 6 weeks after the last one. This study lasted for 10 months. Patients tolerated the procedure without anesthesia. Moderate pain, transient erythema and edema, one hyperpigmentation and one matting were noted. There was no hypopigmentation. 55% (P < 0.002) vessels clearance after one session, 86% after two sessions (P < 0.001), and 98% (P < 0.001) after three sessions were obtained. On two patients, the treatment was completed after two sessions with a full clearance. Data reported in this study were obtained thanks to a computerized calculation of vessels clearance. They are similar or superior to those reported in the literature about 1,064 nm Nd:YAG lasers and leg telangiectasia. Since, it was developed to consider the modification of blood absorption and the methemoglobin formation which leads to an increase of the 1.06 μm wavelength absorption, the non uniform pulse mode emphasizes the efficacy of this 1,064 nm Nd:YAG laser concerning the treatment of blue leg veins telangiectasia between 1 and 2 mm. This mode gives the possibility to deliver high energy while preserving the surrounding tissue and leads to a rapid vessel clearance with reduced pain and few side effects when compared to previously published clinical studies using a 1.06 μm laser. Lasers Surg. Med. 32:160–170, 2003.
 
Tested Combinations of the Varied Parameters
Article
Histological effects of 2.1-micron Ho:YAG and 1.06-micron Nd:YAG laser pulses were compared in the rat brain, with special regard to areas remote from the irradiated site. Laser pulses were delivered through a 0.6-mm glass fiber, the tip of which was either introduced into the caudate nucleus (application mode I), or held at a 2-mm distance above the exposed intact dura. In the latter case, the space between the dura and the fiber tip was filled either with physiological saline (application mode II) or with air (application mode III). In application modes I and II, but not in application mode III, Ho:YAG laser pulses of 1.5 J and 200 microseconds, but not Nd:YAG laser pulses with the same parameters, immediately caused morphological damage to a considerable number of neurons and axons randomly distributed among apparently normal ones in certain areas remote from the irradiated site. A decrease in the energy and an increase in the length of the pulses lowered the incidence of the remote morphological damage. This novel finding may impose limits on the application of Ho:YAG lasers in human endoscopic neurosurgery.
 
Article
The thermal effect of 1.06 microns YAG:Nd laser irradiation at temperature conditions up to 100 degrees C without crater formation on gastrointestinal (GI) tissue samples was investigated. The theoretical and experimental data show that at an intensity of 160-400 W/cm2 laser-induced heating of the tissue with an initial temperature of 20 degrees C leads to coagulation lesions at a temperature no less than 60 degrees C and at a depth of 1.7-2.1 mm.
 
Article
Previous investigations have shown good clinical potential for the use of the 1.32 microns wavelength Nd:YAG laser because its soft tissue absorption is better than that of the 1.06 microns wavelength Nd:YAG laser. The 1.32 microns wavelength Nd:YAG laser has an absorption coefficient in water that is 10 times higher than the 1.06 microns wavelength Nd:YAG laser. A comparative in vivo study of laser soft tissue effects was performed by using the 1.32 microns wavelength and the 1.06 microns wavelength Nd:YAG lasers in a pulsed wave (PW) mode and continuous wave (CW) mode using a non-contact endoscopic delivery system. A standard 5 mm mucosal lesion was made in the canine tracheobronchial tree down to the level of the perichondrium. Soft tissue and cartilage effects were examined by light and scanning electron microscopy, acutely, 1 week and 2 weeks after operation, and a comparison was made between the different laser modalities. To create similar lesions, higher energy was required when using the 1.06 microns wavelength Nd:YAG laser. Soft tissue injury was greater with the 1.06 microns wavelength in CW mode, and no cartilage damage occurred in the PW mode. Soft tissue and cartilage repair after 1 and 2 weeks was better with the 1.32 microns wavelength laser. In comparison, the CO2 laser and the contact Nd:YAG laser proved to be more precise cutting tools than the 1.32 microns wavelength or the 1.06 microns wavelength Nd:YAG lasers. Both Nd:YAG laser wavelengths were useful for coagulation and vaporization of tissues and blood vessels. More studies are needed to determine the effect of the new 1.32 microns wavelengths on endotracheal tumors.
 
Article
Light in the visible and near-infrared region is diffusely scattered in tissues by macromolecules. It was therefore hypothesized that tissue coagulation caused by high-power continuous wave laser irradiation might significantly alter tissue optical properties, resulting in a redistribution of laser energy during the laser ablation process. Infrared transmittance studies confirmed the hypothesis by demonstrating an irreversible decrease in light transmittance (45%) during heating of a 0.75 mm thick slice of tissue. Absorption and scattering coefficients were then determined from transmittance and reflectance measurements on thin slices of raw and coagulated myocardium irradiated with a Nd:YAG laser (1.06 microns). The scattering coefficient was found to increase fourfold (0.427 mm-1----1.74 mm-1) during tissue coagulation, while the absorption coefficient remained relatively unchanged (0.044 mm-1----0.051 mm-1). Calculations indicate that the coagulation-induced changes in tissue optical properties substantially increase surface back-scattering and reduce tissue penetration.
 
Article
A comparison is made of laser anastomoses of the murine vas deferens at different energies with the neodymium (Nd):YAG laser at 1.06 micron and 1.318 micron and with the CO2 laser. A total of 28 welds were performed with a free-hand technique employing a 600-micron silicon fiber with the Nd:YAG and a hand piece with a 500-micron spot size for the CO2. After 6 weeks, all animals were sacrificed and the vasa evaluated for patency. Fifteen out of 28 controls repaired with microsurgical techniques were found to be patent; 4/10 vasa were patent with use of the Nd:YAG at 1.318 micron at laser energies of 300 mW and 500 mW. At 1.06 micron, only 1/4 anastomoses was patent at a power setting of 1 W. None of the anastomoses performed with the CO2 laser was patent. Histologic study revealed intense fibrosis in all the lasered vasa, with sperm granuloma formation associated with most anastomoses. Although this is a preliminary study, it appears that the Nd:YAG laser at 1.318 micron and a power setting of 300-500 mW provides patency rates superior to the Nd:YAG at 1.06 micron and to the CO2 lasers and is equivalent to standard micro-surgical techniques in the murine vas deferens.
 
Article
Laser-assisted microvascular anastomoses can be performed with the most diverse types of laser (Dujovny et al: 4th Annu Gen Sci Meet LANSI, 1986; Godlewski et al: World J Surg 10:329-333, 1986; Gomes et al: Rev Hosp Clin Fac Med Sao Paulo 37:255, 1982; Quigley et al: Laser Surg Med 5:357-367, 1985; Quigley et al: Lancet 1:334, 1985; Quigley et al: Neurosurgery 18(3):292-299, 1986; Jain: J Microsurg 1:436-439, 1980; Jain: Lancet 2:816-817, 1984; Krueger and Almquist: Lasers Surg Med 5:55, 1985; Neblett et al: Neurosurgery 19(6):914-934, 1986; Schober et al: Science 232:1421-1422, 1986; Ulrich et al: 2nd Annu Gen Sci Meet LANSI, 1984; Ulrich and Bock: Optoelectronics in Medicine, Spring-Verlag 418-423, 1986). However, postoperative complications in the form of thromboses and aneurysmatic sacs could be detected in 7-29.8% in longitudinal investigations. By conversion of the beam geometry (1.3 micron Nd:YAG laser, 200 micron light conductor) and use of three concentrically applied 10.0 backstitch sutures in 25 end-to-end anastomoses of the common carotid artery of adult albino rats 0.8-1.2 mm in diameter, early and late complications could be markedly reduced (12%).
 
Article
Photothermal heating of mechanically deformed cartilage accelerates stress relaxation and results in sustained shape change. In this study, shape retention was measured in Nd:YAG laser reshaped porcine septal cartilage. Specimens were laser reshaped either 4 (Group I) or 28 hours (Group II) following extraction from the crania. Specimens were bent into approximately semicircular shapes and irradiated half way between the endpoints of the semicircle. Resultant bend angle was calculated based on linear measurements. Shape retention was calculated by comparing resultant curvature with pre-irradiation measurements. Mechanical deformation alone resulted in initial bend angles varying from 188 degrees to 229 degrees. Resultant bend angles varied from 84 degrees to 194 degrees corresponding to shape retention varying from 58 to 75%. Non-irradiated cartilage retained less than 46% of the original bend. Shape retention was greater in Group II, compared to Group I. In Group I, no cephalocranial difference in shape retention was observed, though in Group II greater shape retention was observed in rostral specimens. While laser heating does significantly reshape cartilage, clinical use of this technology will require "overbending" of the cartilage graft to compensate for this memory effect. The degree of overbending is likely to vary with cartilage type and location.
 
Top-cited authors
Michael Hamblin
  • University of Johannesburg
Rox Anderson
  • Harvard Medical School
Roy G Geronemus
  • New York University
Martin JC van Gemert
  • University of Amsterdam
Merete Haedersdal
  • University of Copenhagen Bispebjerg Hospital Denmark