The Experts below are selected from a list of 1935 Experts worldwide ranked by ideXlab platform
Raimund Hibst - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Erbium:YAG Laser ablation in cutaneous surgery.
Lasers in surgery and medicine, 1996Co-Authors: Roland Kaufmann, Raimund HibstAbstract:Background and Objective Among the various pulsed midinfrared-Lasers studied in skin surgery the 2.94 μm Erbium: YAG Laser has been shown to combine most efficacious ablation with least thermal damage due to its unique absorption characteristics in tissue water. A newly developed high-power Erbium: YAG laboratory Laser providing output energies (up to 1.5 J/pulse) and repetition rates (up to 15 Hz) appropriate for clinical use enabled us to investigate its potential indications in dermatological surgery. Study Design/Materials and Methods Erbium: YAG Laser ablation was performed in vitro on pig skin and in vivo on a total of 30 patients presenting with different skin disorders. Results In vitro ablation efficiency linearly increased with radiant exposure and was inversely correlated with pulse frequency. Ablation rate at 10 Jcm-2 (used clinically) measured from ˜10 μm (at 10 Hz) to 40 μm (at 1 Hz). Also for high repetition rates thermal necrosis did not exceed 50μm, corresponding clinically to capillary bleeding after exposure of the dermis. Superficial lesions, such as epidermal nevi, were easily ablated and re-epithelization was unimpaired owing to the absence of tissue necrosis. In tattoos, exposed pigment particles were precisely removed. However, in deeper lesions the casual onset of bleeding impeded the procedure and scar formation was observed after reepithelization. Conclusion Pulsed 2.94 μm Erbium:YAG Laser surgery allows an extremely precise etching of delicate superficial skin lesions and also should have a potential for skin resurfacing. © 1996 Wiley-Liss, Inc.
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cutting and skin ablative properties of pulsed mid infrared Laser surgery
The Journal of Dermatologic Surgery and Oncology, 1994Co-Authors: Roland Kaufmann, Anke Hartmann, Raimund HibstAbstract:background. Pulsed mid-infrared Lasers allow a precise removal of soft tissues with only minimal thermal damage. objective. To study the potential dermatosurgical usefulness of currently available systems at different wavelengths (2010-nm Thulium: YAG Laser, 2100-nm Holmium: YAG Laser, 2790-nm Erbium:YSGG Laser, and 2940-nm Erbium: YAG Laser) in vivo on pig skin. methods. Immediate effects and wound healing of superficial Laser-abrasions and incisions were compared with those of identical control lesions produced by dermabrasion, scalpel incisions, or Laser surgery performed by a 1060-nm Nd: YAG and a 1060-nm CO2 Laser (continuous and super-pulsed mode). results. Best efficiency and least thermal injury was found for the pulsed Erbium: YAG Laser, leading to ablative and incisional lesions comparable to those obtained by dermabrasion or superficial scalpel incisions, respectively. conclusion. In contrast to other mid-infrared Lasers tested, the 2940-nm Erbium: YAG Laser thus provides a potential instrument for future applications in skin surgery, especially when aiming at a careful ablative removal of delicate superficial lesions with maximum sparing of adjacent tissue structures. However, in the purely incisional application mode pulsed mid-infrared Lasers, though of potential usefulness in microsurgical indications (eg, surgery of the cornea), do not offer a suggestive alternative to simple scalpel surgery of the skin.
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mechanical effects of Erbium YAG Laser bone ablation
Lasers in Surgery and Medicine, 1992Co-Authors: Raimund HibstAbstract:When intending to use pulsed Erbium:YAG Laser radiation for the ablation of small bones, e.g., the ossicular chain or footplate, not only temperature and thermal damage, but also mechanical side effects become important. In studies on desiccated bone the total recoil momentum caused by Laser ablation was measured using a sensitive pendulum. The momentum depends linearly on the radiant energy of the Laser pulse with a slope of 10−4 kg m s−1/J. The temporal course of the recoil force during ablation observed by means of a piezoelectric transducer is nearly proportional to the Laser pulse intensity. By evaluating recoil momentum and mass loss data, the average initial velocity of the plume was calculated to be 230 to 280 m s−1. The kinetic energy is approximately 1% of the input energy. The measurements support to the hypothesis of a thermally induced explosive process. © 1992 Wiley-Liss, Inc.
Hisham Shokeir - One of the best experts on this subject based on the ideXlab platform.
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Topical 5 fluorouracil cream vs combined 5 fluorouracil and fractional Erbium YAG Laser for treatment of severe hypertrophic scars.
Clinical cosmetic and investigational dermatology, 2019Co-Authors: Abeer Attia Tawfik, Maha Fathy, Ashraf Badawi, Noha Abdallah, Hisham ShokeirAbstract:Background Topical 5 fluorouracil (5-FU) has been reported as one of the standard treatments for hypertrophic scars (HTS). Ablative fractional Laser was found to have promising results in the delivery of topical drugs into the skin by creating vertical channels through which the drugs can penetrate the skin. So far there have been no comparative studies performed to compare both modalities in the same patient and same anatomical region, especially in severe HTS. Objective The aim of this study was to compare the effectiveness of topical 5-FU and combined topical 5-FU and Laser in treating severe HTS. Patients and methods Twenty-four severe HTS lesions were treated by 5-FU monotherapy and 5-FU combined with ablative fractional Erbium YAG Laser. Each lesion was divided into two parts. One part was treated with topical 5-FU twice weekly for 8 months. The other part was treated with combined topical 5-FU and ablative fractional Erbium YAG Laser once per month for 8 months. The scars' improvement was evaluated by Vancouver scar scale (VSS) and skin analysis camera. Results The assessment by VSS showed a significant reduction in the mean height, pliability, and vascularity of the lesions which were treated with combined approaches compared to 5-FU monotherapy. Pain and ulceration occurred at a higher rate in the combination therapy group. Conclusion Treatment of severe HTS with combined 5-FU and ablative fractional Erbium YAG Laser is more effective than 5-FU alone.
Roland Kaufmann - One of the best experts on this subject based on the ideXlab platform.
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Grafting of in vitro cultured melanocytes onto Laser-ablated lesions in vitiligo.
Acta dermato-venereologica, 1998Co-Authors: Roland Kaufmann, D Greiner, S Kippenberger, A BerndAbstract:A variety of grafting procedures using autologous melanocytes have achieved promising results in the treatment of vitiligo. We here report on the preparation of an adequate graft recipient bed by pulsed Erbium-YAG Laser skin ablation. In particular, for irregular lesions on delicate sites, which cannot be approached by utilization of suction blisters or dermabrasion, this technique may offer a distinct advantage.
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Pulsed Erbium:YAG Laser ablation in cutaneous surgery.
Lasers in surgery and medicine, 1996Co-Authors: Roland Kaufmann, Raimund HibstAbstract:Background and Objective Among the various pulsed midinfrared-Lasers studied in skin surgery the 2.94 μm Erbium: YAG Laser has been shown to combine most efficacious ablation with least thermal damage due to its unique absorption characteristics in tissue water. A newly developed high-power Erbium: YAG laboratory Laser providing output energies (up to 1.5 J/pulse) and repetition rates (up to 15 Hz) appropriate for clinical use enabled us to investigate its potential indications in dermatological surgery. Study Design/Materials and Methods Erbium: YAG Laser ablation was performed in vitro on pig skin and in vivo on a total of 30 patients presenting with different skin disorders. Results In vitro ablation efficiency linearly increased with radiant exposure and was inversely correlated with pulse frequency. Ablation rate at 10 Jcm-2 (used clinically) measured from ˜10 μm (at 10 Hz) to 40 μm (at 1 Hz). Also for high repetition rates thermal necrosis did not exceed 50μm, corresponding clinically to capillary bleeding after exposure of the dermis. Superficial lesions, such as epidermal nevi, were easily ablated and re-epithelization was unimpaired owing to the absence of tissue necrosis. In tattoos, exposed pigment particles were precisely removed. However, in deeper lesions the casual onset of bleeding impeded the procedure and scar formation was observed after reepithelization. Conclusion Pulsed 2.94 μm Erbium:YAG Laser surgery allows an extremely precise etching of delicate superficial skin lesions and also should have a potential for skin resurfacing. © 1996 Wiley-Liss, Inc.
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cutting and skin ablative properties of pulsed mid infrared Laser surgery
The Journal of Dermatologic Surgery and Oncology, 1994Co-Authors: Roland Kaufmann, Anke Hartmann, Raimund HibstAbstract:background. Pulsed mid-infrared Lasers allow a precise removal of soft tissues with only minimal thermal damage. objective. To study the potential dermatosurgical usefulness of currently available systems at different wavelengths (2010-nm Thulium: YAG Laser, 2100-nm Holmium: YAG Laser, 2790-nm Erbium:YSGG Laser, and 2940-nm Erbium: YAG Laser) in vivo on pig skin. methods. Immediate effects and wound healing of superficial Laser-abrasions and incisions were compared with those of identical control lesions produced by dermabrasion, scalpel incisions, or Laser surgery performed by a 1060-nm Nd: YAG and a 1060-nm CO2 Laser (continuous and super-pulsed mode). results. Best efficiency and least thermal injury was found for the pulsed Erbium: YAG Laser, leading to ablative and incisional lesions comparable to those obtained by dermabrasion or superficial scalpel incisions, respectively. conclusion. In contrast to other mid-infrared Lasers tested, the 2940-nm Erbium: YAG Laser thus provides a potential instrument for future applications in skin surgery, especially when aiming at a careful ablative removal of delicate superficial lesions with maximum sparing of adjacent tissue structures. However, in the purely incisional application mode pulsed mid-infrared Lasers, though of potential usefulness in microsurgical indications (eg, surgery of the cornea), do not offer a suggestive alternative to simple scalpel surgery of the skin.
Abeer Attia Tawfik - One of the best experts on this subject based on the ideXlab platform.
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A Split Face Comparative Study between Intradermal Tranexamic Acid and Erbium-YAG Laser in Treatment of Melasma
The Journal of dermatological treatment, 2020Co-Authors: Sarah Otb, Eman Shaarawy, Ahmad Sadek, Noha Abdulla, Naglaa Agamia, Mona M. Soliman, Abeer Attia TawfikAbstract:Background: Although there are different treatment modalities of melasma, it remains a challenging problem. Erbium-YAG Laser proved its efficacy in melasma improvement with minimal downtime. Tranexamic Acid is a new promising treatment of melasmaObjective: the first objective is to compare between the efficacy of intradermal injection of Tranexamic acid (TA) and Erbium-YAG Laser in the treatment of melasma. The second objective is to use the dermoscope as an objective evaluation method.Patients and methods: A split face study was conducted on 28 patients. One side of the face received intradermal Tranexamic acid injection. The other side was treated with Laser. MASI (Melasma Area and Severity Index) and the dermoscope were used for evaluation of treatment.Results: The MASI scores showed a significant decrease in tranexamic acid treated side. The dermoscope assessment showed no significant difference in both treatment modalities.Conclusion: A promising results were obtained by both intradermal TA and Erbium: YAG Laser, however the TA yields a higher patient satisfaction because of its high efficiency and low cost.
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Topical 5 fluorouracil cream vs combined 5 fluorouracil and fractional Erbium YAG Laser for treatment of severe hypertrophic scars.
Clinical cosmetic and investigational dermatology, 2019Co-Authors: Abeer Attia Tawfik, Maha Fathy, Ashraf Badawi, Noha Abdallah, Hisham ShokeirAbstract:Background Topical 5 fluorouracil (5-FU) has been reported as one of the standard treatments for hypertrophic scars (HTS). Ablative fractional Laser was found to have promising results in the delivery of topical drugs into the skin by creating vertical channels through which the drugs can penetrate the skin. So far there have been no comparative studies performed to compare both modalities in the same patient and same anatomical region, especially in severe HTS. Objective The aim of this study was to compare the effectiveness of topical 5-FU and combined topical 5-FU and Laser in treating severe HTS. Patients and methods Twenty-four severe HTS lesions were treated by 5-FU monotherapy and 5-FU combined with ablative fractional Erbium YAG Laser. Each lesion was divided into two parts. One part was treated with topical 5-FU twice weekly for 8 months. The other part was treated with combined topical 5-FU and ablative fractional Erbium YAG Laser once per month for 8 months. The scars' improvement was evaluated by Vancouver scar scale (VSS) and skin analysis camera. Results The assessment by VSS showed a significant reduction in the mean height, pliability, and vascularity of the lesions which were treated with combined approaches compared to 5-FU monotherapy. Pain and ulceration occurred at a higher rate in the combination therapy group. Conclusion Treatment of severe HTS with combined 5-FU and ablative fractional Erbium YAG Laser is more effective than 5-FU alone.
Ashley J. Welch - One of the best experts on this subject based on the ideXlab platform.
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Erbium: YAG Laser Lithotripsy Mechanism
The Journal of urology, 2002Co-Authors: Kin F. Chan, Joel M. H. Teichman, Gracie Vargas, H. Stan Mcguff, Ho Lee, Angela D. Kamerer, Ashley J. WelchAbstract:Purpose: We tested the hypothesis that the mechanism of long pulse Erbium:YAG Laser lithotripsy is photothermal.Materials and Methods: Human urinary calculi were placed in deionized water and irradiated with Erbium:YAG Laser energy delivered through a sapphire optical fiber. Erbium:YAG bubble dynamics were visualized with Schlieren flash photography and correlated to acoustic emissions measured by a polyvinylidene fluoride needle hydrophone. The sapphire fiber was placed either parallel or perpendicular to the calculus surface to assess the contribution of acoustic transients to fragmentation. Stones were irradiated using desiccated stone irradiated in air, hydrated stone irradiated in air and hydrated stone irradiated in water. Ablation crater sizes were compared. Uric acid stones were irradiated in water and the water was assayed for cyanide.Results: During the early phase of vapor bubble expansion, acoustic transients had minimal effects on calculus fragmentation. Fragmentation occurred due to direct a...
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In vitro Erbium: YAG Laser lithotripsy
Laser-Tissue Interaction XI: Photochemical Photothermal and Photomechanical, 2000Co-Authors: Kin F. Chan, Joel M. H. Teichman, Randolph D. Glickman, Gracie Vargas, Patricia J. Parker, H. Stan Mcguff, Ashley J. WelchAbstract:The potential application of an Erbium:YAG (Er:YAG) Laser (Q 0 = 50 mJ/pulse; τ p = 275 μs; rep. rate = 2, 10 Hz) with a sapphire delivery fiber for intracorporeal Laser lithotripsy was explored. Preliminary measurements on calculus mass-loss and fragmentation efficiency were conducted and results were compared with that of Ho:YAG Laser lithotripsy. Laser induced bubble and lithotripsy dynamics were investigated to assess the mechanism(s) involved in the fragmentation process. Results showed that the fragmentation efficiency (mass-loss/H o - g.μm 2 /J) in Er:YAG Laser lithotripsy was about 2.4 times that of Ho:YAG Laser lithotripsy (used: Q 0 = 500 mJ/pulse; Tp = 250 μs; rep. rate = 10 Hz). Acoustic transients were found to have minimal effect during Er:YAG Laser lithotripsy. Schlieren flash images suggested a predominantly photothermal mechanism due to direct Laser energy absorption, which resulted in recrystallization and plume formation. These events indicated melting and chemical decomposition of the calculus composition. Another observation led to the possibility of a plasma-mediated photothermal mechanism. The 'Moses effect' facilitating pulsed mid-infrared Laser delivery appeared more efficient for the Er:YAG Laser than for the Ho:YAG Laser. With the sapphire fiber, experimental results suggested the potential of an improved treatment modality by the Er:YAG Laser for intracorporeal Laser lithotripsy.