Lasers in Surgery and Medicine
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Fractional Photothermolysis: A New Concept for Cutaneous Remodeling Using Microscopic Patterns of Thermal InjuryAbstract Background and Objectives We introduce and clinically examine a new concept of skin treatment called fractional photothermolysis (FP), achieved by applying an array of microscopic treatment zones (MTZ) of thermal injury to the skin. Study Design/Materials and Methods Two prototype devices emitting at 1.5 μm wavelength provided a pattern of micro‐exposures with variable MTZ density. Effects of different MTZ densities were tested on the forearms of 15 subjects. Clinical effects and histology were assessed up to 3 months after exposure. Treatment of photoaged skin on the periorbital area in an additional 30 subjects receiving four treatments over a period of 2–3 weeks was also tested. Tissue shrinkage and clinical effects were assessed up to 3 months after treatment. Results Pattern densities with spacing of 250 μm or more were well tolerated. Typical MTZ had a diameter of 100 μm and penetrated 300 μm into the skin. Reepithelialization was complete within 1 day. Clinical effects were assessed over a 3‐month period. Histology at 3 months revealed enhanced undulating rete ridges and increased mucin deposition within the superficial dermis. Periorbital treatments were well tolerated with minimal erythema and edema. Linear shrinkage of 2.1% was measured 3 months after the last treatment. The wrinkle score improved 18% (P <0.001) 3 months after the last treatment. Conclusions FP is a new concept for skin restoration treatment. Safety and efficacy were demonstrated with a prototype device. Further clinical studies are necessary to refine the optimum parameters and to explore further dermatological applications. Lasers Surg. Med. 34:426–438, 2004. © 2004 Wiley‐Liss, Inc.
Lasers in Surgery and Medicine - Tập 34 Số 5 - Trang 426-438 - 2004
Laser smoke effect on the bronchial systemAbstract The photoresection of endobronchial tumors produces smoke which is partly inhaled by the patient as well as the surgical staff. In an animal study we investigated whether a single exposure or repetitive exposures to smoke might have harmful side effects on the airways. Eleven sheep were exposed to smoke produced by laser‐vaporizing (6,500 J) sections of bronchial tissue (1 cm3 ) in a Plexiglas chamber. The smoke analysis revealed 0.92 mg/liter particles with a mean particle size of 0.54 μm. Carbon monoxide content was estimated as 0.04%. We measured the effects of one or three separate ten‐minute exposures on airway resistance, gas exchange, and mucociliary clearance rate in the trachea. We found that the smoke inhalation resulted in a decrease of arterial PO2 with relatively little change in airway mechanics. Tracheal mucus velocity, a marker of lung mucociliary clearance, was significantly depressed in a dose‐dependent manner with increasing smoke exposures. Results of bronchoalveolar lavages performed before and one day after the exposure showed that the smoke inhalation induced a severe inflammation with dramatic increases of inflammatory cells. The total number of cells per milliliter increases from 3.2 million to 25 million; percent neutrophils increased from 2.3 to 45.6% and percent macrophages decreased from 86 to 41%. These findings indicate that the side effects of smoke inhalation during intrabronchial laser surgery should not be neglected. The impairment of the defense mechanism of the lung combined with the inflammation as well as hypoxia might be fatal in compromised patients. Effective smoke removal devices should be developed to protect the patients as well as the surgeon.
Lasers in Surgery and Medicine - Tập 7 Số 3 - Trang 283-288 - 1987
Influence of Nd:YAG laser power density and coaxial CO2 on the gastric wallAbstract A detailed understanding is required of the effect of Nd: YAG power density and coaxial CO2 on tissue necrosis in both the acute and healing situation. Lesions were produced by varying peak powers at eight increments of 10 W from 40–110 W/sec for a time duration of 1 sec with and without coaxial CO2 on the rabbit (n=16) stomach. Surface areas and careful histological examinations were performed at 2 hr and 4 days. In further experiments, a total incident energy of 60 or 120 J with varying peak powers from 30‐120 W/sec were applied at a 1‐cm distance. The lesion surface area at 1 cm was 21.7 mm2 compared to 12 mm2 when the fiber tip was held 2 cm away (p < 0.05). Coaxial CO2 at 1 cm reduced the surface area to 10 mm2 (p < 0.001). There was a positive correlation between surface areas and the incidental power (r = 0.86, p < 0.01). There was no significant difference in the mean surface area of lesions at 2 hr compared to those at 4 days, nor was there a correlation between the increasing peak powers with the constant incident energy. Histological features were those of coagulative necrosis (81 %)‐with minimal ulceration (1.6%) at 2 hr with ulceration increasing to 22% at 4 days. These results have helped in planning a safe and effective Nd:YAG photocoagulation study in patients in order to obtain maximum hemostasis with minimal tissue injury.
Lasers in Surgery and Medicine - Tập 4 Số 3 - Trang 247-259 - 1984
physics of surgical lasersAbstract The fundamental physical properties of lasers are discussed. Included in this presentation is a discussion of carbon dioxide, argon, neodymium:YAG and ruby lasers. Laser optics and beam characteristics as well as Q‐switching are presented. Ocular hazards of lasers and preventive measures are discussed.
Lasers in Surgery and Medicine - Tập 1 Số 1 - Trang 5-14 - 1980
The power density of a surgical laser beam: Its meaning and measurementAbstract This paper discusses the fundamental concepts of matter, energy, power, and power density, with specific emphasis on the power density of a laser. It points out that a laser beam does not have a single, unique value of diameter within which all of its radiation is confined. Therefore, a computation of power density requires both a value of diameter, and the value of the fraction of total power which is transmitted within that diameter. Some possible means of measuring diameter, power, and power density are presented.
Lasers in Surgery and Medicine - Tập 2 Số 4 - Trang 301-315 - 1983
Initiation of apoptosis and autophagy by photodynamic therapyAbstract Background and Objectives This study was designed to examine modes of cell death after photodynamic therapy (PDT). Study Design Murine leukemia L1210 cells and human prostate Bax‐deficient DU145 cells were examined after PDT‐induced photodamage to the endoplasmic reticulum (ER). Phase contrast, fluorescence and electron microscopy were used to identify changes in cellular morphology, chromatin condensation, loss of mitochondrial membrane potential, and formation of phagolysosomes. Western blots were used to assess the processing of LC3‐I to LC3‐II, a marker for autophagy. Inhibitors of apoptosis and/or autophagy were used to delineate the contributions of the two pathways to the effects of PDT. Results Both apoptosis and autophagy occurred in L1210 after ER photodamage with the latter predominating after 24 hours. In DU145 cells, PDT conditions causing comparable cytotoxicity only initiated autophagy. PI3‐kinase inhibitors suppressed autophagy in both cell lines as indicated by inhibition of vacuolization and LC3 processing. Conclusions Both autophagy and apoptosis were observed in L1210 cells following ER photodamage. In the Bax‐deficient DU145 cell line only autophagy was observed. Current information suggests that autophagy can function as either a survival or death pathway. We propose that in the context of PDT, this may also be true. Lasers Surg. Med. © 2006 Wiley‐Liss, Inc.
Lasers in Surgery and Medicine - Tập 38 Số 5 - Trang 482-488 - 2006
Cell biology of hematoporphyrin derivative (hpd)Abstract Tissue culture cells were treated with hematoporphyrin derivative (HPD) and analyzed for (1) HPD uptake, (2) HPD washout, and (3) fluorescence changes. The absorption peaks were the same for HPD in solution and HPD bound to cells. HPD was taken up by all cell types rapidly within the first 10 hours of exposure, and leveled off by 20 hours of exposure. HPD came out of all cell types to control levels by 72 hours after removal of the HPD bathing solution. The HPD appeared to come out of the malignant 3‐T‐12 cells more slowly than from the parental (non‐malignant) 3‐T‐3 cells. The fluorescence spectrum of HPD‐treated cells changed markedly from the time that the bathing HPD solution was removed from the cells. As time progressed the weakly fluorescent 590‐nm peak increased greatly and the 615‐nm and 630‐nm peaks decreased significantly.
Lasers in Surgery and Medicine - Tập 2 Số 3 - Trang 261-266 - 1983
Possible hazards from irradiation with the carbon dioxide laserAbstract Previous investigators, using relatively high irradiance levels, have been unable to demonstrate viable tissue in the plume during carbon dioxide laser vaporization. Our study was undertaken to reinvestigate this possibility, particularly at the lower irradiance levels that are currently in clinical use. Fresh post‐mortem skin was injected with a known quantity of bacterial spores and vaporized at different levels of irradiance and energy fluence. The plume and splatter were collected and cultured. Spores were found following the vaporization of five of 13 specimens treated at an irradiance of <500 W/cm2 , while there were none in the 20 specimens treated at an irradiance of >997 W/cm2 . These results show that the widely accepted assumption that the carbon dioxide laser produces a sterile field may be false and that viable particles may be disseminated during vaporization at low irradiance. This may be important when considering the treatment of potentially infectious lesions.
Lasers in Surgery and Medicine - Tập 6 Số 1 - Trang 84-86 - 1986
MR‐guided laser‐induced thermal therapy (LITT) for recurrent glioblastomasAbstract Background and objective Laser‐induced thermal therapy (LITT), coupled with magnetic resonance thermal imaging (MRTI) guidance, provides a minimally invasive and safe approach to treat brain tumors, especially metastases. We report here our experience using this treatment for recurrent glioblastomas. Materials and Methods Four patients, from 40 to 58 years old, were diagnosed with glioblastoma. After total resection, chemotherapy and radiation therapy, recurrence occurred. As each was ineligible for a second surgery, LITT was proposed as salvage therapy. Under stereotactic guidance, a fiberoptic applicator was inserted within the tumor LITT was performed under continuous MRTI. Real‐time feedback control based on MRTI was employed to assess the quality of local tissue destruction and to prevent unwanted damage to nearby structures. Results The procedure was well tolerated with no peroperative neurological deterioration. In the short‐term follow‐up, one transient supplementary motor area syndrome, one epileptic seizure, and one cerebrospinal fluid leakage occurred. All were successfully managed. Post‐procedure MRI showed no complication, satisfying treatment volume, and a decrease in size of the treated tumor. For all patients, recurrence was observed with a mean/median progression free survival of 37/30 days. Mean/median overall survival after LITT was 10.5/10 months. Conclusion Focal tumor control was performed safely using minimally invasive LITT with real‐time MRTI control. LITT could be considered as salvage therapy for high‐grade recurrent gliomas if a 1‐day treatment is considered useful for a few weeks gain in survival. Larger experience will be required to define indications for such infiltrative disease and accurately determine a potentially significant survival gain in good neurological condition associated with this 1‐day procedure. Lasers Surg. Med. 44: 361–368, 2012. © 2012 Wiley Periodicals, Inc.
Lasers in Surgery and Medicine - Tập 44 Số 5 - Trang 361-368 - 2012
Laser thermal therapy: Real‐time MRI‐guided and computer‐controlled procedures for metastatic brain tumorsAbstract Background and Objective We report the final results of a pilot clinical trial exploring the safety and feasibility of real‐time magnetic resonance‐guided laser‐induced thermal therapy (MRgLITT) for treatment of resistant focal metastatic intracranial tumors. Study Design In patients with chemotherapy, whole‐brain radiation, and radiosurgery resistant metastatic intracranial tumors, minimally invasive stereotaxic placement of a saline‐cooled interstitial fiberoptic laser applicator under local anesthesia was followed by laser irradiation during continuous magnetic resonance imaging (MRI) scanning. A computer workstation extracted real‐time temperature‐sensitive information for feedback control over laser delivery. A total of 15 metastatic tumors were treated in 7 patients. Patients were followed with physical exam and imaging for 30 months. Results In all cases, the procedure was well tolerated, and patients were discharged home within 24 hours. Follow‐up imaging at up to 30 months showed an acute increase in apparent lesion volume followed by a gradual and steady decrease. No tumor recurrence within thermal ablation zones was noted. Kaplan–Meier analysis indicated that the median survival was 19.8 months. Conclusion Real‐time magnetic resonance (MR) guidance of laser‐induced thermal therapy (LITT) offers a high level of control. This tool therefore enables a minimally invasive option for destruction and treatment of resistant focal metastatic intracranial tumors. MR‐guided LITT appears to provide a safe and potentially effective treatment for recurrent focal metastatic brain disease. A larger phase II and III series would be of interest to quantify potential median survival advantage. Lasers Surg. Med. 43:943–950, 2011. © 2011 Wiley Periodicals, Inc.
Lasers in Surgery and Medicine - Tập 43 Số 10 - Trang 943-950 - 2011
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