A device independent method for skin color visualization has been developed. Colors reconstructed from a reflectance spectrum are presented on a computer screen by sRGB (standard Red Green Blue) color coordinates. The colors are presented as adjacent patches surrounded by a medium grey border. CIELAB color coordinates and CIE (International Commission on Illumination) color difference (Delta) E are computed. The change in skin color due to a change in average blood content or scattering properties in dermis is investigated. This is done by analytical simulations based on the diffusion approximation. It is found that an 11% change in average blood content and a 15% change in scattering properties will give a visible color change. A supposed visibility limit for (Delta) E is given. This value is based on experimental testing and the known properties of the human visual system. This limit value can be used as a tool to determine when to terminate laser treatment of port- wine stain due to low treatment response, i.e. low (Delta) E between treatments. The visualization method presented seems promising for medical applications as port-wine stain diagnostics. The method gives good possibilities for electronic transfer of data between clinics because it is device independent.

A novel laser system has been developed to study the effects of multiple laser pulses of differing wavelengths on cutaneous blood vessels in vivo, using the hamster dorsal skin flap preparation. The system permits sequenced irradiation with well-defined intrapulse spacing at 532 nm, using a long pulse frequency doubled Nd:YAG laser, and at 1064 nm, using a long pulse Nd:YAG laser. Using this system, we have identified a parameter space where two pulses of different wavelengths act in a synergistic manner to effect permanent vessel damage at radiant exposures where the two pulses individually have little or no effect. Using a two- color pump-probe technique in vitro, we have identified a phenomenon we call green-light-induced infrared absorption (GLIIRA), where a pulse of green light causes photochemical and photothermal modifications to the chemical constituents of blood and results in enhanced infrared absorption. We identify a new chemical species, met-hemoglobin, not normally present in healthy human blood but formed during laser photocoagulation which we believe is implicated in the enhanced IR absorption.

To improve the effectiveness of microsurgical techniques, we have developed a semi-autonomous robotic surgical tool (called the 'Smart Scalpel') as an alternative approach to the treatment of vascular lesions. The Smart Scalpel employs optical reflectance spectroscopy and computer vision to identify and selectively target blood vessels with a focused treatment laser. Since the laser only heats along the diseased blood vessels, collateral damage to adjacent healthy tissue is substantially minimized. The Smart Scalpel also employs rapid real-time feedback analysis for on-line modification of the treatment parameters, quantification of treatment efficacy and compensation for motion tremor. These capabilities allow precise control over the energy dosimetry to achieve optimal treatment result. This paper presents the design of a prototype instrument, methods of the image analysis, and preliminary results with animal models.

We have used resonance Raman scattering as a novel non- invasive optical technology to measure carotenoid antioxidants in human skin of healthy volunteers. Using blue-green laser excitation, clearly distinguishable carotenoid Raman spectra are obtained which are superimposed on a large skin autofluorescence background. The Raman spectra are obtained rapidly, i.e. within about 30 seconds, and the required laser light exposure levels are well within safety standards. Our technique can be used for rapid screening of carotenoid antioxidant levels in large populations and may have applications for assessing the risk for cutaneous diseases.

Photothermal injury to the sebaceous glands is a potential curative treatment for the common skin disease acne vulgaris. Accumulation of the exogenous chromophore indocyanine green in the sebaceous glands may be accomplished using an emulsion or liposomal formulation applied to the skin surface. An emulsion containing 0.09% by weight indocyanine green (ICG) was applied to the epidermis of hamster ears ex vivo and the flank organ in vivo. Fluorescence microscopy demonstrated selective accumulation of ICG in the underlying sebaceous glands. The concentration of ICG that may be expected to accumulate in sebaceous glands of humans was then estimated on the basis of the gland size and orifice area, for the case of topical application of a more concentrated 1% ICG liposomal formulation. Monte Carlo modeling and heat transfer calculations showed that the sebaceous glands containing the exogenous chromophore may be selectively damaged by pulsed 810 nm laser radiation in conjunction with cryogen spray cooling.

Treatment of pigmented lesions in skin with visible or near- infrared nanosecond (ns) laser pulses often causes significant collateral tissue damage because the current approach uses pulses with energy of 300 mJ or larger. Additionally, this requires large Q-switched laser systems. To overcome these disadvantages, we have investigated a different approach in delivering ns laser pulses for cutaneous lesion treatment. Tattoo removal in an animal model with a focused laser beam from a Q-switched Nd:YAG laser has been investigated in two Yucatan micropigs tattooed with blue, black, green and red pigments. The tattoos were treated with a focused beam of 12-ns pulses at 1064 nm, with different depth under the skin surface, while the micropig was translated to achieve an effect of single pulse per ablation site in the skin. With the pulse energy reduced to a range from 38 to 63 mJ, we found that nearly complete clearance was achieved for blue and black tattoos while clearance of red and green tattoos was incomplete. Analysis of the skin appearance suggested that the pulse energy can be decreased to below 20 mJ which may lead to further reduction of the collateral tissue damage and improve the clearance of red and green tattoos.

Propionibacterium. acnes is a Gram positive, microaerophilic bacterium which takes a part in the pathogenesis of inflammatory acne. P. acnes is capable to produce high amounts endogenic porphyrins with no need of any trigger molecules. Light in the violet-blue range (407-420 nm) has been shown to exhibit a phototoxic effect on Propionibacterium acnes when irradiated in vitro. The purpose of our study was to test the clinical effects of a high intensity narrowband blue light source on papulo pustular acne. A total of 35 patients in 3 centers were treated twice a week with a high intensity metal halide lamp illuminating the entire face (20x20 cm2) or the back with visible light in the 407-420 nm range at an intensity of 90 mW/cm² (CureLight Ltd.) for a total of 4 weeks. UV is totally cut off. In each treatment the patient was exposed to light for 8-15 minutes. After 8 treatments, 80% of the patients with mild to moderate papulo-pustular acne showed significant improvement at reducing the numbers of non- inflammatory, inflammatory and total facial lesions. Inflammatory lesion count decrease by a mean of 68%. No side effects to the treatment were noticed. In conclusion, full face or back illumination with the high intensity pure blue light we used exhibits a rapid significant decrease in acne lesions counts in 8 biweekly treatments.

The main goal of this study was to demonstrate the feasibility of using backside infrared imaging to estimate the spatial cryogen temperature distribution during a cryogen spurt. Calculations from numerical models showed that the frontside temperature distribution could be identified at the back side of a thin aluminum sheet. Infrared images were obtained at various timepoints during a cryogen spurt from the back side of an 800-micrometers aluminum sheet and the temperature distribution estimated. The temperature distribution was approximately gaussian in shape. A secondary goal was to calculate the temperature distribution in skin for two cases: 1) uniform cryogen temperature distribution, essentially representative of a 1D geometry assumption; and 2) nonuniform distribution. At the end of a 100-ms spurt, calculations showed that, for the two cases, large discrepancies in temperatures at the surface and at a 60-micrometers depth were found at radii greater than 2.5 mm. These results suggest that it is necessary to consider spatial cryogen temperature gradients during cryogen spray cooling of tissue.

Cryogen spray cooling (CSC) is a technique to protect the epidermis from non-specific thermal injury during laser treatment of various dermatoses. Successful application of CSC in conjunction with laser treatment of heavily pigmented individuals, and high radiant exposures which may be required for effective therapeutic outcomes, requires enhancement of heat removal. We have investigated the thermal mechanisms, and effects of droplet size, density and velocity on heat removal during CSC. Our results suggest that although the inherent thermal diffusivity of skin may be a limiting factor in heat removal, parameters such as droplet size, density, and velocity are important, and should be optimized for maximum heat removal.

In conventional aesthetic rhinoplasty operations, manual or powered rasps are used to reduce the osseo-cartilagenous nasal dorsum. This tactile method requires palpation of the instrument and the dorsum during surgery to estimate the degree of volume reduction, and often requires forceful manipulation of the dorsum which may illicit pain during surgery and contribute to post-operative edema and echymosis. In this preliminary study, we investigated the use of the Erbium:YAG laser ((lambda) equals294 micrometers ) to reduce bone and cartilage using ex-vivo porcine nasal dorsum and human cadaveric tissues. The short pulsed length and high absorption of this laser in biologic tissues results in minimization of thermal injury which are ideal for non- contact optical contouring of osseous and cartilagenous tissues in the face. Two Erbium:YAG lasers were used to ablate fresh porcine nasal bone and compared for their use. One Erbium:YAG laser, the Fidelis Laser, Fontana Medical Lasers, Ljubljana, Slovenija with variable pulse repetition rates (2 to 50 Hz), pulse energy (80 to 1000 mJ), and pulse duration (100, 300, 750 and 1000 microsecond(s) ) was used and compared to the Ultrafine Erbium:YAG laser, Coherent Inc., Santa Clara California, with variable pulse repetition rate (2 to 10 Hz), pulse energy (2-16 J/cm²), and spot diameter (2-6 mm). Only laser parameters approximating the conditions for thermal confinement were evaluated.

This article deals with further development of laser drug delivery methods. In order to estimate the effect of laser- drug interactions, we carried out the chromatographic fractionation of dexamethasone, hydrocortisone, and gentamicine, both prior to and after irradiating them by pulsed Er:YAG laser radiation. The laser radiation parameters were as follows: the wavelength, pulse energy, and pulse duration were, respectively, 2.94 micrometers , 0.7 J, and 100 microsecond(s) . The total laser radiation dose administered to a 100 (mu) l sample of these drug preparations amounted to 150 J. A chromatographic analysis revealed that drug samples exposed to Er:YAG laser radiation did not show any change. The results obtained made it possible to employ pulsed Er:YAG laser radiation to perform laser-acoustic injection of the above-mentioned drug preparations to study the treatment of staphylococcal lesions in 30 guinea pigs. The perforated channel depth was measured and the injected drug solution volume was calculated. It was found that laser injection enabled one to introduce therapeutic doses of drugs, and that it expedited the healing of lesions by 3 to 4 days, as compared to the control group that received the topical application of drugs without laser irradiation.

A new combined photoultrasonic (CPUS) technology for the treatment of infected wounds is suggested. The CPUS principal operation is based on the topical application of a photosensitizer followed by light irradiation in combination with low frequency ultrasonic (US) treatment of wounds. In CPUS, two methods - photodynamic (PDT) and ultrasonic therapies supplement each other beneficially and in conjunction provide a significant effect of deep suppurative inflammatory wounds treatment. The main advantages of the new technology are the combined application of an antibiotic solution and photodynamic therapy to destroy antibiotic- resistant microorganisms, an effective mixing of a photosensitizer in the wound, the US enhancement of photosensitizer impregnation into the membranes of bacteria, the US clearing of wound surface from necrotic products, an increased effective light dose exposure in the whole volume of the deep wound when the light does not penetrate totally inside the wound, an additional bactericidal effect under the US impact, and the combined effect of CPUS activation of the immune system.

The further development of new method of phototherapy based on use of light-emitting diodes (LED) arrays has been presented. LEDs array distribution is side of cylindrical surface, covering pathology region, was used for treatment group of patients with an affected peripheral nervous system. The main group consisted of patients with humeral plexopathy - one of possible neurological manifestation of postmastectomic syndrome as result of breast cancer radical treatment. This disease was accompanied also by some other peripheral nervous system diseases: diabetic polyneuropathy, compression ischemic mononeuropathy, festering wounds and others. The phototherapeutic method is just directed on improvement of patient's conditions in combination with other traditional methods of treatment. The main parameters of photomatrix therapeutic system: wavelength - 660 nm, line width - no more than 20 nm, intensity of radiation on the surface of edema - 0.5-3 mW/cm² (in dependence of apparatuses type). To control and study efficiency of phototreatment ultrasonic dopplerography, thermography, electromyography and viscosimetry have been used.

The double-wavelength laser scanning microphotometer (DWLSM) with high spatial resolution had been developed for in vitro measuring of hair shaft and follicle absorbance. The instrument allows for determining the absorbance distribution across and along hair shaft and follicle. The instrument is based on standard universal binocular microscope. The construction of the instrument and the data processing reduces the influence of the light scattering on the hair and tissue samples.

Results of development of spectrophotometric technique for human hair testing in the laboratory and clinical conditions are presented. Hair tester, which can be used for measurements of optical parameters of in vitro hair samples at three fixed wavelengths of illuminating light, is described. Usage of CCD sensor as photodetector allows one to provide spatial-resolved analysis of the hair optical properties and to measure geometric parameters of the hair sample. Experimental results obtained with designed instrumentation and technique are presented.

We presented RGB video microscopic system for in vitro monitoring of optical properties of hair shaft and follicle and experimental results of study of the hair optical and geometrical properties using RGB analysis techniques.

Method of polarization visualization of superficial layers of multiply scattering medium containing macroinhomogeneities based on the analysis of polarization patterns of a backscattered linearly polarized light is discussed. The polarization properties of a backscattered light were studied for phantom scattering media (diluted milk with low concentrations). The influence of media scattering properties on inhomogeneity image obtained by use of the polarization degree and normalized scattered intensity as visualization parameters is discussed. Quality of reconstructed images was estimated in terms of spatial resolution and image contrast. Depth resolution of the considered polarization imaging in the backscattering mode is discussed. Phenomenological description of the polarization image formation is carried out by means of the concept of statistical distribution of effective optical paths of partial components of scattered optical field. Some peculiarities of the polarization characteristics of backward multiply scattered light, which influence on the polarization images formation, are discussed.

Dye-assisted photothermal welding is a technique used to close wounds by thermally cross-linking collagen across apposed tissue edges. For a successful weld, not only do laser parameters have to be optimized, but also apposition of the incision has to be consistent and controlled. The objective of this study was to quantify the relationship between the applied apposition pressure (i.e., the compressive force holding the wound closed during the welding procedure divided by the area of the skin-to-skin interface) and the tensile strength of the wound following the welding procedure. By using a clamping device made of two complementary pieces, each 3 cm wide with a row of 10 equally spaced blunt wire mesh tips, the apposition pressure along a 2-cm-long incision in each albino guinea pig was quantified using a 127-micrometers -thick load cell and varied from 0-1.8 kgf/cm². A continuous wave, Nd:YAG laser emitting 10.0 W of 1.06-micrometers radiation from a 600-micrometers -diameter fiber irradiating a 5-mm-diameter spot size was scanned across the incision in order to deliver 300 J of total energy. As the apposition pressure of the incisions was increased, the resulting tensile strength of welded skin increased in a sigmoidal manner. For this welding technique, an apposition pressure of at least 1.2 kgf/cm² is necessary to obtain maximum weld strength of the skin (2.56+/- 0.36 kg/cm²).

Previous work demonstrated increased breaking strengths of tissue repaired with liquid albumin solder reinforced with a biodegradable polymer film compared to unreinforced control specimens. It was hypothesized that the breaking strength increase was due to reinforcement of the liquid solder cohesive strength. Immersion in a moist environment can decrease the adhesion of solder to tissue and negate any strength benefits gained from reinforcement. The purpose of this study was to determine if hydrated specimens repaired with reinforced solder would still be stronger than unreinforced controls. A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with 806-nm diode laser light. A poly(DL-lactic- co-glycolic acid) film was used to reinforce the solder (the controls had no reinforcement). The repaired tissues were immersed in phosphate buffered saline for time periods of 1 and 2 days. The breaking strengths of all of the hydrated specimens decreased compared to the acute breaking strengths. However, the reinforced specimens still had larger breaking strengths than the unreinforced controls. These results indicate that reinforcement of a liquid albumin solder may have the potential to improve the breaking strength in a clinical setting.

Successful laser-assisted tissue welding was implemented to provide proper weld strength with minimized tissue thermal injury. We investigated and compared the weld strengths and morphologic changes in porcine small intestinal submucose (SIS) and porcine ureteral tissues with various concentration of indocyanine green (ICG) and with a solid albumin sheet. The study showed that the tissues were welded at lower ICG concentration (0.05 mM) with minimized tissue thermal damage using an 800-nm wavelength diode laser.

Porcine posterior tibial arteries (n equals 50) and saphenous veins (n equals 32) have been welded end-to-end using an 808 nm diode laser combined with an indocyanine green enhanced albumin solder. For comparison, the same welding procedure has been performed with a Holmium:YAG laser without solder. Both lasers were running in continuous wave (cw) regime at a power limited below 1.2 W. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment. The balloon catheter simplified vessel handling and the tight vessel positioning prevented a solder penetration into the lumen. Standard histology revealed for both welding techniques a lateral tissue damage between 2 and 3 mm. The vessels welded with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure 457 +/- 200 mmHg) were independent of the welding technique used.

The surgical treatment of full thickness cartilage defects in the knee joint remains a therapeutic challenge. Recently, new techniques for articular cartilage transplantation, such as mosaicplasty, have become available for cartilage repair. The long-term success of these techniques, however, depends not only on the chondrocyte viability, but also on a lateral integration of the implant. We evaluated the feasibility of cartilage welding using albumin solder that was dye-enhanced to allow coagulation with 808 nm laser diode irradiation. Therefore circular cartilage defects (1-2 mm depth and 6 mm diameter) were made and subsequently repaired using healthy cartilage grafts, which were solder welded through the graft. Conventional histology was compared with viability staining to precisely determine the extent of thermal damage after laser welding.

The laser irradiation of cartilage results in a plastic deformation of the tissue allowing for the creation of new stable shapes. During photothermal stimulation, mechanically deformed cartilage undergoes a temperature dependent phase transition, which results in accelerated stress relaxation of the tissue matrix. Cartilage specimens thus reshaped can be used to recreate the underlying framework of structures in the head and neck. Optimization of this process has required an understanding of the biophysical processes accompanying reshaping and also determination of the laser dosimetry parameters, which maintain graft viability. Extensive in vitro, ex-vivo, and in vivo animal investigations, as well as human trials, have been conducted. This technology is now in use to correct septal deviations in an office-based setting. While the emphasis of clinical investigation has focused on septoplasty procedures, laser mediated cartilage reshaping may have application in surgical procedures involving the trachea, laryngeal framework, external ear, and nasal tip. Future directions for research and device design are discussed.

Laser repair of liver using albumin is a promising method for treating liver trauma. Concentrated human serum albumin is applied to a liver laceration and then denatured using a laser. These repairs were pulled with a material tester to measure the ultimate strength of the laser repair. We show that the ultimate strength of the liver repairs tends to increase with delivered laser energy, that the mode of delivery (pulsed versus continuous) does not matter, that the repair strength correlates with the area of denatured albumin, and that strong welds cause about 1.5 mm of thermal damage.

An in vitro study was conducted to determine the feasibility of using a new range of light-activated surgical adhesives for incision repair in a wide range of tissue types. Biodegradable polymer membranes of controlled porosity were fabricated with poly(L-lactic-co-glycolic acid) (PLGA) and salt particles using a solvent-casting and particulate- leaching technique. The porous membranes were doped with protein solder composed of 50%(w/v) bovine serum albumin solder and 0.5 mg/ml indocyanine green (ICG) dye mixed in deionized water. Tissue incisions were repaired using the surgical adhesive in conjunction with an 805-nm diode laser. Nine organs were tested ranging from skin to liver to the small intestine, as well as the coronary, pulmonary, carotid, femoral and splenetic arteries. Acute breaking strengths were measured and the data were analyzed by Student's T-test. Repairs formed on the small intestine were most successful followed by spleen, atrium, kidney, muscle and skin. The strongest vascular repairs were achieved in the carotid artery and femoral artery. The new surgical adhesive could possibly be used as a simple and effective method to stop bleeding and repair tissue quickly in an emergency situation, or as a substitute to mechanical staples or sutures in many clinical applications.

An in vivo study was conducted to investigate the feasibility, mechanical function, and chronic biocompatibility of a new light-activated surgical adhesive for achieving rapid hemostasis of the puncture site following diagnostic catheterization and interventional cardiac procedures. Porcine carotid arteries (nequals6) and femoral arteries (nequals6) were exposed, and an incision was made in the arterial walls using a 16G needle. The surgical adhesive, composed of a poly(L-lactic-co-glycolic acid) scaffold doped with the traditional protein solder mix of serum albumin and indocyanine green dye, was used to close the incisions in conjunction with an 805-nm diode laser. Blood flow was restored to the vessels immediately after the procedure and the incision sites were checked for patency. The strength and hemostatic abilities of the new surgical adhesive were evaluated in the context of arterial pressure, persistence of hemostatis and presence of any inflammatory reaction after 3 days. After this evaluation period, the surgical procedure was repeated on the carotid arteries (nequals6) and femoral arteries (nequals6) of three additional animals that had been heparinized prior to surgery to closer approximate the conditions seen in a typical vascular surgical setting.

Laser assisted skin closure (LASC) has been shown to accelerate wound healing and to reduce scarring. However, the mechanisms involved during the cutaneous wound repair after LASC remain unclear. This study aimed to evaluate the inflammation process and the wound repair fibroplasia, particularly the involvement of granulation tissue fibroblasts (myofibroblasts).

Laser soldering of tissues is based on the application of a biological solder on the approximated edges of a cut. Our goal was to use laser soldering for sealing cuts in skin under temperature feedback control and compare the results with ones obtained using standard sutures. Albumin solder was applied onto the approximated edges of cuts created in rabbit skin. A fiberoptic system was used to deliver the radiation of a CO₂ laser, to heat a spot near the cut edges, and to monitor and control the temperature. Laser soldering was carried out, spot by spot.

This study was to determine the feasibility and reproducibility of laser welding of cornea with a CO₂ laser system capable of real times infrared fiberoptic radiometric control of tissue temperature. A fiberoptic radiometric temperature control system for the CO₂ 10.6 micrometers laser was developed that enabled a real time nontactile temperature measurement of welding surface. The system was tested on the cornea in 40 in vitro bovine eyes, and also in 6 in vivo corneas of rabbit eyes. Welds performed at a set point temperature of 65 degree(s)C, with or without adjuvant 50% albumin solder. Leaking pressure, surgical time and histologic evaluation were determined for welding and for suturing controls of 6 mm central corneal perforating cuts.

After a 4-year-long pre-clinical experimentation carried out at first on enucleated eyes and then on animal models, we applied a new procedure of laser welding of the cornea on voluntary patients. The welding technique is based on controlled irradiation of the cornea by diode laser radiation (805 nm) operating at low power (60-90 mW) in association with a photoenhancing chromophore applied locally. The welding effect is very effective and selective, because it takes place only in the cut where chromophore is present, while the contiguous tissue remains completely untouched. In the clinical phase, this technique was firstly tested in corneal cuts of increasing length on 25 patients subjected to facoemulsification of the cataract, by both sclero-corneal and corneal tunnels, and to extracapsular cataract extraction by sclero-corneal and corneal cuts. As previously confirmed by histological analysis performed on animal samples, we observed in humans too an early and effective healing process, with a sensible reduction of the post-operatory astigmatism. Based on these positive results, we finally arrived at the first application of diode laser- assisted corneal welding to penetrating keratoplasty (corneal transplantation), where this technique has been employed as far as now in 3 cases to substitute the application of the continuous suture.

The authors report an original 1.9-micrometers diode laser assisted microvascular anastomosis (LAMA) in human. This technique has been applied in 20 patients during reconstructive surgery for digital replantations (nequals6), for digital revascularizations (nequals4) and for free flap transfers (nequals10). LAMA were always performed on vessel (16 arteries and 6 veins) which did not impede the chance of success of the surgical procedure in case of thrombosis. LAMA was performed with a 1.9-micrometers diode laser after placement of 2 equidistant stitches at 180 degrees. The diode spot was obtained by means of a 300-micrometers optic fiber transmitted to the vessel wall via a pencil size hand piece. The following parameters were used: spot size equals 500 micrometers , power equals 70 to 220 mW, pulse duration equals 0.7 to 3 seconds. Ten to 15 spots were applied on each face. The mechanism involved is a thermal effect on the collagen of the adventitia and media leading to a phenomenon which the authors have termed 'heliofusion'. Immediate assessment consisted in evaluating the permeability by patency test (O'Brien) and water tightness. Secondary assessment consisted in evaluating the clinical success, confirmed by Doppler at one month.

Pancreatic cancer diagnosis and management has been enhanced with the application of endoscopic ultrasound. The close proximity of the pancreas to the stomach and duodenum permits detailed imaging with intraluminal ultrasonography and staging of pancreatic tumors. EUS directed fine needle aspiration and injection may be successfully employed with patients with pancreatic cancer. Expandable metal stents can palliate patients with obstruction of the pancreaticobiliary tract as well as the gastroduodenum. The efficacy of EUS in the management of pancreatic cancer is critically reviewed.

The most frequent primary cancers causing malignant obstructive jaundice were pancreatic cancer (57%), hilar biliary cancer (19% including metastatic disease), nonhilar biliary cancer (14%) and papillary cancer (10%). Endoscopic stenting has widely replaced palliative surgery for malignant biliary obstruction because of its lower risk and cost. Self-expandable metal stents are the preferred mode of palliation for hilar malignancies. Plastic stents have a major role in benign biliary strictures. Major complications and disadvantages associated with metallic stents include high cost, cholangitis. malposition, migration, unextractability, and breakage of the stents, pancreatitis and stent dysfunction. Dysfunction due to tumor ingrowth can be relieved by thermal methods (argon plasma coagulator therapy). We present a concise review of the efficacy of metallic stents for palliation of malignant strictures.

The management of gastrointestinal malignancies continues to evolve with the latest available therapeutic and diagnostic modalities. There are currently two driving forces in the management of these cancers: the benefits of minimally invasive surgery so thoroughly demonstrated by laparoscopic surgery, and the shift toward neoadjuvant chemotherapy for upper gastrointestinal cancers. In order to match the appropriate treatment to the disease, accurate staging is imperative. No technological advances have combined these two needs as much as laparascopic ultrasound to evaluate the liver and peritoneal cavity. We present a concise review of the latest application of laparoscopic ultrasound in management of gastrointestinal malignancy.

Transitional cell carcinoma (TCC) of the bladder is most common genitourinary tract cancer and its treatment comprises a large number of surgical procedures in urological oncology. Seventy-five percent (75%) of cases recur within two years and the recurrence rate is correlated with the grade of the initial tumor. While Transurethral Resection of the Bladder (TURB) is the current standard of care, the use of laser offers a proven alternative. Sufficient evidence is available that laser treatment of superficial bladder cancer is as effective as TURB. Laser treatment offers several advantages such as decreased incidence of bladder perforation, a near bloodless procedure, catheter-free procedure, and the possibility of outpatient therapy. It has been reported that laser treatment may reduce the recurrence rate of TCC as compared to electrocautery resection. Furthermore, some studies suggest seeding can be avoided with laser resection; however, both items remain highly controversial.

Benign prostatic hyperplasia (BPH) is a common disease in males older than 50 years of age. 75-80% of this population is considered to have some degree of BPH causing clinical symptoms and requiring urological treatment. Transurethral resection of the prostate (TUR-P) is currently the standard surgical treatment modality for BPH. In an attempt to minimize the need for hospitalization and the associated perioperative and postoperative morbidity, alternatives have been sought. Various types of laser techniques such as interstitial laser coagulation and side-firing technology have been proposed. Numerous studies have shown that laser procedures safely and effectively reduce the volume of the prostate. Intra- and postoperative bleeding are nearly unknown complications for laser procedures, whereas this is the most relevant complication for the TUR-P. Due to significant tissue edema after laser treatment, patients commonly show delayed time to void adequately and, therefore, catheter drainage is often necessary for 3 to 21 days. Retrograde ejaculation is reported to occur less (0- 10%) compared to TUR-P (greater than 60%). Urinary tract infections are very common after interstitial laser coagulation. Although not many long-term clinical data are available, various studies have shown that BPH patients improve in symptom score, flow rate and post-void residual up to 3 years after laser treatment. This paper presents a concise review of efficacy, advantages and disadvantages of the most frequently used laser techniques as well as the long-term clinical data compared to TUR-P.

An endogenous photostimulator (APhS) seems to be a very small physiotherapeutic device allowing to irradiate the part of the gastrointestinal tract (GIT) with light of visible range especially in cases when modern endoscopic equipment cannot be applied. There was studied the effect of a photostimulator on composition of intestinal microflora and the immunologic inspection of patients with dysbacteriosis (dysbioses) of the intestine as a result of diseases of the gastrointestinal tract and after antibacterial therapy for other disturbances. The obtained results are comparable with indices of the control group. At the same time, it should be noted that stimulation of growth of natural flora is recorded in the main group of patients which inhibits the activity of conditioned pathogenic microflora. Indications and contraindications for application of the method of endogenic phototherapy using a photostimulator are defined. The statistical analysis of results of studying the immunity indices testifies to the fact that endogenic phototherapy leads to increased activity of the humoral link of the immunity in this category of patients. Thus, endogenic phototherapy seems to be an effective method of treatment of patients with disturbances of microflora composition of the gastrointestinal tract.

In this prospective study, the efficiency of HoLEP inpatients with prostates larger than 80 grams was to be evaluated. 64 urodynamically obstructed patients with prostate glands of 103 (80-230) grams of weight underwent HoLEP (80 W, 2.0 J, 40 Hz, 550 nm bare laser fibers). The resected weight was 70 (50-200) grams, the resection time was 120.5 (83-170) min., the average resection weight was 0.7 gm/min. The postoperative catheter time was 1.3 (1-3) days. The postoperative hospital stay was 2.5 (1-7) days. HoLEP induced a significant, pronounced and immediate improvement of lower urinary tract symptoms and micturition. The symptom score decreased from 22.3 preoperatively to 5.7 one week and 2.8 one year postoperatively. The peak urinary flow rate of 4.3 ml/sec preoperatively increased to 22 ml/sec one week and 32 ml/sec one year postoperatively. The residual urine dropped from 267 ml preoperatively to 11.5 ml one week and 5.0 ml one year postoperatively. There was one incident of postoperative arterial bleeding, one patient developed urethral stricture and two patients needed a second HoLEP. HoLEP appeared to be a highly effective treatment for prostates larger than 80 grams, with excellent functional results, minor blood loss, low complication rate and very short catheter time and hospital stay.

The prognosis of superficial bladder cancer is strongly related to a high recurrence rate and the presence of concomitant plane tumor lesions such as severe dysplasia or carcinoma in situ. They are frequently overlooked on white light cystoscopy. Furthermore, the traditional transurethral tumor resection of superficial bladder tumor is frequently incomplete. This prospective study aimed to evaluate whether or not 5-ALA induced PPIX fluorescence cystoscopy could increase the detection of superficial bladder tumors and/or plane carcinoma in situ invisible on white light cystoscopy. 100 patients with superficial TCC of the urinary bladder underwent cystoscopy under white light and under blue fluorescence light. 2 hours (1-4 hours) prior to cystoscopy 50 ml 3 percent 5-ALA-solution were intravesically instilled into the empty bladder. All lesions visible on white light cystoscopy were compared with fluorescence findings and, vice versa, all fluorescence findings were compared with white light cystoscopy findings. All lesions visible under white light, and all lesions only visible under 5-ALA induced fluorescence were resected/biopsied and histologically examined.

Two-dimensional (2D) ultrasound imaging is commonly used for diagnosis in a variety of medical fields. However, there are several drawbacks of conventional 2D-ultrasound imaging. These include prostate or transducer movement that produces sets of different images that are difficult to interpret. Also during patient's reexamination correspondence between sets of images before reexamination and after is difficult to establish. This can be described as a problem of correlation between two sets of images: the first created before distortion or examination, the second one after. We propose a method to register 2D ultrasound volumes based on external markers introduced in the prostate. The metal balls are inserted in the prostate at three distinct locations in the prostate. These appear as bright dots in the ultrasound field, serve as reference points, are then outlined through a user-interactive program from two sets of images. Then, the computer program rotates and translates till they match respectively, and displays the mapped points with their corresponding location. Based on this idea we developed an image-guided system for PDT that require high-precision placement of implants. In the planning stage, the system performs an automatic acquisition of 2D transrectal ultrasound images that will ultimately be used to construct the treatment plan. At the time of the therapy, new sets of ultrasound images are acquired and a match is established between the virtual world and the patient's real world with the aid of manually introduced markers and image matching algorithms.

Flat urothelial lesions as well as small papillary tumors are easily missed during transurethral resection (TUR). PDD is based on the detection of protoporphyrin-IX induced fluorescence after topical administration of 5- aminolevulinic acid (ALA). We report on our initial clinical results of 130 procedures in 98 patients. Two hours prior to TUR 1.5 g ALA dissolved in 50 ml 1.4% NaHCO₃ solution was installed intravesically. For fluorescence excitation a blue light source (375-440 nm, Karl Storz) was used. In total 478 biopsies (2-9 per patient) were taken from fluorescent and nonfluorescent areas. Normal nonfluorescent bladder urothelium was blue, whereas cancer epithelium developed a brilliant red fluorescence. During white light cystoscopy, 143 bladder tumors were found. Sixty-three additional tumors were detected because of their positive fluorescence. The overall sensitivity of fluorescence cystoscopy (98%) was greater than that of white light cystoscopy (69%). Their specificities were 51% and 80% respectively.

Bladder cancer remains a serious public health problem in many parts of the world with an estimated 300,000 new cases a year. In the US, there were 53,200 new cases of bladder cancer with 12,200 deaths in 2000. A majority (75%-90%) of these cancers are diagnosed pathologically as transitional cell carcinoma (TCC). Superficial TCC constitutes 85% of newly diagnosed bladder cancer cases. Superficial bladder cancer includes papillary tumors involving only the mucosa (Ta) or submucosa (T1) and flat carcinoma in suit (CIS). Transurethral resection (TUR) of bladder tumor effectively controls the primary tumors, confirms the superficial or non-muscle invasive nature of the disease, provides cytological and histological tumor characteristics for determining prognostic significance and allows for assessment of the extent of bladder tissue involvement by tumor. Intravesical therapy provides a high concentration of drug in contact with tumor-bearing mucosa for prolonged periods, reduces the likelihood of tumor implantation after resection by destroying viable cancer cells, provides a cytotoxic effect on residual carcinoma, and potentially alters precursor mucosal lesions.

40-60% of the men of average age suffer from the violations of sexual functions. Impotence doesn't make direct threat to life; nevertheless this disease essentially reduces quality of life, and consequently deserves the most steadfast attention. There are many methods of treatment of erectile dysfunction. However they are connected with a reception of medicines, which is expensive and has a number of contraindications, or with invasive procedures, or with surgical intervention, that also not always is desirable. We have developed the original device permitting to cause passive erection by creation of a local decompression. The second stage is the effect by an infrared laser radiation (denseness of a potency 4.2 mWt/sm², continuous radiation with length of a wave 0.89 microns, exposition 5 minutes) on erection glans penis. We observed 24 patients with the complaints on insufficient erection (18), premature ejaculation (6); 2 patients in addition presented the complaint on small sizes of the penis. Age of the patients was 24-46 years, on the average 34.3 years. All have received treatment from 15 sessions in day.

The effectiveness and side effects of ureteroscopic HoLL of ureteral stones should be evaluated. In 63 patients (17 female, 46 males) a total of 75 stones of 3-20 mm diameter were treated with ureteroscopic HoLL. 18.7 percent of stones were located in the proximal third, 24.0 percent in the middle third and 57.3 percent in the distal third of the ureter. HoLL was performed with small diameter semirigid and flexible ureteroscopes, 220 or 365 nm flexible laser fibers and a holmium:YAG laser at a power of 5-15 W (0.5-1.0 J, 10- 15 Hz). 47 of 63 patients (74.6 percent) were immediately free of stones, and 8 others (12.6 percent) lost their residual fragments spontaneously within two weeks. Another 2 patients received additional chmolitholysis for uric acid stone fragments, i.e. 90.5 percent of patients were stone free by one sitting of ureterscopic HoLL. Of the remaining 6 patients (9.5 percent) who still had residual calculi 4 weeks after HoLL, 2 asymptomatic patients refused any additional treatment, 2 patients preferred treatment with ESWL, and 2 patients had a successful second HoLL, thereby raising the success rate of ureteroscopic HoLL to 93.7 percent. 2 patients showed contrast medium extravasation on retrograde ureterograms, due to guide wire perforation. No ureteral stricture occurred. In conclusion, transurethral ureteroscopic HoLL proved to be a safe and successful minimal invasive treatment of ureteral calculi.

In Siberia there is a hard epidemic situation on tuberculosis. Urogenital tuberculosis (42.4%) has the first place in the incidence rate among extrapulmonary forms. Complicated and widespread lesions are prevailing. One of the main reasons that is lack of pathognomonic symptoms. So different provocation tests are used. Our investigations have proved provoking influence of a low- intensity laser radiation on a tubercular inflammation. Local transcutaneous effect by an infrared laser radiation allows to provoke an exacerbation of a latent tubercular inflammation in kidneys and to discover it by means of the urinalyses also analysis of blood. In case of an expressed initial pathology of the urinalyses previously therapy ex juvantibus carried out by assignment of brief rates of unspecific preparations, optimum among which is ofromax. This method was used for 60 patients with various urological diseases and has allowed to increase the efficiency of diagnosis on 36%.

Drawbacks to the treatment of bladder calculi demolition include excessive mucosal trauma and bleeding with the use of the electrohydraulic lithotripsy (EHL) and prolonged operating room times with the low wattage holmium laser (HOL). The outcome of bladder stones treated by combining the use of HOL and the EHL is reported. Via the cystoscope, the bladder stones were identified in five male patients and the HOL was used to bore to the center of each stone. The EHL probe was then inserted into each borehole and was used to fragment the stones into pieces which could be removed with an Ellik evacuator. All the stones were fragmented to pieces, which were removed without difficulty. Upon completion, minimal mucosal trauma and stone dust were visualized. No complications were observed.

This manuscript describes the design and construction of device which controls the laser reshaping of cartilage specimens using dynamic measurements of changes in tissue optical properties and surface temperature as feedback control variables. Diffusely transmitted light from an amplitude modulated diode laser ((lambda) equals670 nm, 5 mW) was collected using a multimode optical fiber and measured with a silicon photoreceiver using lock in detection method. Surface temperature was measured with a thermopile. A jig was constructed to maintain porcine nasal septal cartilage specimens (25.0 x 10.0 x 2.0 mm) in deformation during photothermal heating. The jig and specimen were translated relative to a fixed laser spot using two motors controlled using LabView software and a motion control card. Software allowed implementation of several different modes of operation including closed-loop feedback control or open- loop (user defined) conditions. This device has allowed the systematic evaluation of the effect of laser dosimetry on the reshaping process. Design considerations are discussed along with suggestions for clinical device development.

Optical coherence tomography (OCT) was used to obtain cross sectional images of the internal structure of the cochlea in guinea pigs following sacrifice. The 1310 nm source (bandwidth (lambda) equals75 nm) allowed a penetration depth of approximately 1.5 mm. Cross-sectional images (1.87 x 2.00 mm, 10 x 10 micrometers /pixel) were acquired at a frame rate of 1 Hz. Access to the middle ear space was obtained by removing the mastoid bulla. Imaging was performed in situ and also in ex vivo temporal bones. The scala vestibuli, scala media, scala tympani, modiolus and all four and a half turns of the cochlea were identified. These images demonstrate the potential value of OCT for use in determining the internal structures of the cochlea with near-microscopic resolution and at near-real time frame rates.

To visualize the concentration gradients of collagen, elastin and ground substance in histologic sections of vocal folds, an image enhancement scheme was devised. Slides stained with Movat's solution were viewed on a light microscope. The image was digitally photographed. Using commercially available software, all pixels within a color range are selected from the mucosa presented on the image. Using the Movat's pentachrome stain, yellow to yellow-brown pixels represented mature collagen, blue to blue-green pixels represented young collagen (collagen that is not fully cross-linked) and black to dark violet pixels represented elastin. From each of the color range selections, a black and white image was created. The pixels not within the color range were black. The selected pixels within the color range were white. The image was averaged and smoothed to produce 256 levels of gray with less spatial resolution. This new grey-scale image showed the concentration gradient. These images were further enhanced with contour lines surrounding equivalent levels of gray. This technique is helpful to compare the micro-anatomy of the vocal folds. For instance, we find large concentration of the collagen deep in the mucosa and adjacent to the vocalis muscle.

A new technology (OtoLAM) to fenestrate the tympanic membrane with the carbon dioxide laser (CO₂), in the office or the operating room, has been introduced over the last three years. While not new conceptually, this product offers the ability to easily create a precise window into the middle ear using a portable system. Controversy regarding the indications and benefits of this technique, amplified by the costs of the system and the marketing of the technology prior to extensive clinical testing, has plagued the clinical application of this technology. We report our experience over the past year with this system in a busy pediatric otolaryngology practice. Laser fenestration of the tympanic membrane has been useful for the insertion of tympanostomy tubes, and for the minimally invasive evaluation of the middle ear. Our small experience to date reveals that there is a limited role for laser tympanic membrane fenestration in a busy pediatric otolaryngology practice.

Evaluating the benefits of new surgical technologies does not end with the observation of successful instrument-to- tissue interaction. The impact of new technologies in medicine today is also gauged by improvements in patients' daily activities and performance. We present our outcomes assessment tool for judging the value of applying a novel tonsillectomy technique, plasma- mediated ablation using Coblation technology. Plasma- mediated ablation (PMA) achieves soft tissue resection in the oropharynx by energizing protons to break bonds. Less heat is released, allowing for less thermal injury, and possibly less pain, than with tonsillectomy performed using electrocautery alone. Children undergoing tonsillectomy by PMA, were evaluated using our outcomes-based scale, which asked families to report the degree of interruption of normal activities for the patient and their family during the post-tonsillectomy recovery period. A preliminary review of several outcomes assessments exemplify the benefits and limitations of this tool. The tracking of valuable data is weighed against the limitations of a short time course relative to the duration of disability, and a poor response rate. Future work aims to improve this data collection tool to allow application to other new technologies in otolaryngology.

Advances in laser technology have allowed the application of lasers to cosmetic facial skin resurfacing. While this application has been extremely advantageous to patients, the development of pre- and postoperative therapeutic regimens was necessary to mitigate potential complications associated with laser resurfacing. Potential complications of laser resurfacing include prolonged postoperative erythema, hyperpigmentation, hypopigmentation, herpetic, bacterial or candidal infection, and other concerns including scarring and abnormal wound healing. In this report we review the state of the art of preoperative and postoperative care for cosmetic laser resurfacing.

Topical mitomycin-C, a chemotherapeutic agent and a fibroblast inhibitor, has been successfully used in larynx, primarily to treat stenosis. Subglottic, tracheal, and anterior glottic stenosis have all shown promising results in a canine model. Less favorable results have been obtained when topical mitomycin-C is used on the vocal folds following surgical excision of mucosa. In the vocal fold studies, laryngeal videostroboscopy revealed diminished mucosal wave vibration in the vocal folds treated with mitomycin-C as well as a more atrophic appearance to the vibratory surface. The tissue treated with mitomycin-C showed fewer fibroblasts and less collagen. However, inflammatory infiltrate was not significantly different between the treated and untreated tissue. These results are consistent with the known suppression of fibroblast proliferation by mitomycin-C. In contrast to the positive effects of mitomycin-C on stenosis, the observed decrease in the healing response in the vocal fold had negative consequences on vocal fold vibratory pattern.

An imaging system combining optical coherence tomography (OCT) and laser induced fluorescence (LIF) spectroscopy has been built. The system produces both cross-sectional images of tissue structure and fluorescence spectra of surface features. The system has been used to image ex vivo canine aorta with the goal of identifying differences in anatomy and fluorescence between normal canine aorta and canine aorta with an endovascular stent graft. The OCT portion of the system is based on a fiber optic Michelson interferometer. The OCT system measures the intensity of back-reflected infrared light in order to build up images of the subsurface tissue structure. The LIF portion contains a helium cadmium laser, which is used to excite fluorescence in the tissue. Excitation light is guided to the tissue and fluorescence is captured by the addition of a cold mirror into the OCT sample arm optics. The wavelength of 442 nm emitted by the laser is well suited for exciting the main fluorophores in aorta, namely elastin and collagen. It is expected that canine aorta with and without a stent will differ in the relative composition of these fluorophores and can thus be differentiated using LIF spectroscopy. This group has previously used OCT to measure the thickness of different layers in the arterial wall of a porcine model of atherosclerosis. In this paper, we investigate the ability of our combined system to differentiate normal from implanted canine aorta by combining OCT with spectroscopy. We note features of the endovascular stent graft in the OCT image and subtle differences between normal and implanted aorta in the LIF spectra.

One of the last remaining frontiers in angioplasty interventions is successfully recanalizing arteries containing total occlusions. The primary limitation is the inability to pass a guide wire safely across the total occlusion to facilitate therapeutic interventions, such as balloon angioplasty. The Optical Coherence Reflectometry (OCR) guide wire system has demonstrated clinical potential for navigating through total occlusions, but often these lesions are refractory to passage of the guide wire by mechanical force alone. The OCR guide wire has been coupled with low frequency (250-500 kHz), short duration (100 millisecond pulses) radio frequency energy to facilitate guided ablation through the total occlusion. Through a real- time monitoring system and display, the physician is warned if the guide wire approaches the normal arterial wall, allowing the guide wire to be redirected to prevent perforating the vessel. Coupled with the OCR guidance system, the RF ablation allows passage through highly resistant lesions that would not normally be transversed with conventional guide wires. The OCR guided RF guide wire system has been successfully tested in porcine models with cadaveric atherosclerotic diseased arterial grafts.

As part of our ongoing research on spectroscopic differentiation between unstable and stable atherosclerotic lesions, we report data on time-resolved fluorescence of components of arterial intima matrix (different types of cholesterols, lipoproteins, and collagens). Certain compositional features of atherosclerotic plaque have been associated with plaque instability and rupture. We have characterized and compared the time-resolved spectra of structural proteins (Types I and III collagens, and elastin), lipoproteins (LDL, VLDL), and cholesterols (free cholesterol, and cholesteryl oleate and linoleate) induced with nitrogen laser excitation pulses (337 nm, 3 ns) and detected (360-510 nm range, 5 nm interval) with an MCP-PMT connected to a fast digitizer (2 Gsamples/s). Spectral intensities and time-dependent parameters (lifetime (tau) _f; decay constants (tau) ₁ (fast-term), (tau) ₂ (slow-term), A₁ (fast-term amplitude contribution)) derived from the time-resolved spectra were used for samples characterization and comparison. We observed that time- resolved data distinguish collagens from cholesterols and from lipoproteins, and additionally, distinguish different types of cholesterols, different types of lipoproteins and different types of collagen from each other. For instance, the collagen lifetime (390 nm: Type I 5.2 ns, Type III 2.95 ns) was significantly longer than that of cholesterols (free 1.5 ns, linoleate 0.9 ns, oleate 1.0 ns) and that of lipoproteins (LDL 0.95 ns, VLDL 0.85 ns).

Transmyocardial laser revascularization was found to be a new emerging technique for the treatment of end-stage coronary artery diseases. In our study, comparison of the ablation effect of the various infrared solid state laser radiations on myocardial tissue was studied. Tm:YAG, CTH:YAG, CTE:YAG and Er:YAG lasers with the fiber and waveguide delivery systems were prepared and the ablation coefficients for the radiation 2.01 micrometers (Tm:YAG), 2.1 micrometers (CTH:YAG), 2.67 micrometers (CTE:YAG) and 2.94 micrometers (Er:YAG) interacting with myocardial tissue were measured. From the histological examination follows that the channels ablated by Er:YAG laser radiation are without any thermal damage of the surrounding tissue and with the minimal mechanical injury, therefore Er:YAG laser could be considered as a good candidate for the TMLR.

A growing number of studies have demonstrated that autofluorescence and induced fluorescence spectroscopy can be used to distinguish normal and abnormal tissues in vivo. Through photochemical accumulation in atherosclerotic lesions it is possible to obtain induced fluorescence, this accumulation has been demonstrated in many researches. The aim of this study was to diagnose, by aluminum phthalocyanine transadventitial fluorescence, atherosclerotic plaques in artery wall of rabbits. Five male Norfolk rabbits were submitted to a high level cholesterol diet for 9 weeks. When the blood cholesterol level reached around 1000 mg/dl three of these animals were injected intravenously 50(M/50(l of aluminum phthalocyanine (AlPc). After 24 hours these animals were submitted to a surgery to expose the iliac artery. The transadventitial fluorescence spectra were acquired in several points over the artery. Characteristic peaks of the collagen, the porphyrin and the induced by AlPc were observed.

Laser thrombolysis (LT) is under investigation as a safe and rapid therapy for arterial recanalization in acute embolic stroke. Clot formation is a complex process affected by many factors that lead to differences in strength and hemoglobin concentration between samples formed from whole blood. The strength of thrombus formed in vivo also varies with age. We have developed a reproducible and clinically relevant reconstituted clot model for the in vitro assessment of a laser thrombolysis system. Laser thrombolysis experiments were performed using a 577 nm 1 microsecond(s) ec pulsed dye laser at an energy of approximately 25 mJ and a repetition rate of 4 Hz. Laser ablation, tensile strength, scanning electron microscopic, and histological comparisons are made with other in vitro clot models. We have found that the tensile strength of this clot model is directly proportional to the fibrinogen concentration. Laser ablation and tensile pull test studies demonstrate that LT ablation efficiency (in (mu) g/mJ/pulse) is not significantly affected by differences in clot tensile strength. This agrees with previous studies using dye and gelatin. Our results provide support for the effective use of this laser thrombolysis system for the removal of clots of varied age and strength.

A fiber optic catheter connected to a pulsed excimer laser (308 nm) is currently used to extract chronically implanted pacemaker and defibrillator leads at Fluence of 60 mJ/mm² and repetition rate of 40 Hz. The object of this study was to determine the effect of higher repetition rates (80 Hz) in the catheter's cutting performance. The penetration rate (micrometers /sec), and the associated mechanical and thermal effects were measured in soft (porcine myocardium) and hard tissue (bovine tendon) at 60 mJ/mm²-80 Hz, and were compared to the corresponding values at commercially available laser parameters (60 mJ/mm²-40 Hz). Ablation rates were measured with perforation experiments and the extent of thermal and mechanical damage was measured under polarized light microscopy. For hard (soft) tissue, the laser catheter demonstrated penetration speed of 106 +/- 32 (302 +/- 101) micrometers /sec at 40 Hz and 343 +/- 120 (830 +/- 364) micrometers /sec at 80 Hz. Maximum extent of thermal effects at 40 Hz and 80 Hz was 114 +/- 35 micrometers (72 +/- 18) and 233 +/- 63 micrometers (71 +/- 16) respectively. Maximum extent of mechanical effects at 40 Hz and 80 Hz was 188 +/- 63 micrometers (590 +/- 237) and 386 +/- 100 micrometers (767 +/- 160) respectively. In vitro testing of the laser catheter with 80 Hz laser parameters has demonstrated increased penetration speed in both soft and hard fibrous tissue, while maintaining associated thermal and mechanical effects within limited ranges.

A novel CW optical system is designed for breast cancer imaging, which has several distinguished features. It doesn't need an additional baseline measurement for image reconstruction. It measures a portion of the breast tissue at one time, which leads to a much simpler and fast signal processing and also makes it very flexible to use. A spectroscopy calibration approach is developed to reduce random system errors.

The influence of vasoactive pharmacological agents (VPhA) on the spectral characteristics of the breast tissues in vivo has been studied. The effect of adrenaline and its antagonist dibazole on the character of diffuse reflection spectra of the breast registered during puncture biopsy were investigated. Adrenaline and dibazole were injected both locally, i.e. to the examined breast tissue and subcutaneously to the shoulder. The choice of this or that VPhA was caused by the functional condition of an examinee. It has been shown that the main functional units of the stroma of parenchymatous organs and their tumors responsible for the state of spectral characteristics in vivo are considered to be the vessels. The cancerous tissue has a lesser pronounced response compared to the normal one that is indicative of the functional inferiority of the tumor vessels and it is confirmed by the results of morphological examinations including the ultrastructural level. Thus, using VPhA it is possible to have an influence on characteristics of diffuse reflection spectra of the examined tissues in vivo and make diagnostics more effectively.

Sentinel node biopsy utilizing Technetium-99m-labeled sulfur colloid is rapidly becoming a standard part of the surgical treatment of breast cancer. Although this method is effective in identifying sentinel lymph node(s) in the axilla, the non-tumor-specific nature of colloids necessitates removal of the node(s) for subsequent analysis. Tumor-specific radiotracers, such as positron-emitting Fluorine-18-labeled Fluorodeoxyglucose (FDG), have been used with positron emission tomography (PET) to successfully stage breast cancer. Thus, the use of FDG with a handheld probe optimized for detection of beta particles could perhaps help identify cancer-infiltrated nodes during axillary dissection. In this study the ability of a new solid-state beta-sensitive probe to identify tumor- infiltrated lymph nodes was investigated in a phantom study. The axilla and tumor-infiltrated lymph nodes were simulated with gelatin phantoms containing FDG concentrations commonly reported from PET studies. FDG uptake in the organs of a patient was simulated with an anthropomorphic torso phantom. Following examination by the handheld probe, a PET image of the phantom was acquired. The results demonstrated that the probe was capable of identifying lymph nodes containing as little as 10 (mu) l of tumor. This amount of simulated tumor was too small to be detected by the PET scanner. This method, therefore, may be useful in intraoperatively identifying some tumor-infiltrated axillary lymph nodes not detected with PET; potentially increasing the efficiency of axillary dissection. Future clinical trials must be performed to assess the utility of this new technique.

In photodynamic therapy, a photosensitizing dye is injected into the patient and the die accumulates in tumor tissue. The cancer cells are then destroyed by absorbing light of a specific wavelength, usually around 630 nm. One of the strong advantages of this therapy is that it destroys only malignant cells and causes less morbidity than standard treatments like surgery and radiotherapy. There are several other techniques that also utilize light activation of pharmaceutical agents in treatment of cancers such as breast cancer. One method of supplying this light activation is through the use of diode lasers, which are constantly finding new application in all fields of medicine. However these lasers tend to be limited by their high cost per watt and multiple wavelength output. Cryogenically cooling such lasers provides higher power output and therefore longer device lifetime. We report quantification of these results from laser power meter and photospectrometer data.

We are studying the potential use of x-rays, which are collected by non-imaging optics and delivered through stereotactically guided needles by hollow waveguides, for irradiation of tumors. X-rays have greater transparency in tissue than most longer optical wavelengths and may provide a more uniform dose to a tumor without harming normal tissue. Dosimetry is the key to minimal damage. We are investigating the use of fiber optics, tipped with calibrated scintillators and strategically located near the tumor, to measure the delivered dose. We are testing this procedure by using a 3 ns, variable accelerator voltage Fexitron 706 to produce approximately 50 mrads of x-ray energy. We concentrate, homogenize and inject this radiation into meter length, submillimeter hollow waveguides. We place the waveguides in a simulated tumor (a phantom breast). Streak and thermal cameras monitor the energy distribution during the irradiation by observing the distribution of energy as evidenced by fluorescence and heat. Once optimum exposure conditions of placement and dose are determined, tissue studies will begin.

Experiments on the feasibility of x-ray monitoring of laser interstitial thermotherapy (LITT) of breast cancer are presented. Digital images of heated tissue phantoms (including fatty porcine tissue and polyacrylamide/acrylate hydrogel), obtained from an x-ray stereotactic biopsy system, were analyzed for changes in pixel intensity. Tissue phantoms were heated either by a 980 nm diode laser or by resistive heating elements in a custom-made chamber. Analysis was conducted by evaluating the changes in average pixel intensity of regions of interest. Image constancy and stability of the x-ray system were also investigated. Slight changes (less than 5%) dependent on the temperature of the tissue phantom were observed, while changes caused by heat- induced tissue displacement and/or shrinkage were more significant (greater than 10%).

The purpose of these experiments was to compare the temperature increase in ex-vivo porcine mammary chain tissue as a breast tissue model during interstitial laser irradiation with diode lasers emitting at 980 nm and 830 nm. Both wavelengths were delivered at 4.0 W for 10 minutes through a diffusing fiber inserted into ex-vivo porcine tissue. The temperature was measured with a set of 15 thermocouples placed 5, 10, and 15 mm from the fiber axis. The initial rate of temperature increase 5 mm away from the fiber tip was higher at 980 nm (0.12 to 0.20 degree(s)C/s) than at 830 nm (0.10 to 0.16 degree(s)C/s). At 10 mm and 15 mm (areas with less radiation), the rate was smaller than at 5 mm (less than 0.06 degree(s)C/s at 10 mm and less than 0.02 degree(s)C/s at 15 mm) for both wavelengths with no significant difference between the 980 nm and 830 nm radiation. The temperature increase at 5, 10 and 15 mm away from the fiber tip after 10 minutes of irradiation was higher at 980 nm (36 to 45 degree(s)C at 5 mm, 14 to 30 degree(s)C at 10 mm and 9 to 17 degree(s)C at 15 mm) than at 830 nm (27 to 33 degree(s)C at 5 mm, 11 to 17 degree(s)C at 10 mm and 8 to 9 degree(s)C at 15 mm) after 10 minutes. These results were found to be highly dependent on tissue composition (muscle vs. fatty tissue).

Breast cancer presents an ongoing challenge in regard to treatment efficacy and successful clinical outcomes. There has been a challenge to increase the survival rate over the past 50 years and only recently have clinical outcomes improved, although slightly. Thermal treatment regimes have been evolving and most recently, have been applied in situ. A standalone treatment for malignancies is challenging due to the rigor in achieving homogeneity in the distribution of therapeutic temperatures in the tumor and the lack of therapy in the adjacent normal tissue. Although initial work used lasers, contemporary work utilizes radiofrequency (RF) or cryotherapy as a treatment modality. Both monopolar and bipolar RF devices were modeled for the RF treatments in the breast. Using finite element techniques, these two modalities were simulated in breast tissue and the results of the bioheat equation compared for similar sized devices. The model incorporated changing electrical and thermal properties of tissue with temperature, as well as blood flow changes. For thermal treatment, the isotherm of +55 degree(s)C was considered the margin of coagulation necrosis, while for cryotreatment, the -40 degree(s)C isotherm was used. The comparison aids in the selection of the best method to improve clinical outcomes, while paying attention to the size of the applicator and time length of treatment.

High-energy use of 1318 nm laser systems is becoming more prevalent in military and industrial settings. Threshold, ED₅₀, exposure data and mechanism of laser-tissue interaction need to be determined for this wavelength using appropriate animal models that allow for extrapolation to control human exposures. Threshold, ED₅₀, exposure data at 1318 nm for retinal and corneal injury have previously been undertaken and reported for rhesus monkeys. Using comparable methods, we examine exposure data at 1318 nm to determine the ED₅₀ and laser-tissue interaction in the rabbit model to evaluate cornea. We present preliminary data for the ED₅₀ threshold on the cornea from exposure to 1318 nm single laser pulses. Delivery of laser energy is accomplished using an Nd:YAG system producing 1318 nm light in the 0.5 millisecond time exposure regime and in the range of 0 to 500 mJ. Results from this work will aid in the establishment of safety standards for near infrared laser systems.

Near-infrared (NIR) Raman spectroscopy has been studied for the last years for many biomedical applications. It is a powerful tool for biological materials analysis. Toxoplasmosis is an important zoonosis in public health, cats being the principal responsible for the transmission of the disease in Brazil. The objective of this work is to investigate a new method of diagnosis of this disease. NIR Raman spectroscopy was used to detect anti Toxoplasma gondii antibodies in blood sera from domestic cats, without sample preparation. In all, six blood serum samples were used for this study. A previous serological test was done by the Indirect Immunoenzymatic Assay (ELISA) to permit a comparative study between both techniques and it showed that three serum samples were positive and the other three were negative to toxoplasmosis. Raman spectra were taken for all the samples and analyzed by using the principal components analysis (PCA). A diagnosis parameter was defined from the analysis of the second and third principal components of the Raman spectra. It was found that this parameter can detect the infection level of the animal. The results have indicated that NIR Raman spectroscopy, associated to the PCA can be a promising technique for serological analysis, such as toxoplasmosis, allowing a fast and sensitive method of diagnosis.

In dynamic light scattering (DLS), the structure or material of interest, suspended in a fluid, is illuminated by a beam of laser light and the scattered light is interpreted in terms of diffusion coefficient, particle size or its distribution. DLS has shown clear promise as a non-invasive, objective and precise diagnostic modality for investigation of lens opacity (cataract) and other medical and toxicological problems. The clinical potential of LDS has been demonstrated in several species both in vivo and in vitro. In many clinical cases, discernment between normal and diseased patients is possible by simple inspection of the particle size distribution. However a more rigorous and sensitive classification scheme is needed, particularly for evaluation of therapy and estimation of tissue injury. The data supplied by DLS investigation is inherently multivariate and its most efficient interpretation requires a multivariate approach which includes the variability among specimens as well as any correlation among the variables (e.g. across the particle size distribution). We present a brief review of DLS methodology, illustrative data and our efforts toward a diagnostic classification scheme. In particular we will describe application of the Mahalanobis distance and related statistical methods to DLS data.

The effects of heat on malignant tumors are well known. Laser-induced hyperthermia is an alternative to microwave or radio wave tissue heating for cancer treatment. In situ injection of a chromophore that converts light into heat allows selective tissue heating. Our attempts to reproduce published results, using the chromophore ICG to enhance tissue heating, produced unacceptable skin damage. This was likely a function of light delivery methods or ICG diffusion into the skin from the tumor. We therefore set about to investigate the effects of ICG on normal and tumor tissue heating, and to develop methods of light delivery and skin cooling to minimize damage to normal tissues. ICG significantly increased tissue heating during 810 nm laser irradiation. Both argon gas and argon gas with water mist cooled the skin; only the addition of water mist maintained normal skin temperatures during laser treatments. In situ injection of ICG, combined with active cooling of the skin produced selective heating of the tumor. Laser light delivery through a microlens produced lower energy densities in the skin while sufficiently heating ICG-containing tumors. Selective laser-induced hyperthermia may become a useful cancer therapy with refinements in laser energy delivery, chromophore localization, and active cooling methods.

Cryogenically cooling semiconductor diode lasers provides higher power output, longer device lifetime, and greater monochromaticity. While these effects are well known, such improvements have not been quantified, and thus cryogenically operated semiconductor lasers have not been utilized in photodynamic therapy (PDT). We report quantification of these results from laser power meter and photospectrometer data. The emission wavelengths of these low power multiple quantum well semiconductor lasers were found to decrease and become more monochromatic with decreasing temperature. Significant power output improvements also were obtained at cryogenic temperatures. In addition, the threshold current, i.e. the current at which lasing begins, decreased with decreasing temperature. This lower threshold current combined with the increased power output produced dramatically higher device efficiencies. It is proposed that cryogenic operation of semiconductor diode lasers will reduce the number of devices needed to produce the requisite output for many veterinary and medical applications, permitting significant cost reductions.

Elongated soft palate is the most common respiratory disease in brachycephalics. During inspiration, an elongated palate obstructs the glottal opening, causing respiratory distress. Left untreated, elongated soft palate may be life threatening. We conducted a randomized, prospective experimental trial in 20 brachycephalic dogs with redundant or elongated soft palates to compare palate resection using sharp dissection and a CO2 laser. Dogs were assigned standardized clinical scores at 0, 2, 8, 16, and 24 hours postoperatively. Tracheostomy performed at surgery significantly increased clinical scores at 3 of the 5 time measurements, but scores became equal to those without tracheostomies after tracheostomy tube removal. Clinical scores between groups were comparable at 0 and 8 hours. Biopsies of the soft palate were obtained at days 0, 3, 7, and 14. The CO2 laser initially incited greater epithelial separation, carbonization, and necrosis, but by day 3, histologic scores were similar. Inflammation peaked at day 3 in all groups; by day 14 these lesions had resolved. Mean surgical time for the laser was significantly shorter. Both techniques resulted in minimal intraoperative hemorrhage and rapid resolution of inflammation. However, many brachycephalic patients have clinical signs and secondary airway changes that predispose them to postoperative complications; the CO2 laser technique does not obviate the need for intensive care management for 24-28 hours postoperatively. Tracheostomy is not warranted in soft palate resection.

The Neodynium: Yttrium Aluminum Garnet (Nd:YAG) laser has been the mainstay of performing upper respiratory laser surgery in the equine since 1984. The 808-nm diode laser has also been applied transendoscopically as well as the 980-nm diode laser over recent years. It has been shown that Indocyanine Green (ICG) enhances the performance of the 808- nm laser because it is absorbed at 810 nm of light. The 808- nm laser's tissue interaction combined with ICG is equivalent to or greater than the Nd:YAG laser's cutting ability. The 980-nm diode laser performance was similar to that of the Nd:YAG as determined by the parameters of this study. This study compared the depths and widths of penetration achieved with the 808-nm diode laser after intravenous injection of ICG on equine respiratory tissue. It also compared depths and widths of penetration achieved by the non-contact application of the 980-nm diode laser delivering the same energy of 200 joules. The depths and widths of penetration of both diode lasers were compared to themselves and to the Nd:YAG laser with all factors remaining constant.

Five adult performance horses presented with the complaints of exercise intolerance and/or upper airway noise. Endoscopy revealed reduced arytenoid movement, mucosal defects with protruding granulation masses and occasional perilaryngeal swelling. While standing, a 1-cm stab incision was created, and a 5-mm trocar with sleeve was inserted through the cricothyroid membrane using nasopharyngeal endoscopic guidance. A fiber guide containing a 600-micron diode free-beam laser fiber was inserted, and the masses were ablated to the cartilage surface. Lesions determined to be limited to the cartilage substance were further ablated using the laser. Lesions determined to extend through the cartilage were manually debrided using an angled curette. The wounds were left unsutured after placing 2-3 ml of antiseptic ointment subcutaneously. Reexamination revealed resolution of the lesions in all horses, and arytenoid mobility was present. Lesions affecting the corniculate process (two) resulted in noticeable atrophy. The author concludes that laser-assisted debridement of septic tracts in the arytenoid cartilages that have not become completely deformed by the process is a reasonable procedure to restore athletic function.

Obstructive urolithiasis is a common problem in small ruminants and pot-bellied pigs. The most common site of urinary tract obstruction in these species is the urethra. Surgical procedures developed to relieve obstructions, in our experience have been effective in approximately 75% of cases. Urethral stricture is a common complication if the mucosa of the urethra is disrupted. The objective of this project was to evaluate endoscopy guided laser lithotripsy as a therapeutic modality to relieve urethral obstructions in small ruminants and pot-bellied pigs. The study population consisted of patients presented to the Veterinary Medical Teaching Hospital at the University of California Davis with obstructive urolithiasis. Lithotripsy was performed using a Holmium:YAG laser via a 200-micron low water quartz fiber passed through a flexible mini-endoscope. Two types of urinary calculi were managed with this technique, calcium carbonate and calcium hydroxyphosphate. Laser lithotripsy was effective at relieving obstructions caused by both types of calculi when conventional methods had failed. Laser lithotripsy performed via urethral endoscopy is a safe and effective therapeutic modality for management of obstructive urolithiasis in small ruminants and pot-bellied pigs and reduces the risk of post procedural urethral stricture.

In this research we represent the results of approbation of two methods of optical caries diagnostics: PNC-spectral diagnostics and caries detection by laser integral fluorescence. The research was conducted in a dental clinic. PNC-method analyzes parameters of probing laser radiation and PNC-spectrums of stimulated secondary radiations: backscattering and endogenous fluorescence of caries- involved bacteria. Ia-Ne laser ((lambda) equals632.8 nm, 1-2 mW) was used as a source of probing (stimulated) radiation. For registration of signals, received from intact and pathological teeth PDA-detector was applied. PNC-spectrums were processed by special algorithms, and were displayed on PC monitor. The method of laser integral fluorescence was used for comparison. In this case integral power of fluorescence of human teeth was measured. As a source of probing (stimulated) radiation diode lasers ((lambda) equals655 nm, 0.1 mW and 630 nm, 1 mW) and Ia-Na laser were applied. For registration of signals Si-photodetector was used. Integral power was shown in a digital indicator. Advantages and disadvantages of these methods are described in this research. It is disclosed that the method of laser integral power of fluorescence has the following characteristics: simplicity of construction and schema-technical decisions. However the method of PNC-spectral diagnostics are characterized by considerably more sensitivity in diagnostics of initial caries and capability to differentiate pathologies of various stages (for example, calculus/initial caries). Estimation of spectral characteristics of PNC-signals allows eliminating a number of drawbacks, which are character for detection by method of laser integral fluorescence (for instance, detection of fluorescent fillings, plagues, calculus, discolorations generally, amalgam, gold fillings as if it were caries).

Heat transfer rate at the skin-air interface is of critical importance for the benefits of cryogen spray cooling in combination with laser therapy of shallow subsurface skin lesions, such as port-wine stain birthmarks. With some cryogen spray devices, a layer of liquid cryogen builds up on the skin surface during the spurt, which may impair heat transfer across the skin surface due to relatively low thermal conductivity and potentially higher temperature of the liquid cryogen layer as compared to the spray droplets. While the mass flux of cryogen delivery can be adjusted by varying the atomizing nozzle geometry, this may strongly affect other spray properties, such as lateral spread (cone), droplet size, velocity, and temperature distribution. We present here first experiments with sequential cryogen spraying, which may enable accurate mass flux control through variation of spray duty cycle, while minimally affecting other spray characteristics. The observed increase of cooling rate and efficiency at moderate duty cycle levels supports the above described hypothesis of isolating liquid layer, and demonstrates a novel approach to optimization of cryogen spray devices for individual laser dermatological applications.

Cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage in various laser dermatological procedures such as treatment of port wine stain birthmarks and hair removal. However, the spray characteristics and combination of CSC and heating (laser) to obtain optimal treatments have not yet been determined. The distance between the nozzle tip and the skin surface for commercial devices was apparently chosen based on the position at which the cryogen spray reached a minimum temperature, presumably with the expectation that such a minimum would correspond to maximal heat flux. We have systematically measured spray characteristics of various nozzles, such as mean droplet diameter, velocity, temperature, and heat transfer coefficient, as a function of distance from the nozzle tip. Among other interesting correlations between these spray characteristics, it is shown that, for nozzle-to-skin distances between 20 to 80 mm, variations in the heat transfer coefficient are larger than those in the spray temperature and, therefore, maximization of the heat flux should be better dictated by the distance at which the heat transfer coefficient is maximized rather than that at which the spray temperature is minimized. Also, the influence of droplet diameter appears to be more influential on the heat transfer coefficient value than that of droplet velocity. Based on spray characteristic correlations, different ranges for positioning the nozzles are recommended, depending on the clinical application. Also, a 2D finite-difference method has been developed to study the spatial and temporal thermal variations within the skin. Our results show that it is possible to decrease significantly the epidermal damage after laser irradiation provided the heat transfer coefficient is significantly increased. The influence of post-cooling has minimal effects for the cases studied.