In cutaneous vascular laser surgery, hemoglobin and melanin are important skin chromophores that influence treatment of port wine stain (PWS) birthmarks. A potential problem in quantitative chromorphore evaluaton is the error in image analysis associated with a number of factors, including nonuniform illumination and skin curvature. In this study, we used a mannequin head model to investigate how the accuracy of image analysis is influenced by view angle and facial curvature. Our results indicate that view angle and facial curvature affect the accuracy of the recorded color information. From this analysis, we propose that optimal view angles can be determined on an individual patient basis to analyze features on different regions of the face.

Near-infrared wavelengths are absorbed less by epidermal melanin mainly located at the basal layer of epidermis (dermo-epidermal junction), and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelength may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light followed by numerical solution of a bio-heat diffusion equation was utilized to investigate the thermal response of human skin to near-infrared laser irradiation, and compared it with that to visible laser irradiation. Additionally, the effect of skin surface cooling on epidermal protection was theoretically investigated. Simulation results indicated that 940 nm wavelength is superior to 810 and 1064 nm in terms of the ratio of light absorption by targeted blood vessel to the absorption by the basal layer of epidermis, and is more efficient than 595 nm wavelength for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. Dermal blood content has a considerable effect on the laser-induced peak temperature at the basal layer of epidermis, while the effect of blood vessel size is minimum.

Cryogen spray cooling (CSC) is an effective method to minimize epidermal damage during laser treatment of various cutaneous anomalies such as port wine stains, excess hair, and facial rhytides. Radiometric temperature measurements provide a noninvasive method to estimate the skin surface temperature. Since the infrared absorption spectrum of the cryogen film has remained unknown, assumptions for those values may lead to inaccurate temperature estimations. We have constructed several high-pressure infrared transparent cuvettes to determine the absorption coefficient of room temperature R-134a in liquid phase using Fourier Transform Infrared Spectroscopy (FTIR) in the 2.5 - 14 μm spectral bandwidth. Results demonstrate that liquid R-134a has several absorption bands in the infrared, with those between 7 - 10.5 and 11.5 - 12.5 μm being the most prominent. Additionally, the absorption coefficient at two common radiometric bands, 3 - 5 and 7 - 11 μm differ by four orders of magnitude. Results of this study will lead to further improvements in interpreting radiometric temperature measurements when using CSC.

The novel femtosecond NIR (near infrared) laser based high resolution imaging system DermaInspect was used for non-invasive diagnostics of pigmented skin. The system provides fluorescence and SHG images of high spatial submicron resolution (3D) and 250 ps temporal resolution (4D) based on time resolved single photon counting (TCSPC). Pigmented tissue biopsies from patients with nevi and melanoma have been investigated using the tunable 80 MHz femtosecond laser MaiTai with laser wavelengths in the range of 750 - 850 nm. The autofluorescence patterns of different intratissue cell types and structures were determined. The non-linear induced autofluorescence originates from naturally endogenous fluorophores and protein structures like NAD(P)H, flavins, elastin, collagen, phorphyrins and melanin. In addition to autofluorescence, SHG (second harmonic generation) was used to detect dermal collagen structures. Interestingly, pigmented cells showed intense luminescence signals. Further characterization of tissue components was performed via 4D measurements of the fluorescence lifetime (x, y, z, τ). The novel multiphoton technique offers the possibility of a painless high resolution non invasive diagnostic method (optical biopsy), in particular for the early detection of skin cancer.

Optical coherence tomography enables cross-sectional imaging of tissue structure to depths of around 1.5 mm, at high-resolution and in real-time. Incorporation of polarization-sensitivity enables the birefringent properties of tissues to be visualized and quantified. We present polarization-sensitive optical coherence tomography images and quantitative birefringence analysis of in vivo human skin. From measurements on a sample of 5 human volunteers, mean double-pass phase retardation rates of 0.340 ± 0.143, 0.250 ± 0.076 and 0.592 ± 0.142°/μm were obtained for normal skin at the dorsal hand, temple and lower back regions respectively. Compared to these values measured in normal skin, a reduction in birefringence was observed and quantified in human skin following thermal injury. Conversely, increased birefringence was consistently measured at skin sites following wound healing and repair.

Indocyanine green (ICG) is a near-infrared fluorescence contrast agent, which has enormous potential in early tumor diagnosis and therapy. The objective of this study is to develop biodegradable nanoparticles entrapping ICG and to characterize its intracellular uptake and photodynamic activity in different cancer cell lines. Nanoparticles entrapping ICG were engineered, characterized and the intracellular uptake of ICG was investigated in B16-F10 and C-33A cancer cell lines. The photodynamic activity of ICG-loaded nanoparticles was also investigated. The nanoparticles enhanced the intracellular uptake of ICG and showed significant photodynamic activity, especially at very low ICG concentrations. These preliminary studies indicate the potential of efficient tumor cell delivery and tumoricidal effect of ICG when incorporated in nanoparticles.

Chronic foot ulcers are common ailments presented in diabetes, which offer severe complications and are often unresponsive to therapy. In this work it was evaluated the effects of adjunctive Hyperbaric Oxygen Therapy (HBO) treatment and LEDtherapy irradiation on ulcer healing (HBO) in addition to conventional treatment. In ulcers of diabetic foot these treatments lead to a reduction in the probability of amputation up to almost four times compared with patients not receiving such co-adjutant treatment. The LEDtherapy irradiation was given concurrently using an energy density of 4J/cm² for 5 min. During the experiment nine patients with diabetic foot ulcers were submitted for HBO sessions with 2,5 ATM for two hours. The experiment demonstrated the effectiveness of HBO + LEDtherapy treatment by favoring the ulcer healing through an increased fibroblastic response, collagen synthesis and neo-vascularization of the ischaemia, as well as increases in the leukocytic bactericidal activity.

Our goal was statistical assessment of the in vivo cystoscopic optical coherence tomography (OCT) ability to detect neoplasia in human urinary bladder. We analyzed major reasons of false positive and false negative image recognition results. Optical coherence tomography was performed to image the bladder during cystoscopy. The study enrolled 63 patients with suspicion for bladder cancer and scheduled for cystoscopy. The diagnosis was established by histopathology examination of a biopsy. Each biopsy site was examined by OCT. Benign conditions were diagnosed for 31 patients, and dysplasia or carcinoma were diagnosed for 32 patients. Six physicians blinded to all clinical data participated in the dichotomy recognition (malignant or benign) of the OCT images. 98% sensitivity and 72% specificity for the OCT recognition of dysplastic/malignant versus benign/reactive conditions of the bladder are demonstrated. Total error rate was 14.8%. The interobserver agreement multi-rater kappa coefficient is 0.80. The superficial and invasive bladder cancer and high-grade dysplasia were recognized with minimum error rate ranging from 0 to 3.3%. High sensitivity and good specificity of the OCT method in the diagnostics of bladder neoplasia makes OCT a promising complementary cystoscopic technique for non-invasive evaluation of zones suspicious for high-grade dysplasia and cancer.

Introduction and Objectives: We have previously reported the use of high-powered photoselective vaporization of the prostate (PVP) for patients in urinary retention due to benign prostatic hyperplasia (BPH). PVP is a relatively new treatment for bladder outlet obstruction due to BPH, using laser energy to vaporize obstructing prostatic tissue. This study investigates the long-term follow up of patients treated with PVP for urinary retention. Materials and Methods: All participants signed informed consent, and were treated with high power 80 W quasi-continuous wave potassium-titanyl-phosphate (KTP) laser. Ten patients underwent the procedure from December 2001 until the present. One patient was excluded from the study for failure to return for follow-up. Mean patient follow-up was nine months, maximum of twelve months. Results: The mean pre-operative gland size by trans-rectal ultrasound was 48 grams. Mean urethral length was 3.2 cm. Mean laser time was 48.2 minutes and the mean energy usage was 82.2 kJoules. There were no peri-operative complications such as sepsis or measurable postoperative bleeding. The preoperative AUA Symptom Score (AUASS) decreased from a mean of 22.6 preoperatively to 17 at nine months postoperatively (p = 0.032). The Quality of Life Score (QOL) decreased from 4.6 preoperatively to 3.25 at 12 months postoperatively (p = 0.26). The maximum urine flow rate increased from a mean of 7.7 cc/sec preoperatively to 14.5 cc/sec at six months follow-up (p = 0.03). Conclusions: This follow-up study suggests that HP-KTP has a durable response in patients treated specifically for retention. It significantly improved urine flow rate and symptom score, and had a trend towards improvement in subjective quality of life. HP-KTP prostatectomy should be considered in treating patients in retention, especially those with significant co-morbidities or taking anticoagulation.

Introduction and Objective: Photoselective vaporization of the prostate (PVP) remains a relatively new addition to our armamentarium of minimally invasive surgical treatments for symptomatic benign prostatic hypertrophy/enlargement. Early favorable reports of the safety and efficacy of PVP do not alleviate the need to investigate factors that may further improve the safety margin and efficacy outcomes of PVP in the management of symptomatic benign prostatic enlargement (BPE). Consequently, we investigated the role of enlarged or prominent intravesical median/middle lobe of the prostate in mediating urinary symptoms following PVP. Materials and Methods: Forty-one non-consecutive patients diagnosed with BPE were enrolled under an Institutional Review Board approved multi-center protocol at the Hunter McGuire Veterans Administration Medical Center, Richmond, Virginia, for PVP treatment using the 80W quasi-continuous wave KTP laser. Perioperative and postoperative complications/adverse events were assessed. Urodynamic parameters: AUA-SI, QOL, Qmax and PVR; and PSA were assessed at baseline, 1, 3, 6 and 12 months postoperatively. Results: The forty-one patients were sub-stratified based on cystoscopic evidence of prominent median/middle lobe (n=17)(Study Group), and absence of median lobe (n = 24). Seven of seventeen (41.1%) patients with and 10/24 (41.7%) patients without median lobes experienced adverse urinary symptoms, which resolved within 7-8 months. All 41 patients have demonstrated significant improvements in urodynamic, that is, flow rates, post void residual volumes and clinical (QOL) outcome measures. Conclusion: Niagara Green Light PVP procedure did not result in heightened severity of voiding symptoms in those BPE patients with prominent intravesical median lobes.

Minimally invasive thermal therapies for the treatment of prostate cancer offer potential to reduce cost, treatment time, and patient trauma. A drawback to such therapies is that it is often difficult or impossible to know the exact volume of which is being destroyed. In this work, we report on the use of magnetic resonance (MR) thermal imaging to provide real-time feedback control over laser interstitial thermal therapy (LITT) in an in vivo canine prostate model.

Stricture recurrence frequently occurs due to mechanical or thermal insult during endourologic treatment of ureteral and urethral strictures. Optimization of the Er:YAG laser for precise incision of strictures was conducted using ureteral and urethral tisssue samples, ex vivo, and a laparoscopic porcine ureteral model with exposed ureter, in vivo. Erbium:YAG laser radiation with a wavelength of 2.94 microns, pulse lengths of 8, 70, and 220 microseconds, output energies of 2 - 35 mJ, fluences of 1 - 25 J/cm², and pulse repetition rates of 5 - 30 Hz, was delivered through germanium oxide optical fibers in contact with the tissue. Incision of the ureteral wall was achieved in vivo with less than 20 pulses at a laser fluence of 4 J/cm². Thermal damage was reduced from 30 - 60 microns to 10 - 20 microns by shortening the laser pulse duration from 220 to 70 microseconds. Pulse repetition rates above 20 Hz resulted in larger thermal damage zones ranging from 60 - 120 microns. The Er:YAG laser, operating at a pulse duration of approximately 70 microseconds, a fluence of 4 J/cm² or greater, and a repetition rate less than 20 Hz, is capable of rapidly incising urethral and ureteral tissues, in vivo, with minimal thermal and mechanical side-effects.

Surface cooling methods are used in dermatology to protect the skin surface during cosmetic laser procedures. This study investigates cryogen spray cooling of the tissue surface during laser production of deep subsurface tissue legions. Nd:YAG laser radiation with a wavelength of 1.06 microns, output power of 30 Watts, a 7.5-mm-diameter spot, and a pulse duration of 1 s, was delivered to porcine liver and skin samples, maintained at 33 - 37°C and monitored with embedded micro-thermocouples. The cryogen spray was delivered intermittently between laser pulses, with a pulse duration of 60 milliseconds, reptition rate of 0.333 Hz, and a 2-cm-diameter spot. Gross and histologic pathology was used to measure tissue lesion dimensions. Liver lesions measured 4.9 ± 1.2 mm in diameter, while preserving the tissue surface to depth of 2.1 ± 0.4 mm (n = 5). Surface temperatures remained below 40°C, while lesion temperatures ranged between 60 - 70°C. Skin lesions appeared 1 mm below the skin surface and measured ~ 2-mm-diameter (n = 4). This technique may be used to target subsurface anatomical structures in the male reproductive tract for noninvasive male sterilization. In vivo experiments will be necessary to optimize the laser heating and cryogen cooling parameters.

Composite adhesives composed of biodegradable scaffolds impregnated with a biological or synthetic adhesive were investigated for use in wound closure as an alternative to using either one of the adhesives alone. Two different scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biological material, small intestinal sub mucosa, manufactured by Cook BioTech. The biological adhesive was composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser. The synthetic adhesive was Ethicon's Dermabond, a 2-octyl-cyanoacrylate. The tensile strength of skin incisions repaired ex vivo in a rat model, by adhesive alone or in combination with a scaffold, as well as the time-to-failure, were measured and compared. The tensile strength of repairs formed using the scaffold-enhanced biological adhesives were on average, 80% stronger than their non-enhanced counterparts, with an accompanying increase in the time-to-failure of the repairs. These results support the theory that a scaffold material with an irregular surface that bridges the wound provides a stronger, more durable and consistent adhesion, due to the distribution of the tensile stress forces over the many micro-adhesions provided by the irregular surface, rather than the one large continuous adhesive contact. This theory is also supported by several previous ex vivo experiments demonstrating enhanced tensile strength of irregular versus smooth scaffold surfaces in identical tissue repairs performed on bovine thoracic aorta, liver, spleen, small intestine and lung tissue.

Our Scaffold-Enhanced Biological Adhesive (SEBA) system was investigated as an alternative to sutures or adhesives alone for repair of wounds. Two scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biologic material, small intestinal submucosa, manufactured by Cook BioTech. Two adhesive materials were also investigated: (i) a biologic adhesive composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser; and (ii) Ethicon’s Dermabond, a 2-octyl-cyanoacrylate. The tensile strength and time-to-failure of skin incisions repaired in vivo in a rat model were measured at seven days postoperative. Incisions closed by protein solder alone, by Dermabond alone, or by suture, were also tested for comparison. The tensile strength of repairs formed using the SEBA system were 50% to 65% stronger than repairs formed by suture or either adhesive alone, with significantly less variations within each experimental group (average standard deviations of 15% for SEBA versus 38% for suture and 28% for adhesive alone). In addition, the time-to-failure curves showed a longevity not previously seen with the suture or adhesive alone techniques. The SEBA system acts to keep the dermis in tight apposition during the critical early phase of wound healing when tissue gaps are bridged by scar and granulation tissue. It has the property of being more flexible than either of the adhesives alone and may allow the apposed edges to move in conjunction with each other as a unit for a longer period of time and over a greater range of stresses than adhesives alone. This permits more rapid healing and establishment of integrity since the microgaps between the dermis edges are significantly reduced. By the time the scaffolds are sloughed from the wound site, there is greater strength and healing than that produced by adhesive alone or by wounds following suture removal. This hypothesis is supported by the data of this study, as well as, the acute tensile strength data of Part I of this study.

Background. Laser tissue soldering (LTS) is an alternative technique to suturing for tissue repair. One of the major drawbacks of LTS is the weak tensile strength of the solder welds when compared to sutures. In this study, the possibility was investigated for a low cytotoxic crosslinker, acting on amino groups, to enhance the bond strength of albumin solders. Materials and Methods. Solder strips were welded onto rectangular sections of sheep small intestine by a diode laser. The laser delivered in continuous mode mode a power of 170 ± 10 mW at λ=808 nm, through a multimode optical fiber (core size = 200 μm) to achieve a dose of 10.8 ± 0.5 J/mg. The solder thickness and surface area were kept constant throughout the experiment (thickness = 0.15 ± 1 mm, area = 12 ± 1.2 mm²). The solder incorporated 62% bovine serum albumin, 0.38% genipin, 0.25% indocyanin green dye (IG) and water. Tissue welding was also performed with a similar solder, which did not incorporate genipin, as a control group. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Results. The tensile strength of the “genipin” solder was twice as high as the strength of the BSA solder (0.21 ± 0.04 N and 0.11 ± 0.04 N respectively; p~10^-15 unpaired t-test, N=30). Discussion. Addition of a chemical crosslinking agent, such as genipin, significantly increased the tensile strength of adhesive-tissue bonds. A proposed mechanism for this enhanced bond strength is the synergistic action of mechanical adhesion with chemical crosslinking by genipin.

An ex vivo study was conducted to determine the effect of the irregularity of the scaffold surface on the tensile strength of repairs formed using our Scaffold-Enhanced Biological Adhesive (SEBA). Two different scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biological material, small intestinal submucosa, manufactured by Cook BioTech. The scaffolds were doped with protein solder composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser. The tensile strength of repairs performed on bovine thoracic aorta, liver, spleen, small intestine and lung, using the smooth and irregular surfaces of the above scaffold-enhanced materials were measured and the time-to-failure was recorded. The tensile strength of repairs formed using the irregular surfaces of the scaffolds were consistently higher than those formed using the smooth surfaces of the scaffolds. The largest difference was observed on repairs formed on the aorta and small intestine, where the repairs were, on average, 50% stronger using the irregular versus the smooth scaffold surfaces. In addition, the time-to-failure of repairs formed using the irregular surfaces of the scaffolds were between 50% and 100% longer than that achieved using the smooth surfaces of the scaffolds. It has previously been shown that distributing or dispersing the adhesive forces over the increased surface area of the scaffold, either smooth or irregular, produces stronger repairs than albumin solder alone. The increase in the absolute strength and longevity of repairs seen in this new study when the irregular surfaces of the scaffolds are used is thought to be due to the distribution of forces between the many independent micro-adhesions provided by the irregular surfaces.

BACKGROUND: A reliable method of blood vessel fusion or sealing has been developed. This method works by applying RF energy and pressure to the walls of a vessel to create a seal. Several methods are used to evaluate the quality of the seal. The main criteria include pressurizing the vessel to failure and using histology to evaluate the integrity of the seal. Burst pressure testing quantifies seal quality, and histology stains reveal the fusion quality of the seal. In addition, histology can show the comparison of morphology and degree of fusion in different tissues. The purpose of the study was to develop an animal model for the human coronary artery bypass graft (CABG) and saphenous vein harvest procedure. METHODS: Experiments were conducted on ovine femoral veins and porcine epigastric veins to demonstrate, through histology and burst testing, the quality of seals. This research details the process of developing an animal model that best approximates the traditional harvest of the saphenous vein for the CABG procedure. RESULTS: Through a series of acute and chronic labs, this research developed a procedure on the ovine model to simulate a peripheral vascular procedure, similar to a femoral bypass. This peripheral vascular procedure on the ovine uses the femoral vein as an interpositional graft onto the femoral artery. In addition, this research identified a second animal model on which to evaluate the healing effects of sealed side branches in a cardiovascular procedure. This research path used the porcine model for a CABG procedure. The epigastric vein was harvested as an autologous vein graft for bypassing the LAD on the pig heart.

Two temperature controlled laser soldering systems were compared, one based on a GaAs laser and the other on a CO₂ laser. Both systems were used for bonding full thickness incisions. Methods: 47% bovine serum albumin (BSA) solder was used in the CO₂ laser soldering experiments. BSA with 1.8 mg/ml Indocyanine Green (ICG) was used for the GaAs soldering experiments. In both cases the solder was applied onto cuts created in juvenile pig skin and an infrared fiberoptic system was used to monitor and control different temperature and time settings. Differences in tensile strength and wound reparative parameters were compared between GaAs laser, CO₂ laser, and Dermabond glued incisions on the seventh day after the operation. Results: The tensile strength of CO₂ laser-soldered and Dermabond glued incisions were found to be higher than that of the GaAs laser-soldered incisions. Histological study showed better and faster wound healing characteristics of the CO₂ laser soldered incisions, as compared to the GaAs laser-soldered and glued incisions. Conclusions: Preliminary results of temperature controlled CO₂ laser soldered incisions suggest a better wound reparative process over the temperature controlled GaAs laser soldered incisions. Laser soldering offers many advantages over gluing techniques.

Introduction: A feasibility study of small intestinal end to end anastomosis was performed in a rabbit model using temperature controlled CO₂ laser system and an albumin stent. Compared with standard suturing or clipping, this method does not introduce foreign materials to the repaired wound and therefore, may lead to better and faster wound healing of the anastomotic site. Methods: Transected rabbits small intestines were either laser soldered using 47% bovine serum albumin and intraluminal albumin stent or served as controls in which conventional continuous two-layer end to end anastomosis was performed manually. The integrity of the anastomosis was investigated at the 14^th postoperative day. Results: Postoperative course in both treatments was uneventful. The sutured group presented signs of partial bowel obstruction. Macroscopically, no signs of intraluminal fluid leakage were observed in both treatments. Yet, laser soldered intestinal anastomoses demonstrated significant superiority with respect to adhesions and narrowing of the intestinal lumen. Serial histological examinations revealed better wound healing characteristics of the laser soldered anastomotic site. Conclusion: Laser soldering of intestinal end to end anastomosis provide a faster surgical procedure, compared to standard suture technique, with better wound healing results. It is expected that this technique may be adopted in the future for minimal invasive surgeries.

In this study, an NIR fiber laser with an eye safe wavelength of 1.455 μm was used to successfully weld in vitro porcine cornea and sclera tissue. The emission wavelength overlaps an absorption band of water. The laser system was used in combination with a motorized translational system and shutter to control the laser exposure on the tissue being welded. Different welding conditions were analyzed for the porcine cornea and sclera. The welded tissues were examined using histopathology and tensile strength analysis. The NIR welding technique provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. The NIR laser system used in this study can effectively weld cornea and sclera tissue, and this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity.

Optical coherence tomography is a diagnostic imaging technique allowing two dimensional tomographic imaging of tissue architecture. This is a review article on the use of optical coherence tomography in Otolaryngology including original images from human laryngeal tissue and temporal bones (cochlea) in our laboratory. Tissue specimens from normal larynges were imaged with an 850 nm OCT system. Our results showed good correlation between OCT image s and the corresponding haematoxylin-eosin stained histology sections in the normal larynx. Human temporal bones were also imaged using an 1300 nm OCT system. Limited morphological details were obtained due to the high scattering properties of the bony labyrinth.

Introduction: Since the early 1980's, a considerable number of different laser systems have been introduced into reconstructive middle ear surgery. Depending on the ablation mode, however, pressure transients or thermal load to inner ear structures continue to be subject to discussion. Material and methods: We examined single spot ablations by a nanosecond-pulsed, frequency-tripled Nd:YAG-Laser (355 nm, beam diameter 10 μm, pulse rate 2 kHz, power 250 mW) on isolated human mallei. In a second set-up, a similar system (355 nm, beam diameter 20 μm, pulse rate 10 kHz, power 160-1500 mW) was coupled to a scanner to examine the morphology of bone surface ablation over an area of 1mm². A third set-up employed a femtosecond-pulsed CrLiSAF-Oscillator (850 nm, pulse duration 100 fs, pulse energy 40μJ, beam diameter 36 μm, pulse rate 1 kHz) to compare these results with the former and with those obtained from a commercially available Er:YAG laser for ear surgery (Zeiss ORL E, 2940 nm, single pulse, energy 10-25 mJ). Results: In set-up 1 and 2, thermal effects in terms of marginal carbonization were visible in all single spot ablations of 1 s and longer. With ablations of 0.5 seconds, precise cutting margins with preservation of surrounding tissue could be observed. Cooling with saline solution resulted in no carbonization at 1500 mW and a scan speed of 500 mm/s. Set-up 3 equally showed no carbonization, although scanning times were longer and ablation less pronounced. Conclusion: Ultrashort pulsed laser systems could potentially aid further refinement of reconstructive microsurgery of the middle ear.

A novel ultrasonography-guided high intensity focused ultrasound (HIFU) system (FS-100; Force Electronics Co. Ltd, Chongqing, China) was developed for non-invasive thermal ablation of tumor. The proprietary therapy delivery system is an integration of the digital image progressing, automatic control and the high intensity focused ultrasound thermal ablation devices. The therapeutic ultrasound probe (φ = 240 mm) consists of eight circular HIFU transducers with a curved surface of a diameter of 60 mm. Dual focused beams generated from the probe were used in this system for thermal delivery. The probe has the maximal resonance frequency of 1 MHz, a maximal treatment depth of 160 mm and focal spot diameter of 3 mm. The maximal intensity at the focal spot is 10,000 W/cm². The imaging and HIFU components are located on top of the device, therefore, the focused ultrasound beams can be delivered to the patient in a supine position. The motion, targeting and localization of the probe are controlled by a PMAC-PC motion controller and an 8-independent-axis mechanical device. The linear motion error of the probe localization is ≤ 0.1 mm. The ultrasonographic image information is used for treatment planning and therapeutic interventions, such as target definition and registration, visualization of the three-dimensional anatomy of desired target(s), automatic positioning the thermal beams on targets, controlling thermal delivery, and rapid evaluation of target response post-treatment. The preclinical experimental results will be presented. The safety, feasibility and effectiveness of this novel HIFU system will be tested.

Photodynamic Therapy (PDT) is a treatment modality that is based on the administration of a photosensitizer and the following application of light in a wavelength range matching the absorption spectrum of the photosensitizer. Ideally the photosensitizer retains in the tumor tissue more than in normal tissue and thus allows targeted destruction of cancerous tissue. The use of PDT is slowly being accepted as a standard treatment for certain types of cancer. This includes mainly treatment strategies with only palliative intentions (obstructive esophageal cancer and advanced lung cancer) while for certain malignant conditions new applications exists that are already intended for cure (e.g. early stage of lung cancer). The main advantage of PDT is that the treatment can be repeated multiple times safely without major side effects. PDT can be safely combined with already established treatment options like surgery, chemotherapy or radiotherapy. A disadvantage of PDT is the only localized effect of the therapy, which usually cannot significantly alter the outcome of a systemic disease. In this paper we review the history of PDT as well as current clinical applications in oncology and future directions.

We present a first evaluation of the interest of the degree of polarization (DOP) imaging technique for early detection of cervical dysplasia. A set of ten ex vivo samples of cervix have been examined, just after surgical extraction, with an DOP imaging system comprising two linear polarizers, a liquid crystal based polarization rotator, and fast CCD camera. Routine histological examination revealed that for all samples but one, dysplasia was present only in the inner part of the cervix, which cannot be imaged with our current setup. On the other hand, the only sample exhibiting dysplasia in its outer region did show nonzero DOP with, however, a somewhat loose correlation between the DOP and the histological mapping of the dysplasia.

Renal tumors are increasingly detected on abdominal imaging studies. Standard treatment of small renal tumors includes partial or radical nephrectomy, done either open or laparoscopically. Several in situ ablative techniques to treat small renal lesions are currently in various phases of evolution. All involve imparting destructive energy to the tumor while minimizing injury to adjacent normal tissue. Cryotherapy (CryoT), radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFUS) and high-intensity radiation (HIR) are all being evaluated as tools to ablate renal tumors. The goal with these modalities is to minimize the blood loss, tissue manipulation, and morbidity associated with excisional approaches. Animal studies have shown that large, reproducible lesions can be ablated in normal kidney tissue by these new techniques. Studies of human renal tissue response to RFA are just beginning. Ex vivo studies reveal large, reproducible controlled lesions in normal renal tissue, similar to animal studies. In vivo studies have shown no significant toxicity, while efficacy is currently under evaluation. Preliminary clinical studies in humans have revealed that renal tumors are slow to regress after treatment, but about 75% of these small renal tumors appeared well treated. Mixed responses have been observed in the remaining cases. This paper presents a concise review of efficacy, advantages and disadvantages of these new minimal invasive techniques and their possible clinical implication in the future.

This presentation is designed as a brief overview of laser use in gynecology, for non-medical researchers involved in development of new laser techniques. The literature of the past decade is reviewed. Differences in penetration, absorption, and suitable delivery media for the beams dictate clinical application. The use of CO₂ laser in the treatment of uterine cervical intraepithelial lesions is well established and indications as well as techniques have not changed over 30 years. The Cochrane Systematic Review from 2000 suggests no obviously superior technique. CO₂ laser ablation of the vagina is also established as a safe treatment modality for VAIN. CO₂ laser permits treatment of lesions with excellent cosmetic and functional results. The treatment of heavy menstrual bleeding by destruction of the endometrial lining using various techniques has been the subject of a 2002 Cochran Database Review. Among the compared treatment modalities are newer and modified laser techniques. Conclusion by reviewers is that outcomes and complication profiles of newer techniques compare favorably with the gold standard of endometrial resection. The ELITT diode laser system is one of the new successful additions. CO₂ laser is also the dominant laser type used with laparoscopy for ablation of endometriotic implants. Myoma coagulation or myolysis with Nd:Yag laser through the laparoscope or hysteroscope is a conservative treatment option. Even MRI guided percutaneous approaches have been described. No long-term data are available.

With the development of femtosecond and shorter pulsewidth lasers and the ability to amplify these pulses to incredibly high pulsed power has come the ability to produce ultrashort pulses of x-rays. In previous years sessions of this conference we have proposed use of these ultrashort pulses of x-rays to produce high resolution, high image quality three dimensional x-ray images of breast and other areas of the body. Theoretical studies of the impact of increasing higher power of UV and X-Ray sources for sterilization lead us to question whether very short pulses of extremely high power (but low dose, i.e. J/cm2) may have less carcinogenic effect. If this is true, it could potentially allow greater use of such x-ray systems for breast cancer surveillance as well as other areas such as deep body inspection. In addition, it could allow for creation of better images by use of higher resolution, noise reduction and higher repetition rates. Better images should improve detection.

We have studied the dynamic changes in tissue vasculature following the inhalation of hyperoxic gasses in rodents as a model for optical breast cancer detection. We have used a CW apparatus to measure the near infrared (NIR) optical properties of animal models immersed in a liquid tissue phantom. By looking at the transmission of different wavelengths in the NIR, we were able to qualitatively observe changes in blood oxygenation following the inhalation of different mixtures of CO₂ and O₂. These changes enhanced the image contrast between cancerous tissue and normal tissues of the rodents. The oxygenation dynamics of the tumors, following inhalation of the hyperoxic gases, exhibited differences from surrounding tissues in both the magnitude of the observed signal change and the dynamic response.

Bio-Micro Electro Mechanical System (Bio-MEMS) technology was applied to the problem of early breast cancer detection and diagnosis. A micro-device is being developed to identify and specifically collect tumor cells of low abundance (1 tumor cell among 10⁷ normal blood cells) from circulating whole blood. By immobilizing anti-EpCAM (Epithelial Cell Adhesion Molecule) antibodies on polymer micro-channel walls by chemically modifying the surface of the PMMA, breast cancer cells from the MCF-7 cell line, which over-express EpCAM, were selected from a sample volume by the strong binding affinity between the antibody and antigen. To validate the capture of the breast cancer cells, three fluorochrome markers, each identified by a separate color, were used to reliably identify the cancer cells. The cancer cells were defined by DAPI⁺ (blue), CD45^- and the FITC-cell membrane linker⁺ (green). White blood cells, which may interfere in the detection of the cancer cells, were identified by DAPI⁺ (blue), CD45⁺ (red), and the FITC-cell membrane linker⁺ (green). EpCAM/anti-EpCAM binding models from the literature were used to estimate an optimal velocity, 2mm/sec, for maximizing the number of cells binding and the critical binding force. At higher velocities, shear forces (> 0.48 dyne) will break existing bonds and prevent the formation of new ones. This detection micro-device can be assembled with other lab-on-a-chip components for follow-up gene and protein analysis.

Time-resolved laser-induced fluorescence spectroscopy (tr-LIFS) has been studied as a potential tool for in vivo diagnosis of atherosclerotic lesions. This study is to evaluate the potential of a compact fiber-optics based tr-LIFS instrument developed in our laboratory for in vivo analysis of atherosclerotic plaque composition. Time-resolved fluorescence spectroscopy studies were performed in vivo on fifteen New Zealand White rabbits (atherosclerotic: N=8, control: N=7). Time-resolved fluorescence spectra were acquired (range: 360-600 nm, increment: 5 nm, total acquisition time: 65 s) from normal aorta wall and lesions in the abdominal aorta. Data were analyzed in terms of fluorescence emission spectra and wavelength specific lifetimes. Following trichrome staining, tissue specimens were analyzed histopathologically in terms of intima/media thickness and biochemical composition (collagen, elastin, foam cells, and etc). Based on intimal thickness, the lesions were divided into thin and thick lesions. Each group was further separated into two categories: collagen rich lesions and foam cell rich lesions based on their biochemical composition. The obtained spectral and time domain fluorescence signatures were subsequently correlated to the histopathological findings. The results have shown that time-domain fluorescence spectral features can be used in vivo to separate atherosclerotic lesions from normal aorta wall as well discrimination within certain types of lesions.

Near infrared (NIR) femtosecond laser scanning microscopy represents a novel and very promising medical diagnostic imaging technology for non-invasive cross-sectional analysis of living biological tissues. In this study multiphoton imaging has been performed to analyze the structural features of extracellular matrix (ECM) components, e.g. collagen and elastin, of living pulmonary and aortic heart valves. High-resolution autofluorescence and second harmonic generation (SHG) images of collagenous and elastic fibers were demonstrated using multifluorophore, multiphoton excitation at two different wavelengths and non-invasive optical sectioning, without the need of embedding or staining. The quality of the resulting three-dimensional images allowed exact differentiation of the ECM components. These experimental results indicated that NIR femtosecond laser scanning microscopy may prove to be a useful tool for the non-destructive monitoring and characterization of cardiovascular structures.

Cultured 9L cells were incubated with graded doses of pheophorbide-a-hexyl ether (HPPH) and exposed to 665 nm red light from either a noncoherent light source or a KTP-pumped dye laser. Cell death was observed after irradiation using either light source, with the noncoherent light being most effective at the highest HPPH concentrations. To determing the practicality of using the noncoherent light source for clinical PDT, dogs and cats with spontaneous tumors were injected intravenously with 0.15 mg/kg HPPH one hour before their tumors were irradiated with 665 nm noncoherent light (50 mW cm^-2, 100 J cm^-2). Of the 9 tumors treated, 8 complete responses were observed, all of which occurred in animals with squamous cell carcinoma. After 68 weeks of follow up, the median initial disease free interval had not been reached. These data support the use of noncoherent light sources for PDT of spontaneous tumors in animals, representing a cost-effective alternative to medical lasers in both veterinary and human dermatology and oncology.

Sarcoids are a locally invasive cutaneous fibroblastic neoplasia and are the most common skin tumor of equids. Myriad treatments are described in the literature including surgery, topical blistering agents, cryosurgery, immunotherapy, and intralesional chemotherapy. Recurrence or progression of the disease after treatment is common. Two years ago the authors began clinical trials investigating the feasibility of photodynamic therapy for the treatment of sarcoid tumors. The tumor or surgical margins were treated using topical or intra-lesional delta-aminolevulinic acid (ALA) as a photosensitizing agent. The ALA was left in situ for a period of time allowing buildup of protoporphyrin IX (the photosensitizer) prior to irradiation with a 635-nm diode laser. We have initial results in 10 patients with 18 lesions and have seen decrease in tumor size or complete remission in 13 of 18 lesions. Recurrence or progression has been noted in 7 lesions. Results of these trials and follow-up information on clinical patients will be presented for review.

Biosynthetic semiconductor, diazoluminomelanin (DALM), is a polymer of tyrosine, luminol, and nitrite. DALM has a very large cross section of absorption for light from ultraviolet to radio frequencies. This polymer can be made efficiently in a genetically engineered E.coli, JM109/pIC2ORNR1.1 (ATCC# 69905). We have been pursuing ways to couple electromagnetic radiation to vectors using this polymer. DNA capture elements (DCEs; formerly aptamers) have made this possible. We incorporated DCEs into the plasmid of this E. coli to direct binding to whatever microbe or cell desired and to produce DALM attached to the plasmid DNA. Using two other vectors pSV₂neoNR10₁ or pSV₂neoNR800₅ (ATCC # 69617 and 69618, respectively), both propagated in the E. coli host HB101, we have also inserted genes necessary for DALM production into animal and human cell lines (mouse monocytic leukemia: ATCC # CRL- 11771, -11772, -1173, mouse mammary adenocarcinoma: ATCC# CRL-12184, -12185; and human carcinoma of the cervix: ATCC # CRL-12510). The DCE/DALM vectors can be used to tag target cells, detectable by broad-spectrum light absorbance, luminescence, or fluorescence. DCE/DALM can further be activated with light, microwave energy, or by oxidative chemistry to kill the targeted microbes or other cells.

The purpose of this study was to evaluate the laser-tissue interactions of engineered human skin and in-vivo pig skin following exposure to a single 3.8 micron laser light pulse. The goal of the study was to determine if these tissues shared common histologic features following laser exposure that might prove useful in developing in-vitro and in-vivo experimental models to predict the bioeffects of human laser exposure. The minimum exposure required to produce gross morphologic changes following a four microsecond, pulsed skin exposure for both models was determined. Histology was used to compare the cellular responses of the experimental models following laser exposure. Eighteen engineered skin equivalents (in-vitro model), were exposed to 3.8 micron laser light and the tissue responses compared to equivalent exposures made on five Yorkshire pigs (in-vivo model). Representative biopsies of pig skin were taken for histologic evaluation from various body locations immediately, one hour, and 24 hours following exposure. The pattern of epithelial changes seen following in-vitro laser exposure of the engineered human skin and in-vivo exposure of pig skin indicated a common histologic response for this particular combination of laser parameters.

There is no uniformly accepted objective method to diagnose the functional extent of retinal damage following laser eye injury and there is no uniform therapy for laser retinal injury. J.T. Eells, et al, reported the use of Light Emitting Diodes (LED) photoillumination (670 nm) for methanol-induced retinal toxicity in rats. The findings indicated a preservation of retinal architecture, as determined by histopathology and a partial functional recovery of photoreceptors, as determined by electroretinogram (ERG), in the LED exposed methanol-intoxicated rats. The purpose of this study is to use multifocal electroretinography (mfERG) to evaluate recovery of retinal function following treatment with LED photoillumination in a cynomolgus monkey laser retinal injury model. Control and LED array (670 nm) illuminated animals received macular Argon laser lesions (514 nm, 130 mW, 100 ms). LED array exposure was accomplished for 4 days for a total dose of 4 J/cm² per day. Baseline and post-laser exposure mfERGs were performed. mfERG results for five animals post-laser injury but prior to treatment (Day 0) showed increased implicit times and P1 waveform amplitudes when compared to a combined laboratory normal and each animal's baseline normal values. In general, preliminary mfERG results of our first five subjects recorded using both the 103-hexagon and 509-hexagon patterns indicate a more rapid functional recovery in the LED illuminated animal as compared to the control by the end of the fourth day post-exposure. Research is continuing to determine if this difference in functional return is seen in additional subjects and if statistical significance exists.

Laser logs and hopstial medical records were examined to determine the number of horses presented for transendoscopic laser ablation of upper respiratory cysts. The two most common lesions were subepiglottic cysts and dorsal pharyngeal cysts. The majority of the horses presenting with these two cystic lesions were under four years of age. Two horses, six and eight years of age, were presented with maxillary sinus cyst of less than 2 cm diameter as demonstrated by radiography. The two horses which presented for nasal cyst were significantly older than any others, being eighteen and twenty-five years of age. Cysts located in the nasal passage and pharynx were visible endoscopically via either of the nasal passages. In the case of the maxillary sinus cyst, trephination allowed for a visual examination and treatment. All horses were treated by transendoscopic laser ablation using either the Nd:YAG laser or the 50-watt 980 nm diode laser using standing sedation. The twelve-year-old horse with the subepiglottic cyst returned, after receiving laser photoablation, for surgical resection of the deflated cyst as portions of it could still be observed on endoscopic examination. For the remainder of the horses, transendoscopic laser photoablation of the respiratory cyst proved to be a satisfactory means of treating the lesion with minimal complications.

A Ti:Sapphire laser operating at 800 nm and 1 kHz repetition rate, was used to investigate the damage induced to fresh cadaveric porcine tissues. The laser was held constant at a focal spot diameter of 100 μm for pulse widths varying from 120-femtoseconds to 7-nanoseconds yielding a maximum fluence of 12.7 J/cm² irradiation. Polarization optics were used to reduce the energy per pulse to well below tissue ablation threshold fluences. Hollow silica waveguides with a silver inner coating and bore diameters of 300, 500, 750 and 1000 μm were also used for the Ti:Sapphire laser with output pulses <150 fs duration and energy up to 700 μjoules. A high resolution motorized X-Y-Z stage translated the tissue through the beam at 1 mm/sec. A Luxar Novapulse CO₂ surgical laser was used as a standard for comparison. Tissues were processed for light, scanning and transmission electron microscopy by standard protocols. Tissue samples were examined for tissue removal rates, thermal damage to adjacent tissue, and cellular disruption for equivalent fluence levels. The Ti:Sapphire laser demonstrated an increase in removal rate along with a decrease in thermal damage as the pulse widths approached the femtosecond regime for a constant fluence. With femtosecond pulses, ablation still occurred below fluences of 2 J/cm². However, for nanosecond pulses, ablation no longer occurred, showing a decrease in ablation threshold as the pulse width decreases. Because of the reduced thermal effects compared to nanosecond pulses, ultrafast lasers may offer a solution to more precise tissue removal with less damage to surrounding cells as compared to more conventional surgical laser systems.

Comparison of the spatial and temporal information retrieved from near-infrared phase and average intensity (DC) data reveals that these data types can play a complementary role in the study of the temporal and spatial features of the optical response associated with brain activation during a finger-tapping test. The optical data have been collected with a frequency-domain tissue imager at two wavelengths (690 and 830 nm) and have been analyzed using standard filtering and folding-average procedures. DC and phase data show different temporal and spatial features. A plausible explanation of the different behavior of DC and phase data has been attempted by using Monte Carlo simulations.

Although many results on the near infrared spectroscopy and imaging of the human brain have been already published, the signal-to-noise ratio (SNR) of the instrumentation used in these studies has never been systematically optimized for the anatomy of the human head. Assuming a typical anatomical structure of the adult human head, we have studied the SNR of the frequency-domain instrument as a function of the modulation frequency and the source-detector distance. The study was performed both experimentally (using a pulsed laser system) and numerically (using the diffusion approximation and Monte Carlo simulations). For the specified geometry we have found that changes caused by non-homogeneities in the phase and in the ratio of the modulation amplitude to the mean intensity significantly increase with the modulation frequency and exhibit peaks between 400 and 1100 MHz, depending on the source-detector distance. Assuming the shot noise, we have found that the corresponding SNR peaks between 400 and 600 MHz. Increase in the source-detector distance results in the SNR increase only for distances below 30 mm. At larger source-detector distances the higher noise decreases the SNR. Our results show that increasing modulation frequency only to 300 MHz offers a very significant improvement in the functional near-infrared spectro-imaging of the adult human brain compared to the 100 MHz instrument.

Brain edema causes an increase in brain tissue volume which results from an accumulation of transudate due to the increased permeability of the brain capillaries. Assuming the transudate to be the material with a low scattering coefficient, brain edema would decrease scattering coefficient of the brain tissue, and diffuse reflectance from the brain may, therefore, be decreased. We examined whether brain edema can be detected or not by measuring the diffuse light reflected from the brain. We induced brain edema by cold injury in rats. The rat skull was irradiated with 633-nm HeNe laser through an optical fiber, and the diffuse light reflected from the brain was collected through another optical fiber. Intensity of the diffuse light reflectance was measured with a polychromator as functions of the time and position on the skull. We found that intensity of the detected diffuse light reflectance decreased at 24 h after injury in the surround area of the injury, suggesting that brain edema can be detected by measuring the diffuse light reflected from the brain.

Introduction: Optical coherence tomography (OCT) allows high-resolution imaging (less than 10 microns) of tissue structures. A pilot study with OCT and polarization-sensitive OCT (PS-OCT) was undertaken to image ex-vivo neurovascular structures (vessels, nerves) of the canine brachial plexus. Methods: OCT is an interferometry-based optical analog of B-mode ultrasound, which can image through non-transparent biological tissues. With approval of the USC Animal Care and Use Committee, segments of the supra- and infraclavicular brachial plexus were excised from euthanized adult dogs, and the ex-vivo specimens were placed in cold pH-buffered physiologic solution. An OCT beam, in micrometer translational steps, scanned the fixed-position bisected specimens in transverse and longitudinal views. Two-dimensional images were obtained from identified arteries and nerves, with specific sections of interest stained with hematoxylin-eosin for later imaging through a surgical microscope. Results: with the beam scan direction transverse to arteries, the resulting OCT images showed an identifiable arterial lumen and arterial wall tissue layers. By comparison, transverse beam OCT images of nerves revealed a multitude of smaller nerve bundles contained within larger circular-shaped fascicles. PS-OCT imaging was helpful in showing the characteristic birefringence exhibited by arrayed neural structures. Discussion: High-resolution OCT imaging may be useful in the optical identification of neurovascular structures during attempted regional nerve blockade. If incorporated into a needle-shaped catheter endoscope, such a technology could prevent intraneural and intravascular injections immediately prior to local anesthetic injection. The major limitation of OCT is that it can form a coherent image of tissue structures only to a depth of 1.5 - 2 mm.

The distribution of protoporphyrin IX (Pp IX) was investigated in a novel animal model followng administration of 5-aminolevulinic acid (ALA) or its hexyl ester (h-ALA). Pre-cultured tumor spheroids prepared from cell lines or tumor biopsy fragments were injected into the brains of immunodeficient rats. Approximately 3 months after spheroid implantation, Rowett nude rats were injected intra-cranially with the maximum tolerable ALA or h-ALA dose. Animals were sacrificed 4 hours post-injection and their brains removed for fluorescence microscopy analysis. The primary finding of this study is that, in the tumor biopsy model, the tumor-to-normal brain PpIX fluorescence ratio is approximately 3 times higher following direct in situ h-ALA adminstration compared to ALA.

The usefulness of repetitive ALA mediated PDT is being evaluated in a rat brain tumor model. In preliminary experiments an optical fiber was repeatedly introduced directly into the brain to apply light, requiring multiple surgical procedures. In an attempt to refine the animal model, an indwelling light applicator, using a modified microdialysis guide cannula has been developed. The cannula is fixed to the scull and can remain in the rat brain for several weeks without complications. In studies of repetitive PDT the need for repeated mounting in a stereotactic frame and surgical procedures can be eliminated. The applicator also makes it feasible to employ low fluence rates with long treatment times, which correspond to future clinically relevant protocols. The fluence rate distribution was measured in vivo and compared to diffusion theory and Monte Carlo simulations to estimate the tissue optical properties of the rat brain for light at 632 nm. The modeling suggested a reduced scattering coefficient 38 cm^-1, an absorption coefficient 0.46 cm^-1 and a penetration depth 0.14 cm.

The probability of achieving local control with current single-shot, intraoperative PDT treatments of intracerebral gliomas seems improbable due to the length of time required to deliver adequate light fluences to depths of 1 - 2 cm in the resection margin. The results of in vitro experiments indicated that PDT, repeated at weekly intervals, was substantially more effective at inhibiting glioma spheriod growth than single treatment regimes. This prompted the initiation of in vivo studies of repetitive PDT in a rat glioma model. BT₄C cell line tumors were established in the brains of inbred BD-IX rats. Three days following tumor induction, the animals were injected with 250 mg/kg ALA i.p. and four hours later, after the introduction of an optical fiber, light treatment at various radiant energies was given over a 10- to 30-minute interval. Two additional treatments were given at weekly intervals. In vitro experiments verified that spheroids derived from the cell line were sensitive to ALA PDT. Microfluorometry of frozen tissue sections showed that PpIX is produced with a 10 - 20:1 tumor to normal tissue selectivity ratio four hours after 250 mg/kg ALA i.p. Toxic radiant energy levels for ALA PDT have been determined.

An accurate quantification of bilirubin in cerebrospinal fluid (CSF) will provide a simple, sensitive and rapid mechanism for detecting subarachnoid hemorrhage (SAH) and for its differentiation from a traumatic spinal tap. Derivative analysis of the spectrophotometric data provides a model for determining bilirubin in CSF where the primary contaminant is Methemoglobin. Bilirubin values are determined in the range 0-9mg/dl within a methemoglobin concentration of 4.6g/dl using the derivative analysis method. The algorithm is also implemented on test samples in which the bilirubin value is constant (4.6mg/dl) and the methemoglobin varies between 0-9g/dl. The performance of the derivative analysis method is compared to the modified minimum distance method developed in reference one. We suggest a combination of these methods for accurate bilirubin estimation in CSF/hemoglobin. This will provide the foundation for the development of a portable user friendly device for diagnosis of SAH.

This work was aimed at exploring the feasibility of MR-guided laser interstitial thermal therapy (LITT) as an adjuvant to vertebroplasty, especially for the management of spinal metastatic tumors. Such a technique may provide a number of advantages including an additional tool for tumor reduction, improved hemostasis, and high precision and safety in thermal therapy. We report on the development of tools and procedures to facilitate augmentation of vertebroplasty with LITT, and we describe the results of laser thermal treatments in normal canine vertebrae.

This study addresses the development of an MRI-compatible spinal compression harness for use as a research and diagnostic tool. This apparatus adds valuable information to MRI imaging regarding the physiology/biomechanics of intervertebral discs and pathophysiology of back pain in patients and astronauts in space. All materials of the spinal compression apparatus are non-metallic for MRI compatibility. The compact design fits into standard MRI or CT scanners and loading is adjusted to specific percentages of BW with elastic cords. Previously this capability has not been available. Three healthy male subjects were fitted with a spinal compression harness and placed supine in a MRI scanner. Longitudinal distance between T7/8 and L5/S1 discs decreased 5.6 mm with 50% BW compression. Lumbosacral angle increased 17.2 degrees. T2 values of nucleus pulposus from L1/2 to L5/S1 discs increased 18.2±6.1% (±SD) during 50% BW compression and 25.3±7.4% (±SD) during 75% BW compression.

Determining the age of injuries is an important aspect of forensic medicine. Currently, visual inspection and colorimetric measurements are the most common techniques used to assess the age of bruises on a victim's body. Bruises are caused by trauma to the skin and vasculature, and the color will depend on the age, depth, and anatomic site of the hemorrhage. Breakdown products of hemoglobin e.g. biliverdin and bilirubin possess various colors, which can be determined spectrometrically. This study presents reflection spectra collected from bruises in otherwise healthy subjects. A total of 73 spectra of 25 bruises were measured on 13 individuals in the 400-850 nm wavelength region. All injuries were caused by sports activities such as judo and soccer. The bruises were classified according to visual appearance, bilirubin content, oxygenation, and age of the injury. Only bruises with known age and cause were included in the study. Spectral changes of each hematoma were recorded over several days. Preliminary results show large variation in the spectra, caused by differences in age and depth of the bruises. This data may provide a basis for developing an algorithm to determine the age of injuries in e.g. child abuse cases.

Photodynamic therapy is a treatment approach that makes use of a photosensitizer to generate a cell death mechanism in a selective tissue. For its characteristics such as multifocality, high recurrence rate, presence of carcinoma in situ, superficial transitional cell carcinoma of the bladder seems to be an excellent indication for such an approach. Following an overview of thirty years of research, this review focuses on recent developments.

Wound healing is a physiologic process that acts to repair disruptions in the continuity of tissue caused by injury or surgical incision. Keloids and hypertrophic scars are forms of aberrant wound healing, which are characterized by the overproduction of collagen, resulting in an excessive amount of scar tissue. Keloid tumors, by definition, grow outside the boundary of the original tissue damage. Multiphoton microscopy (MPM) is an imaging technique which allows imaging of living specimens, without the use of fixation or stains. Images of collagen fibers are produced by the second harmonic signal intensity generated by endogenous fluorescence through excitation by infrared laser light. A postauricular keloid tumor was excised from a patient. The tissue was dissected, and a portion was imaged using MPM. Normal skin tissue was isolated from a patient undergoing a facelift. A portion of this tissue was also dissected and imaged using MPM. MPM images were taken using a 63X water immersion objective lens on a two-photon microscope and a titanium-sapphire laser. Images were taken beginning at the surface of the tissue and moving in at intervals of 200 nm to a final depth of 30 μm. The two-photon images were used to reconstruct three-dimensional representations of the collagen matrix within the tissues, which are readily contrasted. Density of the collagen within each tissue was also ascertained using depth dependant decay of the image intensity. Multiphoton imaging was successfully used to image the collagen matrix of normal skin and a keloid scar, demonstrating differences in their microstructures.

Stenotic, collapsed, and flow-restricted tracheal airways may result from blunt trauma, chronic infection, and the prolonged endotracheal intubation. This pilot investigation characterizes the degree of shape change produced by Ho:YAG laser (λ=2.12 μm) irradiation of rabbit and pig trachea tissue as a function of laser dosimetry and application protocol. Force displacement curves were generated using fresh lagomorph and porcine tracheal cartilage rings secured in a modified single beam cantilever geometry. These specimens were then irradiated for varying amounts of time and power with the objective of straightening these curved specimens. The degree of shape change was documented photographically. Force and surface temperature were monitored. Confocal microscopy was then used in combination a vital staine (“live-dead assay”) to determine the level of viability of straightened cartilage for selected exposure time-power pairs. Laser Cartilage Reshaping of the trachea may provide a new method to treat severe tracheal injuries without the need for classic open surgical techniques. This pilot investigation is the first step toward demonstrating the feasibility of this technique. Long-term, the design of stents combined with laser irradiation may provide a means to alter tracheal shape.

We are developing a scanned focused ultrasound system for hyperthermia treatment of breast cancer. Focused ultrasound has significant potential as a therapy delivery device because it can focus sufficient heating energy below the skin surface with minimal damage to intervening tissue. However, as a practical therapy system, the focal zone is generally quite small and requires either electronic (in the case of a phased array system) or mechanical steering (for a fixed bowl transducer) to cover a therapeutically useful area. We have devised a simple automated steering system consisting of a focused bowl transducer supported by three vertically movable rods which are connected to computer controlled linear actuators. This scheme is particularly attractive for breast cancer hyperthermia where the support rods can be fed through the base of a liquid coupling tank to treat tumors within the breast while coupled to our noninvasive microwave thermal imaging system. A MATLAB routine has been developed for controlling the rod motion such that the beam focal point scans a horizontal spiral and the subsequent heating zone is cylindrical. In coordination with this effort, a 3D finite element thermal model has been developed to evaluate the temperature distributions from the scanned focused heating. In this way, scanning protocols can be optimized to deliver the most uniform temperature rise to the desired location.

3 μm Er:ZBLAN fiber lasers have many advantages for surgical applications compared to other lasers. Some key advantages include variable pulse width (CW to ~100 μs), high repetition rate (>1 kHz) and relatively high and easily adjustable average power (0 to >10 watts) in a compact air-cooled package. In addition, the simplicity of the laser increases reliability and decreases cost. In this paper, we describe some preliminary experiments with the use of such an Er:ZBLAN surgical fiber laser for the ablation of porcine otic capsule bone tissue; in particular, we describe ablation characteristics as a function of pulse energy and pulse duration.

Identification of proliferating chondrocytes along the periphery of laser ablation sites in irradiated cartilage has led to interest in studying the use of laser heating alone to stimulate chondrocyte growth. However, excessive heat produced by a laser can also cause chondrocyte necrosis and apoptosis. The objective of this study was to evaluate acute injury to cartilage following irradiation by an Nd:YAG (λ=1.32μm) laser in intact ex-vivo tissue specimens. Rabbit nasal septal cartilage was irradiated using an Nd:YAG laser using pulse durations (4, 6, and 8 seconds) and power (4, 6, and 8 watts) settings previously determined to produce cell division. Immediately after laser irradiation, the extent of thermal injury to the cartilage samples was evaluated using a Live/Dead cell viability assay combined with confocal microscopy. Thermal injury was assessed with respect to distribution of live and dead cells surrounding the laser spot where regeneration was previously observed. The cell viability assay identified necrotic tissue within and immediately around the laser spot. Moving away from the center of the laser spot, a mixed population of necrotic and live chondrocytes was observed. As expected, a correlation between irradiation time, power and degree of injury was found. The results of this experiment will be used to determine the threshold required to produce regeneration while minimizing thermal injury.