The ultraviolet fluorescence emission spectra of skin tissues under different pathological conditions were measured at 280nm excitation. At this excitation wavelength, the normal skin showed a primary peak emission at 352nm and this primary peak emission from neoplastic skin shows a blue shift with respect to normal tissue. This blue shift increases as the stage of abnormality increases and it is maximum (19nm) for well-differentiated squamous cell carcinoma. This alteration is further confirmed from fluorescence excitation spectra of the tissues for 340nm emission. The study concludes that the change in the emission of tryptophan around 340nm may be due to partial unfolding of protein.

Time-Resolved Laser-Induced Fluorescence Spectroscopy (TR-LIFS) has the potential to provide a non- invasive characterization and detection of tumors. We utilized TR-LIFS to detect gliomas in-vivo in the rat C6 glioma model. Time-resolved emission spectra of both normal brain and tumor were analyzed to determine if unique fluorescence signatures could be used to distinguish the two. Fluorescence parameters derived from both spectral and time domain were used for tissue characterization. Our results show that in the rat C6 glioma model, TR-LIFS can be used to differentiate brain tumors from normal tissue (gray and white mater) based upon time- resolved fluorescence signatures seen in brain tumors.

Fluorescence spectroscopy has emerged as a promising modality in the discrimination of normal from pathologically diseased cells and tissues. As tissues are highly heterogeneous with many native fluorophores, emission spectra at one or more excitation wavelengths or excitation spectra corresponding to one or more emission wavelengths are used for diagnostic purpose. This could be overcome to great extent by applying synchronous luminescence spectroscopy. In the present study, synchronous luminescence fluorescence spectra of normal, pre malignant and malignant cervical tissues are measured by scanning both excitation and emission monochromator simultaneously with a wavelength difference of 20nm. The synchronous luminescence spectra of normal, pre-malignant and malignant cervical tissues shows the distinct peaks around 300, 350, 525nm with broad peak around 460nm and this may be due to tryptophan, collagen and flavin respectively. The broad band around 460nm may be due to the presence of pyridoxal phosphate, carotenes and lipopigments. Spectral data are also evaluated by both empirical and statistical analysis. Among the various analysis partial least square analysis provides better accuracy than other analysis in the discrimination of normal from abnormal tissues.

Optical Spectroscopy in the diagnosis of diseases has attracted the medical community due to their minimally invasive nature. Among various optical spectroscopic techniques, native fluorescence spectroscopy has emerged as a potential tool in diagnostic oncology. However, still the reasons for the altered spectral signatures between normal and cancer tissues not yet completely understood. Recently, data reported that emission due to the alteration of some proteins is responsible for the transformation of normal in to malignant one. In this regard, the present study is aimed to characterize the native fluorescence spectroscopy of abnormal and normal cervical tissues, at 280nm excitation. From the study, it is observed that the normal and pathologically diseased cervical tissues have their peak emission around 339 and 336nm respectively with a secondary peak around 440nm. The FWHM value of emission spectra of abnormal tissues is lower than that of normal tissues. The fluorescence spectra of normal and various pathological conditions of cancerous tissues were analyzed by various empirical and statistical methods. Among various type of discriminant analysis, combination of ratio values and linear discrimination method provides better discrimination of normal from pre-malignant and malignant tissues.

The detection of cervical intraepithelial neoplasia (CIN) in human uterine cervix is possible through the use of fluorescence and reflectance spectroscopy. Fluorescence and reflectance spectra were recorded from the cervix of over 200 patients. Classification performance for distinguishing high-grade CIN (CIN II and III) from normal squamous, normal columnar and metaplastic tissues is 84%. On average, the intensity of fluorescence for CIN II/III lesions is two-fold less than non-CIN II/III tissue. However, variability in the spectra, associated with specific patient, tissue and instrumental parameters, is also noted and tends to blur the distinction between tissue groups. In particular, the intensity of fluorescence was found to increase with patient's age. The magnitude of age-dependence was evaluated using spectra from two of the largest tissue groups: metaplasia (1089 sites in 90 patients) and normal squamous mucosa (763 sites in 56 patients). The metaplasia class shows a stronger age dependence compared to normal squamous tissue: 7.5%/yr versus 2.6%/yr at 390 nm and 2.8%/yr versus 0.9%/yr at 460 nm, representing a two-fold increase in the intensity of fluorescence over 30 years. Hence, the accuracy of tissue classification algorithms may be improved with proper corrections to the spectra for these variables prior to classification.

Near IR imaging using elastic light scattering and tissue fluorescence under long-wavelength laser excitation are explored for cancer detection. Various types of normal and malignant human tissue samples were utilized in this investigation. A set of images of each tissue sample is recorded. These images are then compared with the histopathology of the tissue sample to reveal the optical fingerprint characteristics suitable for cancer detection. The experimental results indicate that the above approaches can help image and differentiate cancer form normal tissue.

We describe a compact fluorescence spectroscopic tool for in vivo point monitoring of aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence and autofluorescence, as a non-invasive method of differentiating normal and cancerous tissue. This instrument incorporates a 405nm diode laser with a shutter to prevent exposure of tissue to harmful light doses and reduce photobleaching, a bifurcated optical fibre to allow illumination of tissue and collection of fluorescence with a single fibre, a compact grating spectrometer for collection of spectra and a PC for system control. We present spectra obtained using this system both during routine gastro-intestinal (GI) endoscopy for cancer detection and during photodynamic therapy (PDT) of anal intraepithelial neoplasia (AIN) for monitoring of treatment progress. These results illustrate the potential of the system to be used for fluorescence monitoring in a variety of clinical applications.

Changes in the fluorescence intensity at 530 nm and 630 nm are measured as a function of incident intensity and exposure time with 488 nm excitation of Argon ion laser. Photobleaching curves of normal and diseased tissues display double exponential behaviour with different decay rates. Photobleaching rates of fluorophores in solutions mostly display single exponential behaviour while addition of absorber and scatterers results in double exponential profiles. The decay profile of FAD + Protoporphyrin indicates the contribution of both fluorophores in tissue photobleaching at 530 nm. Photobleaching profiles of normal tissues with blood show a fast decay in comparison to the normal and diseased tissues without blood. The fast decay rates of tumors indicate absorption of flavin by porphyrin. Fluorescence photobleaching recovery (FPR) profiles of tissue displays single exponential behaviour but the rates of growth of normal and diseased tissues are different.

Laser tissue welding involves the denaturing and partial renaturing of collagen and elastin. Tissues welded with NIR lasers tuned to the 1455 nm water absorption band have demonstrated high tensile strength with minimal collateral damage. To better understand the welding process, welded tissue samples were investigated using fluorescence imaging and Raman spectroscopy. As part of this study, human aorta, and porcine aorta and skin, specimens were investigated. Emission and excitation/emission wavelengths corresponding to tryptophan and collagen emission and slightly weaker emission for wavelengths corresponding to elastin emission. The inner surface an cross-section images of the aortic specimens exhibited a very high degree of uniformity with no indication of the presence of a weld. The Raman spectra from the aortic specimens at the weld site and a few mm away form the weld were very similar. This work indicates the emission and Raman properties of the collagen helix after welding are very similar to native collagen tissue.

Fluorescence emission and diffuse reflectance spectra of freshly excised cervical tissue were studied with two specially designed contact probes. The objective of the study was to reach a better understanding of the relationship between spectroscopic measurements and cervical tissue morphology. Tissue samples from loop electro-surgical excision and hysterectomy specimens were measured within 20 to 90 minutes of excision. Emission spectra with 337 nm excitation, and reflectance spectra were collected at wavelengths between 370 and 720 nm from different tissue sites. Hematoxylin-eosin stained slides of the measured zones were obtained and compared to the spectra. In one experiment, a contact probe with a central illumination fiber and two concentric rings of detection fibers (radii 0.1 and 1 mm), was placed in contact with the epithelium and used to measure spectra from ectocervix and endocervix. The influence of 5% acetic acid on fluorescence and reflectance spectra was also investigated. In another experiment, a single 100-micron fiber probe was placed perpendicular to a cut edge of tissue and scanned to measure spectra in depth. Depth scans were made over various areas of the cervix

Recent studies suggest that inflammatory cell products may contribute to the evolution of particular cancers leading to new chemoprevention trials exploring the benefit of anti-inflammatory drugs such as aspirin and related products. As part of a prospective trial evaluating this anti-inflammatory strategy for oral cancer, we evaluated a non-invasive optical system to determine if we could use an indirect measure of oral inflammation, mucosal thickness, as a monitoring parameter to evaluate the effectiveness of anti-inflammatory drug therapy. Diffuse reflectance spectroscopy has the potential for probing near-surface structures, however, traditional methods for accounting for scattering of photons are generally invalid for typical epithelial thicknesses. Monte Carlo simulations have shown that, with proper scaling, a simple photon model may be used to predict photon behavior under these conditions. A differential measure, which is very sensitive to small changes, has been shown to have the potential to quantify epithelial thickness. A simple prototype device has been brought from desk, to bench and bedside in a rapid manner to fill a need for a non-invasive measure of oral inflammation. From the theory, a simple feature has been identified that corresponds to patient oral inflammation. Preliminary results from this work are presented and indicate that further development of the approach to enable quantification of epithelial thickness in vivo is warranted.

Polarized fluorescence spectroscopy in the visible range can be used to discriminate different types of human breast tissue, namely, malignant, benign and normal. The bandwidth of the 580nm band of the polarized spectra shows excellent discrimination among the different tissue types. This difference in the bandwidth of the 580nm band provides bio-molecular information of the breast tissues. The spatially dependent fluorescence spectra are recorded from different radial distances of the tissue sample. These spectral profiles show differences in broadening as one goes away from the excitation point. This broadening also provides information on the presence of porphyrin in the breast tissues. Various concentrations of two fluorophores with varying concentrations of scatterers have been studied based on the assumption that porphyrin plays a major role in progress of tumor. Correlations have been made with polarized fluorescence spectra as well as spatial profiles of fluorescence spectra of the different tissues with the measurements of tissue phantoms. Such correlations hint at porphyrin accumulation and scattering effects playing major roles in spectral differences among normal, benign and malignant tumor breast tissues.

In order to assess the capacity for in vivo fluorescence spectroscopi8c analysis of arterial collagen and elastin, fluorescence emission intensity was recorded form rabbit aorta after angioplasty and stent implant, and correlated with extracted elastin and collagen content. FEI from saline treated rabbits after stent implant was higher between 485 and 500 nm than after anti-inflammatory treatment. FEI was significantly decreased after implantation of shorter stents at 476-500 nm. Multiple regression analysis demonstrated an excellent correlation between FEI and elastin and HPLC- measured collagen content at 486-500 nm and 476-480 nm respectively. Conclusions: FEI recorded in vivo form arterial intimal surface, can be successfully used for quantitative assessment of compositional changes in connective tissue. Stent implant can induce changes in intimal arterial structure at discrete sites distant from the stent implant site.

Whether inflammatory responses are always initiated in the vessel wall, followed by secondary blood cell activation, or are initiated by activated circulating cells that trigger secondary changes in arterial structure remains unproved. In a rabbit angioplasty injury model we studied changes in aortic atherosclerotic plaque after autologous re-infusion of blood cells pre-activated in vitro with thrombin. Fluorescence spectroscopic analysis (FSA) was used to measure membrane fluidity of circulating platelets, as well as quantitative changes in collagen and elastin at the arterial inner surface. The results were correlated with atherosclerotic plaque structural characteristics. Injection of activated circulating blood cells caused a significant increase in fluorescence emission intensity from the abdominal aorta at 450 and 500 nm 3 days later. In blood samples treated with thrombin, membrane fluidity was significantly increased compared to controls. In conclusion, our results indicate that activated circulating blood cells can trigger arterial responses, acting not only as a secondary response to arterial inflammation, but also as a primary activation mechanism.

Light scattering spectroscopy (LSS) is a promising optical technique developed for quantitative characterization of tissue morphology as well as in vivo detection and diagnosis of disease such as early cancer. LSS employs a wavelength dependent component of light scattered by epithelial cells and other tissues to obtain information about subcellular structure. We present two novel modalities of LSS, LSS imaging and scattering angle sensitive LSS (a/LSS). LSS imaging provides quantitative information about the epithelial cell nuclei, such as nuclear size, degree of pleomorphism, hyperchromasia, and amount of chromatin. It allows mapping these histological properties over wide areas of epithelial lining. We show that LSS imaging can be used to detect precancerous lesions in optically accessible organs. Using a/LSS, which enables characterization of tissue components with sizes smaller than the wavelength of light, we show that the number of subcellular components with the sizes between 30 nm and few microns scales with the size according to an inverse power-law. We show that the size distribution exponent is an important parameter characterizing tissue organization, for example the balance between stochasticity and order, and has a potential to be applicable for early cancer diagnosis and characterization.

The ability to detect skin cancer accurately, quickly, and non-invasively has been the object of researchers for many years. This paper describes a novel Automated Mueller Matrix Polarimetric Imaging System that has the potential for non- invasive determination of cancerous lesions from their benign counterparts. Our system collects the 16 images used to calculate the 16 Mueller matrix elements in less than 70 seconds. To validate the system, we used known samples that show a maximum error of 1.41 percent in the Mueller matrix. Tissue-phantoms with varying concentrations of scatterers were used to determine the effects of changes in the sample scattering coefficient on the Mueller matrix. The system was also used to image a benign lesion on a human subject to show the ability to collect of polarization information from the skin.

Steady state fluorescence spectroscopic characterization of endogenous porphyrin emission from DMBA treated skin carcinogenesis in Swiss albino mice was carried out. The emission of endogenous porphyrin from normal and abnormal skin tissues was studied both in the presence and absence of exogenous ALA to compare the resultant porphyrin emission characterictics. The mice skin is excited at 405nm and emission spectra are scanned from 430 to 700nm. The average fluorescence emission spectra of mice skin at normal and various tissues transformation conditions were found to be different. Two peaks around 460nm and 636nm were observed and they may be attributed to NADH, Elastin and collagen combination and endogenous porphyrin emission. The intensity at 636nm increases as the stage of the cancer increases. Although exogenous ALA enhances the PPIX level in tumor, the synthesis of PPIX was also found in normal surrounding skin, in fact, with higher concentration than that of tumor tissues.

We examine the use of associative learning techniques as applied to diffuse reflectance spectra as possible methods for accurate in vivo drug concentration measurements. Aluminum phthalocyanine tetrasulphonate was added in known doses to sets of 8 homogenized tissue phantoms that covered a large range of optical properties. Measurements were made using a contact fiberoptic probe at several source/collection separations. Spectra were analyzed using partial least squares (PLS) and neural network (NN) regression using a leave 1/5-out-crossvalidation. Both the PLS and NN models accurately predicted the chromophore concentration within 15 percent. NN models provide lower prediction error, with optimal collection distance 3 mm form the source fiber. Predictions using the PLS models showed a systematic tissue-type dependency that correlated with optical pathlength of the reflected light. The advantages of this method are that it can be used for any chromophore, it requires only simple point spectroscopy and it is model- independent.

TOOKAD (WST09: Steba Beheer, Netherlands) is a bacteriochlorophyll-based photosensitizer with a near-infrared absorption at approximately 760-770 nm in its photoactive monomeric form. In aqueous solution the drug aggregates into a non-photoactive form, with an absorption maximum at approximately 812-825 nm. We describe non-invasive pharmacokinetic measurements using diffuse reflectance spectra (DRS) with a surface contact probe in a rabbit model. Spectra were collected over a 120 min period encompassing infusion and clearance of TOOKAD. Factor analysis of the spectra was used to calculate the disaggregation rate to the monomeric form, vasculature clearance, and accurate in vivo spectra of each form of the drug. Immediately following infusion, the drug has a significant aggregated component. Disaggregation occurs with a rate constant, k equals 0.07 min^-1. Peak monomer concentration occurs < 30 min post-infusion, then begins clearing from the skin at a rate k equals 0.004 min^-1. The monomer in vivo absorption spectrum has a peak at approximately equals 765 nm, while the aggregate peak is at 830 nm.

Optical imaging of ex vivo tissue models to study heart fibrillation is normally performed using voltage-sensitive dyes. Upon stimulation by an electrode, time-dependent fluorescence or absorption signals are recorded, often in trans-illumination geometry. In order to provide quantification of the origins of these signals inside the tissue, the locally varying optical properties of the tissue have to be known and their change due to the presence of the dyes. To provide experimental input for further modeling efforts, we have performed depth dependent measurements with a fiber optic laser source inside the tissue, recording light profiles on the tissue surface, mainly in transmission geometry. From these measurements, optical properties have been extracted and the obtained profiles have been used as input into a preliminary image reconstruction scheme, together with Monte Carlo simulations. Experiments at different locations in the same sample show the variation of optical properties. Additionally, effects from the presence of heterogeneities on the signal have been investigated.

Tests that can quickly and efficiently detect traces of illegal performance enhancing drugs are becoming essential. Certain performance enhancing drugs lead to an increase in the count of red blood cells. The proportion of blood made up of red cells is normally around 42 percent. At least 90 percent of Rubidium measured in whole blood is located in the red blood cells. If Rubidium Chloride (RbCl) is given to an athlete around 30 minutes before competing and a sample of their blood (a drop on a filter) was subsequently tested for Rubidium content, the test will give a direct indication of the red blood cell count. In this contribution, we describe an efficient and fast test based on spectroscopic techniques that can be used to detect trace levels of Rubidium. Our experiments employed Rubidium nitride (RbNO3) and trace levels down to 0.3 percent were successfully detected.

This paper deals with photosensitizer quantification in patients undergoing photodynamic therapy. Both fluorescence and diffuse reflectance spectroscopy were applied to evaluate concentration of sulphonated aluminum phthalocyanine in different tissues. The mixtures of Intralipid, blood and photosensitizer with different concentrations were used as standard samples to solve the problem in question. While fluorescence method is more sensitive and more convenient to apply in clinics, the absorption technique may be applied to non fluorescent dyes and used to evaluate the shifts in adsorption peak position due to interaction of dye with tissues. Finally, the concentration dynamics of non fluorescent dye (cobalt phthalocyanine) in patients was obtained with the use of absorption method alone.

Optical diffusion tomography is a new imaging modality that offers significant potential in medical applications. The resulting nonlinear image reconstruction problem is further complicated by the fact that for practical imaging variable source excitation and detector coupling needs to be accounted for in order to obtain quantitative images. We formulated the joint problem of coupling coefficient estimation and three-dimensional image reconstruction in a Bayesian framework, and the resulting estimates are computed in an iterative coordinate-descent optimization scheme. Simulations show that this approach is an accurate and efficient method for simultaneous reconstruction of absorption and diffusion coefficients, as well as the coupling coefficients.

Fluorescence spectroscopy of the endogenous emission of brain tumors has been researched as a potentially important method for the intraoperative localization of brain tumor margins. In this study, we investigate the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) for demarcation of primary brain tumors by studying the time-resolved spectra of gliomas of different histologic grades. Time-resolved fluorescence (3 ns, 337 nm excitation) from excised human brain tumor show differences between the time-resolved emission of malignant glioma and normal brain tissue (gray and white matter). Our findings suggest that brain tumors can be differentiated from normal brain tissue based upon unique time-resolved fluorescence signature.

Our purpose is to spectrally probe the main brain absorbers. The determination of their spatial distribution remains a challenge. According to anatomical data, the proposed 3D model of the rat pial-cortical vascular networks is divided into three parts: (1) the pial vessels could be approximated by a dense layer of around 250 micrometers depth; (2) the penetrating vessels repartition is described as periodic hexagonal prisms with three modules; (3) the capillary network is modelized using a periodic tiling of polyhedron with a density of 817mm.mm^-3 and a branching pattern of 10000mm^-3. With anaesthetized rats under stereotaxic conditions, in vivo time-resolved brain spectroscopy experiments are presented. The setup is designed to allow broadband time-resolved spectroscopy using a streak camera. A femtosecond white light continuum is produced by focusing 800nm pulses (0.5mJ, 1kHz, 150fs) in an adapted third order non linear medium. In the case of water, the spectrum expands over 380-780nm with an efficiency of 20 percent. Mathematical homogenization techniques could be applied to the radiative transfer equation with this geometrical vascular architecture and might be useful to analyze in depth time-resolved spectroscopy of such complex media.

The goal of this study is to test the feasibility of using noise factor/eigenvector bands as general clinical analytical tools for diagnoses. We developed a new technique, Noise Band Factor Cluster Analysis (NBFCA), to diagnose benign tumors via their Fourier transform IR fiber optic evanescent wave spectral data for the first time. The middle IR region of human normal skin tissue and benign and melanoma tumors, were analyzed using this new diagnostic technique. Our results are not in full-agreement with pathological classifications hence there is a possibility that our approaches could complement or improve these traditional classification schemes. Moreover, the use of NBFCA make it much easier to delineate class boundaries hence this method provides results with much higher certainty.

Accurate in vivo optical property data in the ultraviolet to visible range are scarce for many endoscope-accessible organs, yet such information is essential for understanding light propagation and identifying dosimetry standards for biomedical optical spectroscopy. We have performed a preliminary study towards the development of a reflectance-based system for endoscopic measurement of tissue optical properties relevant to fluorescence spectroscopy. To address the constraint of instrument channel diameter and strong attenuation of light in the spectral region of interest, maximum fiber separation distance was limited to 2.5 mm. Measurements were performed on tissue phantoms for a range of optical properties relevant to gastrointestinal mucosal tissues in the ultraviolet to visible range: absorption coefficients from 1 to 25 cm^-1 and reduced scattering coefficients from 5 to 25 cm^-1. Neural network and partial least squares algorithms were trained on radial reflectance profiles generated by a Monte Carlo model as well as by experimental data. These routines were then used to estimate absorption and reduced scattering coefficients from reflectance data. Results are discussed in terms of the optimization of models for optical property determination.

The Single Fiber Scanning Endoscope (SFSE) is a miniature flexible endoscope with unique features that promises to open new minimally invasive procedures for previously inaccessible diseases. There is a need for enhancement of depth cues and 3D measurement in procedures using monoscopic endoscopes. The SFSE uses scanning acquisition that gives it unique imaging properties which are advantageous for 3D vision algorithms -- simultaneous images can be created from multiple sensors all having common viewpoints but different lighting directions. A radiometric dual exists between array and scanning acquisition systems, so scanning acquisition images appear to have the light source originating from the sensors and the viewpoint at the scanner location. Disparity and photometric stereo techniques are investigated. A novel method for interactive virtual lighting allows the surface to be illuminated from any virtual lighting direction, even those not physically possible with endoscope, for use with either monocular or binocular images. This enhances or provides depth cues from shading and parallax. Using the photometric stereo method a 3D mesh representing the surface shape is obtained. A combination of disparity stereo and photometric stereo techniques creates dense range maps and measurements. The ability to make dense 3D measurements allow accurate volume measurements for dosage, risk estimation, and healing progress evaluations.

Several research groups have been developing optical-spectroscopy methods, often mediated by fibre-optic probes, to noninvasively identify dysplasia and cancer in situ and in real time: often called 'optical biopsy'. Researchers at Los Alamos National Laboratory (Los Alamos, New Mexico) have developed the method of elastic-scattering spectroscopy (ESS). ESS is a point measurement that is sensitive to the morphological changes at the cellular and sub-cellular level, including changes in the size and/or density of the nuclei, mitochondria or other organelles. It is therefore sensitive to morphology features that a pathologist looks for during histological examination. We report on the first stages of a clinical study currently under way at the Middlesex Hospital an University College London, designed to test the ESS method for identification of dysplasia in Barrett's oesophagus. Preliminary results using elastic-scattering spectroscopy during endoscopic examination show that this technique has potential as a real-time test for in vivo detection of dysplasia or early cancer within Barrett's mucosa, or at least as a guide to assist in locating optimum sites for biopsy. Initial data sets are encouraging and the randomly chosen testing and training sets give specificities and sensitivities comparable to the accuracy of histology. It is evident that the ESS technique is proving to be convenient for the physicians given its speed and compatibility with endoscopic equipment. It is intended to begin prospective trials in the next few months to assess the systems suitability for general clinical practice.

A confocal micro endoscope has been developed to examine cellular pathology during optical biopsy. The system employs a flexible fiber optic catheter coupled to a slit-scan confocal microscope to image tissue at remote locations in the body. The catheter of the confocal micro endoscope consists of a fiber-optic imaging bundle, a miniature objective, and a miniature focusing mechanism. The system has a lateral resolution of 1.8 micrometers and an axial resolution of 25 micrometers . The confocal micro endoscope can operate in a grayscale or multi-spectral imaging mode. Extensive work has been done to design a new miniature objective and focusing mechanism that will allow the catheter to be routed through the therapeutic channel of a clinical endoscope. We present the design for a miniature F/1 achromatic objective with nearly diffraction limited performance. The objective will be coupled to a pneumatic focusing mechanism to provide focus control to 200 micrometers below the surface of the tissue. The new catheter has an overall diameter of 3mm with a rigid tip of only 20mm in length.

Sized-fiber reflectometry describes a device and method for measuring absorption and reduced scattering of tissue using optical fibers with different diameters. The device used in this paper consists of two fibers with diameters of 200 and 600 microns. Each fiber emits and collects its own backscattered light. Monte Carlo simulations tabulating the diffuse reflectance collected by 200 and 600 micron fibers in a semi-infinite homogenous media are presented for an absorption, (mu) _a range of 0.2-30 cm^-1 and a reduced scattering, (mu) _s range of 10-200 cm^-1. The diffuse reflectance collected by a 600 micron fiber may be approximated by a near relation to the 200 micron fiber. An empirical relation is derived relating the reduced scattering coefficient to the diffuse reflectance collected with 200 and 600 micron fibers. The sensitivity of the relation is determined for changes in each fiber measurement. Finally, in vivo diffuse reflection measurements and reduced scattering coefficient of skin are presented using the aforementioned fiber sizes with a wavelength range of 400-800 nm.

A digitized fluorescence endoscopic imaging (DFEI) system combined with 5-Aminolevulinic Acid (5-ALA) induced protoporphyrin IX (PPIX) was developed for the detection of neoplasms in the oral cavity and uterine-cervix. The system has the capability of producing both the digital and video fluorescence images in real time, and also quantifying the fluorescence images. The results show that using the DFEI system associated with the fluorescence image quantification method, both high sensitivity and specificity can be achieved during the head and neck, and obstetric and gynaecology clinical trials. The red fluorescence intensity distribution in the lesion area can also be obtained after digital image processing to better understand the situation of PPIX accumulation in the tissues. Furthermore, applying the intensity ratio IR/IB at red and blue wavelength regions of the tissue targeted, where IR includes the intensity of PPIX fluorescence and red tissue autofluorescence, and IB is the intensity of diffusely back-scattered excitation blue light, different histopathological grades of lesions can be classified by the DEFI system, suggesting a significant potential of the noninvasive optical biopsy for the early cancer detection.

The Environmental Protection Agency (EAP) designated phosphorus as hazardous material; it is flammable and poisonous. Phosphorus attacks the respiratory system, liver, kidneys, jaw, teeth, blood, eyes, and skin. Phosphorus is an element that has a high detection limit when using laser-induced breakdown spectroscopy (LIBS) techniques. In order to improve on detection limits, laser-induced fluorescence spectroscopy (LIFS) has been proposed, as an extension to LIBS. The ultimate goal of this work is to use the combined LIBS & LIFS techniques to detect the presence of phosphorus in air and to measure its level. In order to provide 'proof-of-concept' results, the sample used for our experiment was prepared using the 'igniting' strip of a safety match box. The spectrally and temporally resolved detection of the specific atomic emission revealed analytical information about the elemental composition of the sample. A tunable Ti: sapphire laser, at the resonance wavelength of 253.4 nm, was then used to probe the plume by exciting the phosphorus element and we measured the fluorescence from the atoms at 213.62 nm and 214.91 nm. The whole experiment was carried out in a few minutes. We have thus demonstrated for the first time, to our knowledge, the use of LIBS and LIFS in air quality monitoring and in particular for phosphorus detection.

Optical spectroscopy has previously ben used to investigate mitochondrial function in muscle, but spectral overlap of the absorbing species in muscle has limited the accuracy of these determinations. This report demonstrates a multispectral approach to determine cytochrome c redox state in the isolated perfused heart using partial least squares analysis. Optical spectra were acquired in the visible region from the surface of the isolated perfused guinea pig heart and interpreted using reference spectra obtained from in vitro solutions. Calibration spectra were acquired form separate light scattering solutions that contained cytochrome c or myoglobin in both oxidized and reduced states. Cytochrome c redox state and myoglobin oxygen saturation were determined separately form each spectrum obtained form 16 guinea pig hearts during baseline perfusion with oxygenated buffer, during 90 seconds of ischemia and during recovery following the ischemic period. A brief delay between myoglobin deoxygenation and cytochrome c reduction was determined, demonstrating that both processes could be determined simultaneously form the same spectra. This approach may lead to improved determinations of mitochondrial function in the isolated perfused heart.

Today in the world there are a lot of effective methods to treat different disease with the use of low-level laser (LLL) radiation. And there are a number of well-known effective noninvasive optical diagnostic techniques, such as a laser fluorescence spectroscopy (LFS), elastic-scattering spectroscopy (ESS), absorption spectroscopy (ABSS), etc. In this paper the first experience of the complex laser-optical therapeutic-diagnostic treatment for the erosive-ulcerative impairments (EUI) of the upper part of the gastrointestinal tract (UPGT) are discussed. The EUI of the UPGT very often have a resistance to a medicamentous therapy and the treatment of that is very difficult in this case. The method of LLL irradiation through an endoscope has been used to increase the efficiency of LLL-therapy and to monitor a general process of recovery respectively. The standard biopsy was investigated to estimate the effect of care as well. As it is shown in this paper the in-situ ABSS allows to optimize the LLL treatment parameters for each patient and for each procedure if the laser has effect on a blood circulation in the irradiated zone. In this case the doctors can see the considerable effect and the reduction period of the cure for EUI. Otherwise, the ABSS indicates that there will be no any effect of LLL therapy for such patient and another methods of treatment are needed. The LFS in this case shows the absence of effect during the care course too. On the basis of analysis of the obtained results this paper presents our current understanding of mechanisms of the laser-induced fluorescence diagnostics and LLL therapy effect for EUI of the UPGT. Today this technique has the official approval of the Ministry of Health of Russian Federation.

Skin reactions to stimuli such as UV irradiation include vascular changes and stimulation of melanin production. Both reactions alter the color appearance of the skin. Skin color reactions were evaluated visually by a trained dermatologist and using a diffuse reflectance spectrometer in the visible range. Our results provide strong evidence that mixed vascular and pigment reactions cannot be visually separated. The involvement of each chromophore can only be identified spectroscopically.