The early detection and localization of bronchial cancer remains a challenging task. Autofluorescence bronchoscopy is emerging as a useful diagnostic tool with improved sensitivity and specificity. Evidence exists that the native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic or to carcinoma in situ (CIS). Early lesions in the bronchi tend to show a decrease in autofluorescence in the green region of the spectrum when excited with violet light and a relative increase in the red region of the spectrum. Several endoscopic imaging devices relying on these optical properties of bronchial mucosa have been developed. An industrial endoscopic autofluorescence imaging system for the detection of early cancerous lesions in the bronchi has been developed in collaboration with the firm Richard Wolf Endoskope GmbH, Knittlingen (Germany) and its performance has been evaluated in a previous clinical study. A second study, presented in this article, aims to optimize the spectral design of the device. Twenty-four lung cancer or high risk patients were enrolled in this study to assess the influence of additional backscattered red light on the tumor-to-healthy tissue contrast and to compare the effect of a narrow band violet excitation to a large band violet excitation. In our study we observed a three times higher contrast between cancer and healthy tissue, when backscattered red light was added to the violet excitation. The comparison between a narrow and a large band violet excitation indicated an increase of the tumor-to-healthy tissue contrast by the narrow band excitation.

Changes in the metabolism can be assumed as a first sign of several ocular diseases. If such metabolic alterations are detectable, diseases might be treatable, before morphological alterations are manifest. The redox pairs of co-enzymes fluoresce after excitation and change their fluorescence properties depending on the oxidative state of cellular metabolism. Metabolic by-products and connective tissue exhibit also auto-fluorescence. The detection and discrimination of endogenous fluorophores at the fundus by selected excitation or evaluation of emission spectra is not possible with a high spatial resolution. The lifetime of electrons in the excited stage is also substance specific and is not influenced by the absorption spectra of non-fluorescent substances at the fundus. For that reason, a Laser Scanning Ophthalmoscope was developed for the 2-dimensional measurement of time - resolved auto-fluorescence at the living human eye-ground. In first studies, different changes in auto-fluorescence were found after respiration of oxygen between fundus sites. Between young and older persons as well as patients suffering from age-related macular degeneration different lifetime-ranges were detected from the same anatomical region. For comparison, lifetime measurements were performed on single substances. In a first step of interpretation, the frequency distribution of each lifetime in a region of interest can be compared between in vivo and in vitro measurements. Presenting the results in Tau 1-Tau 2 diagrams, specific clusters can be found in both types of measurement, covering each other partially and allowing interpretation of measurements from the living human eye.

We propose a new technique for caries imaging by the spectral analysis of teeth luminescence excited by the near UV light. This diagnostic/control method can be applied for the all optically accessible teeth surfaces. The photo-physical studies suggest that hydroxylapatite luminescence, excited in the near UV, comes from de-excitation of crystalline structure defects in interaction with charge donating/accepting en ironment.

The objectives of this study are to characterize the autofluorescence spectra of normal and tumoral esophageal epithelial cells and to link the cellular spectra with a data basis of in vivo tissular spectra. Our preliminary results show that no difference in spectral distribution can be observed between squamous cell carcinoma, adenocarcinoma and normal cells. A statistical significant difference is observed between the average intensity of the raw spectra of the different cell types. Nucleus autofluorescence presents the same spectral shape as cytoplasm, but with lower intensity.

Benign and malignant mammary tumors were induced in rats using a potent carcinogen, N-ethyl-N-nitrosurea (ENU). Induced tumors were examined under near-infrared (NIR) fluorescence imaging (excitation wavelength 670 to 730 nm, detection wavelength 750 and 800 nm) to search for a difference in the photophysical properties of the tumors reflecting their pathologic status. Three benign and eight malignant tumors were examined optically and pathologically. The non-enhanced optical images showed a significantly lower (P<0.05) spontaneous fluorescent signal in the benign tumors than in their malignant counterparts. The precise chemical origin for the observed differences in tumor autofluorescence remains undetermined. It can be hypothesized that the reported high concentration of porphyrins, NIR-fluorescing compounds, in the malignant lesions, could account for the observed increased autofluorescence.

We report on the design, development, and performance of a versatile and mobile fiber-optic based time-resolved fluorescence apparatus for in-vivo spectroscopy of biological tissues. The apparatus is of modular design which allows for facile interfacing with different pulsed light sources and fiber-optic probes. Main features of the apparatus include: 1) fast acquisition of fluorescence decays with high temporal resolution (0.3 ns) for a broad range of emission wavelengths (300 to 850 nm) and lifetimes (0.3 ns to ms), 2) near real time analysis of fluorescence decays via a Laguerre deconvolution technique, and 3) compatibility with the clinical environment (endoscopic procedures or other intraoperative uses). The apparatus is currently employed for in-vivo studies of diseased tissues (cardiovascular and oncological applications).

In this work a compact fluorosensor has been built for point-monitoring and imaging applications. The instrument has been applied in fluorescence studies on green vegetation and on malignant tissue. The instrument is based on a violet diode laser, an integrated spectrometer and optical fibers for light delivery and collection of the fluorescence signal. This combination makes the system very compact. The high laser output power allows for coupling of the laser light into a hyperspectral diagnostic imaging instrument, developed and built by Science and Technology International. In point-monitoring mode, the instrument has been tested on superficial skin tumors and when using δ-aminolevulinic acid induced protoporphyrin IX as a tumor sensitizer, good contrast between normal and malignant tissue was achieved, clearly demonstrating its feasibility in cancer diagnostics. In imaging mode, the instrument functioned solely as a light source, coupling the excitation light into the hyperspectral imaging instrument. The set-up was tested by studying chlorophyll fluorescence from vegetation. The fluorescence signal showed a low signal-to-noise ratio mainly because of inefficient light coupling into the imaging instrument.

An imaging system that records autofluorescence images calibrated by the cross-polarized reflection images from excitation was instrumented to evaluate the capabilities of a calibrated autofluorescence imaging method for detecting neoplastic lesions. Cervical tissue was selected as the living tissue material. It was found that neoplastic lesions can be differentiated from surrounding normal tissue based on the contrast in the calibrated autofluorescence signals, which from neoplastic lesions were generally lower than that from normal cervical tissue.

This study investigates the potential of a new multi-modal lanthanide chelate complex for specifically targeting brain tumor cells. We report here results from ongoing studies of up-take, sub-cellular localization and binding specificity of this new molecular imaging probe. Fluorescence microscopy investigations in living rat C6 glioma tumor cells demonstrate that the new imaging agent has affinity for glioma cells and binds to mitochondria.

Tissue fluorescence spectroscopy and imaging are being investigated as potential methods for non-invasive detection of pre-neoplastic change in the lung and other organ systems. A substantial contribution to tissue fluorescence is known to arise from endogenous cellular fluorophores. Using steady-state and time-resolved fluorescence spectroscopy and imaging, we characterized the endogenous fluorescence properties of immortalized and carcinogen-transformed human bronchial epithelial cells. Non-invasive sensing of endogenous molecular biomarkers associated with human bronchial pre-neoplasia will be discussed.

cDNA-microarrays for expression profiling rely on the assumption that the fluorescence signal is linearly proportional to the concentration of the markers. Yet, interactions amongst different markers and with the substrate might affect the chromophore quantum yield and lead to an erroneous reading. To indirectly evaluate quantum yield changes and their relevance for DNA-microarray reading, we studied the effect on fluorescence lifetime by using a system for fluorescence lifetime imaging. Quenching of the fluorescence emission were observed in the tight environment represented by a DNA microarray due to concentration and to interactions with the processing chemicals present on the substrate.

Optical characterization of biopsies can be used to discern between tissues when performing diffuse optical tomography of the female breast. The theory used for deriving the optical properties of such highly scattering media is based on the diffusion approximation. However, focusing the study in the regime of geometries comparable to the scattering mean free path, the diffusion approximation must be rearranged. Here we present several theoretical assumptions in this direction. In order to investigate the validity of the improved theory, experiments were made involving the transmittance of laser light through turbid phantom models. After the validation of our theoretical model, we have managed to derive the optical properties of over 50 excised breast tissue samples.

The most comprehensive description of light scattering was obtained by simultaneous measurement of its spectral, angular, azimuthal, and polarization characteristics. In studies with physical tissue models consisting of aqueous suspensions of microspheres, we showed that this comprehensive information reveals the properties of the internal structure of the samples. In the studies with a rodent model of colon carcinogenesis, we demonstrated the feasibility of detecting slight alterations of tissue micro-architecture by recording the multi-dimensional data characterizing tissue light scattering. We showed for the first time that such light scattering "fingerprinting" can be used to detect changes in tissue micro-architecture even at the earliest pre-dysplastic stages of carcinogenesis, much earlier than currently known histological, molecular, or genetic markers.

The technique of scanning flow cytometery (SFC) was adopted for measurement of erythrocyte indices: volume, hemoglobin concentration and surface area. The method has been verified on two types of mammalian red cells: human and murine. In order to access distribution of values, precision and stability of inverse algorithm of reconstitution of size and refractive index of microsphere from light scattering angular dependency (indicatrix) have been increased performing analysis of Fourier spectrum of indicatrix. Volume - hemoglobin concentration (V-HbC) map was obtained following well-known procedure of isovolumetric sphering, presented by Technicon Instruments. Additionally new method for measurement of paired distribution of erythrocyte surface area (S) and hemoglobin content (Hb) was implemented via registration of spherical stage in the course of colloid-osmotic hemolysis. Approach to characterization with SFC of native red cells in nonspherical stage is demonstrated.

Fluorescence imaging has shown a potential for demarcation of basal cell carcinoma (BCC), which is the most common type of skin cancer. The technique is based on imaging the fluorescence from protoporphyrin IX (Pp IX), after application of α-5-aminolevulinic acid (ALA). One limitation with the technique is that it is sensitive for undesired local intensity variations. But it has been shown that by combining autofluorescence, i.e. fluorescence without any externally applied photosensitiser, and the Pp IX fluorescence, higher contrast between tumour and normal skin can be obtained. This has earlier been reported using a laser-based technique allowing for simultaneous recording of autofluorescence and Pp IX fluorescence. In this work we present a method, using a simple set up for multispectral imaging assisted by computerised image warping. The set up was evaluated investigating 9 patients with histologically verified BCC located in the face. Z-images, defined as the ratio between the autofluorescence and the Pp IX fluorescence images, were obtained and compared to the clinically marked tumour borders. Agreement with the tumour border was found in 8 out of the 9 patients. These results imply that multispectral fluorescence imaging is a potential diagnostic tool for demarcation of BCC.

Fluorescence diagnostic techniques are notable amongst many other optical methods, as they offer high sensitivity and non-invasive measurements of tissue properties. However, a combination of multiple scattering and physical heterogeneity of biological tissues hampers the interpretation of the fluorescence measurements. The analyses of the spatial distribution of endogenous and exogenous fluorophores excitations within tissues and their contribution to the detected signal localization are essential for many applications. We have developed a novel Monte Carlo technique that gives a graphical perception of how the excitation and fluorescence detected signal are localized in tissues. Our model takes into account spatial distribution of fluorophores and their quantum yields. We demonstrate that matching of the refractive indices of ambient medium and topical skin layer improves spatial localization of the detected fluorescence signal within the tissue. This result is consistent with the recent conclusion that administering biocompatible agents results in higher image contrast.

A novel Monte Carlo (MC) technique for photon migration through 3D media with the spatially varying optical properties is presented. The employed MC technique combines the statistical weighting variance reduction and real photon paths tracing schemes. The overview of the results of applications of the developed MC technique in optical/near-infrared reflectance spectroscopy, confocal microscopy, fluorescence spectroscopy, OCT, Diffusing Wave Spectroscopy (DWS) and Doppler flowmetry are presented.

We have conducted a preliminary study of the potential for diagnostic spectroscopy based on elastic light scattering to serve as a method for optically-guided biopsy to reduce sampling errors and thereby improve sensitivity, in detecting prostate cancer. This method also has the potential to provide real-time diagnostic assistance in surgical and treatment procedures.

Successful management of malignant melanoma depends on early detection and diagnostic accuracy. However studies have found a diagnostic accuracy of malignant melanoma amongst dermatologists of only 80% compared with histological diagnosis, results are generally poorer with family practitioners and dermatology trainees. Elastic scattering spectroscopy (ESS) is a non-invasive procedure that utilises elastically scattered light. A related technique, reflectance spectrometry, may discriminate between benign and malignant pigmented lesions in vivo. Objectives: We have therefore assessed an ESS biopsy system in the diagnosis of melanocytic lesions in vivo and compared the results to both clinical and histopathological diagnosis. Patients/Methods: One hundred melanocytic lesions from 77 patients attending our pigmented lesion clinic between 1999 and 2001 or seen at our Melanoma Day were examined clinically and divided into benign, dysplastic or malignant lesions. ESS spectra were acquired at several points from each lesion and adjacent normal skin. Lesions were then excised and sent for histological examination. Results: Lesions were histologically classified as 12 malignant melanoma (3 in-situ), 14 dysplastic naevi and 57 benign naevi (a further 17 clinically benign naevi were included which were not selected for excision). Clinical examination had a sensitivity of 75% and specificity of 91% for detection of malignant melanoma from other melanocytic lesions and overall diagnostic accuracy of differentiating melanocytic lesions of 71%. ESS spectral diagnosis classified by linear discriminant analysis indicated a sensitivity of 84% and specificity of 65% for detection of malignant melanoma from other melanocytic lesions. However the ESS spectral diagnosis included several readings per lesion and clinically this is not relevant. Therefore an ESS per lesional diagnosis was taken as the most aggressive diagnosis. This had a sensitivity of 100% and specificity of 75% for detection of malignant melanoma from other melanocytic lesions and overall diagnostic accuracy of differentiating melanocytic lesions of 69%. Discussion: These data suggest that ESS may be capable of differentiating malignant melanoma, dysplastic and benign naevi with a high sensitivity and provide adjuvant information to clinical examination by a dermatologist, which could be useful in the triage of melanocytic lesions.

Pigmented skin lesions have been studied by optical diffuse reflectance spectroscopy. Our measure system consists of a portable visible near infrared (550-1000 nm) spectrometer, tungsten-halogen lamp and fibre optic probes. The system was tested in steady state conditions. After that, a reproducibility study of normal and pigmented skin spectra was carried out. A small scale study has been conducted in human volunteers with different clinically evaluated lesions. The analysis of the collected spectra is shown.

There is currently a search for an automated, objective and non-invasive system that would accurately diagnose pigmented skin tumours. Systems that measure either the spatial or the spectral characteristics of light reflected from the skin have shown promise for this purpose but only a few studies have combined spatial and spectral information. We plan to study this and consequently need to construct a cost-effective research spectral imaging system but the design will require a compromise between spatial and spectral information. Here, the effect, on diagnostic accuracy, of reducing the spectral resolution of spectrophotometry data was studied. Also studied was the effect of reducing the spectral range to that of the sensitivity range of low-cost detectors. There was no significant fall in the diagnostic power when the spectral resolution was reduced from 3.8nm to 50nm, and when the spectral range was reduced from 320-1100nm to 400-1000nm. Therefore, in the design of the spectral imaging system emphasis was placed on spatial resolution and a standard detector was used. The spectral imaging system contains a broadband light source, diffraction grating monochromator and CMOS camera and achieves 10nm spectral resolution over a spectral range of 400-1000nm, with a spatial resolution of 40 microns over a field of view of 2cm.

We investigated a novel method combining principal component analysis (PCA) and supervised learning technique, support vector machine (SVM), for classifying carcinoma lesion from normal tissue with light-induced autofluorescence. The autofluorescence spectral signals were collected in vivo from 85 nasopharyngeal carcinoma lesions and 131 normal tissue sites from 59 subjects during routine nasal endoscopy. With the combined PCA and SVM classifying algorithm, the achieved overall accuracy is over 97%, companied with 95% sensitivity and 99% specificity for discriminating carcinoma from normal tissue. In comparison with the previously developed algorithms based on PCA method, this new method outperforms threshold- and probability-based PCA algorithms in all instances. The experimental results indicate great promise for autofluorescence spectroscopy based detection of small carcinoma lesion in the nasopharynx and other tissues.

The applicability of reflectance spectroscopy to detect pathological changes in human liver tissue was investigated. Post mortem reflectance spectra were collected from liver tissue originating from 13 individuals. A point counting method was applied to determine relative areas of connective tissue, liver cells with or without fat vacuoles, and vascular spaces in the liver. Preliminary results show that the amount of fat and connective tissue in liver can be estimated from reflectance spectra.

Terahertz frequency spectroscopic imaging studies of teeth are reported. The aim is to establish the characteristic properties of enamel and dentine at these high frequencies. Changes to the THz characteristics as a result of various types of tooth abnormalities are reported showing the potential of this technique for dental diagnosis

A new micro measuremen system - according to the principle of he EMPHO-System -has been developed to record tissue remission spectra within the range of 510 to 590nm. The device hardware basically involves a white LED,optical fibers,and a miniaturized grating spectrometer. In general,exact computation of blood oxygen saturation and relative hemoglobin concentration from these tissue remisson spectra is not possible. The main reason is that -except for oxyhemoglobin and desoxyhemoglobin -many other light-scattering and light-absorbing substances such as dopa-melanin and bilirubin cause measuremen errors. A new algorithm for the determination of local blood oxygen saturation and relative hemoglobin concentration from tissue remisson spectra is presented. This method is based on he probability of light photons propagation and reference coefficients. In addition, the algorithm also takes other light-scattering and light-absorbance substances in biological tissue into consideration. The method is compared with the standard procedure of Kubelka and Munk. Among others these two approaches are applied to the tissue remission spectra of ischaemia with subsequent reactive hyperemia. The calculated blood oxygen saturation and relative hemoglobin concentration of both methods are presented and discussed.

Raman spectroscopy has been employed to measure the varying concentrations of two oral bacteria in simple mixtures. Evaporated droplets of centrifuged mixtures of Streptococcus sanguis and Streptococcus mutans were analyzed via Raman microspectroscopy. The concentration of s. sanguis was determined based upon the measured Raman spectrum, using partial least squares cross-validation, with an r² value of 0.98.

When human tear film’s constituents are identified, it is diagnostically useful. Surface enhanced Raman scattering (SERS) can quickly measure, the components at their low concentrations. Reproducible spectra were collected from evaporated gold thin film and silver mirror reaction glass substrates. Synthetic tears were measured on optimised substrates as proof of principle. Further analysis was used to discriminate between diseased and normal tears.

The composition of human brain tissue and brain tumors were studied by near infrared Raman spectroscopy with 785 nm excitation. The amounts of lipids, cholesterol, protein and water in fresh specimens were determined from Raman spectra by a combination of pure component spectra. Normal brain tissue was found to contain higher levels of lipids and cholesterol, brain tumors such as glioma and meningeoma displayed less lipids and cholesterol, but more proteins, in particular more hemoglobin-like molecules. These results demonstrate the applicability of Raman spectroscopy for real-time, in vivo, intraoperative diagnosis.

The potential of optical spectroscopic detection for the early detection of malignancy is becoming more widely accepted. Many studies have demonstrated the potential of Raman spectroscopy for the identification and classification of malignant changes, with valuable insight into possible applications. However much of the work has been undertaken without clear recognition of the biochemical changes that distinguish between the different stages of malignant progression. Raman mapping experiments have been undertaken in an attempt to increase understanding of the biochemical changes involved in the development of oesophageal malignancy. Pseudocolour maps of the significant principal component scores have been generated. The peaks of the corresponding principal component loads have been identified, by comparison with constituent spectra and published spectral identities. Investigating the measured biochemical changes in greater detail, further demonstrates the potential of near infrared Raman spectroscopy for the analysis of biological tissue.

Here is presented a new method to detect and classify microorganisms from their polarimetric response in the mid-infrared range (2-12 μm) measured by FTIR ellipsometry. Apart from the ellipsometric measurements, the performance of the methods also stands on the simplicity of sample preparation and on the data analysis. Spectroscopic ellipsometry is a non-invasive optical characterization technique sensitive to the polarization of the light reflected or transmitted by a sample. The extreme sensitivity of ellipsometry allows the detection of minute changes on the sample surface, even at the monomolecular layer level. In the mid-infrared range each molecule exhibits a characteristic absorption fingerprint, thus making ellipsometry chemically selective. FTIR ellipsometry is used here for the first time to analyze bacteria grown in culture media. Sample preparation is extremely simple and consists of the evaporation of a droplet of an aqueous suspension of microorganisms on a planar surface. Ellipsometric measurements are performed on the solid residue left on the surface after the evaporation of the droplet. Data analysis can be divided in two steps. First, simplification of the measured spectra by Principal Component Analysis (PCA), which is one of the existing multivariate statistical techniques commonly used to eliminate redundant information. Second, classification of the simplified spectra using a standard clustering method. As a result, we show how this method can be employed to discriminate and identify bacteria at the species level. The results of this experiment are very promising for the application of ellipsometry for analytical purposes in biochemistry and in medicine.

Rupture of lipid-rich arterial atheromas is believed to be the cause of most acute coronary events. We show that high sensitivity and specificity in the detection of these lesions is possible through whole blood varying from 0 to 3mm using near-infrared reflectance spectroscopy. This enables the use of a non-occlusive, intra-coronary catheter to screen high-risk patients to guide therapy.

An optical tissue diagnosis technique, often called "optical biopsy", has been developed, It is based on the simultaneous determination of the optical properties of tissues such as the reduced scattering coefficient μ_s’ and the absorption coefficient μ_a. These data are obtained by applying a small diameter probe (ψ 2mm) on tissues, through the working channel of usual endoscopes. The simultaneous determination of μ_a and μ_s’ with a local probe was made possible by the consideration of the first two moments of the phase function and a proven model of light propagation in tissues at propagation length comparable to the scattering mean free path. Non-invasive measurements of the optical coefficients of superficial tissues have been obtained in vivo (stomach) at different wavelength.

Hexyl aminolevulinate (HAL) fluorescence cystoscopy is being investigated as a new diagnostic tool for the detection of flat urothelial malignancies in bladder cancers. However, the influence of the bladder instillation time on the performance of this detection modality has not been addressed up to now. We report our initial experience comparing different instillation schedules of HAL cystoscopy in the diagnosis of superficial bladder cancer. A total of 718 fluorescent positive (433) and fluorescence negative (285) biopsies have been taken in the bladder of 143 patients using the Storz D-light fluorescence imaging system (Karl Storz, Tuttlingen, Germany) which allows both white and blue light (380-450 nm) bladder wall inspection. Following hospitalisation, 50 ml of HAL (8mM) phosphate buffer solution was instilled into the bladder of patients during one hour (1 hour protocol involving 57 patients), or during two hours followed by a two hours resting time after removal of the solution (2+2 hours protocol involving 86 patients). Both instillation subgroups were homogeneous in terms of proportion of high risk disease, previous BCG treatment and/or recurrent disease. This study indicates that the instillation duration does not influence the results of HAL (Hexvix) fluorescence cystoscopy in our conditions. Compared to the standard use of ALA, HAL (Hexvix) fluorescence cystoscopy allows a significant reduction of the instillation time (to less than one hour) without prejudicing the efficacy of the method, what represents a real advantage in daily clinical practice.

Breast cancer is the most commonly occurring cancer in women. The lifetime risk of being diagnosed with breast cancer is approximately 1 in 10 thereby the highest out of all cancers. Breast cancer screening programs have been shown to decrease the mortality rates of women between ages 50-69, since cancers are detected at an earlier, more favourable stage. It is apparent that the development of breast cancer is a slow process following initial transformation of the breast tissue. Hence, there has been a strong effort within the research community to understand risk factors for the disease. Risk factors are defined as those characteristics that are more common in people with the disease when compared to the normal population. Quantification of an individual's breast cancer rate may lead that individual to modify her lifestyle and/or diet. Lifestyle changes could lead to a reduction in the incidence of breast cancer. Anatomically, the presence of increased amounts of fibroglandular tissue raises the estimated risk by up to 6 fold (correct for age), hence representing one of the strongest known risk factors pertaining to the entire female population. In this study the relative area of mammographic densities within a mammogram will be used as a global risk assessment tool. It has been shown previously that quantification of water, lipids, haemoglobin and other tissue chromophores of the optically interrogated breast tissue, which also gives rise to the mammographic densities, is feasible through near-infrared spectroscopy. Thus, the hypothesis for this study is that optical transillumination spectroscopy provides consistent and/or complementary information to conventional mammography in quantifying breast tissue density.

Type 2 diabetes mellitus is a global epidemic with the number of affected subjects exceeding 4% of the adult population world-wide. Undiagnosed and untreated, the disease results in long-term complications such as myocardial infarction, stroke, and blindness. Treatment reduces the number and severity of long-term complications but treatment is often delayed by a time-lag of 10 years or more from the onset of disease to diagnosis. Earlier diagnosis can be achieved by systematic screening programs but the potential time won is unknown. The aim of the present study was to develop a mathematical model estimating the prediagnostic duration of type 2 diabetes mellitus using lens autofluorescence as an indicator of lifetime glycemic load. Fluorometry of the human is lens a quantitative measurement which is attractive because of the ease by which it can be performed. It is our hope that lens fluorometry will prove useful in estimating the prediagnostic duration of type 2 diabetes mellitus in population studies, a property of profound clinical relevance that is difficult to estimate by any other currently available method.

We investigated 48 normal patients and 25 diseased patients using our laser-induced autofluorescence spectra detection system during their regular colonoscopy. The colon and rectum mucosa autofluorescence were excited by 405 nm continue wavelength laser. We observed that cancer or diseased colorectal mucosa, their autofluorescence spectra are significantly different from normal area. The autofluorescence spectra intensity at about 500 nm was been used for our intensity ratio characteristics intensity for our diagnostic algorithm. The intensity ratios of R_I-680/I-500 and R_I-630/I-500 were performed to identify the detection area. From experimental result we concluded that both intensity ratios of R_I-680/I-500 and R_I-630/I-500 as guidelines can detect cancerous and polyps disease completely. Our investigation provided some useful insight for laser induced autofluorescence spectra as a diagnosis technique for clinical application.

Raman Spectroscopy is an optical diagnostic technique applied in this study to characterise breast tissue by biochemical signature spectra. In cross-validated results, Raman Spectroscopy identifies invasive breast carcinoma with 75 - 97% agreement with Histology opinion. Axillary lymph nodes from patients with breast carcinoma were mapped with confocal Raman Spectroscopy and colour-weighted principal component analysis (PCA) images were used to identify local biochemical features and correlate these with parallel section slides analysed with routine histology.

Based on thousands cases, the discrimination in auto fluorescence Raman spectra between serum of normal human and cancer patients are found. The criteria for diagnosing cancer are also obtained after statistical analysis over experiment results. The accuracy of serum spectrum detecting results of esophageal cancer human is 82.7%. In addition, we find the resonate Raman frequency of guanine base in DNA sample depending on ultraviolet resonate Raman spectrum. The resonant Raman shifts of guanine base in DNA sample are 1337cm^-1 and 1485cm^-1 . And the resonant wave-length is 250nm.

Recently,non-inv sive diagnostic devices using infrared light have been developed and widely use for clinical applications. To develop these devices, optical properties of biological tissue are necessary. We proposed new optical measurement method. By using time-resolved reflectance spectroscopy and Monte Carlo simulation for the analysis of light propagation in sample, it is considered that this new method is able to measure the optical properties of small biological tissues in vivo. In this study,we investigated the possible optical property measurements of superficial layer using this new method. As the later part of the profile of time-resolved reflectance is influenced by the optical property of the deeper layer, time-gating technique is necessary for the measurement of the optical properties of only the superficial layer in order to use the early profile of the time-resolved reflectance measurement. The function f(t), which is described in the new method, is used for evaluation of the measurement of the superficial layer. We suggest that by using the time-gating technique for the new method and small source-detector spacing, the optical properties of the superficial layer with thickness is more than source-detector spacing, can be obtained.

Diagnosis established by means of fluorescence spectroscopy is currently used in the field of urology and bronchology. Its major advantage is that it allows the diagnosis of epithelial dysplasia or malignant proliferation even if routine diagnostic endoscopy fails to reveal any macroscopic changes. The authors present results of their observations that deal with fluorescence diagnosis of colorectal carcinoma. They examined the wet microscopic mounts of healthy colon mucosa and compared them to that prepared from colon mucosa affected by adenocarcinoma. The diagnosis of adenocarcinoma was verified by using clinical and histology means. Fluorescence spectra of tissue samples, excited by means of 488 and 514.5 nm lines of Ar ion laser and/or by He-Ne laser line 632.8 nm, have been studied. This study demonstrated differences in both the spectral shape and in the signal intensity (at unchanged spectral shape) of photoluminescence spectra emitted from tissue affected by adenocarcinoma as compared to that of healthy colon mucosa. The results encourage us to continue the study aimed at development of the diagnostic system usable in the clinical practice.

In this paper we describe a compact, portable light-emitting diode (LED)-based fiber-optic system allowing in vivo diffuse reflectance spectra registration in visible and near IR spectral range at two distances between illuminating and collecting fibers. The construction of fiber optic probe is adapted for endoscopy application. We further report the preliminary results of in vivo discrimination between of the benign and malignant tissues and different types of malignant tissues in the animal models.

Dynamic scattering of coherent light by moving particles causes a Doppler shift of the original frequency, depending on the velocity and the scattering angles. This phenomenon was used for the detection of abnormal spontaneous muscle activity caused by the denervation of muscles. Transmission measurements of low frequency modulated laser irradiation have been made in 110 denervated first dorsal interosseous who had previously been imposed to electromyography which detected abnormal activity. Measurements have also been made in 173 normal muscles. The laser used was a diode laser emitting at 830nm and a pulse generator modulated the laser radiation to a low repetition frequency of 84Hz. While passing through the denervated muscles, the incoming laser beam gets a frequency shift due to the contraction of the denervated muscle fibers and mixes with the ballistic part of the beam. To analyze the inherent information the outcoming laser light was transformed into electric current by a photodiode and the signal after being selected by an A/D card was submitted to the Fast Fourrier transformation. The findings of our suggested method have been compared to those of the normal muscles as well as to the electromyographic findings of each denervated muscle.

Directional dependence of reflected laser light and of the laser induced fluorescence signals performed both on the intact hard dental tissues, such as enamel, dentine, cementum and on the tissues pathologically affected by caries (superficial, intermediate, and deep). The laser induced fluorescence spectra were collected at different angles of observation and were correlated with the different scattering and reflectance properties of the hard dental samples

Laser-induced fluorescence and Raman spectra were measured from normal and tumorous human blood serum in an attempt to discover some values useful in discrimination between normal and tumorous cases. Red shift of fluorescence peak and decrease of fluorescence intensity were observed after samples radiated by laser. According to one thousand twenty-two samples’ spectra, three parameters α, β and Δλ are introduced to distinguish normal, benign and malignant from one another. The application of such parameters in clinical diagnosis was researched. The practical instrument of laser-induced serum fluorescence and resonance Raman spectra for cancer diagnosis or incipient cancer is designed, by combining laser spectroscopy, biomedical, photo-electron technology, controlling technology and computer technology. The instrument is intelligent for operating and diagnosing. The clinic application of this instrument has been carried out successfully in the diagnosing of some cancer (such as stomach cancer, liver cancer, etc); the accuracy is about 85%. It develops a new technology in the field of cancer diagnosis.