Neoplastic tissue can be detected by its increased fluorescence compared to surrounding normal tissue after the injection of the tumor-localizing compound Photofrin®. In vivo fluorescence photometry is a non-imaging photodetector which detects the 690 nm fluorescence of the porphyrin. The sensitivity of the instrumentation has allowed the detection of micrometastases in both pre-clinical and clinical studies using low, non-photosensitizing levels of the drug. The technique is now being applied to the 9,10 dimethyl-1,2-.benzanthracene (DMBA)induced hamster buccal cheek pouch carcinoma model to obtain data on the correlation between Photofrmn® uptake and tumor development. This model shows consistent time patterns of tumor development as well precancerous leukoplakia lesions and has been well documented as an animal model of oral epidermoid carcinogenesis. The buccal cheek pouches of Syrian Golden hamsters were exposed to a 0.5% DMBA in acetone thrice weekly for specified time durations. Hamsters were subsequently injected with 1.0 mgfkg of Photofrmn® within the various stages of tumor development. Twenty-four hours post-injection, fluorescence due to drug uptake was measured by in vivo fluorescence photometry. Mucosal tissues were subsequently biopsied and used for extraction assays. Results demonstrate that Photoflin® is retained in DMBA treated tissue with a linear relationship between length of application and Photofrin® uptake and fluorescence. This relationship establishes that premalignant lesions can be distinguished from normal tissue by Photofrmn® uptake and fluorescence and suggest that Photofrmn® uptake and fluorescence can be used in a predictive manner to diagnose and determine the progression of individual lesions.

Visualization of earlystagecancer turnsout to be a keypoint in dinical oncology. Ruorescence detection of systemicallyadministered dyes provento accumulate in tumors is one type of diagnostic procedure. The occurrence of endogenous chromophores in malignant tissue has been observed through laserinduced fluorescence in the red spectral range between 550nm and 750nm. Following lumination aftemating between violet and blue lines from a Kr-laser, an optkal mu1tkhanne1 analyser has detected fluorescence in defined areas wfthin chemically induced bladder tumors in rats. The same technique has also been used for the quantitative comparison of fluorescence in human gastrointestinal tumors in nude mice in-vivo. Results show that endogenous porphynns are present in rat bladder tumors as well as in gastrointestinal tumors in nude mice. A correlation between the porphyrin-related fluorescence signal and the histopathological examination indicates that the porphyrin content is dependent upon the tumor grading.

on the basis of clinical protocols, phase Il-studies have been started to evaluate photodynamic diagnosis (PDD) for early visualization of cancer in bladder and lung. As tumor marker the fluorescent and photosensitizing polyporphyrin Photofrin II is used in a dose, which has been proven to avoid photosensitization of the patients skin. The drug is administered systemically in a concentration of mostly 0,4 mg/kg bodyweight. Fluorescence of Photofrin II in tissue is detected by an image intensifying CCD-camera coupled to endoscopes usually used in both medical disciplines. Video presentation of the marker fluorescence occurs with high contrast due to realtime image processing following two wavelength excitation of the tissue with laser light. Keypoint of the new diagnostic method is the correlation of the fluorescence contrast and the histological examination of biopsies removed from these areas. As example 87 biopsies has been taken from 1 7 patients suffering from bladder cancer. While all tumorous samples (n = 1 6) show strong fluorescence, about 30% of the biopsies are judged as false positive. A variety of premalignant diseases has been found in these sections. No false negative results are obtained up to now.

Interstitial tumor therapy guided by imaging techniques is a minimally invasive and promising surgical approach which will become clinically practical only when simple and safe modalities of control of vascular supply to tumors are available. In a novel experiment utilizing the Advanced Technology Laboratories Mark IX/HDI (Bothell, Washington) ultrasound scanner, the carotid artery (approximately 2.5 mmin diameter) of a New Zealand white rabbit was identified and then clamped using the Endo-Clip' disposable applier with medium-large clips. The Mark lx, equipped with a 10 MHz linear array transducer, guided and localized the tip of the EndoClipt1 tO therabbit's carotid artery. The artery was then clamped, and the Mark IX showed the cessation of blood flow within the carotid. The experimental result is revolutionary since the ultrasound not only provided the visualization of the arterial vessel, but also helped guide the surgical instrument used for clamping. The scanner provides a diagnostic medium comparable to that of Digital Subtraction Angiography, but without the need of intravenously injected contrast materials. More importantly, ultrasound has the ability to discern not only anatomical features, but also foreign objects, such as surgical instruments or clips. This additional feature of ultrasound, discerned from our experiment, provides further insight into the use of this kind of diagnostic modality as a monitor during vascular surgical procedures. A minimally invasive transcutaneous entry procedure is thus possible with the use of high spatial resolution scanner guidance to desired vessels. The ramifications of this experiment are far reaching, since technology with greater soft tissue contrast and the abifity to visualize the irreversible effects of energy deposition in tissues exists with Magnetic Resonance Imaging (MRJ). The feasibility of this approach has been ascertained via the above experimental fmding, and now needs to be further pursued.

Cultures of human leukemic undifferentiated cells (named FLG29. 1) and saphenous vein internal wall were studied by IR microscopy and ATR techniques, respectively. The effect of cell differentiation into osteoclastic characteristics induced by TPA enzyme was tested. Two different pools of differentiated and undifferentiated cells, carefully washed with saline, were centrifuged on BaF2 discs, dried in a vacuum chamber and measured by an IR-PLAN' microscope. Five cell filled fields and one empty field were selected by visual inspection for sample and reference IR measurements respectively. The effect of freezing on the endothelial venous wall was tested using 5 independent segments cut longitudinally into two parts, one of which was stored for 2 hours in liquid nitrogen. The fresh and defrosted samples were gently dried by gauze imbibition and flattened on the free surface of a ZnSe crystal, for ATR measurements. In both cases JR spectra were taken at 4 cm' resolution in the range 4OOO--7OO cm' and were analyzed by measuring the peak frequency and the area beneath 14 absorbing bands. Peak frequency shifts were tested by analysis of variance. Band areas were compared by analysis of covariance, with reference to amide II band. Results. In the FLG cells spectra, statistically significant frequency shifts were found in the regions of CH3 and esthenc CO stretching (p <0.001) and in the areas of the bands peaked at 2926, 2860, 1740, 1 186 and 1087 cm' (at least p <0.02). In venous wall spectra no significant (p <0.2) effects due to freezing were revealed.

Near infrared optical spectroscopy (NIR) is a recognized technique for the study of the cellular oxygen metabolism, and oxygen delivery to the tissue. During the last few years, this technique has become useful for the study of the regional cerebral oxygen saturation (rSO2); however, up to date no report exists showing the values of the normal variability of the rSO2 in humans. In the present study, rSO2 was measured via in vivo optical spectroscopy (INVOS 2910, Somanetics, Troy, MI) in 100 randomly selected adults (aged 16 to 78), who displayed no symptoms nor clinical signs of cerebral disorder. The sample population consisted of 51 males and 49 females (16 to 78 years old); 27 had dark skin and 73 had light skin. The mean rSO2 found was 68.6 5.6. The relationship between mean rSO2 and age was studied using the regression analysis. No association between age and rSO2 was found (p = 0.132). The correlation of mean rSO2 with sex and with color were evaluated by a two sample t-test for each. There was no significant difference between the mean rSO2 for females and the mean rSO2 for males (p =0.132). However, the mean rSO2 for light skin individuals was significantly higher than the mean rSO2 for dark skin individuals (rSO2 =69.50 forlight skin, rSO2 =66.15 for dark skin; p =0.0078). The advantages of infrared spectroscopy are evident; this is a noninvasive, simple, relatively inexpensive technology, easily interpreted and suitable for continuous monitoring of rSO2 at bedside or during brain surgery. We consider NW infrared spectroscopy the best actual technique for early detection of acute cerebral hypoxia, and a method for anticipation of undesirable outcome in these patients.

Time dependent records obtained with a cerebral oximeter are presented. Case studies include the monitoring of patients undergoing neurovascular and open heart procedures during conditions of extracorporeal circulatory support, deep hypothermia and circulatory arrest. An example of a response curve during injection of infrared tracer into the cerebral circulation is presented; recordings of desaturation periods as a result of induced hypoxia in adult volunteers are included.

The long term goal of this research is the development of an implantable miniature intracranial pressure (ICP) sensor based on a transmissive optical approach. The proposed sensor will be composed of a pressure sensing membrane, an optical transmitter and receiver, and a signal transport mechanism. Two transpoit mechanisms were investigated one using a fiber optic approach and the other a telemetric approach each of which would be used depending on the desired application of intracranial pressure monitoring. Once implanted this sensor could not only be used to continuously monitor ICP but also be used in the development of a new generation of "smart" hydrocephalus shunts to provide feedback from intracranial pressure measurements to control flow through the valve. The current treatment of hydrocephalus relies on implantable shunts which employ passive, pressure operated, mechanical valves. These valves and their associated components must be selected by the surgeon such that the rate of flow through the shunt at the desired maximum pressure is in balance with the given rate of cerebrospinal fluid accumulation. Difficulties with the biomechanics and confounding by the changes in the condition of the patient with time lead to a high rate of complications in hydrocephalus shunting. It is envisioned that in the new design the passive opening of the shunt valve will be replaced by direct pressure detection using the proposed sensor, a control module, and an electronically operated valve. With this design the surgeon could select diverse pressure/flow characteristics to match the individual patient, to tune the device to accommodate changes in the patient, and to monitor the ICP signal externally. The primary focus in this article is to describe the preliminary design of the optically based implantable ICP sensor and present the in vitro results obtained from the optical bench top prototype.

Blood hematocrit is routinely determined in the clinic by analysis of blood samples. This paper introduces an non-invasive method for measuring arterial blood hematocrit which, when combined with pulse oximetry, potentially enables simultaneous monitoring of hemoglobin concentration and oxygen saturation. It is based on the same principles underlying pulse oximetry, except two light sources that emit close to isobestic wavelengths of oxy/deoxyhemoglobin in the near-infrared band (800 nm and 1300 nm) are employed. Hematocrjt is related to the ratios of the pulsatile and nonpulsatile components of the diffuse intensity transmitted through a blood-perfused tissue at these wavelengths. To test the feasibility of the method, we developed an in vitro light-scattering model with optical properties similar to those of skin tissue. Measurements were made using semiconductor light sources and detectors. We discuss the experimental results in the context of theoretical predictions that show the effect of variations in the volume fraction of blood and water in tissue. Finally, potential problems concerning calibration in a clinical setting are addressed.

Near infrared light generated by specialized instrumentation was passed through artificially oxygenated human blood during simultaneous sampling by a co-oximeter. Characteristic absorption spectra were analyzed to calculate the ratio of oxygenated to reduced hemoglobin. A positive linear regression fit between diffuse transmission oximetry and measured blood oxygenation over the range 23% to 99% (r² equals .98, p < .001) was noted. The same technology was used to pass two channels of light through the scalp of brain-injured patients with prolonged, decreased level of consciousness in a tertiary care neuroscience ICU. Transmission data were collected with gross superficial-to-deep spatial resolution. Saturation calculation based on the deep signal was observed in the patient over time. The procedure was able to be performed clinically without difficulty; rSO₂ values recorded continuously demonstrate the usefulness of the technique. Using the same instrumentation, arterial input and cerebral response functions, generated by IV tracer bolus, were deconvoluted to measure mean cerebral transit time. Date collected over time provided a sensitive index of changes in cerebral blood flow as a result of therapeutic maneuvers.

A new cerebral oximeter which monitors field saturation in the human brain continuously and noninvasively is described. An overview of the features of the equipment is presented. The basic function of the equipment is illustrated with examples of absorption of infrared light in a homogeneous scattering medium. A clinical test result demonstrating the effectiveness of the system is included.

This paper addressed two important aspects of dental analysis: (1) location and (2) identification of the types of teeth by means of 3-D image acquisition and segmentation. The 3-D images of both maxillaries are acquired using a wax wafer as support. The interstices between teeth are detected by non-linear filtering of the 3-D and grey-level data. Two operators are presented: one for the detection of the interstices between incisors, canines, and premolars and one for those between molars. Teeth are then identified by mapping the imprint under analysis on the computer model of an 'ideal' imprint. For the mapping to be valid, a set of three reference points is detected on the imprint. Then, the points are put in correspondence with similar points on the model. Two such points are chosen based on a least-squares fit of a second-order polynomial of the 3-D data in the area of canines. This area is of particular interest since the canines show a very characteristic shape and are easily detected on the imprint. The mapping technique is described in detail in the paper as well as pre-processing of the 3-D profiles. Experimental results are presented for different imprints.

Recent advances in fluorescence spectroscopy of the lens reveal the potential of a non-invasive device and methodology to sensitively measure changes in the lens of the eye associated with diabetes mellitus. The system relies on the detection of the spectrum of fluorescence emitted from a selected volume (approximately 1/10 mm³) of the lens of living human subjects using low power excitation illumination from monochromatic light sources. The sensitivity of this technique is based on the measurement of the fluorescence intensity in a selected region of the fluorescence spectrum and normalization of this fluorescence with respect to attenuation (scattering and absorption) of the incident excitation light. The amplitude of the unshifted Rayleigh line, measured as part of the fluorescence spectrum, is used as a measure of the attenuation of the excitation light in the lens. Using this methodology we have demonstrated that the normalized lens fluorescence provides a more sensitive discrimination between diabetic and non-diabetic lenses than more conventional measurements of fluorescence intensity from the lens. The existing instrumentation will be described as well as the proposed design for a commercial version of the instrument expected to be ready for FDA trials by late 1992. The results from clinical measurements are used to describe a relationship between normalized lens fluorescence and hemoglobin A1c levels in diabetic patients.

Differences in the oxygenation state of benign and malignant breast biopsies, and human breast cancer xenografts in immune-deficient mice were monitored using a spectrophotometer with integrating sphere. The breast biopsies were maintained below -50 degree(s)C and the mouse model tumors maintained in growth medium at 0 degree(s)C. Tissue sections 500 (mu) thick were allowed to come up to room temperature for mounting between quartz slides and were evaluated over the wavelength region 240 - 2500 nm. Data collection was done within 10 minutes of the removal of the biopsies from storage and, within 5 minutes for the xenografts. That this preparation protocol allowed us to study the samples very close to the in- vivo state was evident from the lack of deoxyhemoglobin in the benign samples. Component analysis performed in the 300 - 800 nm region showed that the malignant samples contained predominantly deoxygenated blood while the benign samples exhibited oxyhemoglobin signature. Absorption peaks due to fat and traces of bilirubin were also resolved in some of the samples. Assuming that the samples are very nearly representative of the in-vivo condition, these hemoglobin differences may well serve as a basis for imaging tumors or, for tissue characterization in a minimally invasive environment.

A new method to estimate airway mucosa blood perfusion is proposed based on the fluorescein perfusion fluorometry principles, which allows both high temporal resolution and high sensitivity measurements to be performed. Preliminary results were obtained on different conditions of rat trachea vascularization, which provide interesting perspectives for an application to the bronchial ischemia problems in lung transplantation.

In quite a large number of disorders, reduced flexibility of red blood cells (RBC) can be detected. In cardiovascular diseases it is supposed that rigidification of RBC may be regarded as a pathogenetic factor aggravating ischemia by disturbing capillary perfusion. Most methods established so far to estimate RBC deformability are hard to standardize and include large measurement errors. We present a low-cost system to determine RBC shape and flexibility. It combines laser diffraction of RBC in Couette flow with automated computer assisted image analysis. Effortless handling allows the system to be used for RBC elongation measurements even in routine diagnostics. Analysis of the whole information content of diffraction patterns reduces errors due to noisy diffraction patterns of working a little off axis. The system allows detection of very small changes in flexibility (less than 5%). The accuracy of measurement is not affected by variation of hematocrit or the intensity of transmitted light. Using the newly developed system it is demonstrated (1) that mechanically induced RBC rigidification may occur without hemolysis; (2) that in photodynamic therapy (e.g., pheophorbide A) RBC rigidification occurs during irridation; and (3) that in-vitro aging of conserved blood may partly be inhibited by calmodulin antagonists (e.g., fendiline).

In our previous list of various technologies for our program for laser induced subsurface imagery, we have added these additional procedures: polarized light, confocal microscopy, and intravascular Doppler for kinetic imagery with the 3-D volumetric scanner display. To the report of Phase I, transillumination, we now add transillumination with single or multiplex fiber optics. This provides for the development of deeper imagery, either directly or by diffusion of tissue. For cancer foci, with added specific chromophores, fiber optics in this PDT program can produce imagery directly in the tissue by the fiber optic or by induced fluorescence of the cancer mass.

The three techniques of CW, time-gated, and frequency modulation measurements are examined and compared for their ability to provide clues to the macroscopic optical properties of multilayer random media. For each illumination scheme, a simple algorithm is described which is capable of identifying important parameters such as the ratio of macroscopic absorption cross-sections across layer boundaries, and the depth of boundaries in two- and three-layer media. The algorithms are developed by consideration of data from Monte Carlo simulations, and in the case of the time- and frequency-domains, are tested by using them to analyze experimental data.

A method for the reconstruction of 3-D images of the interior of dense scattering media, based on the analysis of time-resolved backscattered signals is described. The method evaluates a linear perturbation equation by a progressive iterative backprojection scheme. A key feature of the method is the use of weighting functions which estimate the impact that absorption of photons in the interior have on the response of detectors located at the surface. Examples of reconstructed images shown are based on the analysis of simulated data for multilayered media and simulated and experimental data for media containing finite-volume absorbers. These results contain features which indicate that images having high resolution are obtainable even in the limiting case where the view angle is restricted to only backscattered signals and the absorption contrast across an interior boundary is 1%. A general scheme, similar to a layer- stripping approach, is described for the case where signals emerging about a target are measured.

Attempts to recover images from objects which diffuse radiation pose an especially challenging problem in terms of defining a suitable reconstruction algorithm and with regard to identifying an appropriate computing environment for efficient processing. In this paper we consider both issues and, in particular, describe results of an algebraic technique for imaging the interior of objects which diffuse penetrating radiation using a new multicomputer environment. Two important issues which arise when considering the numerical solution of ultra large problems are the numerical precision achieved and the overall computing efficiency. Our interest in this problem concerns the possibility of obtaining 3-D optical images of tissue which could identify the availability of oxygen by evaluating oxygen- dependent changes in the near infrared spectrum of hemoglobin. These studies were motivated by recent reports from our group and others, which showed promising results for imaging in dense scattering media given only diffusely scattered signals. In our model we assume the use of an NIR laser to provide the input radiation and suitable detectors to measure both transmission and backscatter. In our present work we assume a simple Markov process model for the way in which the energy travels in the medium, but it should be noted that the reconstruction technique we propose can use any model, including nonlinear as well as linear effects, and higher order processes. Current simulations are in 2-D but the methods are easily extended to 3-D. The algorithms we propose are more closely related to algebraic reconstruction algorithms such as ART, SIRT, and SART than to algorithms based on the Born and Rytov approximations such as used for tomographic imaging with diffracting sources. Our algorithms are a significant departure from those based on these standard algebraic methods. We assume only a probabilistic knowledge of the path of the radiation, and minimal knowledge of the absorption profile of the medium. In more traditional algebraic methods, a matrix, w, is assumed, where w_ij represents the fractional area of the jth image cell intercepted by the ith ray. The equation which is solved is w]^*f] equals p], where f] represents the absorption of each of the cells and p] the detector readings. It is assumed that [w] is known. Typically the dimension of p] is M and the dimension of f] is N, where M < N in most cases of practical interest. Standard methods are available for the solution of such equations such as least squares, linear programming, or the Kaczmarz method. We propose a different model of the physical problem. We assume that the radiation entering the medium travels through the medium according to some well defined probabilistic model which can be simulated using relaxation techniques. An example of a relaxation technique is the solution of Laplace's equation using the standard five point grid template. That computational model is based on a simple discrete approximation to the partial differential equation.

This paper describes an iterative perturbation approach for imaging the absorption properties of a dense scattering medium. This method iteratively adjusts a current estimate until the calculated photon fluxes for the estimated medium match the detected readings. The inverse update in each iteration is accomplished by solving a linear perturbation equation. It is similar to the compensation theory method used in electrical impedance tomography. A comparison was made between the methods of conjugate gradient descent and projection onto convex sets for the solution of the perturbation equation. The former converges more rapidly, but can yield an inaccurate solution where the problem is underdetermined. The latter can incorporate many types of a priori information to reach a correct solution, but progresses very slowly. A multi-grid, progressive reconstruction technique is proposed, which computes the fine details with the help of the coarse structure. It is quite effective in forcing the correct solution and reducing computation time. These methods have been used to reconstruct several inhomogeneous media containing simple structures, from steady-state reflectance data. Two sets of data are tested: one calculated according to the perturbation model, and the other using Monte-Carlo methods. When the difference between the absorption distributions of the test medium and the initial estimate is localized, a single step of the perturbation approach can resolve the absorption distribution reasonably well to within 5 transport mean free pathlengths from the surface. At greater depths, the reconstruction is less reliable.

An exact interface condition for photon diffusion is derived. The condition involves a single parameter, which depends on the index of refraction. Exact formulas are given for this parameter, which is also plotted.

The acousto-optic tunable filter (AOTF) spectrometer has been used to measure various gases of clinical interest using infrared spectroscopy. The AOTF is a birefringent crystal capable of high speed, random wavelength access. Various crystals can cover the range from 250 nm to 5 microns. Infrared transmitting fibers have been used for remote diagnostics of carbon dioxide and anesthesia gas. We will report on system specifications such as sensitivity, noise, and drift.

Reconstructing deep-tissue images in real time using spectrophotometric data from optically diffusing thick tissues has been problematic. Continuous wave applications (e.g., pulse oximetry, regional cerebral saturation) ignore both the multiple paths traveled by the photons through the tissue and the effects of scattering, allowing scalar measurements but only under limited conditions; interferometry works poorly in thick, highly-scattering media; frequency- modulated approaches may not allow full deconvolution of scattering and absorbance; and pulsed-light techniques allow for preservation of information regarding the multiple paths taken by light through the tissue, but reconstruction is both computation intensive and limited by the relative surface area available for detection of photons. We have developed a picosecond times-of-flight and absorbance (TOFA) optical system, time-constrained to measure only photons with a narrow range of path lengths and arriving within a narrow angel of the emitter-detector axis. The delay until arrival of the earliest arriving photons is a function of both the scattering and absorbance of the tissues in a direct line between the emitter and detector, reducing the influence of surrounding tissues. Measurement using a variety of emitter and detector locations produces spatial information which can be analyzed in a standard 2-D grid, or subject to computer reconstruction to produce tomographic images representing 3-D structure. Using such a technique, we have been able to demonstrate the principles of tc-TOFA, detect and localize diffusive and/or absorptive objects suspended in highly scattering media (such as blood admixed with yeast), and perform simple 3-D reconstructions using phantom objects. We are now attempting to obtain images in vivo. Potential future applications include use as a research tool, and as a continuous, noninvasive, nondestructive monitor in diagnostic imaging, fetal monitoring, neurologic and cardiac assessment. The technique may lead to real-time optical imaging and quantitation of tissues oxygen delivery.

The years of research and clinical study of brain oximetry using continuous light has brought to the attention of medical scientists and clinicians the great advantage of simple, economical, portable, optical methods, on the one hand, and the need for precision, reliability of calibration, and absolute quantitation, on the other. As the usefulness of the device increases, so do the demands for reliability and precision.

Due to lack of optimal properties of the officially admitted photosensitizer hematoporphyrin derivative (HPD), new sensitizers with better properties, such as the main absorption in the visible red range, higher chemical stability, higher tumor selectivity, and lower skin and dark toxicity, have to be found and investigated. In the present study, the effect of Photosan as active fraction of HPD was compared to Photofrin, HPD, HPD enriched with monomers (HPD-M) and polymers (MPD-P), to aluminum chloride tetrasulfonated phthalocyanine (AlClTSPc) and meso-tetraphenylporphyrin tetrasulfonate (TPPS₄). Test parameters in fast screening tests were the membrane integrity of human skin fibroblasts, singlet oxygen and hydroxy radical formation, and absorption and fluorescence properties. The screening tests used were a modified trypan blue exclusion test, an oxygen consumption measuring set-up with polarographic electrodes (Clark-style) and absorption and fluorescence spectrophotometry. While HPD, HPD-M and Photofrin II were highly efficient in the membrane integrity testing compared to Photosan III, HPD-P and AlClTSPc showed less efficiency and TPPS almost no membrane related activity. When HPD and related compounds were taken, the efficiency of induction of the membrane damage was in general correlated with the formation of reactive oxygen species and with the monomer content of the substance.

The results of investigations connected with stomach and lung cancerous tissue diagnostics and identification with a laser-endoscope spectroanalyzer are presented in this paper. Spectral measurements were carried out with endoscopy during surgery and after ektomy. It has been known since the beginning of this century that tumors have specific red fluorescence under UV light. We used this fact as a diagnostic criterion. However, we concluded that the most effective method of sensitive and reliable diagnostics was based on the simultaneous registration and scattering of autofluorescence from laser light applied for excitation. It should be noted that fluorescence is excited and registrated in the red spectral range. Application of this method allows for the identification of malignant lung and stomach tumors, as well as cancerous disease parabronchial or undermucousal tumors which can be inaccessible with known endoscopy procedures. The method also makes it possible to distinguish malignant and benign tumors. The relative simplicity and low cost of this technique allow the hope of good clinical applications in the near future.