The objective of the study was to design and to investigate laser fiber delivery system for treatment of obstructed human internal tubular organs using endoscopic techniques. This system eliminates the main disadvantages of both applied contact and non-contact probes, namely surface contamination with concomitant hydrothermal probe deterioration and large beam divergence with poor energy density, respectively. Proposed silica or sapphire probes produce quasi-collimated beam with specific outside diameter and power distribution. To provide comparative analysis of laser delivery systems' optical properties with non-contact endoscopic probes 'steady beam distance' (SBD) and 'steady beam ratio' (SBR) coefficients are proposed. The calculation results are presented in the form of the plots of the SBR - coefficients and SBDs for a 2.0 mm specific outside beam diameter versus laser wavelength, delivery fiber core diameter and its numerical aperture for both probe material. Additionally, the cross power distributions along the SBD were studied. Results obtained could provide a useful tool to designers of non-contact fiber delivery systems intended for a variety of medical applications, including endoscopic surgery with cw or pulse laser tissue irradiation, skin de-epithelialization, laser-induced fluorescence and photodynamic therapy.

Optical biopsy of stomach mucosa was performed afterwards oral administration of encapsulated hyperflav (single dose was chosen to provide 0.1 - 0.15 mg/kg b.w.) A sufficient fluorescence contrast of suspicions versus normal tissue was obtained after incubation time from 4 to 10 hours. Fluorescence was induced by He - Cd laser coupled to fiber optic probe inserted into a biopsy channel of the endoscope. Fluorescent spectra were recorded in the range from 500 nm up to 700 nm with 2 nm resolution. We took two groups of patients with benign and malignant ulcer of the stomach and erosive gastritis. The first group consisted of 59 patients (male/female 36/23) was carried out with optical biopsy of stomach mucosa. The second group consisted of 60 patients (male/female 39/21) was carried out by routine method: gastroscopy and biopsy from 5 - 7 places of macroscopically changed mucosa.

Previous measurement by Qu et al, of laser-induced fluorescence in bronchus tissue are simulated using an electromagnetic (EM) scattering model. The EM parameters derived indicate that the changes in the epithelium thickness with carcinoma in situ can be detected with an optical radar process, hence providing an early detection of cancer. Further simulation using the EM model indicates various practical methods of extracting the thickness changes. These include frequency modulated continuous wave optical radar, multilaser continuous wave radar and low coherence interferometry. Initial optical experiments and calculations clarify which method is likely to lead to the development of endoscope instrumentation, but the availability of suitable optical components is a major consideration. Some early interferometry results indicate that a resolution of at least 40 micrometers can be readily reached for histological imaging. For 10 micrometers cell resolution, additional techniques are required.

Crohn's disease is an inflammatory bowel disease of unknown etiology. The mechanism of the initial mucosal alterations is still unclear: ulcerations overlying lymphoid follicles and/or vasculitis have been proposed as the early lesions. We have developed a new and original method combining endoscopy of fluorescence angiography for identifying the early pathological lesions, occurring in the neo-terminal ileum after right ileocolonic resection. The patient population consisted of 10 subjects enrolled in a prospective protocol of endoscopic follow-up at 3 and 12 months after surgery. Fluorescence imaging showed small spots giving a bright fluorescence distributed singly in mucosa which appeared normal in routine endoscopy. Histopathological examination demonstrated that the fluorescence of small spots originated from small, usually superficial, erosive lesions. In several cases, these erosive lesions occurred over lymphoid follicles. Endoscopic fluorescence imaging provides a suitable means of investigating the initial aspect of the Crohn's disease process in displaying some correlative findings between fluorescent aspects and early pathological mucosal alterations.

In this abstract we describe the use of photodynamic therapy (PDT) to recanalize occluded biliary metal stents. In patients with jaundice secondary to obstructed metal stents PDT was carried out 72 hours after the administration of m THPC. Red laser light at 652 nm was delivered endoscopically at an energy intensity of 50 J/cm. A week later endoscopic retrograde cholangiogram showed complete recanalization of the metal stent.

Microcirculatory disorders of the gastrointestinal tract appear to be a major compound of the multiple organ dysfunction syndrome secondary to sepsis or septic shock. A better analysis of mucosal hypoperfusion in critically ill patients with sepsis may be helpful for the comprehension of this high mortality-associated syndrome. Fluorescence endoscopy has been recognized as a non-invasive method for both spatial and temporal evaluation of gastrointestinal mucosal perfusion. We performed this imaging technique during routine gastric endoscopy in patients with sepsis criteria. The study included gastric observation and appearance time of gastric fluorescence after an intravenous 10% sodium - fluorescein bolus. Qualitative analysis of high fluorescence areas was compared with mucosal blood flow measurements by laser - Doppler flowmetry. We concluded that the fluorescence endoscopic imaging in critically ill patients with sepsis may reveal spacial and temporal differences in the mucosal microcirculation distribution.

A newly-developed, coherent detection imaging system has been applied for high-resolution optical imaging in biological tissues. Our system employs a two-dimensional heterodyne detection technique which has been demonstrated to be capable of both enhanced detection and speckle averaging of spatially distorted laser signals emerging from turbid media. Results of imaging through biological objects in vivo are presented.

A real time functional near infrared imager (fNIRI) was introduced. The imager was controlled by a computer and the signals from the detectors were converted and processed in real time. A user-friendly software was programmed with Visual C++ language. Relative changes of oxy - Hb, Hb, and total blood concentration in 16 channels and the corresponding images can be displayed in real time on the computer. The imager was used as a real time monitor in psychological tests to record the response of the frontal cortex of human subjects. In mental work and pattern recognition tests, we recorded oxygen consumption and blood flow changes of volunteers' frontal cortex. The psychological results showed that the lower part of the left frontal gyres had intensive relation to pattern recognition and has definite boundaries. However, the mental work involved more zones of the frontal gyres and may be a complex conceptual model. The results also suggested that the human brain has an precise and complicated adjustability. The oxygen supplement in the stimulated area increased as the neuron stimulation.

Spectral radar is an optical sensor for tomography, working in the Fourier domain, rather than in the time domain. The scattering amplitude a (z) along one vertical axis from the surface into the bulk can be measured within one exposure. No reference arm scanning is necessary. One important property of optical coherence tomography (OCT) sensors is the dynamic range. We will compare the dynamic range of spectral radar with standard OCT. The influence of the Fourier transformation on the dynamic range of spectral radar will be discussed. The clinical relevance of the in vivo measurements will be demonstrated.

Important aims in dermatology are the measurement of pathological alterations of human skin and on the other hand the quantification of the influences caused by pharmaceutic and cosmetic products. We present modifications of the well- established coherence radar that allow in vivo measurement of human skin, in spite of involuntary body movements and bloodflow. The measuring field can be varied from 100 X 100 micrometers ² to 5 X 5 mm². The measuring time is 5 to 15 s and the longitudinal measuring uncertainty is about 2 micrometers . A fiber optical implementation allows the separation of the sensor head from the mechanical scan. The mobile and compact sensor head can now be freely positioned and adjusted to each part of the patient's skin. Disturbances caused by unavoidable movement of the patient can be compensated by modified setups of the coherence radar. We show measurements of clinical and cosmetic relevance.

Our investigations have been devoted to OCT capabilities in imaging normal and diseased tooth structures and different types of oral mucosa. OCT tomograms distinctly exhibit the structural elements of oral mucosa. Depending on localization and keratinization, different types of mucosa are also seen in OCT images. OCT images of those parts where epithelium evidences high keratinization substantially differ from images of those parts where epithelium evidences low or no keratinization in its normal state. OCT imaging allows one to clearly differentiate between caries and noncaries lesions, which is very important in practical dentistry. OCT has made it possible to quite accurately diagnose a fissure caries in the early stage that has been unreliable with an X- ray examination. The OCT technique is capable of dynamic monitoring the restorative process. It also allows in vivo examination of fillings as well as the state of surrounding tissues. It is possible to detect filling defects caused by an incorrect filling procedure either during the process of restoration of some time later. The results of our investigations suggest that OCT is a potentially useful modality for clinical and research dentistry.

The method is based on representation of an original image as a complex envelope of some hypothetical pseudocoherent wave field. The imaginary part of the new complex image is connected to its real part by means of the 2-D Hilbert transform. It is supped that the complex envelope satisfies conditions for wave equation in the original image registration plane. The effect of controlled levels of the contrast and space-resolving power is ensured using the wave equation inversion procedure in depth with further analysis of the series of new virtual images.

A moire interferometer is presented which was specially designed for the study of middle ear mechanics. The apparatus is based on phase shift projection moire interferometry, and allows full field quantitative measurement of the shape and deformation of three-dimensional surfaces. Phase shifting and grating noise removal is obtained by piezo-actuated movements of the gratings in the projection and the viewing optical path, respectively. Object shape is then calculated from the recordings of four phase shift moire topograms. The angle between projection and viewing direction is very small, so that observation of the eardrum is possible with minimal shadow problems caused by the bony structures in the vicinity of the eardrum. Measurements obtained on a calibration object and on in-vitro middle ear preparations are presented.

The basic use of low coherence interferometry is measuring the intensity of light reflected from defined depths in a partially transparent object. The light back-scattered from a certain depth in the object carries information about the medium through which it has passed. Absorption and scattering attenuate the intensity of the light, and will thus reduce the interference signal from a given depth. One single interference measurement will not discriminate between attenuation due to absorption and scattering. However, by measuring the interference signal at several different wavelengths, discrimination between the two parameters is possible, if they vary differently with wavelength. Especially when measurements are performed in a wavelength region where the scattering coefficient is constant, measurements at two different wavelengths will give the difference in absorption at the two wavelengths. We present preliminary measurements on scattering and absorbing solutions showing a qualitative difference in absorption measured at 810 and 830 nm. As an absorbing solution we used a commercially available dye with an absorption maximum at 800 nm while intralipid was used to introduce scattering. The aim of the work is to measure the oxygenation saturation of blood through absorption measurements at different wavelengths using low coherence interferometry.

Combined analysis of optic-geometrical characteristics makes it possible to comprehensively evaluate the morphological and functional state of the cytological object, which can not be done during visual observation. The technique is discussed for real-time monitoring of the functional status of platelets using computer-aided phase microscope (CPM) 'Cytoscan'. High accuracy and sensitivity of CPM with respect to determination of local temporal phase make it possible to register the dynamic processes in the voluntarily chosen points and sections of micro-objects, to obtain the Fourier's spectra and other characteristics suitable for statistical analysis. Human platelets were prepared from venous blood of healthy donors and pregnant women by standard methods, suspended in culture medium 199 and treated by different doses of 6% Infukoll HES. Nonfixating and nonstaining cells were studied with CPM: height accuracy 0.5 nm, magnification 1000, acquisition time 4 - 30 s. In our experiments we used time resolution about 0.03 s and 30 x lens with numerical aperture 0.65. During investigations of temporal processes a certain section was chosen in the topogram of cell image and local values for the phase of scattered wave in each of the points of the chosen cell's profile were measured. On the basis of the results of automated phase image analysis of optic-geometrical characteristics of living cells, the new quantitative express-method for evaluating of the functional status of human platelets was developed and tested. The structural changes of cells were visualized in alteration of 3-D images, phase profiles, in the decrease of mean cell phase diameters, heights, volumes, in disturbance of histograms of phase heights distribution by cell image points. New data on the behavior of platelets treated by Infukoll in vitro and in vivo were obtained. Analysis of intracellular dynamics was allowed to characterize the cell's regions of maximal activity, but the intensity of processes taking place in these regions in accordance with frequencies as well. The difference between the calculated values of frequencies (from 0.1 to 17 H) is associated with the influence of Infukoll on the metabolism and functional activity of living platelets.

In the incidence of malignant melanoma, which is the most lethal skin cancer, has risen around the world more than 15 times over the last 50 years and continues to increase. Diagnosis of skin tumors can be automated based on the introduction of digital imaging in dermatology. Automated diagnosis is based on certain physical features and color information that are characteristic of benign, dysplastic or malignant tissue. In this paper, the research is addressed towards the problem of segmentation of digital images based on color information and specifically was a selected feature called variegated coloring. Neural networks - Kohonen model - were used for the automatic identification of variegated coloring and self organizing maps (SOMs) were applied to the segmentation of color images of skin cancer. A set of 12 images was used and the results were compared with the segmentation procedure of a clinical expert. The results have shown that the Kohonen model of neural networks can utilize the chromatic information of color skin images to successfully segment skin cancers from the surrounding skin.

The rising of pathological processes was proved to induce alterations of the intrinsic autofluorescence properties of biological tissues, that can be exploited for diagnostic purposes. In oncology, applications of autofluorescence as a parameter for in situ cancer detection in several organs are reported. In this work, autofluorescence properties of normal and tumor tissue in the brain are described, suitable for a real-time diagnostic application. Studies were performed both on ex vivo resected samples, by microspectrofluorometric techniques, and in vivo, during surgical operation, by means of fiber-optic probe. Significant differences were found in autofluorescence emission properties between normal and tumor tissues, concerning both spectral shape, peak position and signal amplitude. The potential of autofluorescence as a parameter to distinguish neoplastic from normal condition opens interesting prospects for improving of the efficacy of neurosurgical operations, by allowing an intraoperative delineation of tumor resection margins through a noninvasive technique.

Measurement of gastrointestinal intramucosal pH has been recognized as an important factor in the detection of hypoxia-induced dysfunctions. However, current pH measurement techniques are limited in terms of time and spatial resolution. A major advance in accurate pH measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-4,5- carboxyfluorescein (BCECF). This study aimed to demonstrate the feasibility of fluorescence imaging technique to measure in vivo the pH of intestine. The intestine was inserted in an optical chamber placed under a microscope. Animals were injected i.v. with the pH-sensitive fluorescent dye BCECF. Fluorescence was visualized by illuminating the intestine alternately at 490 and 470 nm. The emitted fluorescence was directed to an intensified camera. The ratio of emitted fluorescence at excitation wavelengths of 490 and 470 nm was measured, corrected and converted to pH by constructing a calibration curve. The pH controls were performed with a pH microelectrode correlated with venous blood gas sampling. We concluded that accurate pH measurements of rat intestine can be obtained by fluorescence imaging using BCECF. This technology could be easily adapted for endoscopic pH measurement.

The adhesion of leukocytes to microvascular endothelium has been recognized as an important factor in the development of multiple organ dysfunction after a septic insult. We tested the hypothesis whether inhaled NO would reduce leukocyte rolling and / or leukocyte adhesion in the mesenteric venule preparation in endotoxemic rats. This study was performed with fluorescence imaging microscopy using a closed chamber for in vivo mesentery visualization. Leukocytes were selectively stained with acridine red. Compared to saline, endotoxemia was associated with increases in the flux of rolling leukocytes and in adherent and emigrated leukocytes. Inhaled nitric oxide treatment had no effects on leukocyte behavior in saline treated rats, whereas it reduced adherent and emigrated leukocytes in endotoxin-treated rats. In conclusion, we demonstrated that endotoxemia-induced leukocyte infiltration was related to an increase in the number of rolling leukocytes and subsequent adhesion and emigration in the mesenteric venule. Our results clearly showed that inhaled NO reduces leukocyte adhesion and transmigration in mesenteric venule of endotoxemic rats presumably by interfering with specific cell adhesion molecules.

The present study was designed to monitor novel ideas in the acquisition and manipulation of data in an X-ray imaging system. A grid was sandwiched between two cascaded imaging plates (Ips). Using a fan-beam X-ray tube and a single exposure scheme, the two Ips, respectively, recorded gridless and grid (GLG) type information of the object. Referring to the mathematical model of the GLG technique, it was explained that the collected data associated with the gridless IP was of high (S/N) and suppressed scattered components. Based on this assumption and using a Gaussian convolution kernel representing the effect of scattering, a technique was proposed to estimate scatter parameters of the GLG plates. Then, a Kalman filter was developed to restore noisy blurred images of the GLG techniques using the Ips data and estimated parameters. The results are shown for both the computer simulated and real X-ray phantom data.

Coefficients of light absorption (mu) _a and scattering (mu) _s for biological tissues lie within a broad range. Minimum ones foe healthy eye tissues up to higher values (f.e.(mu) _aequals 0.3 cm ^-1 and (mu) _s equals 40 cm ₁ at 633 nm for muscle tissues $1)) for other and mainly turbid tissues. The specific feature of the transparent PLZT ceramics (having absorption (mu) _a>0.1 cm ^-1 in the visible and in the near infrared spectrum range) is electrically controlled light scattering. The present work reports on experimental results of the light transport and backscattering for PLZT 9/65/35 (Pb_0.91La_0.09Zr_0.65Ti_0.350₃). We propose PLZT ceramics with fast and continuously controllable light scattering as an optical phantom for photon migration studies and for scattering obstacles in vision disability tests.

Asymmetry of light backscattering from a shear flow of 1 mm thick layer of whole blood was measured. The blood samples from different health and diseased individuals were placed in a gap of a cylindrical Couette cell with inner cylinder rotating with variable rates. Probing was performed with a CW He-Ne laser (633 nm). The difference in intensities of backscattered light detected through a transpatent wall of the stationary outer cylinder with a photodetector located at variable distances from the illuminating beam along and opposite to the flow directions depends on the distance between the illuminating and detecting probes, on shear rate, on hematocrit, and on the type of disease. The experiments conducted with blood samples from patients suffering from heart disease, bronchial asthma, and rheumatoid arthritis showed stable and reproducible difference in the amount of asymmetry. This makes the technique potentially applicable for optical biomonitoring and, also, for the study of rheology of concentrated suspensions of large deformable particles, like erythrocytes.

Sol-get techniques have become very popular recently due to their high chemical homogeneity, low processing temperatures, and the possibility of controlling the size and morphology of particles. The sol-gel-derived materials provide excellent matrices for a variety of organic and inorganic compounds. One of the most important features of doped sol-gel materials is their ability for preservation of chemical and physical properties of the dopants. This feature marks those materials as almost unique hosts for a number of biologically important molecules which can be utilized in a number of biomedical applications. The advantages of sol-gel technology used for construction of biomedical sensors, laser materials or for delayed drug delivery, will be discussed.

It is obvious that medical equipment must be sterile before it can be used for the patient's diagnosis or treatment. The frequently used sterilization methods are applying hot steam or ethanol. This can, however, cause damage to the delicate optical instruments, such as all kinds of endoscopes. Plasma sterilization is an alternative process, which is performed at much lower temperature (50 degree(s)). It is very effective regarding the sterility of cleaned devices, whereas it is less harmful to the instruments. In the study described, the optical transmittance of endoscopic optical systems which underwent several cycles of sterilization was measured. We have demonstrated that plasma process, compared to the hot steam process, is more protective of the optical instruments.