Garry V. Papayan

Spectrometer for fluorescence–reflection biomedical research

A fluorescence–reflection multichannel fiber spectrometer has been developed that makes it possible to carry out a wide range of biomedical research, including estimating the concentration of glycation end-products in the skin and the oxidation–reduction state of various tissues. It has the feature of being able to simultaneously record diffuse reflection spectra and fluorescence emission. The fluorescence is excited by an LED that emits at 365 nm. The fluorescence spectra are recorded in the 400–750 nm region, while the reflection spectra are recorded in the 350–750 nm region. The convergence of the results of the measurements is 1.6%. A technique is proposed for correcting the autofluorescence index of the skin that makes it possible to sharply reduce its dependence on the degree of skin pigmentation. The possibilities of the device are illustrated by examples of biomedical research.

Multispectral fluorescence organoscopes for in vivo studies of laboratory animals and their organs

The fluorescence organoscope provides real-time observation and recording of multispectral images of the organs of experimental animals in the light of intrinsic and secondary fluorescence in the visible and near-IR regions. The multispectral imaging system is based on a high-sensitivity RGB-television array. The fluorescence is excited by means of a combined lamp–laser illuminator or an LED array. Structurally, the device is made in two versions: based on a general-purpose support and on a specialized support. The possibilities of the device are illustrated by examples of biomedical research.

Method of estimating the biological age of skin by means of a fluorescence multispectral video dermatoscope

A method is proposed for evaluating age changes of the skin, based on an analysis of images obtained by means of the EcoSkin fluorescence dermatoscope. Parameters calculated by multiple regression analysis that combine information on aging at the molecular and morphological levels serve as integral markers of age changes of the skin. Measurements on sections of the skin subjected to solar action or protected from it make it possible to evaluate the photoage and bioage of the skin separately. Measurements of the corresponding parameters in seventy women with skin phototypes II and III, aged from 13to93years, provided correlation coefficients of 0.83-0.87 with calendar age. When age according to the persons external appearance was taken into account, these coefficients increased to 0.92-0.94.

Illuminator for photodynamic therapy and fluorescence diagnosis with lightguide output of the radiation

Mercury and halogen lamps that possess mutually supplementary spectral responses are used simultaneously in an illuminator intended for phototherapy and fluorescence diagnosis. Their radiation is summed and delivered to an object through a liquid lightguide. Two summation methods--spectral and angular--are tested experimentally. The best results are given by the latter method, in which convergent beams from the lamps are directed into the lightguide at different angles. The total optical power at the lightguide output is 14.5W in the 300-800-nm range. The working spectral interval is selected by means of switchable interference filters on command from a built-in processor. The influence of the spectral width of the radiation on the efficiency with which the radiant flux is used is estimated.

Fluorescence video dermatoscope

This paper describes a fluorescence video dermatoscope intended for the diagnosis of skin diseases. It is a compact hand-held device with a built-in LED illuminator and a color RGB television camera with progressive scanning and digital output. The video signals are recorded and processed by computer. The observation is carried out in the light of intrinsic or secondary fluorescence, as well as in ordinary white light. The device makes it possible to quantitatively estimate the brightness and color features of the patients skin. Examples are given of the use of the device in medical practice.

System for fluorescence diagnosis and photodynamic therapy of cervical disease

This system is designed for development of fluorescence diagnosis and photodynamic therapy methods for cervical pathologies. Diagnosis is performed on the basis of multispectral autofluorescence images obtained using various types of excitation, as well as images in reflected white light after exposure to acetic acid. Said diagnosis is performed using an expert system for automatic recognition of cervical neoplasms; this expert system has been validated using verified images obtained from 151 patients. Based on test results, a sensitivity of 0.85–0.95 and specificity of 0.78–0.97 are obtained, depending on the scope of the differential diagnosis. It is shown that fluorescence images can be used to monitor photodynamic therapy.

Fiber fluorescence–reflection spectrometer with multiwave excitation

A multipurpose fiber fluorescence–reflection spectrometer with multiwave excitation is intended for biomedical studies, including studies in autofluorescence light. For this use, it is equipped with an LED-based illuminating system possessing a number of technical features: fluorescence excitation by radiation with wavelengths 365, 405, and 450 nm, synchronized switching of blocking filters at the excitation wavelength, and rapid switching of illumination with white light and the exciting radiation. This device makes it possible to observe changes of living objects from diffuse reflection and fluorescence spectra recorded virtually simultaneously. The possibilities of the device are illustrated by using it to study how the autofluorescence-excitation conditions affect the metabolic status of myocardium.

Optical-fiber spectrometer system for carrying out intraoperation studies

This paper describes a spectrometer system for carrying out intraoperation studies by the methods of fluorescence and reflection spectroscopy, including two specialized devices: for dynamic fixation of a fiber-optic probe on a functioning heart and automatic rinsing of blood from its surface. An example is given of using the system in fluorescence studies of experimental ischemia of the rat myocardium under in vivo conditions.