Yury V. Kistenev

Screening of patients with bronchopulmonary diseases using methods of infrared laser photoacoustic spectroscopy and principal component analysis

Abstract. A human exhaled air analysis by means of infrared (IR) laser photoacoustic spectroscopy is presented. Eleven healthy nonsmoking volunteers (control group) and seven patients with chronic obstructive pulmonary disease (COPD, target group) were involved in the study. The principal component analysis method was used to select the most informative ranges of the absorption spectra of patients’ exhaled air in terms of the separation of the studied groups. It is shown that the data of the profiles of exhaled air absorption spectrum in the informative ranges allow identifying COPD patients in comparison to the control group.

Exhaled air analysis using wideband wave number tuning range infrared laser photoacoustic spectroscopy

Abstract. The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient’s exhaled air are presented. The study involved lung cancer patients (N=9), patients with chronic obstructive pulmonary disease (N=12), and a control group of healthy, nonsmoking volunteers (N=11). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatography–mass spectrometry method (GC–MS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GC–MS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.

Investigation of the electric field distribution in the human brain based on MRI and EEG data

This work is devoted to the development of the approach to restoration of the spatial-temporal distribution of electric field in the human brain. This field was estimated from the model derived from the Maxwell’s equations with boundary conditions corresponding to electric potentials at the EEG electrodes, which are located on the surface of the head according to the standard “10-20” scheme. The MRI data were used for calculation of the spatial distribution of the electrical conductivity of biotissues in the human brain. The study of the electric field distribution using our approach was carried out for the healthy child and the child with autism. The research was carried out using the equipment of the Tomsk Regional Common Use Center of Tomsk State University.

Improvement of the multiphoton fluorescence microscopy images quality using digital filtration

In our study we used rank-order filter, the emissions filter on the base of the criteria of Pearson, Gaussian filter and median filterfor improving the is fluorescence lifetime imaging microscopy (FLIM) data. The data obtained with the FLIM technology are the distribution with a pronounced peak, while during measurement the peak value is measured with an error. According to the analysisthe Gaussian filter is more useful to improve quality of FLIM data.Spatial filtering allows to reduce the noise component, obtained in the course of measurements, including reduction the influence of the individual bursts. Filtering in time scale allows to determine a peak value of intensity more accurately.This research was carried out using the equipment of Tomsk Regional Common Use Center of Tomsk State University.

Possibilities of cytospectrophotometry of oncological prostate cancer tissue analysis in the TGz spectral range

Absorption spectra of paraffin-embedded prostate cancer and healthy tissues have been measured in the 0.2-3 THz range. The Principal Component Analysis and the Support Vector Machine (SVM) were applied to analyze experimental data. The SVM classifier was created which allows to distinguish the healthy tissues from tumor tissues, including classification of tumor tissue stage according to the Gleason scale.

Analysis of exhaled air of patients with myocardial infarction by laser spectroscopy and data mining

Myocardial infarction (MI) causes partial or complete necrosis of the heart muscle. It means that muscle cells are wiped, and the contractility of the heart decreases. Today, for the MI diagnosis is based on the ECG recording or specific biomarkers identifying in the patients blood, the most specific of which are: creatine phosphokinase (CPK), CPK-MB, fatty acids binding protein (H-FABP), myoglobin troponin-I, and troponin-T. Additionally to these biomarkers in the MI patients’ blood, there are many other products of metabolism in damaged muscles, which are excreted from the body human body, including through exhaled air. The results of MI patients’ exhaled air analysis using photoacoustic laser spectroscopy and data mining are presented.

Diagnostics of oral lichen planus based on analysis of volatile organic compounds in saliva

The ability of diagnostics of oral lichen planus (OLP) based on spectral analysis of saliva using the THz spectroscopy is presented. The study included 8 patients with clinically proven OLP. The comparison group consisted of 8 healthy volunteers. Absorption spectra of the saliva was measured using time-domain spectrometer T-spec (EXPLA) in the range 0.2-3THz and have been considered as the feature vectors of the state. The spatial distribution of the objects under study in the feature space was analyzed using principle component analysis. The groups under study were shown to separate in full. Thus, the saliva analysis by the THz spectroscopy technique can be potentially used as a method of noninvasive diagnostics of the OLP.

Breath air measurement using wide-band frequency tuning IR laser photo-acoustic spectroscopy

The results of measuring of biomarkers in breath air of patients with broncho-pulmonary diseases using wide-band frequency tuning IR laser photo-acoustic spectroscopy and the methods of data mining are presented. We will discuss experimental equipment and various methods of intellectual analysis of the experimental spectra in context of above task. The work was carried out with partial financial support of the FCPIR contract No 14.578.21.0082 (ID RFMEFI57814X0082).

A comparison study of optical coherence elastography and laser Michelson vibrometry

Quantitative elastography is a power technique to detect and analyze the changes in biomedical properties of tissues in normal and pathological states. In this study, two noncontact elastography techniques, laser Michelson vibrometry (LMV) and optical coherence elastography (OCE), were utilized to quantify the Young’s modulus of tissue-mimicking agar phantoms of various concentrations. Low-amplitude (micrometer scale) elastic waves were induced by a focused air-pulse delivery system and imaged by the respective systems. The Young’s modulus as assessed by both elastographic techniques was similar and was compared to the stiffness as measured by uniaxial mechanical testing. The results show that both techniques accurately quantified the elasticity. OCE can provide absolute elastic wave temporal profile, depth-resolved measurement and superior displacement sensitivity compared to LMV, but LMV is significantly cheaper (10X) and easier to implement than OCE.

Noncontact phase-sensitive dynamic optical coherence elastography at megahertz rate

Dynamic optical coherence elastography (OCE) techniques have shown great promise at quantitatively obtaining the biomechanical properties of tissue. However, the majority of these techniques have required multiple temporal OCT acquisitions (M-B mode) and corresponding excitations, which lead to clinically unfeasible acquisition times and potential tissue damage. Furthermore, the large data sets and extended laser exposures hinder their translation to the clinic, where patient discomfort and safety are critical criteria. In this work we demonstrate noncontact true kilohertz frame-rate dynamic optical coherence elastography by directly imaging a focused air-pulse induced elastic wave with a home-built phase-sensitive OCE system based on a 4X buffered Fourier Domain Mode Locked swept source laser with an A-scan rate of ~1.5 MHz. The elastic wave was imaged at a frame rate of ~7.3 kHz using only a single excitation. In contrast to previous techniques, successive B-scans were acquired over the measurement region (B-M mode) in this work. The feasibility of this method was validated by quantifying the elasticity of tissue-mimicking agar phantoms as well as porcine corneas ex vivo at different intraocular pressures. The results demonstrate that this method can acquire a depth-resolved elastogram in milliseconds. The reduced data set enabled a rapid elasticity assessment, and the ultra-fast acquisition speed allowed for a clinically safe laser exposure to the cornea.