Mikhail Kirillin

Contrasting properties of gold nanoshells and titanium dioxide nanoparticles for optical coherence tomography imaging of skin: Monte Carlo simulations and in vivo study

The effect of silica/gold nanoshells and titanium dioxide nanoparticles on the optical properties of skin is studied. By implementing in vivo measurements and Monte Carlo simulations, we analyze the efficiency of using these nanoparticles as contrasting agents for optical coherence tomography (OCT) imaging of skin. In vivo measurements are performed on pig skin, where nanoparticle suspension drops have been applied. The identification of skin layers is performed by comparison with corresponding histology images. Experimental results exhibit an increase in contrast of the obtained OCT images after a single nanoparticles application. Multiple applications do not lead to increase in the obtained contrast. To interpret the obtained experimental OCT images of skin and understand the mechanisms of contrasting, a set of Monte Carlo calculations is performed. The results of the simulations exhibit good qualitative agreement with the experimental images, and prove that the contrasting originates from the nanoparticles added, while the contrast of inclusion originates from the absence of nanoparticles within it and their presence in the surrounding area.

In vivo study of the effect of mechanical compression on formation of OCT images of human skin.

Modern optical diagnostic techniques often require deformations of the studied bio-tissues for image acquisition. This paper discusses the effect of mechanical compression on the formation of OCT images of human skin. The study was performed in vivo on human volunteers of different age. We show that application of compression to human skin induces changes in optical properties of the sample associated with elasticity of different skin layers. These changes induce an increase in the contrast of interlayer boundaries. Further application of compression causes the appearance of dark areas in the OCT images obtained, likely associated with interstitial or intracellular water inflow to the observed region. The effects studied are of importance for proper interpretation of obtained OCT images in diagnosis of skin pathologies.

Criteria for pathology recognition in optical coherence tomography of fallopian tubes

An increase of infertility and chronic pelvic pains syndrome, a growing level of latent diseases of this group, as well as a stably high percentage (up to 25% for infertility and up to 60% for the chronic pelvic pains syndrome) of undetermined origin raises the requirement for novel introscopic diagnostic techniques. We demonstrate abilities of optical coherence tomography (OCT) as a complementary technique to laparoscopy in diagnostics of fallopian tubes pathologies. We have acquired OCT images of different parts of fallopian tubes in norm and with morphologically proven pathology. Based on comparative analysis of the OCT data and the results of histological studies, we have worked out the subjective OCT criteria for distinguishing between unaltered and pathologic tissues. The developed criteria are verified in blind recognition tests. Diagnostic efficacy of OCT diagnostics in the case ofpelvic inflammatory diseases has been statistically evaluated, and high diagnostic accuracy (88%) is shown. Basing of the subjective criteria, an attempt to develop independent criteria aimed for automated recognition of pathological states in fallopian tubes is undertaken. Enhanced diagnostic accuracy (96%) of the developed independent criteria is demonstrated.

Monte Carlo simulation of brain sensing by optical diffuse spectroscopy

Abstract We report on development of adapted Monte Carlo based algorithm and code for simulation of light propagation in turbid media with complex geometry aimed for simulation of optical diffuse spectroscopy signal in noninvasive brain sensing. Simulation will allow to determine optimal characteristics of a prototype device for optical diffuse brain sensing. The developed Monte Carlo code can be efficiently parallelized both for SMP and distributed memory systems. We show that the speed-up of the developed algorithm almost linearly depends on the number of nodes/threads in a utilized system.

Quantitative evaluation of atherosclerotic plaques using cross-polarization optical coherence tomography, nonlinear, and atomic force microscopy

Abstract. A combination of approaches to the image analysis in cross-polarization optical coherence tomography (CP OCT) and high-resolution imaging by nonlinear microscopy and atomic force microscopy (AFM) at the different stages of atherosclerotic plaque development is studied. This combination allowed us to qualitatively and quantitatively assess the disorganization of collagen in the atherosclerotic arterial tissue (reduction and increase of CP backscatter), at the fiber (change of the geometric distribution of fibers in the second-harmonic generation microscopy images) and fibrillar (violation of packing and different nature of a basket-weave network of fibrils in the AFM images) organization levels. The calculated CP channel-related parameters are shown to have a statistically significant difference between stable and unstable (also called vulnerable) plaques, and hence, CP OCT could be a potentially powerful, minimally invasive method for vulnerable plaques detection.

Towards increase of diagnostic efficacy in gynecologic OCT

Gynecologic applications of optical coherence tomography (OCT) are usually performed in combination with routine diagnostic procedures: laparoscopy and colposcopy. In combination with laparoscopy OCT is employed for inspection of fallopian tubes in cases of unrecognized infertility while in colposcopy it is used to identify cervix pathologies including cancer. In this paper we discuss methods for increasing diagnostic efficacy of OCT application in these procedures. For OCT-laparoscopy we demonstrate independent criteria for pathology recognition which allow to increase accuracy of diagnostics. For OCT-colposcopy we report on application of device for controlled compression allowing to sense the elasticity of the inspected cervix area and distinguish between neoplasia and inflammatory processes.

Topical problems of biophotonics.

Optical methods in biomedicine have experienced an outstanding development in recent decades and are currently successfully translated from research laboratories to medical practice. Some of them, such as optical coherence tomography and photodynamic therapy, have become a common tool for clinicians while others, such as optical diffuse tomography or laser-driven acceleration for radiation therapy, are on their way from optical bench to medical instrumentation. This Special Issue presents a collection of papers based on reports delivered at the 3 biannual International Symposium “Topical Problems of Biophotonics – 2011”. The issue includes both review and research papers covering a wide range of topics varying from microscopic studies at subcellular scale to diagnostics and treatment in clinical practice. The cellular and intracellular studies are presented by four papers discussing perspective medical nanotools such as quantum dots (Loginova, p. 848, Balalaeva, p. 860) and nanodiamonds (Lin, p. 838) for imaging applications, hybrid nanocomposite films (Matteini, p. 868) aimed for treatment procedures and a paper revealing novel potential of nonlinear microscopy technique (Medyukhina, p. 878). The section on advanced laser techniques in biomedicine co-jointed with workshop on clinical biophotonics contributes four papers ranging from optical techniques in ophthalmology (Koinzer, p. 889) and mammology (Poellinger, p. 815) to laser therapy of brain injury (Huang, p. 827) and novel laser-driven sources for hadron therapy (Hofmann, p. 903). The Symposium held in July 2011 was organized by the Institute of Applied Physics of the Russian Academy of Sciences, the Nizhny Novgorod Medical Academy and the University of Nizhny Novgorod in collaboration with Gycom Ltd., Kvantron-NN Ltd., and the Government of Nizhny Novgorod Region. 227 participants from 22 countries took part in the Symposium, including scientists from Australia, Austria, Belgium, Canada, China, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Japan, The Netherlands, Romania, Russia, Spain, Sweden, Switzerland, Taiwan, United Kingdom, and the USA. The symposium program included four parallel topical conferences “Optical Bioimaging”, “Nanobiophotonics”, “Neuroimaging and Neurodynamics” and “Advanced Lasers in Biomedicine”, and the German-Russian workshop “Clinical Biophotonics”, thus covering a broad spectrum of topics in biophotonics. The German-Russian Workshop “Clinical Biophotonics” provided the platform for cooperation between researchers and clinicians. It was organised in cooperation with project “German-Russian Network Biotechnology” sponsored by the Federal Ministry of Education and Research, and LIFE-Center,

Nanoparticles for Contrasting OCT Images of Skin

Contrasting of skin forming elements in optical coherence tomography (OCT) images after application of silica/gold nanoshells or titanium dioxide nanoparticles in solution is discussed. The study is performed both by Monte Carlo simulations and in vivo on animals. The result show that application of both types of nanoparticles produces contrast increase in the OCT images of skin. The increase in OCT signal level originates from the higher backscattering on nanoparticles compared to that on skin forming elements. The increase of contrast in the OCT images originates from the difference in nanoparticles concentration within different skin constituents. These experimental results are confirmed qualitatively by Monte Carlo simulations based on multilayer skin model.

Fluence compensation in raster-scan optoacoustic angiography

Modern optical imaging techniques demonstrate significant potential for high resolution in vivo angiography. Optoacoustic angiography benefits from higher imaging depth as compared to pure optical modalities. However, strong attenuation of optoacoustic signal with depth provides serious challenges for adequate 3D vessel net mapping, and proper compensation for fluence distribution within biotissues is required. We report on the novel approach allowing to estimate effective in-depth fluence profiles for optoacoustic systems. Calculations are based on Monte Carlo simulation of light transport and account for complex illumination geometry and acoustic detection parameters. The developed fluence compensation algorithm was tested in in vivo angiography of human palm and allowed to overcome significant in-depth attenuation of probing radiation and enhance the contrast of lower dermis plexus while preserving high resolution of upper plexus imaging.

Quantitative optical diagnostics in pathology recognition and monitoring of tissue reaction to PDT

Optical coherence tomography (OCT) is currently actively introduced into clinical practice. Besides diagnostics, it can be efficiently employed for treatment monitoring allowing for timely correction of the treatment procedure. In monitoring of photodynamic therapy (PDT) traditionally employed fluorescence imaging (FI) can benefit from complementary use of OCT. Additional diagnostic efficiency can be derived from numerical processing of optical diagnostics data providing more information compared to visual evaluation. In this paper we report on application of OCT together with numerical processing for clinical diagnostic in gynecology and otolaryngology, for monitoring of PDT in otolaryngology and on OCT and FI applications in clinical and aesthetic dermatology. Image numerical processing and quantification provides increase in diagnostic accuracy. Keywords: optical coherence tomography, fluorescence imaging, photod