Using Doppler optical coherence tomography (DOCT) we study stress-related intracranial hemorrhages (ICHs) in newborn rats. We investigate a masked stage of ICH development that corresponds to the first 4 h after the stress. We show that this period is characterized by significant changes in the diameter of the sagittal vein and the velocity of the cerebral venous blood flow (CVBF). We discuss diagnostic abilities of wavelet-based methods and consider an adaptive technique allowing us to reveal clearest distinctions in the dynamics of CVBF between normal and stressed newborn rats. Finally, we conclude that the venous insufficiency in newborns and a ...
A comparative study of physical, chemical, and combined enhancement of transdermal transport of optical clearing agents (OCAs) is presented. As a physical enhancer of diffusivity, ultrasound (US) with a frequency 1 MHz and a power 1.1 W in the continuous mode was used, and dimethyl sulfoxide (DMSO) was used as a chemical enhancer. OCA (glycerol and polyethylene glycol-400 in equal proportion) was topically applied to the rat skin in vivo as alone or as together with the enhancers. Monitoring of skin optical clearing was implemented using an optical coherence tomography. The results have shown that the attenuation coefficient of ...
Morphological changes of the adipose tissue at phototreatment are studied in vitro using optical coherence tomography. The 200 to 600 μ m fat tissue slices are used in the experiments. The observed change in the tissue structure was associated with fat cell lipolysis and destruction caused by the photodynamic effect. It is found that overall heating of a sample from room to physiological temperature leads to deeper and faster morphology tissue changes if other processing conditions are kept constant. These data support the hypothesis that photodynamic/photothermal treatment induces fat cell lipolysis during some period after treatment.
This handbook deals with laser and coherent-domain methods as applied to biomedical diagnostics, environmental monitoring, and materials inspection. It is a second edition of the two-volume Handbook of Coherent-Domain Optical Methods for Biomedical Diagnostics, Environmental and Material Science published by Kluwer Academic Publishers in 2004. The appearance of this book was stimulated by the recent rapid progress in novel photonics technologies on the basis of diode lasers, broadband femtosecond lasers (Ti: Sapphire or Cr: F€orsterite), light-emitting diodes (LEDs), and superluminescence diodes (SLDs). Such technologies are applicable in many fields, namely, biomedical, environmental, and material diagnostics and monitoring. The main ...
Imaging methods such as optical coherence tomography (OCT), confocal reflectance/ fluorescence microscopy, second-harmonic generation microscopy, and 2-photon microscopy are limited by the optical scattering properties of the skin to superficial depths. Optical clearing technique using high refractive index and hyperosmolarity agents can reduce the scattering of biological tissues. With this approach, better optical imaging depth and contrast have been presented and deeper optical treatment has been achieved. However, noninvasive optical clearing of skin in vivo is difficult, because the outermost layer of the skin, the stratum corneum, presents a significant barrier to topically applied OCAs. In this work, OCT imaging ...
The delivery of gold nanoparticles (nanocages coated with a layer of silicon dioxide (40/20 nm)) dispersed in the solution (glycerol + polyethylene glycol-400, 1 : 1) into the skin tissue is studied experimentally in vivo. From the data of optical coherence tomography and histochemical analysis it follows that simple application of suspension of nanoparticles is not efficient enough for delivery of the particles into the skin as a result of passive diffusion. It is shown that fractional laser microablation of skin before the application of the suspension, followed by the topical treatment by ultrasound allows penetration through the epidermis layer and ...
The possibility of visualising the distribution of gold nanoparticles in liver by means of the method of optical coherence tomography is studied experimentally in model samples of beef liver in vitro and rat liver ex vivo. In the experiments we used the gold nanoparticles in the form of nanocages with resonance absorption in the near-IR spectral region. In the model studies the suspension of nanoparticles was applied to the surface of the sample, which then was treated with ultrasound. In the ex vivo studies the suspension of nanoparticles was injected to the laboratory rats intravenously. The image contrast and the ...
The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 μm depth and 31% enhancement in image depth Zthreshold.
In this paper, we overview the basic principles, recent results, advantages, limitations, and future of the optical clearing method in application to many fields of biology and medicine. We also discuss the possibility of noninvasive assessment of molecular diffusion in tissues using the optical coherence tomography technique. Issues of safety and toxicity of application of different endogenous and exogenous molecules to tissues are outlined.
Valery V. Tuchin, PhD, holds the Optics and Biophotonics Chair and is a Director of Research-Educational Institute of Optics and Biophotonics at Saratov State University, Head of Laboratory on Laser Diagnostics of Technical and Living Systems, Inst. of Precise Mechanics and Control, RAS. His research interests include biophotonics, biomedical optics and laser medicine, physics of optical and laser measurements. He has authored more than 300 peer-reviewed papers and books. He has been awarded Honored Science Worker of the Russian Federation and SPIE Fellow; he is a Vice-President of Russian Photobiology Society. In 2007 he was awarded the SPIE Educator Award. He is a FiDiPro Professor of University of Oulu (Finland).