This is the first tomography-presentation of the optical properties of a normal canine prostate, in vivo, in its native intact environment in the pelvic canal. The imaging was performed by trans-rectal near-infrared (NIR) optical tomography in steady-state measurement at 840 nm on three sagittal planes across the right lobe, middle-line, and left lobe, respectively, of the prostate gland. The NIR imaging planes were position-correlated with concurrently applied trans-rectal ultrasound, albeit there was no spatial prior employed in the NIR tomography reconstruction. The reconstructed peak absorption coefficients of the prostate on the three planes were 0.014, 0.012, and 0.014mm?1. The peak reduced scattering coefficients were 5.28, 5.56, and 6.53mm?1. The peak effective attenuation coefficients were 0.45, 0.43, and 0.50mm?1. The absorption and effective attenuation coefficients were within the ranges predictable at 840nm by literature values which clustered sparsely from 355 nm to 1064 nm, none of which were performed on a canine prostate with similar conditions. The effective attenuation coefficients of the gland were shown to be generally higher in the internal aspects than in the peripheral aspects, which is consistent with the previous findings that the urethral regions were statistically more attenuating than the capsular regions.

We used a mobile wireless near-infrared sensor for the noninvasive recording of cerebral hemoglobin concentration changes during cigarette smoking. Each measurement included 5 min of rest, 5 min of smoking imitation, and 5 min of actual smoking. We observed significant effects of the tobacco smoking on temporal changes in the human brain at time scales ranging from 200ms to about 1min. The most reproducible effects were an increase of the heartbeat rate and a decrease in the heartbeat power spectral density during smoking. Significant but highly individual changes due to smoking were observed in temporal patterns of hemodynamic fluctuations in 5–50 s time scales. We have also found statistically significant slow increases in both oxy- and deoxy-hemoglobin concentrations during smoking.

We have proposed an interferometric setup for biomedical analysis in transillumination modality. Wavelength dependence of optical properties must be considered for selecting source and sample. An expansion of the sample optical properties, around the central wavelength of emission, serves to account for spectral effects. Expected spectral values depend on the central moments of the source, and specific constants associated to the optical properties of the sample. By matching wavelength characteristics of source and sample, a first-order approximation is applicable. In such case, the expected values are exactly the optical properties evaluated at the central wavelength. Furthermore, in the first-order approximation, the transillumination interferometer yields the integrated attenuation of the sample at the central wavelength of emission. We verify the latter assertion by performing a wavelength-dependent Monte Carlo analysis to calculate the response of the transillumination interferometer. Recovered attenuation coefficients, for imaging and characterization scenarios, are in agreement with the value computed at the central wavelength of the source.

Rotating orthogonal polarization imaging provides images of the polarization properties of scattering media which are free from surface reflections. Previously the technique has been demonstrated using manually rotated Glan–Thompson polarizers to control and analyze the polarization state of the light entering and emerging from the tissue. This paper describes a system that performs these functions using liquid crystal retarders. The system is tested using a polarizing target embedded within a scattering medium and is compared with Monte Carlo simulations. The results compare well with those obtained with manual rotation of polarizers. The liquid crystal based approach has advantages over the previous system in terms of ease of use, speed, and repeatability and is therefore an important step towards taking the technique into routine clinical use.

Early embryonic imaging of cardiovascular development in mammalian models requires a method that can penetrate through and distinguish the many tissue layers with high spatial and temporal resolution. In this paper we evaluate the capability of Optical Coherence Tomography (OCT) technique for structural 3D embryonic imaging in mouse embryos at different stages of the developmental process ranging from 7.5 dpc up to 10.5 dpc. Obtained results suggest that the collected data is suitable for quantitative and qualitative measurements to assess cardiovascular function in mouse models, which is likely to expand our knowledge of the complexity of the embryonic heart, and its development into an adult heart.

Many up-to-date optical techniques have been developed and applied recently in clinical practice for obtaining qualitatively and quantitatively new data from the investigated lesions. Due to their high sensitivity in detection of small changes, these techniques are widely used for detection of early changes in biological tissues. Light-induced fluorescence spectroscopy (LIFS) is one of the most promising techniques for early detection of cutaneous neoplasia. Increasing number of recent publications have suggested that optical coherence tomography (OCT) also has potential for non-invasive diagnosis of skin cancer. This recent work is a part of clinical trial procedure for introduction of LIFS technique into the common medical practice in National Oncological Medical Center in Bulgaria for diagnosis of non-melanoma skin cancer. We focus our attention here on basal cell carcinoma lesions and their specific features revealed by LIFS and OCT analysis. In this paper we prove the efficiency of using the combined LIFS-OCT method in skin lesions studies by integrating the complimentary qualities of each particular technique. For LIFS measurements several excitation sources, each emitting at 365, 385 and 405 nm maxima are applied. An associated microspectrometer detects in vivo the fluorescence signals from human skin. The main spectral features of the lesions and normal skin are discussed and their possible origins are indicated. OCT images are used to evaluate the lesion thickness, structure and severity stage, when possible. The obtained results could be used to develop a more complete picture of optical properties of these widely spread skin disorders. At the same time, our studies show that the combined LIFS-OCT method could be introduced in clinical algorithms for early tumor detection and differentiation between normal/benign/malignant skin lesions.

In order to enhance the optical clearing effect of topically applied optical clearing agents (OCAs), we evaluated the effect of propylene glycol (PG) as a chemical penetration enhancer (PE) on optical clearing of skin in vitro by observation and measurement of optical-transmittance and diffuse-reflectance spectra. Three OCAs, i.e., glycerol, D-sorbitol and PEG400, and two other penetration enhancers, Azone and Thiazone, were used in this study. The results indicated that the decrease of reduced scattering coefficient caused by OCA/PG was larger than that by pure OCA, and the change by OCA/water was the least after the same treatment time. There were significant differences for the reduced scattering coefficient at 630 nm after 120 min application of agents between OCA and OCA/PG. The efficacy of optical clearing caused by OCA/PG depended on the OCA itself. When PEG400 was mixed with three different PEs, we found the optical clearing were different. The penetration enhancing ability of PG was much better compared to Azone, and suboptimal to Thiazone. Also, this study provides evidence for the use of PG as a PE in order to improve skin optical clearing.

Intralesional injection of triamcinolone (TMC) preparations is an effective therapy for cystic acne lesions. However, invasive delivery techniques limit the use of this modality to a relatively narrow class of cases. Skin permeability can be enhanced through creating a lattice of microzones (islets) of light-induced limited thermal damage in the upper layers of epidermis. In this paper, we directly compared safety and efficacy of delivering TMC acetonide with this novel technique versus conventional intralesional injection for treatment of inflammatory acne lesions. A combination of an intense pulsed light system and a specially designed appliqu′e with a pattern of absorbing centers has been used to create the lattice of islets of damage (LID). Quantitative analysis has included estimation of the following parameters: redness, diameter, and height of acne lesions. Clinical photography has been used to document dynamics of lesion development at successive visits (two hours, 24 hours and one week post-treatment). Seven subjects have participated in the study. No difference in lesion dynamics between the treatment and control groups was observed at two-hours follow-up. At 24-hours/one-week follow-ups, TMC-injected and TMC-LID-delivered groups have demonstrated 82%/93% and 80%/89% improvement in height of lesions in comparison to control (60%/68%). Delivery of TMC with the newly proposed LID technique is at least as effective as intralesional injection for treating inflammatory acne lesions. Enhancement of skin permeability using LID approach is a promising technique for accelerating delivery of various compounds to their target areas in the skin.

We report on the use of a fiber-based Mueller-matrix optical coherence tomography (OCT) system with continuous source-polarization modulation for in vivo imaging of early stages of skin cancer in SENCAR mice. A homemade hand-held probe with integrated optical scanning and beam delivering optics was coupled in the sample arm. The OCT images show the morphological changes in skin resulting from pre-cancerous papilloma formations that are consistent with histology, thus demonstrating the system’s potential for early skin cancer detection.

The measurement of cholesterol and triglycerides in blood by Z-scan technique is proposed. The nonlinear refractive index of cholesterol and triglycerides was found to vary linearly with concentration. Hence by calculating the nonlinear refractive index it is possible to measure their concentration in the sample. These measured values are found in equivalence with conventional colorimetric method.

Dynamic light scattering (DLS) is a promising technique for early cataract detection and for studying cataractogenesis. A novel probabilistic analysis tool, the sparse Bayesian learning (SBL) algorithm, is described for reconstructing the most-probable size distribution of α-crystallin and their aggregates in an ocular lens from the DLS data. The performance of the algorithm is evaluated by analyzing simulated correlation data from known distributions and DLS data from the ocular lenses of a fetal calf, a Rhesus monkey, and a man, so as to establish the required efficiency of the SBL algorithm for clinical studies.

We are pleased to present this special issue of JIOHS, which focuses on optical technologies in the study of tissues and biological liquids. The selected papers were presented during Saratov Fall Meeting — XII International School for Junior Scientists and Students on Optics, Laser Physics and Biophotonics (September 23–26, 2008, Saratov, Russia) in the framework of the following workshops: “Optical Technologies in Biophysics and Medicine,” “Nanostructures and Nanoparticles,” “Microscopic and Low-Coherence Methods in Biomedical Applications,” and “Internet Biophotonics.” All eight papers in this special issue are research papers.