This PDF file contains the front matter associated with SPIE Proceedings Volume 7563, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Naked eye observation has up to recently been the main method of determining skin erythema (vasodilatation) and blanching (vasoconstriction) in skin testing. Since naked eye observation is a highly subjective and investigatordependent method, it is difficult to attain reproducibility and to compare results reported by different researchers performing their studies at different laboratories. Consequently there is a need for more objective, quantitative and versatile methods in the assessment of alterations in skin erythema and blanching caused by internal and external factors such as the intake of vasoactive drugs, application of agents on the skin surface and by constituents in the environment. Since skin microcirculation is sensitive to applied pressure and heat, such methods should preferably be noninvasive and designed for remote use without touching the skin. As skin microcirculation further possesses substantial spatial variability, imaging techniques are to be preferred before single point measurements. An emerging technology based on polarization digital camera spectroscopy - Tissue Viability Imaging (TiVi) - fulfills these requirements. The principles of TiVi (1) and some of its early applications (2-5) are addressed in this paper.

Analysis of the first and second order statistical properties of light is a powerful means of establishing the properties of a medium with which the light has interacted. In turn, the first and second order statistical properties of the medium dictate the manner in which light interacts with the medium. The former is the inverse problem and the latter is the forward problem. Towards an understanding of the propagation of light through complex structures, such as biological tissue, one might choose to explore either the inverse or the forward problem. Fundamental to the problem, however, is a physical parametric model that relates the two halves; a model that allows prediction of the measured effect or prediction of the parameters based on measurements. This is the objective of our study. As a means of characterizing the first and second order properties of tissue, we discuss measurements with differential interference contrast microscopy using a phasestepping approach. First and second order properties are characterized respectively in terms of scatter phase functions and spatial power spectral densities. Results are shown for representative tissue.

A significant challenge in the field of mammography that has yet to be overcome involves providing adequate image quality for detection and diagnosis, while minimizing the radiation dose to the patient. An emerging x-ray technology, high energy phase contrast imaging holds the potential to reduce the patient dose without compromising the image quality, which would benefit the early detection of breast cancer. The purpose of this preliminary study was to compare the image quality of high energy phase contrast images to conventional x-ray images at typical mammography energies. The experimental settings were selected to provide similar entrance exposures for the high and low energy images. Several phantoms were utilized in this study to provide a comprehensive image quality comparison, in an effort to investigate the clinical potential of high energy phase contrast imaging. An ACR phantom was utilized for quantitative comparison through an observer study, while a new tissue-equivalent phantom was utilized for a qualitative investigation. Finally, an acrylic-edge phantom was employed to provide an illustration of the edge enhancement in the phase contrast images as compared to the conventional images. The results from the multi-faceted comparison indicate the potential of high energy phase contrast imaging to provide comparable image quality at a similar or decreased patient dose.

A systematic investigation of the polarization characteristics of the auto-fluorescence of normal and benign human breast tissues is carried out complementing our earlier studies on normal and cancer tissues. Co- and cross-polarized auto-fluorescence are collected in the 500 to 700nm range through excitation at 488nm using laser as excitation source. A number of parameters, capturing spectral variations are extracted in the co- and cross-polarized channels through singular value decomposition and wavelet decomposition, which differentiate normal and benign tissues. The correlation matrix differs significantly in normal and benign tissues reflecting the presence of different fluorophores. The eigenvectors corresponding to the dominant eigenvalues reveal differences between tissue types. The co-polarized component being sensitive to intrinsic fluorescence shows different behavior for normal and benign tissues in the emission domain of known fluorophores. Interestingly, the benign tissue samples show correlation properties intermediate to malignant and normal cases. In the wavelet domain the standard deviation of percentage fluctuation reveal differences between tissues type. The correlation characteristics manifest prominently in the wavelet low pass (average) domain.

Meningioma cell cultures were prepared from frozen cell samples in 96 wells culture plates. Semiconductor light sources (LED) in seven different wavelength ranges were used to illuminate the wells, three different irradiation doses were selected per LED. Control cultures using three different concentrations of FBS were processed for comparison. Cell proliferation, viability, and cytotoxicity were measured every 24 hours for 6 days, using the XTT colorimetric assay (Roche^R). None of the irradiated cultures exhibit cytotoxicity; but some of them exhibit proliferation inhibition. The larger proliferation was detected at a 0.05J/cm² dose, for all LEDs; but for the orange and violet LEDs generated the bigger proliferation rate was measured. Results show the improvement of meningioma cell proliferation using illumination in some given wavelength ranges.

We present a theoretical overview of key physical limitations for application-oriented nanostructure design. We focus on such promising applications as: nanodot-assisted optical imaging, and photo-thermal therapy with the help of nanostructures. For these applications we consider the following nanostructures: metal-coated nanoshells and metal nanoparticles. The actual design of relevant nanoobjects for particular applications must include consideration of such phenomena as: plasmon resonance, light scattering, light absorption. These phenomena are considered for model systems of various designs for different parameters of radiation. Our model estimations are compared with experimental results when such results are available. The conclusions are formulated as a paradigm "desired vs. feasible".

We have developed a phase stabilized swept source optical coherence tomography (PhS-SSOCT), that shows an axial resolution of 10 μm, phase sensitivity of 0.04 radians, imaging depth of up to 6 mm in air and a scanning speed of 20 kHz for a single A-line. In this paper, the PhS-SSOCT is applied to quantify gas microbubbles in blood in vitro. The results indicate that the system is able to detect bubbles of diameters greater than 10 μm using the structural image and the microbubbles of diameter less than 10 μm could be detected using the temporal phase response. Images of the bubbles of diameters 600 μm, 405 μm and 6 μm along with their phase responses are presented. Results indicate that the PhS-SSOCT could be potentially used for rapid assessment of blood microbubbles in vivo that cause diseases associated with decompression sickness, venous and arterial gas emboli and barotraumas. Eventually, PhS-SSOCT can be utilized as an early diagnostic tool for clinical purposes.

The technique of nanoparticles dynamics studies based on selective plane illumination microscopy and statistical particle tracking velocimetry has been developed. It allows for the visualization of water suspended gold nanoparticles dynamics. Distribution of particles temperature and velocity of their ordered motion could be obtained with spatial resolution of several micrometers. The proposed technique could be used for the studies of photothermal and photophorethic effects induced by laser irradiation in colloidal systems.

Both laser Doppler perfusion monitoring (LDPM) and imaging (LDPI) are versatile methods for investigation of the microcirculation of the skin and other organs. Even after about 30 years of use, true everyday clinical applications are however, still sparse with the possible exception of burn depth assessment and LDP has to be regarded as a laboratory rather than a clinical tool. The principles of laser Doppler perfusion monitoring and imaging and its evolution as a research and clinical tool are addressed in this paper.

We combine diffusing wave spectroscopy and dynamic light scattering microscopy to simultaneous non-invasive imaging of skin blood microcirculation. We demonstrate for the first time to our knowledge that the local blood micro-flows and blood microcirculation can be observed and analyzed quantitatively at the the biological zero, when the arterial and vein flows are stopped completely. We show that the biological zero signal arises from the local blood micro-flows observed postmortem up to 100 minutes. The high sensitivity of diffusing correlation technique and the feasibility for non-invasive measurement of skin blood microcirculation is thus demonstrated, and the potential for methodology can now be explored.

Currently, laser perfusion imaging (LDPI) is undergoing a technology shift from scanning beam perfusion imagers to whole field systems. The latter can be subdivided in laser Doppler methods systems based on high speed CMOS cameras, and laser speckle contrast analysis (LASCA) technologies using slow imaging arrays, mostly CCD-based. In scanning beam systems, a collimated laser beam scans the tissue with diffusely back reflected light being captured with a single detector. In whole field systems a large tissue area is illuminated, and the reflected light is imaged onto an array and captured at once. Unlike scanning beam systems, both whole field methods enable perfusion imaging at video rate. In this study we experimentally compare the scanning beam LDPI principle with whole field LDPI, using Intralipid phantoms. For the tissue phantoms, the Monte Carlo simulation technique will be used as a reference. From measurements on Intralipid phantoms compared to Monte Carlo, we conclude that in whole field LDPI the flux image, representing the first order moment of the power spectrum of photocurrent fluctuations is much closer related to real perfusion than for scanning beam systems. This difference can be explained in terms of the different behaviour of dynamic speckle patterns generated in both methods, in response to varying tissue optical properties.

Laser speckle contrast imaging (LSCI) is becoming an established method for full-field imaging of blood flow dynamics in animal models. A reliable quantitative model with comprehensive noise analysis is necessary to fully utilize this technique in biomedical applications and clinical trials. In this study, we investigated several major noise sources in LSCI: periodic physiology noise, shot noise and statistical noise. (1) We observed periodic physiology noise in our experiments and found that its sources consist principally of motions induced by heart beats and/or ventilation. (2) We found that shot noise caused an offset of speckle contrast (SC) values, and this offset is directly related to the incident light intensity. (3) A mathematical model of statistical noise was also developed. The model indicated that statistical noise in speckle contrast imaging is related to the SC values and the total number of pixels used in the SC calculation. Our experimental results are consistent with theoretical predications, as well as with other published works.

Since its discovery in 1842 by Christian Johann Doppler, the Doppler Effect has had many applications in the scientific world. In recent years, the phenomenon has been integrated with Optical Coherence Tomography (OCT) yielding Doppler Optical Coherence Tomography (DOCT), a technique that is useful for high-resolution imaging of the skin microcirculation. However, interpretation of DOCT images is rather challenging. Thus, our study aims to aid understanding of DOCT images with respect to parameters of microcirculation components such as blood vessel size, depth and angular position. To this end, we have constructed a gel-based tissue and blood-flow model for performing DOCT studies under well controlled conditions. We present results from a pilot study using a gel-based tissue and blood flow model. Human blood was pumped through the model at various velocities from a commercial calibrated syringe pump, serving as a standard reference point for all velocity measurements. The range of velocity values was chosen to coincide with that found in the human vasculature. Simultaneous DOCT imaging at different flow rates contributed to establishing the capabilities and limitations of the DOCT system under investigation. We present preliminary results as first step to developing a robust validation protocol with which to aid future research in this area.

We describe applications of silica (core)/gold (shell) nanoparticles and ICG dye to photothermal treatment of phantoms, biotissue and spontaneous tumor of cats and dogs. The laser irradiation parameters were optimized by preliminary experiments with laboratory rats. Three dimensional dynamics of temperature fields in tissue and solution samples was measured with a thermal imaging system. It is shown that the temperature in the volume region of nanoparticles localization can substantially exceed the surface temperature recorded by the thermal imaging system. We have demonstrated effective optical destruction of cancer cells by local injection of plasmon-resonant gold nanoshells and ICG dye followed by continuous wave (CW) diode laser irradiation at wavelength 808 nm.

Laser speckle contrast measurements provide effectively instantaneous maps of dermal perfusion, using easily obtainable hardware, but such maps are qualitative. Clinical applications of these techniques require a good theoretical and experimental foundation of understanding before relating them to a physiologically significant, quantitative perfusion value. We have confirmed that multiple-exposure laser speckle methods produce the same spectral information as laser Doppler measurements when applied to targets such as human tissue with embedded moving scatterers. This confirmation is based on both computer simulation of laser speckle data and experimental measurements on Brownian motion and skin perfusion using a laser Doppler system and a multiple-exposure laser speckle system. The Power Spectral Density (PSD) measurements of the light fluctuations derived using both techniques are equivalent. Dermal perfusion images can therefore be measured in exactly equivalent terms by either laser speckle contrast or more laborious scanning laser Doppler methods. Most analyses relating laser speckle contrast to perfusion depend on assuming a particular temporal autocorrelation function for the light intensity fluctuations in biospeckle. Using multiple-exposure laser speckle allows the autocorrelation function to be measured rather than assumed. Measured autocorrelation functions and their related power spectra for dermal perfusion are presented, including measurements under arterial occlusion to investigate a 'biological zero': the speckle blur relating to the remaining movement of tissue constituents when there is no net blood flow.

The estimate of tissue optical properties is an important challenge in biomedical science. In the research of precancerous diagnosis and glucose concentration detection, the accuracy of chromospheres concentrations measurement depends on the measurement of absorption coefficient. So determining the absorption coefficient accurately is crucial both in vivo and in vitro. The Double-Integrating-Spheres (DIS) system is widely used in measuring optical properties of tissue. As there are light losses, sphere alters and cross talk in the measurement with DIS system, the estimating error of the optical properties increases, especially for absorption coefficient. Based on the DIS setup, the Monte Carlo simulation and principle of the integrating sphere are applied to investigate the effects of light loss and cross talk with various parameters of sample. According to the investigation, a fast correcting method is introduced to modify the measuring results. After a calibration dataset was employed, the algorithm based on artificial neutral network is applied to modify the measurement with DIS system. The modified results indicate that the reconstruction accuracy of absorption coefficient is fully improved compared with the uncorrected ones.

Previous studies have focused on different tissue samples treated with optical clearing agents(OCAs), which showed premising results of optical clearing on decreasing light scattering effects to some degree. However, optical properties obtained from different tissue sections even from the same tissue presented variable results, which further could make it difficult to understand the mechanism of optical clearing. In this talk, we introduced tissue-like phantoms with stabile optical properties which are in accord with those of human tissues. Firstly, tissue-like phantoms mimicking the optical properties of human skin were fabricated. And then by using glycerol as enhancer, optical clearing effects of tissue-like phantom was investigated. When glycerol was added more and more into tissue-like phantom, the values of transmitted intensity presented an ascending tendency and the total attenuation coefficients decreased by degrees. The changes of optical property parameters especially scattering coefficients, showed that the addition of glycerol led to a reduction in scattering effects of tissue-like phantoms. In conclusion, the application of a robust tissue-like phantom could potentially quantify optical clearing effects, and further this would facilitate optical clearing technique to be used in light-based diagnoses and therapies.

In this work it is shown using spectral-luminescent methods that eosin and anthracene bind to human serum albumin globules. Comparison of eosin lifetimes in water, propyl alcohol and human serum albumin allows to establish that probability of the processes of nonradiating deactivation of eosin triplets decreases when eosin is bound to protein. It is shown that molecules of energy donor (eosin) and acceptor (anthracene) in protein globule can be localized on the distance of electron clouds overlapping and as a result triplet-triplet energy transfer occurs.

In this paper we provide a way to distinguish features of renal blood flow autoregulation mechanisms in normotensive and hypertensive rats based on the discrete wavelet transform. Using the variability of the wavelet coefficients we show distinctions that occur between the normal and pathological states. A reduction of this variability in hypertension is observed on the microscopic level of the blood flow in efferent arteriole of single nephrons. This reduction is probably associated with higher flexibility of healthy cardiovascular system.

In our previous work optical coherence tomography (OCT) has been proved to be a useful tool for monitoring of diffusion of chemical agents (water, glycerol) within human tooth dentine. Such diffusion studies are interesting for tooth therapy (diffusion of medicinal preparations) and cosmetics (chemical whitening agents). Here we compare different wetting schemes in which the sample is either merged in the liquid agent so that the probe beam is to pass through a layer of liquid, or subjected to wetting through a special window from the back side. In spite of certain difference revealed, the order of magnitude of the diffusion time constant and the permeability coefficient are shown to be the same in both cases.

Cellulite is considered as a disease of the subcutaneous fat layer that appears mostly in women and consists of changes in fat cell accumulation together with disturbed lymphatic drainage, affecting the external appearance of the skin. The photodynamic and selective photothermal treatments may provide reduction the volume of regional or sitespecific accumulations of subcutaneous adipose tissue on the cellular level. We hypothesize that light irradiation of stained fat tissue at selected temperature leads to fat cell lypolytic activity (the enhancement of lipolysis of cell triglycerides due to expression of lipase activity and cell release of free fat acids (FFAs) due to temporal cell membrane porosity), and cell killing due to apoptosis caused by the induced fat cell stress and/or limited cell necrosis.

This report outlines results from an independent study assessing the clinical potential of an emerging, contemporary imaging technology. Tissue Viability (TiVi) imaging is an easily implemented, non-invasive, and portable technique which maps the blood circulation in the surface dermal layer. However, its routine clinical implementation awaits the development of the necessary standardised protocols. Thus the pilot study examines the efficacy of a novel TiVi imaging device within a localised skin blood flow occlusion protocol. The test was administered to the upper volar forearm of 19 healthy subjects (10:9 Female:Male) for 5 different time periods ranging from 5 to 25 seconds. Dermal areas corresponding to 100 × 100 pixels (2.89 cm²) were monitored for 60 seconds prior to, during and after each occlusal test. Our results support the relevance of a TiVi occlusion protocol for physiological assessment of the skin microcirculation.

Spectral techniques used for early diagnosis of skin cancer give to the investigators diagnostically important features usually in the process of comparison of signals received from normal and abnormal skin sites. In this study are presented some initial results of fluorescence for early detection of cutaneous tumors. However, due to great variety of optical properties and choromophores' distribution spectra of "normal" skin could have observable differences between themselves. Diagnostically significant features, such as intensity, appearance of specific minima or maxima in the spectra received, depend from anatomic place, ages, cutaneous phototype, when are measured in vivo. Therefore, development of objective differentiation algorithms for early diagnosis of skin pathologies will strongly depend from our understanding - what is the influence of major fluorophores and absorbers in the spectra observed in defined as "healthy" skin sites, and how these spectral peculiarities could influent the spectra received from lesion sites, distorting our diagnosis. In such way, we could obtain complete picture of normal skin fluorescence properties, which will be the background for comparison with any cutaneous pathology, appearing on the patient skin surface, useful for early diagnostics and alert for pre-cancerous conditions and large areas observations.