There has been increasing interest both for fundamental research and clinical applications in using laser speckle contrast imaging to image flow. Laser speckle contrast imaging utilizes intrinsic tissue contrast from dynamic light scattering. It provides a rather simple way of imaging, for example, blood flow and its spatial and temporal variations. In this report we will try to extend the capabilities of speckle contrast imaging by using longer excitation wavelength in order to increase the imaging depth and to provide additional contrast imaging enhanced by resonance optical absorption.

We present an approach for using dynamic laser speckle data to quantify biophysical dynamics including ordered flows and random motions. The approach yields images that resemble laser speckle contrast images, but instead of relying on the statistics of the local time integrated intensity values calculated over temporal and sliding spatial windows as is done in LSCI, ellipticity imaging (EI) directly yields images that quantify the relative dominance of long-range correlations in the temporal dimension of a series of speckle patterns to the short-range correlations in the same dimension. Theory behind EI and simulated EI images will be presented.

We present an approach for using dynamic laser speckle data to quantify biophysical dynamics including ordered flows and random motions. The approach yields images that resemble laser speckle contrast images, but instead of relying on the statistics of the local time integrated intensity values calculated over temporal and sliding spatial windows as is done in LSCI, ellipticity imaging (EI) directly yields images that quantify the relative dominance of long-range correlations in the temporal dimension of a series of speckle patterns to the short-range correlations in the same dimension. Flow phantom and in vivo mouse EI studies will be presented.

Laser speckle contrast imaging (LSCI) of flow has been widely used in biomedical applications yet questions on whether LSCI can be quantitative are still being raised. We analyzed LSCI from the first principle and provided a complete procedure covering the system calibration, static scattering removal, and measurement noise estimation and removal to obtain a genuine flow speckle contrast. We demonstrated the power of our recipe by imaging flow moving at varying speeds and an excellent linearity between the measured and input flow speed from 0mm/s to 40mm/s was achieved, suggesting that the true flow speed may be obtained from LSCI.

Laser speckle contrast imaging (LSCI) is a promising tool to measure blood flow in preclinical research and clinical applications. LSCI uses the dynamics of light scattering with red blood cells to create blood flow maps. In this talk, we report on recent progress for using LSCI to measure blood flow in behaving macaques in conjunction with calcium imaging and optical stimulation of the visual cortex. Additionally, we explore methods to extend LSCI to three-dimensional imaging.

Here we introduce a novel non-invasive, wearable VCSEL-based sensor platform for multipoint in-vivo measurements of blood perfusion. The proposed wearable blood perfusion sensors operate on the principles of LDF. These systems comprise one or more wearable devices additionally integrating an accelerometer and skin thermometer, and a wireless data acquisition module, ultimately benefitting from fibre-free implementation and ability to be connected to study synchronisation of skin blood flow under different conditions. The proposed sensors have been used on healthy volunteers of different age and enabled the finding of statistically significant differences in synchronisation of skin blood flow associated with age.

Quantitative blood flow measurements using optical coherence tomography (OCT) have a wide range of clinical applications. Speckle-decorrelation—based flowmetry has the advantage of being potentially angle insensitive, but it has not been able to reliably produce quantitative flowmetry. Using a flow phantom to simulate realistic flow conditions, we performed a systematic study of the effects of multiple scattering on OCT signal decorrelation. We have replicated the decorrelation behavior measured in in vivo retinal flow and are currently using previous work on the effects of flow velocity gradients to incorporate multiple scattering into the model for OCT signal decorrelation.

Monitor seed germination by Biospeckle Optical Coherence Tomography (OCT) was proposed to predict crop yields at the stage of the selection of seeds. Biospeckle OCT used speckle contrast which is defined by the ratio of standard deviation to mean value of the temporal fluctuation of OCT intensities to indicate the biological activities of seeds. Seeds were germinated and measured by OCT. Some seeds were boiled as a comparison of the level of biological activities. The contrast of Biospeckle OCT was found to be related to the biological activities of seeds. The relationship of crop yields and contrast will be reported.

The temporal fluctuations of laser speckles and hence the dynamics of optical vortices are modulated by light scattering particles diffusion, governed by tissue viscoelasticity. We studied the stochastic motion of optical vortices and proposed a new method to evaluate tissue viscoelasticity by quantify the mean squared displacement (MSD) of vortices in the pseudo-phase representation of laser speckles. We observed the confined diffusion of the vortices and retrieved the diffusion coefficient and the MSD saturation level. These parameters are measured for different gel phantoms and tissue samples. We observe strong correlation between the viscoelasticity measured using our approach and standard rheometry.

In this study, we explore the feasibility to noninvasively characterize individual cell motion in the postcapillary vessels of human skin. Our preliminary data of ten healthy volunteers show that the following dynamic parameters can be extracted: blood flow velocity, number of adherent leukocytes, and number and diameter of vessels. Moreover, we show the variation in the blood flow velocity within the same vessel over time, between nearby vessels and between different body sites.

Current report considers development of a real-time biophysically-based skin digital simulator for the purpose of realistic rendering of skin appearance. An optical model of human skin considering spatial/volumetric variations such surface roughness, distribution of blood, melanin, collagen, index of blood oxygen saturation, water, pigment content, etc. has been developed and incorporated with physically based renderer developed in-house. The developed framework is used in the evaluation of skin appearance changes, rigorous validation against data obtained during clinical studies is presented.

Dynamic in vivo monitoring of transferrin receptor-ligand engagement in live intact animals was demonstrated using FRET approach. The experiment was performed using both intensity- and lifetime-based measurements. Using hybridized oligos as FRET standard, we demonstrate that it is possible to obtain the same FRET quantification via intensity and lifetime-based measurements. Overall, both measurement methods provided the same FRET quantification trends of receptor engagement over 120 minutes of imaging. However, intensity FRET approach required 18 measurements, whereas lifetime FRET required only one measurement. Hence, macroscopic fluorescence lifetime FRET enables simple and rapid acquisition for the assessment of targeted drug delivery in longitudinal preclinical pharmacology.

In mammals, the oviduct is where a new life initializes with a series of reproductive events taking place, including gametes transport, fertilization, and embryo transfer. Although dynamic assessment of these processes in the oviduct is greatly desired, available imaging techniques are largely in vitro and ex vivo, not suitable for the native tissue and cell dynamics. Here, we present an in vivo imaging approach based on OCT and a dorsal imaging window, which is capable to probe the mouse oviduct and the reproductive processes in a high-resolution, 3D, dynamic, functional, and quantitative fashion, opening new opportunities for mammalian reproductive research.

A comprehensive understanding about time-dependent, photoinduced processes affecting the appearance of human tissues is essential for new advances in numerous fields, from biology and medicine to biomedical photonics and computer graphics. However, the dynamics of photobiological phenomena leading to skin appearance changes over time remains an elusive research topic. In this work, we present a novel physiologically-based framework for the simulation and visualization of tanning dynamics, one of the most prominent and persistent of these phenomena. The proposed framework provides a platform for the replicable testing of scientific theories and new technologies related to time-dependent skin responses to light exposure.

Patients with spinal cord injuries are at high risk for pressure ulcers in bony prominent regions. To develop a better understanding of the methods of treating and preventing pressure ulcers, we have developed a voxilization based model of the ischial tuberosity based on a Monte Carlo framework. The 3D model of the underside of the pelvis, the ischial tuberosity, allows for variation of the layers of the skin, fat, and muscle created in Solidworks. This model can aid in the study of methods of improving and maintaining skin health and help with rehabilitation and prevention of pressure ulcers.

The study offers a possibility of using such biocompatible chemical as glycerol as a biomarker for early diagnostics of diabetes mellitus complications, in particular, for assessing the degree of myocardial lesion evidence by the stage of skin glycation in the process of diabetes development and treatment. The study was aimed to find the difference in glycerol permeability of rat tissues of control and diabetic groups in order to show the possibility of glycerol usage as a biomarker of diabetes impact on superficial and internal tissues. The investigation presents translation the experimental studies from ex vivo to in vivo conditions.

The present work demonstrates the visualization of the intracellular distribution of upconversion nanoparticles (UCNPs) by microscopy at temperature variation with excitation in the NIR spectral range and detection of upconversion luminescence in the VIS range. The cell viability is scored for cytotoxic effects of UCNPs at dark and light exposed conditions. Non-functionalized UCNPs incubated with the cells are found to be endocytosed by cells. The obtained results confirm a high sensitivity of the luminescent UCNPs to the temperature variations within cells. UCNPs are promising alternatives to traditional fluorescent labels for cell imaging and possess prominent potentials in biological and clinical applications.

The study of blood microcirculation is one of the most important problems of the medicine. This is caused by the fact that many diseases, such as cardio-vascular diseases, atherosclerosis, diabetes, chronic venous insufficiency, oncology diseases, cause functional and morphological changes of blood microcirculation. We present the results of experimental study of changes of blood microcirculation of pancreas in rats with diabetes and subcutaneous blood flow in conditions of development of malignant tumor by using Laser Speckle Contrast Imaging (LSCI) at application of optical clearing agents. The influence of x-ray contrast OmnipaqueTM 300, solution of glucose, glycerol, PEG-300, and PEG-400 was investigated.

The development of BCI technologies, along with the detection of signs associated with the simplest motor functions, requires decoding more complex cognitive processes associated with fine motor skills, positioning, and attention. EEG signals are usually the main source of information. The choice of suitable numerical methods is important for the reliable identification of emerging structural changes in the EEG. In this study, we discuss the changes in the correlation characteristics when making decisions in comparison with background electric activity. We demonstrate significant distinctions in the scaling features between background records and EEG signals associated with mental intentions. The study was supported by the Ministry of Education and Science of the Russian Federation within the framework of the Federal Target Program "Research and development in priority areas of development of the scientific and technological complex of Russia for 2014-2020" (agreement 14.577.21.0282).

In this study, we consider how the removal of bad segments influences the characterization of the scaling features and the complexity of physiological data such as the cerebral blood flow. We apply several widely used data processing techniques for signals with different amounts of missing segments in order to verify the ability of determining the functioning regime when various parts of data are excluded at the preprocessing stage. We demonstrate that all the techniques show that positively correlated time series are significantly less sensitive to excluded segments and enable the characterization of the object’s properties even under the condition of an extreme data loss.

Analysis of biological signals for revealing characteristic oscillatory patterns is an important task for the implementation of human-machine interaction systems. In this context, oscillatory patterns detected on biological signals can be used as commands for hardware control or communication. In this paper, we propose a technique for identifying characteristic oscillatory patterns on myographic data in real time, based on analysis of the spatio-temporal and time-frequency properties of a multichannel EMG set.

Tissue optical clearing technique plays an important role in three-dimensional visualization of intact organs or rodent bodies. As a typical organic-solvent based clearing method, 3DISCO renders the turbid tissues transparent by the strategy of minimizing light scattering, and can achieve high transparency and substantial size reduction, which could facilitate imaging of large-volume tissues. However, for heme-rich tissues, tissue transparency and image quality by 3DISCO are limited due to the strong absorption ability of hemes. To address this problem, we proposed an optimized 3DISCO clearing protocol to enhance the transparency of the heme-rich tissues and facilitate high-resolution imaging inside these tissues.

On a series of multilayer phantoms with different location of fluorescent layer we modelled the propagation of clearing front (the front of lowered scattering) from tissue surface into depth. The sequence of fluorescence spectra was measured at successive replacement of phantom layers with the layers with lowered scattering. Obtained experimental results on the “kinetics of fluorescence under optical clearing” were interpreted based on computer simulations performed using a hybrid method combining the Monte Carlo photon-tracing approach and the transfer matrix approach. The patterns found in model experiments were used to interpret the results obtained in vivo in pilot measurements on rat skin.

In current study, we examined the application of new LSCI based system combining multi-wavelength light source and hyperspectral camera for the depth-resolved monitoring of tissue flow phantoms. Also, proposed system has been verified for quantitative in-depth measurements of perfusion changes during occlusion in human finger.

Confocal Raman microscopy (CRM) has been used to measure depth-dependent profiles of porcine skin ex vivo in the high wavenumber (HWN) region after application of optical clearing agent (OCA). 70 % Glycerol and 100 %iohexol (Omnipaque™) solutions were used as OCAs and applied to the porcine ear skin within 30 and 60 min of treatment. Using deconvolution procedure with 10 Gaussian functions the changes of profiles of hydrogen bound water molecule types normalized on protein has been analyzed up to 200µm depth.

The modern non-invasive neurophysiological diagnostic EEG is one of the main methods, which gives an idea of the structure of the work of the cerebral cortex and its functional features. As part of this work we have adapted wavelet-based techniques for the analysis of multi-channel recordings of electrical activity of the brain during the solution of various cognitive tasks.

Rapidly activated transcription factors (NF-kB, STAT-family, CREB/ATF and others) are critically important for regulating downstream events resulting from the pro-inflammatory signaling and cell stress, including heat shock and unfolded protein response. We developed and tested a family of transcription factor-recognizing stabilized oligonucleotide duplex-based probes (ODND) for direct detection and potential imaging of transcription factor activation in situ and in vivo. Using model systems and time-domain fluorescence lifetime (FL-TD) microscopy (FLIM) as well as macroscopic imaging measurements we determined that ODND based on interacting emitting and non-emitting FRET near-infrared fluorophore pairs reveal statistically significant changes of FL associated with the interaction of transcription factors with the probes carrying specific recognition sequences. The obtained results in vitro and in situ have strong potential in designing the strategies directed at the imaging of transcription activation machinery in common human pathologies.

The problem of extracting useful for medical diagnosis information from bid experimental data measured by 2D and 3D optical imaging is of great importance. We are discussing challenges and perspectives of medical diagnosis using machine learning analysis of big volume experimental data of IR and THz tissue imaging. It is planned to discuss peculiarities of tissue optical clearing for tissue imaging in IR and THz spectral ranges, methods of extracting of informative features from experimental data, creating of multiclass classification using machine learning methods. The examples of these approaches for medical diagnosis, including cancer tissues, lymphedema, etc., will be presented.

In recent decades, there has been an increase in patients with malignant tumors of the abdominal organs. The ability to recognize the suspect tissue in a second without interruption of the procedure is able to dramatically increase the effectiveness of the surgical removal of the cancerous tumors. In this study, we present experimental studies with a fine-needle fiber optic probe comprising emitting and collecting fibers for measurements of fluorescence intensity and diffuse reflectance. The obtained results demonstrate high specificity and sensitivity for the classifier based on the multimodal approach.

Video plethysmography (vPPG) is a noninvasive, remote diagnostics method that monitors cardiac activity by measuring subtle variations in the optical properties of skin driven by heart pulsations. However, the mechanism responsible for the vPPG signal, in particular, the fluctuation of the skin color at heart rate, is not well understood. Using optical coherence tomography (OCT), we show that the optical attenuation coefficient of the outermost layer of the epidermis is modulated at heart rate, being the modulation surrogate for the mechanical changes in the skin. We propose a hydraulic shock hypothesis to explain the phenomenon.

Obesity affects 93 million adults in the U.S. Several studies show that BMI ratio does not fully characterize the patient’s pathophysiology. Muscle metabolism may be a more useful metric in the characterization of pathologies associated to weight gain. Near Infrared Spectroscopy (NIRS) measurement of muscle oxygenation can be used to study muscle metabolism. Commercial NIRS systems fail to produce accurate results in the presence of excess adipose thicknesses (AT). We have used Monte Carlo models of light transfer to probe the optimal source-detector separation for NIRS in the obese. We will demonstrate our system validation in optical phantoms and volunteers.

As with fluorescence microscopy techniques, there is a growing demand for enhancing spatial resolution of SHG microscopy to see more details. We extend the subtractive imaging method to SHG microscopy to enhance the spatial resolution and contrast. This method is based on the intensity difference between two images obtained with circularly polarized Gaussian and doughnut-shaped beams, respectively. By characterizing the intensity and polarization distributions of the two focused beams, we verify the feasibility of the subtractive imaging method in polarization dependent SHG microscopy. The resolution and contrast enhancement in different biological samples is demonstrated. A 1.3-fold resolution improvement is achieved and a significant contrast enhancement is obtained without any prior information of samples. And we demonstrate the possibility of further enhancement of spatial resolution and contrast using a partial aperture illumination strategy.

Volumetric photoacoustic imaging (PAI) images of normal and brain infarction model and the oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) image were acquired and compared with [18F]FDG PET uptake statistically. Functional PA signals (each p=0.001) and [18F]FDG PET uptake (p=0.002) of the left and right brain were significantly difference in the infraction model. From these results, we could distinguish the infarction region from PAI and [18F]FDG PET image. Edge of infarction area in PAI was more clear than [18F]FDG PET image, due to its high ultrasonic resolution. Thus, we demonstrated the feasibility of PAI for evaluation of brain infarction in mouse.

In vivo tissue optical clearing techniques can efficiently overcome these problem. In this work, we combined hyperspectral imaging (HSI) and laser speckle contrast imaging (LSCI) to simultaneously monitor the changes in cortical and cutaneous microvascular blood oxygen saturation and blood flow under assistance of in vivo skull and skin optical clearing techniques, and quantitatively compared the difference between cerebral and cutaneous arteriovenous functional responses when the hypoxic stimulations was performed. This work provides a feasible solution to realize visualization of in vivo monitoring cerebral and cutaneous microvascular reactivity with minimal invasiveness.

Based on the changed leisure behavior, that means on the fact that vacationers spend their free time more and more in the mountains or in sunny regions by the sea, the use of sunscreen is of particular importance. The effectiveness of sunscreens against harmful UV radiation from the sun is characterized by the sun protection factor (SPF). For its determination, the minimum erythema dose, i.e. the dose of UV radiation causing sunburn in case of unprotected skin and sunscreen-treated skin is used. Thereby a sunburn is generated, which actually should be prevented by the sunscreen. This method is therefore unsatisfactory. At the Charité, a physical, non-invasive method for the determination of sunscreens was developed. The measuring method used here is based on the so-called "photon banana". UV radiation is applied to the sunscreen-treated skin through an optical fiber. Parts of the light are reflected, other parts are scattered in the tissue and emerge elsewhere. This light passes "banana-shaped" through the upper skin layer and passes through the sunscreen twice. It is detected with optical fibers and a detector. The excitation occurs using LEDs. Very good correlations between the measured SPF values and the SPF values determined in the test laboratories under in vivo conditions could be achieved.

In this study, we applied the Mueller matrix microscope to the detections of human Crohn’s disease samples at different pathological stages, whose structural features are complex for the accurate diagnosis. Here the Mueller matrix derived parameters of the abnormal tissues in different regions are calculated and analyzed. For more quantitative studies, a textural feature analyzing method named Tamura method is adopted to provide some textural feature parameters. The experimental and simulated results suggest that the Mueller matrix derived parameters and textural feature analyzing technique can be helpful to characterize pathological tissues at different stages with distinct microstructural features quantitatively.

In this study we present an upgraded OCTA/PAT system which uses 3D printing extensively in the probe manufacturing for light weight and easier handling. We recruited and imaged patients with various inflammatory and neoplastic skin diseases and performed quantitative analyses of the vascular networks to generate 5 parameters representing different features of the vascular network. Using these features we were able to identify the diseased part of the skin in 3D and observed different changes depending on the type of disease. We demonstrated that the combined OCTA/PAT system obtains information of the skin vasculature, which cannot be gained by other techniques.

Although optical coherence tomography (OCT) is routinely used to image the eye, in more turbid tissues, additional contrast is often needed, for example to distinguish between benign fibrous tissue and tumor in breast. This contrast can be provided by optical coherence elastography (OCE) and attenuation imaging. Here, we present images from human mastectomy specimens, co-registered with histology, and assess the improvement in tissue differentiation gained by fusing these contrast mechanisms into a hybrid image. Additionally, we explore the dependence on compression of the attenuation coefficient, and report the optimal preload to apply to maximize OCT penetration depth.

In this study, we use the Mueller matrix derived parameters to obtain the accurate orientations information of turbid media. The experimental results of tissue phantoms and Monte Carlo simulations suggest that the Mueller matrix derived parameters have the ability to distinguish the anisotropy orientations of cylindrical scatterers and birefringence in a complex medium. The preliminary application on bovine tendon tissue samples also demonstrates that the parameters can be used to reveal the accurate anisotropy orientations in biological tissues. The results indicate that the anisotropy orientations information can be helpful for future biomedical studies or diagnosis.