This PDF file contains the front matter associated with SPIE Proceedings Volume 10412 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

An 8-channel Silicon PhotoMultiplier (SiPM) probe and Time-to-Digital-Converter (TDC) realize a higher-throughput, cheaper and compact detection chain for time-resolved optical mammography than photomultiplier tubes (PMTs) and Time Correlated Single Photon Counting (TCSPC) boards, providing comparable estimate of optical properties with increased optical responsivity.

A time-resolved Diffuse Optical Tomography system based on multiple view acquisition, pulsed structured light illumination and detection with spatial compression is proposed. Reconstructions on heterogeneous tissue mimicking phantoms are presented.

We proposed the extremely compact beans-size snap-shot mid-infrared spectroscopy that will be able to be built in smartphones. And also the easy preparation method of thin-film samples generated by ultrasonic standing wave is proposed. Mid-infrared spectroscopy is able to identify material components and estimate component concentrations quantitatively from absorption spectra. But conventional spectral instruments were very large-size and too expensive to incorporate into daily life. And preparations of thin-film sample were very troublesome task. Because water absorption in mid-infrared lights is very strong, moisture-containing-sample thickness should be less than 100[μm]. Thus, midinfrared spectroscopy has been utilized only by analytical experts in their laboratories. Because ultrasonic standing wave is compressional wave, we can generate periodical refractive-index distributions inside of samples. A high refractiveindex plane is correspond to a reflection boundary. When we use a several MHz ultrasonic transducer, the distance between sample surface and generated first node become to be several ten μm. Thus, the double path of this distance is correspond to sample thickness. By combining these two proposed methods, as for liquid samples, urinary albumin and glucose concentrations will be able to be measured inside of toilet. And as for solid samples, by attaching these apparatus to earlobes, the enhancement of reflection lights from near skin surface will create a new path to realize the non-invasive blood glucose sensor. Using the small ultrasonic-transducer whose diameter was 10[mm] and applied voltage 8[V], we detected the internal reflection lights from colored water as liquid sample and acrylic board as solid sample.

We significantly improve the estimation of the absorption and reduced scattering coefficients, and second-order similarity parameter γ from spatially resolved reflectance by extending the inverse model with the third-order similarity parameter δ.

We demonstrate numerically the increased resolution of the image of a pure absorber as recorded by a scanning system composed of aligned source-detector when only polarization-preserving photons are selected.

The optical performance of a volume scanner is analyzed using modelling software. The existence of an embedded scattering volume with a 2.5% difference in scattering coefficient from the host media may be detected.

To evaluated capabilities of multispectral TD-DOT systems in reflection geometry, we performed a measurement campaign on multimaterial composition phantoms. Results show correct composition gradation of inclusions but still lack absolute accuracy.

A framework for efficient formulation of the inverse model in diffuse optical tomography, incorporating parallel computing is proposed. Based on 24 subjects, a tenfold speed increase and a hundredfold memory efficiency is reported, whilst maintaining reconstruction quality.

We describe a reciprocity relation for polarized radiative transport between arbitrarily positioned sources and detectors separated by a scattering medium. Applications to polarized Diffuse Optical Tomography are shown which allow for efficient computation of the sensitivity kernel.

Utilizing a modified analytical solution of the radiative transfer equation allows to fit both the spatial frequency domain reflectance and the phase. The additional information then allows to correct for surface reflections.

When light is incident upon tissue, imaging contrast can be obtained from a range of interactions including absorption, scattering and fluorescence. Clinical optical imaging systems are typically optimized to report on a single contrast source, for example, using standard RGB cameras to produce white light reflectance images or filter-based approaches to extract fluorescence emissions. Hyperspectral imaging has the potential to over-come the need for specialized instrumentation, by sampling spatial and spectral information simultaneously. In particular, spectrally resolved detector arrays (SRDAs) now monolithically integrate spectral filters with CMOS image sensors to provide a robust, compact and low cost solution to video rate hyperspectral imaging. However, SRDAs suffer from a significant limitation, which is the inherent tradeoff between spatial and spectral resolution. Therefore, the properties of the SRDA including the number of filters, their wavelength and bandwidth, needs be optimized for tissue imaging. To achieve this, we have developed a software framework to optimize spectral band selection, simulating the hyperspectral sample illumination, data acquisition and spectral unmixing processes. Our approach shows early promise for selecting appropriate spectral filters, which allows us to maintain high spatial resolution for imaging.

In this work an analytical model for the time-resolved signal emitted by a uniformly distributed Raman scatterer in a diffusive parallelepiped is derived and validated with Monte Carlo (MC) simulations.

We investigate methods of linearizing the problem of diffuse reflectance spectroscopy. Simulations show the effective optical pathlength varying in a scattering medium as a function of wavelength, total absorption, and chosen polarization channels.

Diffuse reflectance spectroscopy has been widely used in the field of biological tissue characterization with various modalities [1-5,6]. One of these modalities consists in measuring the spatially resolved diffuse reflectance (SRDR). In this technique, light is collected at multiple distances from the excitation point. The obtained reflectance decay curve is used to determine scattering and absorption properties of the tissue [7], which are directly related to tissue content and structure. Existing systems usually use fiber optics to collect light reflected from the tissue and transfer it to an optical sensor [1,6]. Such devices make it possible to perform SRDR measurements directly in contact with the tissue. However, they offer poor spatial sampling of the reflectance and low light collection efficiency. We propose to overcome these limitations by using a CMOS sensor placed in contact with the tissue to achieve light collection with high spatial sampling over several millimeters and with increased fill factor. Our objective in this paper is to demonstrate the potential of our instrument to determine the optical properties of tissues from SRDR measurements. We first describe the instrument and the employed methodology. Then, preliminary results obtained on optical phantoms are presented. Finally, the potential of our system for SRDR measurements is evaluated through comparison with a fiber-optic probe previously developed in our laboratory [6,8].

We developed a compact, fast, hand-held hyperspectral imaging system for 2D neural network-based visualization of skin chromophores and blood oxygenation. Here, we present results of the system tests on healthy volunteers.

With pulse wave periodic beating taken into account we assess the influence of blood volume and oxygen saturation changes on the measurements of diffuse reflectance spectra of human skin in the visible and NIR spectral range.

In the present work, we show the capacity of spatially resolved Diffuse Reflectance Spectroscopy (DRS) to identify live and dead worms in ex vivo Onchocerca ochengi nodules. It demonstrates the potential of DRS to diagnose the worm state and to monitor the effect of a drug on macrofilariae. These results have been obtained in constrained conditions, leading to the proposal of a rigorous acquisition and analysis protocol that may contribute to standardized measures in diffuse optics.

Non-contact scanning at small source-detector separation enables imaging of cerebral and extracranial signals at high spatial resolution and their separation based on early and late photons accounting for the related spatio-temporal characteristics.

Diffuse correlation tomography was utilized to noninvasively monitor 3D blood flow changes in three types of healing mouse femoral grafts. Results reveal the spatial and temporal difference among the groups.

We have successfully applied a custom-made handheld fluorescence camera for intraoperative fluorescence detection of indocyanine green in a feasibility study on sentinel lymph node mapping in patients with vulvar, cervical, endometrial and ovarian cancer.

We investigated depth heterogeneity in the abdomen using time-domain diffuse optical spectroscopy at 3 source-detector distances, finding a higher water content in shallower regions, possibly ascribed to fat heterogeneity and/or skin contributions.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial inflammation. The current treatment paradigm for earlier, more aggressive therapy places importance on development of functional imaging modalities, capable of quantifying joint changes at the earliest stages. Diffuse optical tomography (DOT) has shown great promise in this regard, due to its cheap, non-invasive, non-ionizing and high contrast nature. Underlying pathological activity in afflicted joints leads to altered optical properties of the synovial region, with absorption and scattering increasing. Previous studies have used these optical changes as features for classifying diseased joints from healthy. Non-tomographic, single wavelength, continuous wave (CW) measurements of trans-illuminated joints have previously reported achieving this with specificity and sensitivity in the range 80 – 90% [1]. A single wavelength, frequency domain DOT system, combined with machine learning techniques, has been shown to achieve sensitivity and specificity in the range of 93.8 – 100% [2]. A CW system is presented here which collects data at 5 wavelengths, enabling reconstruction of pathophysiological parameters such as oxygenation and total hemoglobin, with the aim of identifying localized hypoxia and angiogenesis associated with inflammation in RA joints. These initial studies focus on establishing levels of variation in recovered parameters from images of healthy controls.

Advanced processing of high-speed video-capillaroscopy data revealed that erythrocytes speed follows variations of arterial blood pressure, whereas intensity of light returned from a single capillary is almost unmodulated at the heartbeat frequency.

We present the Dual-Step system and method we developed to achieve 2D quantitative maps of optical properties. It is non-contact, quantitative for both absorption and scattering, large field, and spectrally resolved. The present study shows the results obtained on rats and figures the interest of the approach to address complex in-vivo samples.

Spatially resolved reflectance was measured on various phantoms and in vivo to evaluate its performance in determining their optical properties. To obtain reliable results it was necessary to use the absolute values of the reflectance.

We describe an optical system and a method for measuring the human iris spectral reflectance in vivo by hyperspectral imaging analysis. It is important to monitor age-related changes in the reflectance properties of the iris as they are a prognostic factor for several eye pathologies. In this paper, we report the outcomes of our most recent research, resulting from the improvement of our imaging system. In particular, a custom tunable light source was developed: the images are now acquired in the spectral range 440 - 900 nm. With this system, we are able to obtain a spectral resolution of 20nm, while each image of 2048 x 1536 pixels has a spatial resolution of 10.7 μm. The results suggest that the instrument could be exploited for measuring iris pigmentation changes over time. These measurements could provide new diagnostic capabilities in ophthalmology. Further studies are required to determine the measurements’ repeatability and to develop a spectral library for results evaluation and to detect differences among subsequent screenings of the same subject.

In this work we introduce a theoretical model for light propagation in multilayered, turbid cylinders with an infinitely thick bottom layer, which can be applied to the study of biological systems such as the human head. Our approach was validated with experiments on a three-layered phantom and with Monte Carlo simulations. We show that the absorption and the reduced scattering coefficient of the deepest layer can be retrieved within reasonable errors.

Unhealthy nutrition trends determination technique is described. Combination of optical spectroscopy and electrical impedancemetry will lead to development of a healthcare device that will predict unhealthy eating habits and decrease risk factors of diseases development.

Human skin surface has unevennesses called sulcus cutis and crista cutis. It is known that these affect the light propagation in human skin. In this study, we made a prototype of skin tissue phantom and investigated its spectral properties and problems to be solved.

Two variations of a depth-selective back-projection filter for functional near-infrared spectroscopy (fNIRS) systems are introduced. The filter comprises a depth-selective algorithm that uses inverse problems applied to an optically diffusive multilayer medium. In this study, simultaneous signal reconstruction of both superficial and deep tissue from fNIRS experiments of the human forehead using a prototype of a CW-NIRS system is demonstrated.

An optical instrument for nailfold fluorescence capillaroscopy and image registration has been developed. With this instrument, an effect of increasing fluorescence intensity in the spectral range of NADH fluorescence during ischemia was detected.

This work reports on a time-domain image reconstruction algorithm for fluorescence lifetime tomography exploiting information contained whole fluorescence TPSFs. The results show the possibility to distinguish 4 different fluorophores with different lifetimes.

A cost-effective and high-speed 3D diffuse optical tomography system using high power LED light sources and silicon photodetectors has been designed and built, that can continuously scan and reconstruct spectroscopic images at a frame rate of 2 fps. The system is experimentally validated with tissue mimicking cylindrical resin phantom having light absorbing inhomogeneities of different size, shape and contrast, and at different locations.

In hyperspectral imaging, a push broom method is very common. A sample is illuminated along a single line and reflected light is gathered from the same line. Effects of the illumination geometry on recorded intensity due to the colocation of illumination and data acquisition are investigated by simulating a push broom system geometry using Monte Carlo simulation. Multiple sets of realistic tissue optical parameters are used in the simulations, while illumination line width and its numerical aperture are varied. Values of recorded angular dependent radiance are compared, revealing observable effects of illumination line width. Some effects of illumination line numerical aperture that vanish at experimentally achievable illumination widths are also observed.

We implemented a ring-scanning mechanism in a prostrate type for breast tumor detection. Reconstructed μ_a and μ_s′ images of multi-layers scanning are presented in good outcomes, showing it’s promising for the 3D scanning of breast.

We consider L1-regularization of spectrally constrained DOT. Three popular algorithms are investigated: iteratively reweighted least square algorithm (IRLS), alternating directional method of multipliers (ADMM) and fast iterative shrinkage-thresholding algorithm (FISTA). We evaluate different regularizers and algorithms on a 3D simulated multi-spectral example.

A new approach to optical measuring blood oxygen saturation was developed and implemented. This technique is based on an original three-stage algorithm for reconstructing the relative concentration of biological chromophores (hemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the probing radiation source. The numerical experiments and approbation of the proposed technique on a biological phantom have shown the high reconstruction accuracy and the possibility of correct calculation of hemoglobin oxygenation in the presence of additive noise and calibration errors. The obtained results of animal studies have agreed with the previously published results of other research groups and demonstrated the possibility to apply the developed technique to monitor oxygen saturation in tumor tissue.

Blood perfusion as the supply of tissue with blood and therefore oxygen is a key factor in clinical practice. Especially in the field of flap surgery, a reduced perfusion of transplanted skin or operated areas is often cause of various complications. The success of microvascular reconstructions is directly related to the flap perfusion. The intraoperative and postoperative assessment of the anastomoses is of great importance in order to recognize possible complications at an early stage and to revise them in good time. Is the affected tissue located on the face, successful treatment and rapid healing is even more important since aesthetic aspects play a not insignificant role. A poor perfusion is often concealed, since methods are missing for an objective assessment of the perfusion status. A method with increasing importance for clinical practice is given by hyperspectral imaging. We developed a new hyperspectral imaging system that can be used to observe tissue oxygenation and other tissue parameters and present the technical background and the parameter validation.

A calibration free method to detect particle size information is presented. A possible application for such measurements is the investigation of raw milk since there not only the fat and protein content varies but also the fat droplet size. The newly developed method is sensitive to the scattering phase function, which makes it applicable to many other applications, too. By simulating the light propagation by use of Monte Carlo simulations, a calibration free device can be developed from this principle.

Caffeine is the most widely consumed psychoactive substance in the world. It affects many tissues and organs, in particular central nervous system, heart, and blood vessels. The effect of caffeine on vascular smooth muscle cells is an initial transient contraction followed by significant vasodilatation. In this study we investigate the use of diffuse reflectance spectroscopy (DRS) for monitoring of vascular changes in human skin induced by caffeine consumption. DRS spectra were recorded on volar sides of the forearms of ten healthy volunteers at time delays of 0, 30, 60, 120, and 180 minutes after consumption of caffeine, while one subject served as a negative control. Analytical diffusion approximation solutions for diffuse reflectance from three-layer structures were used to assess skin composition (e.g., dermal blood volume fraction and oxygen saturation) by fitting to experimental data. The results demonstrate that cutaneous vasodynamics induced by caffeine consumption can be monitored by DRS, while changes in the control subject not consuming caffeine were insignificant.

Diffuse optical tomography (DOT) is showing promise for breast tumor detection by estimating optical property coefficients of breast tissue. In our previous study, we have successfully reconstructed the synthetic data into three-dimensional (3-D) images with a cylindrical model. Thus, the work within this study develops a 3-D image reconstruction algorithm of DOT with a breast-like model for screening breast tumor. Reconstruction results show that the quality of reconstructed images can be effective for tumor screening.

The Monte Carlo method is often referred as the gold standard to calculate the light propagation in turbid media [1]. Especially for complex shaped geometries where no analytical solutions are available the Monte Carlo method becomes very important [1, 2]. In this work a Monte Carlo software is presented, to simulate the light propagation in complex shaped geometries. To improve the simulation time the code is based on OpenCL such that graphics cards can be used as well as other computing devices. Within the software an illumination concept is presented to realize easily all kinds of light sources, like spatial frequency domain (SFD), optical fibers or Gaussian beam profiles. Moreover different objects, which are not connected to each other, can be considered simultaneously, without any additional preprocessing. This Monte Carlo software can be used for many applications. In this work the transmission spectrum of a tooth and the color reconstruction of a virtual object are shown, using results from the Monte Carlo software.