Medicine › Radiology, Nuclear Medicine and Imaging

Optical Imaging and Spectroscopy Techniques

Works Count: 40463

Wikipedia

Description

This cluster of papers focuses on the use of optical imaging and spectroscopy techniques for biomedical applications, particularly in the field of neuroimaging and tissue characterization. It covers topics such as near-infrared spectroscopy, diffuse optical tomography, fluorescence molecular imaging, and the monitoring of brain oxygenation. The research also explores methods for simulating light-tissue interaction and measuring tissue optical properties.

Keywords

Near-Infrared Spectroscopy; Optical Imaging; Tissue Optical Properties; Fluorescence Molecular Imaging; Diffuse Optical Tomography; Brain Oxygenation Monitoring; Functional Neuroimaging; Monte Carlo Simulation; Hyperspectral Imaging; Cerebral Blood Flow Measurement

Fluorescence imaging with near-infrared light: new technological advances that enable in vivo molecular imaging

2003-01-01

Vasilis Ntziachristos , Christoph Bremer , Ralph Weissleder

View PDF Chat

Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnosis

2015-01-01

Valery V. Tuchin

This third edition of the biomedical optics classic Tissue Optics covers the continued intensive growth in tissue optics-in particular, the field of tissue diagnostics and imaging-that has occurred since 2007. … This third edition of the biomedical optics classic Tissue Optics covers the continued intensive growth in tissue optics-in particular, the field of tissue diagnostics and imaging-that has occurred since 2007. As in the first two editions, Part I describes fundamentals and basic research, and Part II presents instrumentation and medical applications. However, for the reader's convenience, this third edition has been reorganized into 14 chapters instead of 9. The chapters covering optical coherence tomography, digital holography and interferometry, controlling optical properties of tissues, nonlinear spectroscopy, and imaging have all been substantially updated. The book is intended for researchers, teachers, and graduate and undergraduate students specializing in the physics of living systems, biomedical optics and biophotonics, laser biophysics, and applications of lasers in biomedicine. It can also be used as a textbook for courses in medical physics, medical engineering, and medical biology.

Advanced Time-Correlated Single Photon Counting Techniques

2005-01-01

Wolfgang Becker

View PDF Chat

Non-invasive optical spectroscopy and imaging of human brain function

1997-10-01

Arno Villringer , Britton Chance

Brain activity is associated with changes in optical properties of brain tissue. Optical measurements during brain activation can assess haemoglobin oxygenation, cytochrome-c-oxidase redox state, and two types of changes in … Brain activity is associated with changes in optical properties of brain tissue. Optical measurements during brain activation can assess haemoglobin oxygenation, cytochrome-c-oxidase redox state, and two types of changes in light scattering reflecting either membrane potential (fast signal) or cell swelling (slow signal), respectively. In previous studies of exposed brain tissue, optical imaging of brain activity has been achieved at high temporal and microscopical spatial resolution. Now, using near-infrared light that can penetrate biological tissue reasonably well, it has become possible to assess brain activity in human subjects through the intact skull non-invasively. After early studies employing single-site near-infrared spectroscopy, first near-infrared imaging devices are being applied successfully for low-resolution functional brain imaging. Advantages of the optical methods include biochemical specificity, a temporal resolution in the millisecond range, the potential of measuring intracellular and intravascular events simultaneously and the portability of the devices enabling bedside examinations.

Non-invasive neuroimaging using near-infrared light

2002-10-01

Gary E. Strangman , David A. Boas , Jeffrey P. Sutton

Medical hyperspectral imaging: a review

2014-01-20

Guolan Lu , Baowei Fei

Hyperspectral imaging (HSI) is an emerging imaging modality for medical applications, especially in disease diagnosis and image-guided surgery. HSI acquires a three-dimensional dataset called hypercube, with two spatial dimensions and … Hyperspectral imaging (HSI) is an emerging imaging modality for medical applications, especially in disease diagnosis and image-guided surgery. HSI acquires a three-dimensional dataset called hypercube, with two spatial dimensions and one spectral dimension. Spatially resolved spectral imaging obtained by HSI provides diagnostic information about the tissue physiology, morphology, and composition. This review paper presents an overview of the literature on medical hyperspectral imaging technology and its applications. The aim of the survey is threefold: an introduction for those new to the field, an overview for those working in the field, and a reference for those searching for literature on a specific application.

View PDF Chat

In vivo near-infrared fluorescence imaging

2003-09-12

John V. Frangioni

System for long-term measurement of cerebral blood and tissue oxygenation on newborn infants by near infra-red transillumination

1988-05-01

M. Cope , David T. Delpy

Through-skull fluorescence imaging of the brain in a new near-infrared window

2014-08-01

Guosong Hong , Shuo Diao , Junlei Chang +7 more

View PDF Chat

Three-dimensional probabilistic anatomical cranio-cerebral correlation via the international 10–20 system oriented for transcranial functional brain mapping

2003-12-12

Masako Okamoto , Haruka Dan , Kuniko Sakamoto +7 more

Characterization of the near infrared absorption spectra of cytochrome aa3 and haemoglobin for the non-invasive monitoring of cerebral oxygenation

1988-03-01

Susan Wray , Mark Cope , David T. Delpy +2 more

QUANTIFICATION OF CEREBRAL OXYGENATION AND HAEMODYNAMICS IN SICK NEWBORN INFANTS BY NEAR INFRARED SPECTROPHOTOMETRY

1986-11-01

J S Wyatt , David T. Delpy , M. Cope +2 more

MCML—Monte Carlo modeling of light transport in multi-layered tissues

1995-07-01

Lihong V. Wang , Steven L. Jacques , Liqiong Zheng

Looking and listening to light: the evolution of whole-body photonic imaging

2005-03-01

Vasilis Ntziachristos , Jorge Ripoll , Lihong V. Wang +1 more

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

2013-05-16

Felix Scholkmann , Stefan Kleiser , Andreas Metz +4 more

View PDF Chat

HomER: a review of time-series analysis methods for near-infrared spectroscopy of the brain

2009-03-26

Theodore J. Huppert , Solomon Diamond , Maria Angela Franceschini +1 more

Near-infrared spectroscopy (NIRS) is a noninvasive neuroimaging tool for studying evoked hemodynamic changes within the brain. By this technique, changes in the optical absorption of light are recorded over time … Near-infrared spectroscopy (NIRS) is a noninvasive neuroimaging tool for studying evoked hemodynamic changes within the brain. By this technique, changes in the optical absorption of light are recorded over time and are used to estimate the functionally evoked changes in cerebral oxyhemoglobin and deoxyhemoglobin concentrations that result from local cerebral vascular and oxygen metabolic effects during brain activity. Over the past three decades this technology has continued to grow, and today NIRS studies have found many niche applications in the fields of psychology, physiology, and cerebral pathology. The growing popularity of this technique is in part associated with a lower cost and increased portability of NIRS equipment when compared with other imaging modalities, such as functional magnetic resonance imaging and positron emission tomography. With this increasing number of applications, new techniques for the processing, analysis, and interpretation of NIRS data are continually being developed. We review some of the time-series and functional analysis techniques that are currently used in NIRS studies, we describe the practical implementation of various signal processing techniques for removing physiological, instrumental, and motion-artifact noise from optical data, and we discuss the unique aspects of NIRS analysis in comparison with other brain imaging modalities. These methods are described within the context of the MATLAB-based graphical user interface program, HomER, which we have developed and distributed to facilitate the processing of optical functional brain data.

View PDF Chat

Optical tomography in medical imaging

1999-01-01

Simon Arridge

We present a review of methods for the forward and inverse problems in optical tomography. We limit ourselves to the highly scattering case found in applications in medical imaging, and … We present a review of methods for the forward and inverse problems in optical tomography. We limit ourselves to the highly scattering case found in applications in medical imaging, and to the problem of absorption and scattering reconstruction. We discuss the derivation of the diffusion approximation and other simplifications of the full transport problem. We develop sensitivity relations in both the continuous and discrete case with special concentration on the use of the finite element method. A classification of algorithms is presented, and some suggestions for open problems to be addressed in future research are made.

Deep-tissue anatomical imaging of mice using carbon nanotube fluorophores in the second near-infrared window

2011-05-16

Kevin Welsher , Sarah P. Sherlock , Hongjie Dai

Fluorescent imaging in the second near-infrared window (NIR II, 1–1.4 μm) holds much promise due to minimal autofluorescence and tissue scattering. Here, using well-functionalized biocompatible single-walled carbon nanotubes (SWNTs) as … Fluorescent imaging in the second near-infrared window (NIR II, 1–1.4 μm) holds much promise due to minimal autofluorescence and tissue scattering. Here, using well-functionalized biocompatible single-walled carbon nanotubes (SWNTs) as NIR II fluorescent imaging agents, we performed high-frame-rate video imaging of mice during intravenous injection of SWNTs and investigated the path of SWNTs through the mouse anatomy. We observed in real-time SWNT circulation through the lungs and kidneys several seconds postinjection, and spleen and liver at slightly later time points. Dynamic contrast-enhanced imaging through principal component analysis (PCA) was performed and found to greatly increase the anatomical resolution of organs as a function of time postinjection. Importantly, PCA was able to discriminate organs such as the pancreas, which could not be resolved from real-time raw images. Tissue phantom studies were performed to compare imaging in the NIR II region to the traditional NIR I biological transparency window (700–900 nm). Examination of the feature sizes of a common NIR I dye (indocyanine green) showed a more rapid loss of feature contrast and integrity with increasing feature depth as compared to SWNTs in the NIR II region. The effects of increased scattering in the NIR I versus NIR II region were confirmed by Monte Carlo simulation. In vivo fluorescence imaging in the NIR II region combined with PCA analysis may represent a powerful approach to high-resolution optical imaging through deep tissues, useful for a wide range of applications from biomedical research to disease diagnostics.

View PDF Chat

Time resolved reflectance and transmittance for the noninvasive measurement of tissue optical properties

1989-06-15

Michael S. Patterson , B. Chance , Brian C. Wilson

When a picosecond light pulse is incident on biological tissue, the temporal characteristics of the light backscattered from, or transmitted through, the sample carry information about the optical absorption and … When a picosecond light pulse is incident on biological tissue, the temporal characteristics of the light backscattered from, or transmitted through, the sample carry information about the optical absorption and scattering coefficients of the tissue. We develop a simple model, based on the diffusion approximation to radiative transfer theory, which yields analytic expressions for the pulse shape in terms of the interaction coefficients of a homogeneous slab. The model predictions are in good agreement with the results of preliminary in vivo experiments and Monte Carlo simulations.

Noninvasive, Infrared Monitoring of Cerebral and Myocardial Oxygen Sufficiency and Circulatory Parameters

1977-12-23

Frans F. Jöbsis

The relatively good transparency of biological materials in the near infrared region of the spectrum permits sufficient photon transmission through organs in situ for the monitoring of cellular events. Observations … The relatively good transparency of biological materials in the near infrared region of the spectrum permits sufficient photon transmission through organs in situ for the monitoring of cellular events. Observations by infrared transillumination in the exposed heart and in the brain in cephalo without surgical intervention show that oxygen sufficiency for cytochrome a,a 3 , function, changes in tissue blood volume, and the average hemoglobin-oxyhemoglobin equilibrium can be recorded effectively and in continuous fashion for research and clinical purposes. The copper atom associated with heme a 3 did not respond to anoxia and may be reduced under normoxic conditions, whereas the heme-a copper was at least partially reducible.

Near infrared spectroscopy (NIRS): A new tool to study hemodynamic changes during activation of brain function in human adults

1993-05-01

Arno Villringer , J. Planck , C. Hock +2 more

Diffuse optics for tissue monitoring and tomography

2010-06-02

Turgut Durduran , Regine Choe , Wesley B. Baker +1 more

This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative … This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative assessment of oxy- and deoxy-hemoglobin concentrations and blood flow are desired. The theoretical basis for near-infrared or diffuse optical spectroscopy is developed, and the basic elements of diffuse optical tomography are outlined. We also discuss diffuse correlation spectroscopy, a technique whereby temporal correlation functions of diffusing light are transported through tissue and are used to measure blood flow. Essential instrumentation is described, and representative brain and breast functional imaging and monitoring results illustrate the workings of these new tissue diagnostics.

View PDF Chat

In Vivo Confocal Scanning Laser Microscopy of Human Skin: Melanin Provides Strong Contrast

1995-06-01

Milind Rajadhyaksha , Melanie C. Grossman , Dina Esterowitz +2 more

Boundary conditions for the diffusion equation in radiative transfer

1994-10-01

Richard C. Haskell , Lars O. Svaasand , Tsong‐Tseh Tsay +3 more

Using the method of images, we examine the three boundary conditions commonly applied to the surface of a semi-infinite turbid medium. We find that the image-charge configurations of the partial-current … Using the method of images, we examine the three boundary conditions commonly applied to the surface of a semi-infinite turbid medium. We find that the image-charge configurations of the partial-current and extrapolated-boundary conditions have the same dipole and quadrupole moments and that the two corresponding solutions to the diffusion equation are approximately equal. In the application of diffusion theory to frequency-domain photon-migration (FDPM) data, these two approaches yield values for the scattering and absorption coefficients that are equal to within 3%. Moreover, the two boundary conditions can be combined to yield a remarkably simple, accurate, and computationally fast method for extracting values for optical parameters from FDPM data. FDPM data were taken both at the surface and deep inside tissue phantoms, and the difference in data between the two geometries is striking. If one analyzes the surface data without accounting for the boundary, values deduced for the optical coefficients are in error by 50% or more. As expected, when aluminum foil was placed on the surface of a tissue phantom, phase and modulation data were closer to the results for an infinite-medium geometry. Raising the reflectivity of a tissue surface can, in principle, eliminate the effect of the boundary. However, we find that phase and modulation data are highly sensitive to the reflectivity in the range of 80-100%, and a minimum value of 98% is needed to mimic an infinite-medium geometry reliably. We conclude that noninvasive measurements of optically thick tissue require a rigorous treatment of the tissue boundary, and we suggest a unified partial-current--extrapolated boundary approach.

View PDF Chat

Recent advances in diffuse optical imaging

2005-02-03

Adam Gibson , Jeremy C. Hebden , Simon Arridge

We review the current state-of-the-art of diffuse optical imaging, which is an emerging technique for functional imaging of biological tissue. It involves generating images using measurements of visible or near-infrared … We review the current state-of-the-art of diffuse optical imaging, which is an emerging technique for functional imaging of biological tissue. It involves generating images using measurements of visible or near-infrared light scattered across large (greater than several centimetres) thicknesses of tissue. We discuss recent advances in experimental methods and instrumentation, and examine new theoretical techniques applied to modelling and image reconstruction. We review recent work on in vivo applications including imaging the breast and brain, and examine future challenges.

A diffusion theory model of spatially resolved, steady-state diffuse reflectance for the noninvasive determination of tissue optical properties in vivo

1992-07-01

Thomas J. Farrell , Michael S. Patterson , Brian C. Wilson

A model based upon steady-state diffusion theory which describes the radial dependence of diffuse reflectance of light from tissues is developed. This model incorporates a photon dipole source in order … A model based upon steady-state diffusion theory which describes the radial dependence of diffuse reflectance of light from tissues is developed. This model incorporates a photon dipole source in order to satisfy the tissue boundary conditions and is suitable for either refractive index matched or mismatched surfaces. The predictions of the model were compared with Monte Carlo simulations as well as experimental measurements made with tissue simulating phantoms. The model describes the reflectance data accurately to radial distances as small as 0.5 mm when compared to Monte Carlo simulations and agrees with experimental measurements to distances as small as 1 mm. A nonlinear least-squares fitting procedure has been used to determine the tissue optical properties from the radial reflectance data in both phantoms and tissues in vivo. The optical properties derived for the phantoms are within 5%–10% of those determined by other established techniques. The in vivo values are also consistent with those reported by other investigators.

Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high-resolution optical imaging of intrinsic signals.

1990-08-01

Ron D. Frostig , Edmund E. Lieke , Daniel Y. Ts’o +1 more

We have shown previously the existence of small, activity-dependent changes in intrinsic optical properties of cortex that are useful for optical imaging of cortical functional architecture. In this study we … We have shown previously the existence of small, activity-dependent changes in intrinsic optical properties of cortex that are useful for optical imaging of cortical functional architecture. In this study we introduce a higher resolution optical imaging system that offers spatial and temporal resolution exceeding that achieved by most alternative imaging techniques for imaging cortical functional architecture or for monitoring local changes in cerebral blood volume or oxygen saturation. In addition, we investigated the mechanisms responsible for the activity-dependent intrinsic signals evoked by sensory stimuli, and studied their origins and wavelength dependence. These studies enabled high-resolution visualization of cortical functional architecture at wavelengths ranging from 480 to 940 nm. With the use of near-infrared illumination it was possible to image cortical functional architecture through the intact dura or even through a thinned skull. In addition, the same imaging technique proved useful for imaging and discriminating sensory-evoked, activity-dependent changes in local blood volume and oxygen saturation (oxygen delivery). Illumination at 570 nm allowed imaging of activity-dependent blood volume increases, whereas at 600-630 nm, the predominant signal probably originated from activity-dependent oxygen delivery from capillaries. The onset of oxygen delivery started prior to the blood volume increase. Thus, optical imaging based on intrinsic signals is a minimally invasive procedure for monitoring short- and long-term changes in cerebral activity.

View PDF Chat

A quantitative comparison of NIRS and fMRI across multiple cognitive tasks

2010-11-02

Xu Cui , Signe Bray , Daniel M. Bryant +2 more

View PDF Chat

NIRS-SPM: Statistical parametric mapping for near-infrared spectroscopy

2008-09-18

Jing Ye , Sungho Tak , Kitae Jang +2 more

Near-infrared spectroscopy as an index of brain and tissue oxygenation

2009-12-01

John M. Murkin , Miguel Arango

View PDF Chat

Optical properties of biological tissues: a review

2013-05-10

Steven L. Jacques

A review of reported tissue optical properties summarizes the wavelength-dependent behavior of scattering and absorption. Formulae are presented for generating the optical properties of a generic tissue with variable amounts … A review of reported tissue optical properties summarizes the wavelength-dependent behavior of scattering and absorption. Formulae are presented for generating the optical properties of a generic tissue with variable amounts of absorbing chromophores (blood, water, melanin, fat, yellow pigments) and a variable balance between small-scale scatterers and large-scale scatterers in the ultrastructures of cells and tissues.

Determining the optical properties of turbid media by using the adding–doubling method

1993-02-01

Scott A. Prahl , Martin J. C. van Gemert , Ashley J. Welch

A method is described for finding the optical properties (scattering, absorption, and scattering anisotropy) of a slab of turbid material by using total reflection, unscattered transmission, and total transmission measurements. … A method is described for finding the optical properties (scattering, absorption, and scattering anisotropy) of a slab of turbid material by using total reflection, unscattered transmission, and total transmission measurements. This method is applicable to homogeneous turbid slabs with any optical thickness,albedo, or phase function. The slab may have a different index of refraction from its surroundings and may or may not be bounded by glass. The optical properties are obtained by iterating an adding-doubling solution of the radiative transport equation until the calculated values of the reflection and transmission match the measured ones. Exhaustive numerical tests show that the intrinsic error in the method is < 3% when four quadrature points are used.

A Quantitative Comparison of Simultaneous BOLD fMRI and NIRS Recordings during Functional Brain Activation

2002-10-01

Gary E. Strangman , Joseph P. Culver , John H. Thompson +1 more

Principles, Techniques, and Limitations of Near Infrared Spectroscopy

2004-08-01

Marco Ferrari , Leonardo Mottola , Valentina Quaresima

In the last decade the study of the human brain and muscle energetics underwent a radical change, thanks to the progressive introduction of noninvasive techniques, including near-infrared (NIR) spectroscopy (NIRS). … In the last decade the study of the human brain and muscle energetics underwent a radical change, thanks to the progressive introduction of noninvasive techniques, including near-infrared (NIR) spectroscopy (NIRS). This review summarizes the most recent literature about the principles, techniques, advantages, limitations, and applications of NIRS in exercise physiology and neuroscience. The main NIRS instrumentations and measurable parameters will be reported. NIR light (700-1000 nm) penetrates superficial layers (skin, subcutaneous fat, skull, etc.) and is either absorbed by chromophores (oxy- and deoxyhemoglobin and myoglobin) or scattered within the tissue. NIRS is a noninvasive and relatively low-cost optical technique that is becoming a widely used instrument for measuring tissue O 2 saturation, changes in hemoglobin volume and, indirectly, brain/muscle blood flow and muscle O 2 consumption. Tissue O 2 saturation represents a dynamic balance between O 2 supply and O 2 consumption in the small vessels such as the capillary, arteriolar, and venular bed. The possibility of measuring the cortical activation in response to different stimuli, and the changes in the cortical cytochrome oxidase redox state upon O 2 delivery changes, will also be mentioned. Key words: tissue oximetry, oxidative metabolism, optical imaging, blood flow, oxygen consumption, exercise physiology

Illuminating the developing brain: The past, present and future of functional near infrared spectroscopy

2009-07-25

Sarah Lloyd‐Fox , Anna Blasi , Clare E. Elwell

Biomedical Optics, Principles and Imaging

2008-01-01

Lihong V. Wang , Hsin‐I Wu , Barry R. Masters

The Journal of Biomedical Optics (JBO) is a Gold Open Access journal that publishes peer-reviewed papers on the use of novel optical systems and techniques for improved health care and … The Journal of Biomedical Optics (JBO) is a Gold Open Access journal that publishes peer-reviewed papers on the use of novel optical systems and techniques for improved health care and biomedical research.

View PDF Chat

Estimation of optical pathlength through tissue from direct time of flight measurement

1988-12-01

David T. Delpy , M. Cope , Pieter van der Zee +3 more

Quantitation of near infrared spectroscopic data in a scattering medium such as tissue requires knowledge of the optical pathlength in the medium. This can now be estimated directly from the … Quantitation of near infrared spectroscopic data in a scattering medium such as tissue requires knowledge of the optical pathlength in the medium. This can now be estimated directly from the time of flight of picosecond length light pulses. Monte Carlo modelling of light pulses in tissue has shown that the mean value of the time dispersed light pulse correlates with the pathlength used in quantitative spectroscopic calculations. This result has been verified in a phantom material. Time of flight measurements of pathlength across the rat head give a pathlength of 5.3+or-0.3 times the head diameter.

The Virtual Family—development of surface-based anatomical models of two adults and two children for dosimetric simulations

2009-12-17

Andreas Christ , Wolfgang Kainz , Eckhart G. Hahn +7 more

The objective of this study was to develop anatomically correct whole body human models of an adult male (34 years old), an adult female (26 years old) and two children … The objective of this study was to develop anatomically correct whole body human models of an adult male (34 years old), an adult female (26 years old) and two children (an 11-year-old girl and a six-year-old boy) for the optimized evaluation of electromagnetic exposure. These four models are referred to as the Virtual Family. They are based on high resolution magnetic resonance (MR) images of healthy volunteers. More than 80 different tissue types were distinguished during the segmentation. To improve the accuracy and the effectiveness of the segmentation, a novel semi-automated tool was used to analyze and segment the data. All tissues and organs were reconstructed as three-dimensional (3D) unstructured triangulated surface objects, yielding high precision images of individual features of the body. This greatly enhances the meshing flexibility and the accuracy with respect to thin tissue layers and small organs in comparison with the traditional voxel-based representation of anatomical models. Conformal computational techniques were also applied. The techniques and tools developed in this study can be used to more effectively develop future models and further improve the accuracy of the models for various applications. For research purposes, the four models are provided for free to the scientific community.

Digital Image Processing, Third Edition

2009-01-01

Rafael C. González , Richard E. Woods , Barry R. Masters

View PDF Chat

Model for laser Doppler measurements of blood flow in tissue

1981-06-15

R. F. Bonner , Ralph Nossal

A theory is developed which relates quasi-elastic light scattering measurements to blood flow in tissue micro-vasculature. We assume that the tissue matrix surrounding the blood cells is a strong diffuser … A theory is developed which relates quasi-elastic light scattering measurements to blood flow in tissue micro-vasculature. We assume that the tissue matrix surrounding the blood cells is a strong diffuser of light and that moving erythrocytes, therefore, are illuminated by a spatially distributed source. Because the surrounding tissue is considered to be stationary, Doppler shifts in the frequency of the scattered light arise only from photon interactions with the moving blood cells. The theory implies that the time decay of the photon autocorrelation function scales proportionally with cell size and inversely with mean translational speed. Analysis of multiple interactions of photons with moving cells indicates the manner in which spectral measurements additionally are sensitive to changes in blood volume. Predictions are verified by measurements of particle flow in model tissues.

Optical properties of human skin, subcutaneous and mucous tissues in the wavelength range from 400 to 2000 nm

2005-07-22

Alexey N. Bashkatov , Elina A. Genina , Vyacheslav I. Kochubey +1 more

The optical properties of human skin, subcutaneous adipose tissue and human mucosa were measured in the wavelength range 400–2000 nm. The measurements were carried out using a commercially available spectrophotometer … The optical properties of human skin, subcutaneous adipose tissue and human mucosa were measured in the wavelength range 400–2000 nm. The measurements were carried out using a commercially available spectrophotometer with an integrating sphere. The inverse adding–doubling method was used to determine the absorption and reduced scattering coefficients from the measurements.

Interpretation of near-infrared spectroscopy signals: a study with a newly developed perfused rat brain model

2001-05-01

Yoko Hoshi , Norio Kobayashi , Mamoru Tamura

Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret … Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret near-infrared spectroscopy signals. Changes in CBF and total hemoglobin (tHb) were in parallel, although tHb showed no change when changes in CBF were small (≤10%). Increasing CBF caused an increase in oxygenated hemoglobin (HbO 2 ) and a decrease in deoxygenated hemoglobin (deoxy-Hb). Decreasing CBF was accompanied by a decrease in HbO 2 , whereas changes in direction of deoxy-Hb were various. Cerebral blood congestion caused increases in HbO 2 , deoxy-Hb, and tHb. Administration of pentylenetetrazole without increasing the flow rate caused increases in HbO 2 and tHb with a decrease in deoxy-Hb. There were no significant differences in venous oxygen saturation before vs. during seizure. These results suggest that, in activation studies with near-infrared spectroscopy, HbO 2 is the most sensitive indicator of changes in CBF, and the direction of changes in deoxy-Hb is determined by the degree of changes in venous blood oxygenation and volume.

QUANTITATIVE OPTICAL SPECTROSCOPY FOR TISSUE DIAGNOSIS

1996-10-01

Rebecca Richards‐Kortum , Eva M. Sevick‐Muraca

▪ Abstract The interaction of light within tissue has been used to recognize disease since the mid-1800s. The recent developments of small light sources, detectors, and fiber optic probes provide … ▪ Abstract The interaction of light within tissue has been used to recognize disease since the mid-1800s. The recent developments of small light sources, detectors, and fiber optic probes provide opportunities to quantitatively measure these interactions, which yield information for diagnosis at the biochemical, structural, or (patho)physiological level within intact tissues. However, because of the strong scattering properties of tissues, the reemitted optical signal is often influenced by changes in biochemistry (as detected by these spectroscopic approaches) and by physiological and pathophysiological changes in tissue scattering. One challenge of biomedical optics is to uncouple the signals influenced by biochemistry, which themselves provide specificity for identifying diseased states, from those influenced by tissue scattering, which are typically unspecific to a pathology. In this review, we describe optical interactions pursued for biomedical applications (fluorescence, fluorescence lifetime, phosphorescence, and Raman from cells, cultures, and tissues) and then provide a descriptive framework for light interaction based upon tissue absorption and scattering properties. Finally, we review important endogenous and exogenous biological chromophores and describe current work to employ these signals for detection and diagnosis of disease.

Monte Carlo Simulation of Photon Migration in 3D Turbid Media Accelerated by Graphics Processing Units

2009-10-21

Qianqian Fang , David A. Boas

We report a parallel Monte Carlo algorithm accelerated by graphics processing units (GPU) for modeling time-resolved photon migration in arbitrary 3D turbid media. By taking advantage of the massively parallel … We report a parallel Monte Carlo algorithm accelerated by graphics processing units (GPU) for modeling time-resolved photon migration in arbitrary 3D turbid media. By taking advantage of the massively parallel threads and low-memory latency, this algorithm allows many photons to be simulated simultaneously in a GPU. To further improve the computational efficiency, we explored two parallel random number generators (RNG), including a floating-point-only RNG based on a chaotic lattice. An efficient scheme for boundary reflection was implemented, along with the functions for time-resolved imaging. For a homogeneous semi-infinite medium, good agreement was observed between the simulation output and the analytical solution from the diffusion theory. The code was implemented with CUDA programming language, and benchmarked under various parameters, such as thread number, selection of RNG and memory access pattern. With a low-cost graphics card, this algorithm has demonstrated an acceleration ratio above 300 when using 1792 parallel threads over conventional CPU computation. The acceleration ratio drops to 75 when using atomic operations. These results render the GPU-based Monte Carlo simulation a practical solution for data analysis in a wide range of diffuse optical imaging applications, such as human brain or small-animal imaging.

View PDF Chat

A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application

2012-03-28

Marco Ferrari , Valentina Quaresima

A review of the optical properties of biological tissues

1990-01-01

W. F. Cheong , Scott A. Prahl , Ashley J. Welch

The known optical properties (absorption, scattering, total attenuation, effective attenuation, and/or anisotropy coefficients) of various biological tissues at a variety of wavelengths are reviewed. The theoretical foundations for most experimental … The known optical properties (absorption, scattering, total attenuation, effective attenuation, and/or anisotropy coefficients) of various biological tissues at a variety of wavelengths are reviewed. The theoretical foundations for most experimental approaches are outlined. Relations between Kubelka-Munk parameters and transport coefficients are listed. The optical properties of aorta, liver, and muscle at 633 nm are discussed in detail. An extensive bibliography is provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

Dynamic Light Scattering

1985-01-01

R. Pecora

Dynamic light scattering: a practical guide and applications in biomedical sciences

2016-10-06

Jörg Stetefeld , Sean A. McKenna , Trushar R. Patel

View PDF Chat

The present and future use of functional near‐infrared spectroscopy (fNIRS) for cognitive neuroscience

2018-08-07

Paola Pinti , Ilias Tachtsidis , Antonia F. de C. Hamilton +4 more

Abstract The past few decades have seen a rapid increase in the use of functional near‐infrared spectroscopy (fNIRS) in cognitive neuroscience. This fast growth is due to the several advances … Abstract The past few decades have seen a rapid increase in the use of functional near‐infrared spectroscopy (fNIRS) in cognitive neuroscience. This fast growth is due to the several advances that fNIRS offers over the other neuroimaging modalities such as functional magnetic resonance imaging and electroencephalography/magnetoencephalography. In particular, fNIRS is harmless, tolerant to bodily movements, and highly portable, being suitable for all possible participant populations, from newborns to the elderly and experimental settings, both inside and outside the laboratory. In this review we aim to provide a comprehensive and state‐of‐the‐art review of fNIRS basics, technical developments, and applications. In particular, we discuss some of the open challenges and the potential of fNIRS for cognitive neuroscience research, with a particular focus on neuroimaging in naturalistic environments and social cognitive neuroscience.

View PDF Chat

Dynamic light scattering : the method and some applications

1993-01-01

Wyn Brown

List of contributors 1. Dynamic scattering from multicomponent polymer mixtures in solution and in bulk 2. Single photon correlation techniques 3. Noise on photon correlation functions and its effects on … List of contributors 1. Dynamic scattering from multicomponent polymer mixtures in solution and in bulk 2. Single photon correlation techniques 3. Noise on photon correlation functions and its effects on data reduction algorithms 4. Data analysis in dynamic light scattering 5. Dynamic light scattering and linear viscoelasticity of polymers in solution and in the bulk 6. Dynamic properties of polymer solutions 7. Application of dynamic light scattering to polyelectrolytes in solution 8. Simultaneous static and dynamic light scattering: application to polymer structure analysis 9. Dynamic light scattering from dense polymer systems 10. Dynamic light scattering from polymers in solution and in bulk 11. Dynamic light scattering from polymer gels 12. Dynamic light scattering from rigid and nearly rigid rods 13. Light scattering in micellar systems 14. Critical dynamics of binary liquid mixtures and simple fluids studied using dynamic light scattering 15. Application of dynamic light scattering to biological systems 16. Diffusing-wave spectroscopy Index

The effects of protocol factors and participant characteristics on functional near-infrared spectroscopy data quality after stroke

2025-06-25

Erin L. Meier , Lisa Bunker , Hana Kim +4 more | Neuroimage Reports

Development of a multiparameter phantom system for multispectral imaging

2025-06-25

Xingjun Gao , Zhisheng Wu , Xiaopeng Chen +4 more | Biomedical Optics Express

Hyperspectral Imaging for Benign and Malignant Diagnosis of Breast Tumors

2025-06-24

Yihui He , Yihan Zhao , Jiajia Xu +7 more | Journal of Biophotonics

ABSTRACT Objective To assess the feasibility of combining microscopic hyperspectral imaging (370–1100 nm) with a lightweight 1D‐CNN for rapid, label‐free discrimination of benign and malignant breast tumors. Methods Breast specimens … ABSTRACT Objective To assess the feasibility of combining microscopic hyperspectral imaging (370–1100 nm) with a lightweight 1D‐CNN for rapid, label‐free discrimination of benign and malignant breast tumors. Methods Breast specimens (43 malignant, 39 benign) were imaged; 2 050 000 pixel spectra were preprocessed (dark‐current subtraction, white‐reference calibration, Savitzky–Golay smoothing, z‐score normalization) and input to a custom 1D‐CNN. Performance was benchmarked against SVM, AlexNet, and LSTM using accuracy, sensitivity, specificity. Results The 1D‐CNN achieved 90.43% accuracy, 89.10% sensitivity, 91.34% specificity, exceeding baseline models. Conclusions Combining HSI with 1D CNN enables rapid and highly accurate classification of breast tumors, providing a new approach to rapid pathological diagnosis.

Near-Infrared Spectroscopy to Assess Covert Volitional Brain Activity in Intensive Care

2025-06-23

Pardis Zarifkar , Matthew Kolisnyk , Marwan Othman +7 more | Neurocritical Care

Detecting covert consciousness in unresponsive patients is challenging. Although functional magnetic resonance imaging and advanced electroencephalography paradigms can identify volitional brain activity, the limited accessibility of these technologies necessitates alternative … Detecting covert consciousness in unresponsive patients is challenging. Although functional magnetic resonance imaging and advanced electroencephalography paradigms can identify volitional brain activity, the limited accessibility of these technologies necessitates alternative approaches. Functional near-infrared spectroscopy may provide a portable solution in the intensive care unit. We assessed the feasibility of functional near-infrared spectroscopy with verbal motor commands to detect volitional brain activity in acute disorders of consciousness (DoC). Functional near-infrared spectroscopy recordings and clinical assessments were obtained from 50 patients with DoC with acute brain injury, with data analyzed post hoc and visually at the bedside. Twenty healthy volunteers served as controls. After quality control, data from 19 controls and 36 patients were analyzed. Cortical activation was detected in 18 (96%) controls and 16 (44%) patients. Among 13 minimally conscious patients, volitional activity was found in 8 (62%), whereas 8 (35%) of 23 clinically unresponsive patients showed activation. Volitional brain activity in the latter was associated with higher odds of command following within a week, although it was not statistically significant (odds ratio 3.1, 95% confidence interval 0.7-15.8; p = 0.14). Visual bedside analysis showed high specificity (90%) but moderate agreement (κ = 0.4) with post hoc computational analysis. Functional near-infrared spectroscopy with motor commands can detect volitional brain activity in acute DoC, although data quality issues remain a limitation.

Identification of Migraine Subtypes Using Functional Near‐Infrared Spectroscopy Data: A Domain‐Based Feature Extraction

2025-06-23

Begüm Kara Gülay , Nilüfer Zengin , F. Ozturk +3 more | Journal of Biophotonics

ABSTRACT Migraine diagnosis relies on subjective patient reports and International Headache Society guidelines, leading to misdiagnoses. In clinical practice, objective, reliable diagnostic tools are needed. To address this, the study … ABSTRACT Migraine diagnosis relies on subjective patient reports and International Headache Society guidelines, leading to misdiagnoses. In clinical practice, objective, reliable diagnostic tools are needed. To address this, the study proposes a framework utilizing functional near‐infrared spectroscopy (fNIRS) to distinguish healthy individuals, interictal migraine patients with and without aura. The approach focuses on prefrontal cortex (PFC) activity, extracting features from oxyhemoglobin, deoxyhemoglobin, and total hemoglobin in time, frequency, and time‐frequency domains. XGBoost applied to time‐frequency features of oxyhemoglobin in the left PFC demonstrated outstanding performance, achieving 92% balanced accuracy, 89% sensitivity, 95% specificity, and 89% F1 score. Non‐invasive fNIRS with Machine Learning offers a promising, cost‐effective alternative to traditional diagnostic methods, enhancing early and accurate diagnosis, leading to better‐targeted treatments and improved outcomes. The study provides a strong foundation for future research and clinical applications in migraine diagnosis.

Indocyanine green angiography processing and analysis pipeline for the assessment of indeterminate burn wounds

2025-06-23

Héctor A. García , Mary Junak , B. Donahue +4 more | Journal of Biomedical Optics

Determining the depth of injury in burn wounds is critical to inform surgical decision-making and enhance outcomes. Clinical assessment yields poor accuracy in the early post-burn period, and histologic analysis … Determining the depth of injury in burn wounds is critical to inform surgical decision-making and enhance outcomes. Clinical assessment yields poor accuracy in the early post-burn period, and histologic analysis of biopsies (the gold standard) is time-consuming and clinically unfeasible. Indocyanine green angiography (ICGA) has provided very promising results; however, the evidence is still limited, and the details on instrumentation, measurement setup, and data processing/analysis (when reported) are considerably heterogeneous. A processing and analysis pipeline was developed to interpret ICGA data from experimental burn studies in a way that provides objective, generalizable, and reproducible interpretation. Different burns were created on the dorsal aspect of adult pigs, and ICGA was performed. ICGA measurements were then compared with different processing steps. Features were extracted from the indocyanine green angiography (ICG) kinetics curves at specific regions of interests and ran individual and group analyses to decide on the wound severity. To this end, the features were analyzed both separately and groupwise. The repeatability of the study was enhanced by processing steps where ICG curves were normalized by their area under the curve (AUC). Peak value ( IMAX ), residual AUC (rAUC), mean transit time (MTT), full width at half maximum (FWHM), and ingress ( s1 ) and egress ( s2 ) slopes presented the strongest correlation with burn severity. MTT and FWHM were almost independent of the processing steps included in the pipeline, providing high reliability between imaging sessions and inter-subject comparisons. Superficial burns presented significantly higher IMAX , rAUC, s1 , and s2 , as well as lower FWHM, when compared with the ICG kinetics from normal tissue, whereas the contrary happens for deep burns. We highlight the utility of a pre-processing step and judicious choice of parameters to use when interpreting ICGA data from indeterminate depth burn wounds to maximize the accuracy in severity estimation.

Time-Series Autoregressive Models for Point and Interval Forecasting of Raw and Derived Commercial Near-Infrared Spectroscopy Measures: An Exploratory Cranial Trauma and Healthy Control Analysis

2025-06-21

Amanjyot Singh Sainbhi , Logan Froese , Kevin Y. Stein +7 more | Bioengineering

Cerebral near-infrared spectroscopy (NIRS) systems have been demonstrated to continuously measure aspects of oxygen delivery and cerebrovascular reactivity. However, it remains unknown whether the prediction of these cerebral physiologic signals … Cerebral near-infrared spectroscopy (NIRS) systems have been demonstrated to continuously measure aspects of oxygen delivery and cerebrovascular reactivity. However, it remains unknown whether the prediction of these cerebral physiologic signals into the future is feasible. Leveraging existing archived data sources, four point and interval-forecasting methods using autoregressive integrative moving average (ARIMA) models were evaluated to assess their ability to predict NIRS cerebral physiologic signals. NIRS-based regional cerebral oxygen saturation (rSO2) and cerebral oximetry index signals were derived in three temporal resolutions (10 s, 1 min, and 5 min). Anchored- and sliding-window forecasting, with varying model memory, using point and interval approaches were used to forecast signals using fitted optimal ARIMA models. The absolute difference in the forecasted and measured data was evaluated with median absolute deviation, along with root mean squared error analysis. Further, Pearson correlation and Bland–Altman statistical analyses were performed. Data from 102 healthy controls, 27 spinal surgery patients, and 101 traumatic brain injury patients were retrospectively analyzed. All ARIMA-based point and interval prediction models demonstrated small residuals, while correlation and agreement varied based on model memory. The ARIMA-based sliding-window approach performed superior to the anchored approach due to data partitioning and model memory. ARIMA-based sliding-window forecasting using point and interval approaches can forecast rSO2 and the cerebral oximetry index with reasonably small residuals across all populations. Correlation and agreement between the predicted versus actual values varies substantially based on data-partitioning methods and model memory. Further work is required to assess the ability to forecast high-frequency NIRS signals using ARIMA and ARIMA-variant models in healthy and cranial trauma populations.

Solid breast tumors phantom emulating oxy and deoxyhemoglobin concentrations for near infrared imaging

2025-06-20

M. Victoria Waks-Serra , Demián A. Vera , Nicolás A. Carbone +4 more | PLoS ONE

Significance: Continuous-wave near-infrared spectroscopy (CW-NIRS) is a valuable, inexpensive and non-invasive tool for complementary diagnose breast cancer. The use of phantoms has proven to be a very powerful way to … Significance: Continuous-wave near-infrared spectroscopy (CW-NIRS) is a valuable, inexpensive and non-invasive tool for complementary diagnose breast cancer. The use of phantoms has proven to be a very powerful way to evaluate different experimental approaches as well as to test possible diagnostics equipment. The phantoms developed in this work can properly emulate either benign or malignant tumors and, in contrast to those constructed with actual biological chromophores, require no special storage, being thus stable in time. Aim: In this work we study the feasibility of employing two artificial absorbents as a replacement for oxygenated and deoxygenated hemoglobin concentrations in breast tumors, allowing discrimination benign from malignant tumors in CW transmittance NIRS experiments. Approach: Tumor phantoms were made of epoxy resin containing two kinds of absorbents to emulate the absorption curves of the hemoglobins in concentrations that reproduce those of benign and malignant tumors (fibroadenoma and adenocarcinoma respectively). CW transmittance NIRS experiments were carried out to evaluate the approach which was also compared with Monte Carlo (MC) simulations. Results: Results show that the constructed tumor phantoms are feasible to reproduce the desired targets. Additionally, the retrieved concentrations agree with the proposed ones. Thus, it is possible to construct a phantom containing inclusions emulating a fibroadenoma and/or an adenocarcinoma suitable for testing mammography algorithms or equipment. Conclusions: We have successfully designed, constructed, and validated tumor phantoms emulating both benign and malignant breast tumors. The transmittance experiments carried out agree very well with MC simulations. In addition, it was possible to obtain a map of absorbent concentrations recovered from the diffuse imaging experiments.

Mobile human brain imaging using functional ultrasound

2025-06-18

Sadaf Soloukey , Luuk Verhoef , Frits Mastik +7 more | Science Advances

Imagine being able to study the human brain in real-world scenarios while the subject displays natural behaviors such as locomotion, social interaction, or spatial navigation. The advent of ultrafast ultrasound … Imagine being able to study the human brain in real-world scenarios while the subject displays natural behaviors such as locomotion, social interaction, or spatial navigation. The advent of ultrafast ultrasound imaging brings us closer to this goal with functional ultrasound imaging (fUSi), a mobile neuroimaging technique. Here, we present real-time fUSi monitoring of brain activity during walking in a subject with a clinically approved sonolucent skull implant. Our approach uses personalized 3D-printed fUSi helmets for stability, optical tracking for cross-modal validation with functional magnetic resonance imaging, advanced signal processing to estimate hemodynamic responses, and facial tracking of a lick licking paradigm. These combined efforts allowed us to show consistent fUSi signals over 20 months, even during high motion activities such as walking. These results demonstrate the feasibility of fUSi for monitoring brain activity in real-world contexts, marking an important milestone for fUSi-based insights in clinical and neuroscientific research.

Structured light imaging mesoscopy: detection of embedded morphological changes in superficial tissues

2025-06-18

Mahsa Parsanasab , Aarohi M. Mehendale , Kavon Karrobi +2 more | Journal of Biomedical Optics

Current paradigms for the optical characterization of layered tissues involve explicit consideration of an inverse problem which is often ill-posed and whose resolution may retain significant uncertainty. Here, we present … Current paradigms for the optical characterization of layered tissues involve explicit consideration of an inverse problem which is often ill-posed and whose resolution may retain significant uncertainty. Here, we present an alternative approach, structured light imaging mesoscopy (SLIM), that leverages the inherent sensitivity of raw spatial frequency domain (SFD) reflectance measurements for the detection of embedded subsurface scattering changes in tissue. We identify wavelength-spatial frequency ( λ-fx ) combinations that provide optimal sensitivity of SFD reflectance changes originating from scattering changes in an embedded tissue layer. We specifically consider the effects of scattering changes in the superficial dermis which is a key locus of pathology for diverse skin conditions such as cancer, aging, and scleroderma. We used Monte Carlo simulations in a four-layer skin model to analyze the SFD reflectance changes resulting from changes in superficial dermal scattering across wavelength ( λ=471 to 851 nm) and spatial frequency ( fx=0 to 0.5/mm). Within this model, we consider different values for epidermal melanin concentration to simulate variations in skin tone. Monte Carlo simulations revealed that scattering changes within the superficial dermis produce SFD reflectance changes which are maximized at specific ( λ-fx ) pairs and vary with skin tone. For light skin tones, SFD reflectance changes due to scattering reductions in the superficial dermis are maximized at λ=621 nm and spatial frequency fx≈0.33/mm . By contrast, for darker skin tones, maximal SFD reflectance changes occur at wavelengths in the near-infrared ( λ≥811 nm ) at a spatial frequency of fx≈0.25/mm . Interestingly, the change in SFD reflectance produced by such scattering changes is most uniform across all skin tones when using the longest wavelength tested ( λ=851 nm ) and a spatial frequency of fx≈0.22/mm . Taken together, our computational model identifies specific ( λ-fx ) pairs to optimally detect embedded structural alterations in the superficial dermis. The findings establish the SLIM methodology as a means to detect morphological changes in an embedded subsurface tissue layer by leveraging inherent sensitivities of spatial frequency domain reflectance. This approach promises to enable simplified clinical tracking of subsurface microstructural alterations without the explicit need to consider an inverse problem approach.

The functional near infrared spectroscopy applications in children with developmental diseases: a review

2025-06-17

Jing Wang , Zhuo Zou , Haoyu Huang +5 more | Frontiers in Neurology

This review provides a comprehensive synthesis of the application of functional near-infrared spectroscopy (fNIRS) in pediatric developmental disorders, with a particular emphasis on its potential for clinical translation. fNIRS is … This review provides a comprehensive synthesis of the application of functional near-infrared spectroscopy (fNIRS) in pediatric developmental disorders, with a particular emphasis on its potential for clinical translation. fNIRS is a portable and non-invasive brain imaging technique that detects the relative concentration changes of oxyhemoglobin (HbO 2 ), deoxyhemoglobin (HbR), and total hemoglobin in the cerebral cortex. These measurements effectively reflect cortical activation, making fNIRS a valuable tool in the field of pediatric neurodevelopmental research. The inherent resistance of fNIRS to interference, coupled with its adaptability to naturalistic settings, renders it particularly well-suited for pediatric populations. In this context, we undertook a meticulous and comprehensive literature search, employing predefined strategies and stringent inclusion/exclusion criteria (which are elaborated upon in the text). Our aim was to identify and review fNIRS studies across a wide range of developmental disorders. These disorders encompass cerebral palsy (CP), autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), conditions related to preterm infants, hypoxic–ischemic encephalopathy (HIE), and idiopathic language disorders. Our synthesis uncovers distinct hemodynamic patterns associated with specific developmental disorders. For example, autism spectrum disorder (ASD) is marked by atypical activation within social brain networks, whereas attention deficit hyperactivity disorder (ADHD) is characterized by diminished activation in the prefrontal cortex. These findings not only shed light on the neurophysiological foundations of these disorders but also highlight the potential of fNIRS as a diagnostic biomarker. This review aims to inform the clinical application of fNIRS by providing a critical evaluation of its mechanistic insights and potential clinical pathways, thereby advancing its role in the diagnosis and management of developmental disorders.

Optical tissue clearing and 3D imaging of intact primate testicular tissue: a novel technology development

2025-06-17

Pauline Wanjiku Kibui , Sarah Weischer , Nicola von Ostau +4 more | bioRxiv (Cold Spring Harbor Laboratory)

Abstract Classical histology struggles to preserve three-dimensional spatial context, prompting the emergence of optical tissue clearing techniques that enable imaging of intact specimens at cellular or subcellular resolution. These techniques … Abstract Classical histology struggles to preserve three-dimensional spatial context, prompting the emergence of optical tissue clearing techniques that enable imaging of intact specimens at cellular or subcellular resolution. These techniques have revolutionised fields like cell biology, developmental biology, and neuroscience. However, their application in reproductive biology remains unexplored – particularly in studying the complexities of testicular development. We developed a novel, efficient and affordable toolbox for studying intact testicular tissues, PT-CLEAR3D, that stands for primate testis – whole mount staining, tissue clearing and three-dimensional imaging. Intact testicular tissues from humans (transgender model), common marmosets and macaques underwent antibody labelling, clearing with organic solvents, and three-dimensional imaging using light sheet fluorescence microscopy. Marker specificity was confirmed by immunofluorescence staining of 3 and 25 µm testicular sections, followed by imaging with confocal. The testicular structure was evaluated using several markers: spermatogonia (melanoma-associated antigen 4), least differentiated spermatogonia (Piwi-like protein 4), Sertoli cells (vimentin and SRY-Box transcription Factor 9), peritubular myoid cells and vasculature (alpha-smooth muscle actin), and NucSpot as a nuclear dye. PT-CLEAR3D efficiently achieved optical transparency while a commercial kit that was ran in parallel was inefficient. This study presents a pioneering three-dimensional visualization of intact testicular samples of up to 50 mm 3 in size and imaging depth of up to 4.5 mm across three primate species. Remarkably, PT-CLEAR3D revealed critical details at both tissue and cellular levels such as the spatial distribution of germ and somatic cells, cellular bridges, and vasculature. Furthermore, PT-CLEAR3D enabled three-dimensional reconstructions that effectively reduce confirmation bias enhancing our observation of spermatogonial clones organized as single cells, pairs, and quartets. Importantly, it adeptly identified testicular pathology and the persistence of germ cell clones in select tubules within the transgender testis following hormonal suppression of spermatogenesis. This technological development offers a versatile toolbox with benefits such as applicability across multiple species, fluorophore multiplexing, compatibility with different fixatives and deep tissue volumetric imaging with cellular resolution. Overall, PT-CLEAR3D establishes a foundation for spatial evaluation of testicular development, presenting substantial potential for advancing our understanding of the intricate kinetics of spermatogenesis in health and disease.

Full non-LTE multi-level radiative transfer. I. An atom with three bound infinitely sharp levels

2025-06-17

Thibault Lagache , F. Paletou , M. Sampoorna | Astronomy and Astrophysics

The standard nonlocal thermodynamic equilibrium (non-LTE) multi-level radiative transfer problem only takes into account the deviation of the radiation field and atomic populations from their equilibrium distribution. We aim to … The standard nonlocal thermodynamic equilibrium (non-LTE) multi-level radiative transfer problem only takes into account the deviation of the radiation field and atomic populations from their equilibrium distribution. We aim to show how to solve for the full non-LTE (FNLTE) multi-level radiative transfer problem, also accounting for deviation of the velocity distribution of the massive particles from Maxwellian. We considered, as a first step, a three-level atom with zero natural broadening. In this work, we present a new numerical scheme. Its initialisation relies on the classic, multi-level approximate Λ-iteration (MALI) method for the standard non-LTE problem. The radiative transfer equations, the kinetic equilibrium equations for atomic populations, and the Boltzmann equations for the velocity distribution functions were simultaneously iterated in order to obtain self-consistent particle distributions. During the process, the observer's frame absorption and emission profiles were re-computed at every iterative step by convolving the atomic frame quantities with the relevant velocity distribution function. We validate our numerical strategy by comparing our results with the standard non-LTE solutions in the limit of a two-level atom with Hummer's partial redistribution in frequency, and with a three-level atom with complete redistribution. In this work, we considered the so-called cross-redistribution problem. We then show new FNLTE results for a simple three-level atom while evaluating the assumptions made for the emission and absorption profiles of the standard non-LTE problem with partial and cross-redistribution.

Flexible Cervical Photodynamic Therapy Device

2025-06-16

Teng Jin , Yijia Li , Qin Li +3 more | Translational Biophotonics

ABSTRACT Cervical cancer is the fourth most common cancer among women worldwide. It is a malignant tumor that originates from the cervix. Conventional treatments for cervical cancer, such as surgical … ABSTRACT Cervical cancer is the fourth most common cancer among women worldwide. It is a malignant tumor that originates from the cervix. Conventional treatments for cervical cancer, such as surgical resection, radiotherapy, and chemotherapy, are invasive and often result in adverse reactions. Photodynamic therapy is a noninvasive local treatment method. Given its fewer side effects, low cost, and short healing time, it is regarded as an alternative method for treating cervical precancerous lesions. We have designed a therapeutic device for both the cervix and cervical vault. This device is primarily composed of a circular light‐emitting diode array as the light source, a cylindrical light guide, and a flexible trumpet‐shaped light homogenizer. The light homogenizer is flexible, cost‐effective, and can be manufactured using a mold. Verification is initially accomplished through Monte Carlo simulation, to explore light transportation within tissues, and then by a physical measurement setup. The results indicate that the irradiance at the output end of the equipment can reach up to 98 mW/cm 2 , with the coefficient of variations along the axis being less than 14.2%, which provides a low‐cost and effective solution for the treatment of cervical cancer and precancerous lesions.

Multi-parametric functional optical spectroscopy to monitor the metabolic and vascular changes in small head and neck tumors in vivo with radiation stress

2025-06-16

Jing Yan , Pranto Soumik Saha , Md. Zahid Hasan +2 more | Biomedical Optics Express

Wireless Nano Irradiance Meter Based on Upconversion Luminescence Lifetime

2025-06-14

Alejandro Casillas‐Rubio , Marco Laurenti , Juan Pedro Cascales +3 more | Advanced Optical Materials

Abstract Measuring light irradiance, or power density, within a material is essential for ensuring the precision, efficiency, and safety of light‐based technologies, such as photodynamic therapies, optical sensing, and material … Abstract Measuring light irradiance, or power density, within a material is essential for ensuring the precision, efficiency, and safety of light‐based technologies, such as photodynamic therapies, optical sensing, and material processing. However, this task becomes particularly challenging in scenarios involving highly scattering or absorbing media, dynamic systems with varying properties, or confined and hardly accessible compartments. These challenges can be addressed by using colloidal luminescent nanomaterials with luminescence lifetimes strongly dependent on excitation irradiance. Building on this, an upconversion lifetime‐based Nano Irradiance Meter (nIM) is proposed, employing, on SrYb 3 + F 5 :@CaF 2 upconverting nanoparticles. This nIM operates within the first biological window and allows the direct estimation of laser irradiance, without prior knowledge of the area illuminated by the excitation beam. The feasibility of the sensor is validated through a calibration process, correlating the lifetime of the 770 nm upconversion luminescence of Tm 3 + ions with the 967 nm excitation irradiance. The sensor achieved a sensitivity of 0.9% W −1 cm 2 at low irradiances (≈17 W cm −2 ) and 0.008% W −1 cm 2 at high irradiances (≈5 kW cm −2 ), surpassing previously reported results based on ratiometric luminescence approaches. Finally, its robust performance under real‐life conditions across various media is demonstrated.

Rapid and efficient optical tissue clearing for volumetric imaging of the intact and injured spinal cord in mice

2025-06-13

Andrew Buxton , Frank L. Jalufka , Margaret E. Hruska +2 more | Frontiers in Neuroscience

Tissue clearing and 3D imaging have emerged as powerful techniques to assess the cellular and tissue-level architecture of the spinal cord. With the rapidly increasing variety and complexity of optical … Tissue clearing and 3D imaging have emerged as powerful techniques to assess the cellular and tissue-level architecture of the spinal cord. With the rapidly increasing variety and complexity of optical tissue clearing techniques, there is a critical need for optimization and streamlining of tissue-specific protocols, particularly when dealing with injury or disease states. We evaluated and combined multiple organic solvent-based techniques to develop sciDISCO: a spinal cord injury-optimized DISCO tissue clearing protocol. sciDISCO allows for the robust clearing, labeling, and 3D imaging of the intact spinal cord, as well as clearing around and through the lesion site formed after contusive spinal cord injury. In addition, we have identified alternatives for hazardous chemicals commonly used in organic solvent-based clearing including dichloromethane and dibenzyl ether. In this study, we demonstrate the compatibility of sciDISCO with multiple different labeling techniques to provide robust analysis of unique neuronal populations and morphologies in addition to cellular and tissue-level changes occurring following spinal cord injury.

Exploratory Study on Screening Dementia Based on Frontal Polar Cognitive Activation Using Portable Wireless Functional Near-Infrared Spectroscopy

2025-06-13

Atsumichi Tachibana , Shun Irie , Yumie Ono +5 more | Cureus

Multiple Spatial‐Spectral Encoding Empowered High Fidelity Snapshot Spectral Imaging

2025-06-11

Xuechan Lang , Tingkui Mu , Pengfei Xu +3 more | Laser & Photonics Review

Abstract Computational snapshot spectral imaging (C‐SSI) technique combining ingenious hardware encoding and powerful software decoding module has established a new paradigm for hyperspectral imaging. However, current encoding mechanisms still face … Abstract Computational snapshot spectral imaging (C‐SSI) technique combining ingenious hardware encoding and powerful software decoding module has established a new paradigm for hyperspectral imaging. However, current encoding mechanisms still face limitations: the spatial‐spectral encoding model merges spatial and spectral information into a 2D measurement, making it difficult to decouple 3D datacube under high compression ratio; Multiple spectral encoding model requires excessive measurements, limiting imaging system design flexibility. To address these challenges, a Multiple SpAtial‐SpEctral encoding model (MSA‐SE) is proposed to implement efficient pixel‐level encoding with spatial multiplexing in this study. A corresponding masks fusion attention network (MFANet) is developed to reconstruct broadband spectra. Specially, spatial‐spectral synergistic correlation and information entropy metrics are introduced for the first time to comprehensively evaluate the encoding capacity of encoding element and analyze its underlying impact mechanisms on spectral reconstruction. Furthermore, to experimentally demonstrate the effectiveness of MSA‐SE encoding model, a C‐SSI system (CI‐ORRIS) is constructed based on the simple combination of a multi‐aperture lens array and an on‐chip continuous variable filter (CVF). The system produces spectral images of 66 channels during 440–700 nm, achieving a maximum spectral resolution of 3.7 nm, which is nearly 5 times higher than that of the original resolution of CVF.

DermaGlow: Objective Quantification of Melanin, Erythema and Skin-tone Using Wearable Optical Spectroscopy

2025-06-09

Tarek Hamid , Paul Flores , Jung-Ah Byun +3 more | Proceedings of the ACM on Interactive Mobile Wearable and Ubiquitous Technologies

Accurate characterization of the skin is essential for optimizing diagnostic and therapeutic dermatological tools, as well as technologies like pulse oximetry that rely on skin perfusion. Traditionally, optical spectroscopy has … Accurate characterization of the skin is essential for optimizing diagnostic and therapeutic dermatological tools, as well as technologies like pulse oximetry that rely on skin perfusion. Traditionally, optical spectroscopy has been used for skin assessments through devices like commercial colorimeters, which are high-cost instruments that, while precise, only provide single measurements rather than continuous data. Additionally, medical wearable devices that use this technology often show variable accuracy based on skin tone. The limitations of existing devices demonstrate the need for a solution that can provide low-cost, accurate, and continuous skin monitoring across varying skin tones in a wearable form-factor. This paper introduces DermaGlow, a novel wearable optical spectroscopy framework designed for low-cost, non-invasive monitoring of melanin, erythema, and skin tone. DermaGlow utilizes an off-the-shelf multi-spectrum wearable device available in various configurations to enable real-time, personalized assessments across diverse skin conditions and skin tones. We assess the performance of the DermaGlow algorithm against a state-of-the-art colorimeter in a comprehensive user study involving a diverse group of 77 subjects, demonstrating a normalized mean absolute error (NMAE) of 5.33% (melanin) and 4.18% (erythema), and ΔE values less than 2.5 for CIE LAB measurements. Furthermore, we present an algorithm that utilizes DermaGlow outputs to correct for pulse oximeter inaccuracies typically found in those with darker skin pigmentation, resulting in an up to 75% decrease in mean absolute error (MAE) in hypoxic readings across skin tones relative to arterial blood measurements. Our findings highlight DermaGlow's potential for short and long-term skin monitoring and as a significant enhancement to existing wearable devices, particularly in improving the accuracy of pulse oximeter readings across different skin tones.

Data-Driven Calibration for Wearable Brain Functional Imaging Devices

2025-06-08

Bo Pang , Yunyi Zhao , Shufan Yang | 2022 IEEE Congress on Evolutionary Computation (CEC)

Study on resting-state functional connectivity characteristics under hypnosis using functional near-infrared spectroscopy

2025-06-05

Zhisong Zhang , Wanqiu Tan , Yuhong Ma +7 more | Frontiers in Psychology

Objective Numerous studies suggest that hypnosis has significant potential in mental health and cognitive disorder treatments. However, the mechanisms by which hypnosis influences brain activity and functional network connectivity remain … Objective Numerous studies suggest that hypnosis has significant potential in mental health and cognitive disorder treatments. However, the mechanisms by which hypnosis influences brain activity and functional network connectivity remain unclear. This study employed functional near-infrared spectroscopy (fNIRS) to investigate resting-state functional connectivity (rsFC) under hypnosis. Methods Twenty-six healthy college students participated in the study. Resting-state oxygenated hemoglobin (HbO) data were collected from the prefrontal cortex (PFC) during both control aware and hypnotic states. Functional connectivity strengths between these states were analyzed to assess changes in brain activity associated with deep hypnosis. Results A total of 55 paired samples t -tests were conducted across 11 regions of interest (ROIs), revealing statistically significant differences ( p &lt; 0.05) in functional connectivity strength between the control state and hypnotic state in 10 paired comparisons. Increased connectivity during hypnosis (6 pairs): LBA9-RBA10 ( t = −2.672, p = 0.013), LBA6-RBA46 ( t = −2.948, p = 0.007), LBA46-RBA46 ( t = −2.516, p = 0.019), RBA8-RBA46 ( t = −2.689, p = 0.013), RBA9-RBA46 ( t = −2.090, p = 0.047), LBA10-RBA10 ( t = −2.315, p = 0.029); Decreased connectivity during hypnosis (4 pairs): LBA9-LBA45 ( t = 2.064, p = 0.049), LBA6-LBA45 ( t = 3.151, p = 0.004), LBA8-LBA45 ( t = 2.438, p = 0.022), LBA8-RBA9 ( t = 2.085, p = 0.047). No significant differences were observed in connectivity strength between other ROI pairs. Conclusion Hypnosis appears to modulate the function of the DLPFC, PFC, and related regions, enhancing specific brain network functional connectivity. This preliminary study demonstrates that resting-state functional connectivity analysis using fNIRS is a valuable approach for studying brain activity during hypnosis.

A dual-branch deep learning model based on fNIRS for assessing 3D visual fatigue

2025-06-05

Yan Wu , Tongzhou Mu , S. Q. Qu +2 more | Frontiers in Neuroscience

Introduction Extended viewing of 3D content can induce fatigue symptoms. Thus, fatigue assessment is crucial for enhancing the user experience and optimizing the performance of stereoscopic 3D technology. Functional near-infrared … Introduction Extended viewing of 3D content can induce fatigue symptoms. Thus, fatigue assessment is crucial for enhancing the user experience and optimizing the performance of stereoscopic 3D technology. Functional near-infrared spectroscopy (fNIRS) has emerged as a promising tool for evaluating 3D visual fatigue by capturing hemodynamic responses within the cerebral region. However, traditional fNIRS-based methods rely on manual feature extraction and analysis, limiting their effectiveness. To address these limitations, a deep learning model based on fNIRS was constructed for the first time to evaluate 3D visual fatigue, enabling end-to-end automated feature extraction and classification. Methods Twenty normal subjects participated in this study (mean age: 24.6 ± 0.88 years; range: 23–26 years; 13 males). This paper proposed an fNIRS-based experimental paradigm that acquires data under both comfort and fatigue conditions. Given the time-series nature of fNIRS data and the variability of fatigue responses across different brain regions, a dual-branch convolutional network was constructed to separately extract temporal and spatial features. A transformer was integrated into the convolutional network to enhance long-range feature extraction. Furthermore, to adaptively select fNIRS hemodynamic features, a channel attention mechanism was integrated to provide a weighted representation of multiple features. Results The constructed model achieved an average accuracy of 93.12% within subjects and 84.65% across subjects, demonstrating its superior performance compared to traditional machine learning models and deep learning models. Discussion This study successfully constructed a novel deep learning framework for the automatic evaluation of 3D visual fatigue using fNIRS data. The proposed model addresses the limitations of traditional methods by enabling end-to-end automated feature extraction and classification, eliminating the need for manual intervention. The integration of a transformer module and channel attention mechanism significantly enhanced the model’s ability to capture long-range dependencies and adaptively weight hemodynamic features, respectively. The high classification accuracy achieved within and across subjects highlights the model’s effectiveness and generalizability. This framework not only advances the field of fNIRS-based fatigue assessment but also provides a valuable tool for improving user experience in stereoscopic 3D applications. Future work could explore the model’s applicability to other types of fatigue assessment and further optimize its performance for real-world scenarios.

Hyperspectral abdominal laparoscopy with real-time quantitative tissue oxygenation imaging: a live porcine study

2025-06-05

Oscar MacCormac , Conor C. Horgan , Dale J. Waterhouse +7 more | Frontiers in Medical Technology

Background Ischaemia is a critical complication, and can result in poor surgical outcomes. While intra-operative overt ischaemia can be perceived with the naked eye, timely recognition of borderline perfusion can … Background Ischaemia is a critical complication, and can result in poor surgical outcomes. While intra-operative overt ischaemia can be perceived with the naked eye, timely recognition of borderline perfusion can prevent post-operative ischaemic complications, which is particularly relevant for colorectal anastomoses. Consequently, there is a clinical need for new technologies to intra-operatively assess tissue oxygenation (indicative of end organ perfusion), with minimal disruption to the surgical workflow. Here we present a hyperspectral imaging (HSI) system for laparoscopic surgery. This system provides live, easy to interpret, tissue oxygenation (StO 2 ) maps with associated quantitative values. Methods White light view and tissue oxygenation maps were reconstructed from a protoype laparoscopic Hyperspectral Surgical System (HSS). First, in a live porcine model (55 kg female), the mesentery of a small bowel loop was temporarily occluded with a laparoscopic grasper, then released whilst being imaged with HSI. The quantitative StO 2 values obtained from the HSS were compared with those of a non-invasive tissue oximetry probe (Moor VMS-Oxy, Moor Instruments Ltd, United Kingdom). Secondly, mimicking a laparoscopic colon resection and anastomosis, the colorectal junction was mobilised laparoscopically, exteriorised, transected, anastomosed and repositioned in the abdominal cavity. In order to compare healthy and ischaemic colon, the distal part was intentionally devascularised. Tissue oxygenation maps were compared with indocyanine green fluorescence angiography (ICG-FA) of the anastomotic region. Results The HSS was used as the primary scope to complete a laparoscopic colorectal anastomosis, providing a simultaneous white light view and hyperspectral information. Quantitative results from small bowel imaging were shown to correlate with measurements from the superficial tissue oximetry probe. Real-time tissue oxygenation maps were shown to visually correlate with ICG-FA. Conclusion The HSS can guide laparoscopic surgical procedures whilst providing visual and quantitative tissue oxygenation information in a live animal model. This paves the way for further studies to assess clinical applications.

A study on resting-state functional near-infrared spectroscopy in patients with different outcomes of prolonged disorders of consciousness

2025-06-02

Yanli Liang , Xin Liang , Yijiang Li +4 more | Frontiers in Neurology

To explore the characteristics of resting-state functional connectivity in patients with different outcomes of prolonged disorders of consciousness (pDoC) by studying resting-state near-infrared imaging in patients with pDoC. 60 patients … To explore the characteristics of resting-state functional connectivity in patients with different outcomes of prolonged disorders of consciousness (pDoC) by studying resting-state near-infrared imaging in patients with pDoC. 60 patients with pDoC were processed with resting-state near-infrared imaging and divided into unresponsive wakefulness syndrome/vegetative state (UWS/VS) group, minimally conscious state (MCS) group and escape minimally conscious state (EMCS) group according to the post-treatment state of consciousness, to analyze the difference of resting-state functional connectivity in patients with different outcomes of patients with pDoC. Functional connectivity (FC) between frontal lobe and left occipital lobe, frontal lobe and right occipital lobe, and left and right occipital lobes decreased in the UWS/VS group compared with the MCS group; functional connectivity between frontal lobe and left occipital lobe, frontal lobe and right occipital lobe, and left and right occipital lobes decreased in the UWS/VS group compared with the EMCS group; functional connectivity did not show any significant difference between the EMCS and MCS groups; and functional connectivity was more centralized in the MCS group and EMCS group. Different outcomes of patients with pDoC have different degrees of decline in functional connectivity between frontal lobe and occipital lobe and between occipital lobe, resting-state functional near-infrared spectroscopy has a certain reference significance for the prognosis of patients with pDoC, and it is helpful for exploring the exploration of the conscious residual brain areas.