Optical imaging and spectroscopy for the study of the human brain: status report

Neurophotonics, Journal Year: 2022, Volume and Issue: 9(S2)

Published: Aug. 30, 2022

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit novel methods to explore brain health function. While first focused on neurophotonic tools mostly applicable animal studies, here, we highlight optical spectroscopy imaging relevant noninvasive human studies. We outline current state-of-the-art technologies software advances, most recent impact these neuroscience clinical applications, identify areas where innovation needed, provide outlook for future directions.

Language: Английский

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Frequency-Domain Techniques for Cerebral and Functional Near-Infrared Spectroscopy

Frontiers in Neuroscience, Journal Year: 2020, Volume and Issue: 14

Published: April 7, 2020

This article reviews the basic principles of frequency-domain near-infrared spectroscopy (FD-NIRS), which relies on intensity-modulated light sources and phase-sensitive optical detection, its non-invasive applications to brain. The simpler instrumentation more straightforward data analysis continuous-wave NIRS (CW-NIRS) accounts for fact that almost all current commercial instruments cerebral have embraced CW technique. However, FD-NIRS provides with richer information content, complements or exceeds capabilities CW-NIRS. One example is ability measure absolute properties (absorption reduced scattering coefficients) tissue, thus concentrations oxyhemoglobin deoxyhemoglobin in brain tissue. measured values such hemoglobin reported literature animal models human newborns, infants, children, adults. We also review application functional studies focused slower hemodynamic responses activity (time scale seconds) faster signals been linked neuronal activation 100 ms). Another power related different regions sensitivity featured by intensity phase data. report recent developments take advantage this feature maximize tissue relative superficial extracerebral (scalp, skull, etc.). contend latter capability a highly appealing quality FD-NIRS, measurements may result significant advances field sensing

Language: Английский

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The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

Sensors, Journal Year: 2020, Volume and Issue: 20(17), P. 4844 - 4844

Published: Aug. 27, 2020

Adequate oxygen delivery to a tissue depends on sufficient content in arterial blood and flow the tissue. Oximetry is technique for assessment of oxygenation by measurements light transmission through blood, which based different absorption spectra oxygenated deoxygenated hemoglobin. Oxygen saturation provides information adequacy respiration routinely measured clinical settings, utilizing pulse oximetry. saturation, venous (SvO2) entire (StO2), related supply tissue, several oximetric techniques have been developed their assessment. SvO2 can be non-invasively fingers, making use modified oximetry, retina, using Beer-Lambert Law. StO2 peripheral muscle cerebral means various modes near infrared spectroscopy (NIRS), relative transparency The primary problem oximetry discrimination between hemoglobin scattering elements attenuation measurement, isolating effect are presented current review, with limitations.

Language: Английский

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Functional near-infrared spectroscopy for the assessment and treatment of patients with disorders of consciousness

Frontiers in Neurology, Journal Year: 2025, Volume and Issue: 16

Published: Feb. 3, 2025

Background Advances in neuroimaging have significantly enhanced our understanding of brain function, providing critical insights into the diagnosis and management disorders consciousness (DoC). Functional near-infrared spectroscopy (fNIRS), with its real-time, portable, noninvasive imaging capabilities, has emerged as a promising tool for evaluating functional activity nonrecovery potential DoC patients. This review explores current applications fNIRS research, identifies limitations, proposes future directions to optimize clinical utility. Aim examines application monitoring DoC. Specifically, it investigates value combining brain-computer interfaces (BCIs) closed-loop neuromodulation systems patients DoC, aiming elucidate mechanisms that promote neurological recovery. Methods A systematic analysis was conducted on 155 studies published between January 1993 October 2024, retrieved from Web Science Core Collection database. Results Analysis 21 eligible diseases involving 262 revealed significant findings. The prefrontal cortex most frequently targeted region. proven crucial assessing connectivity activation, facilitating Furthermore, plays pivotal role treatment through techniques such deep stimulation (DBS) spinal cord (SCS). Conclusion As noninvasive, real-time tool, holds promise advancing assessment Despite limitations low spatial resolution need standardized protocols, demonstrated utility residual activity, detecting covert consciousness, therapeutic interventions. In addition levels, offers unique advantages tracking hemodynamic changes associated neuroregulatory treatments, including DBS SCS. By feedback cortical facilitates optimizing strategies supports individualized planning. Continued research addressing technical methodological challenges will further establish an indispensable diagnosis, prognosis,

Language: Английский

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Review of recent advances in frequency-domain near-infrared spectroscopy technologies [Invited]

Biomedical Optics Express, Journal Year: 2023, Volume and Issue: 14(7), P. 3234 - 3234

Published: June 1, 2023

Over the past several decades, near-infrared spectroscopy (NIRS) has become a popular research and clinical tool for non-invasively measuring oxygenation of biological tissues, with particular emphasis on applications to human brain. In most cases, NIRS studies are performed using continuous-wave (CW-NIRS), which can only provide information relative changes in chromophore concentrations, such as oxygenated deoxygenated hemoglobin, well estimates tissue oxygen saturation. Another type known frequency-domain (FD-NIRS) significant advantages: it directly measure optical pathlength thus quantify scattering absorption coefficients sampled tissues direct measurements absolute concentrations. This review describes current status FD-NIRS technologies, their performance, advantages, limitations compared other methods. Significant landmarks technological progress include development both benchtop portable/wearable sensitive front-end photonic components, high-frequency phase measurements. Clinical technologies discussed context needed areas improvement. The concludes by providing roadmap toward next generation fully wearable, low-cost systems.

Language: Английский

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Applications of near-infrared spectroscopy in neurocritical care

Neurophotonics, Journal Year: 2023, Volume and Issue: 10(02)

Published: June 30, 2023

SignificanceAcute brain injuries are commonly encountered in the intensive care unit. Alterations cerebrovascular physiology triggered by initial insult can lead to neurological worsening, further injury, and poor outcomes. Robust methods for assessing continuously at bedside limited.AimIn this review, we aim assess potential of near-infrared spectroscopy (NIRS) as a tool monitor critically ill patients with acute injury well those who high risk developing injury.ApproachWe first review basic principles cerebral blood flow regulation how these altered after injury. We then discuss role NIRS different injuries. pay specific attention (1) identify new clinical (2) non-invasively measure intracranial pressure (ICP) autoregulation, (3) optimal (BP) targets that may improve patient outcomes.ResultsA growing body work supports use injured patients. is routinely used during cardiac surgeries neurologic events, there some evidence treatment algorithms using oximetry result improved In be autoregulation an "optimum" BP where status best preserved. Finally, has been utilized thresholds correlate outcome focal hemorrhages.ConclusionsNIRS emerging function Future will aimed technical refinements diagnostic accuracy, larger scale trials establish definitive impact on

Language: Английский

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Rapid diffused optical imaging for accurate 3D estimation of subcutaneous tissue features

iScience, Journal Year: 2025, Volume and Issue: 28(2), P. 111818 - 111818

Published: Jan. 23, 2025

Conventional light imaging in living tissues is limited to depths under 100 μm by the significant tissue scattering. Consequently, few commercial devices can image lesions beneath surface, or measure their invasion depth, critical dermatology. We present 3D-multisite diffused optical (3D-mDOI) an approach that combines photon migration techniques from diffuse tomography, with automated controls and analysis for estimating lesion's depth via its coefficients. 3D-mDOI a non-invasive, low-cost, fast, contact-free instrument capable of subcutaneous structures volumes through multisite-acquisition re-emitted diffusion on sample surface. It offers rapid estimation Breslow essential staging melanoma. To standardize performance, employs customized calibrations using physical phantoms, explore system's 3D reconstruction capabilities. find reconstruct up 5 mm below requiring ∼300 s computation time.

Language: Английский

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Influence of Tissue Curvature on the Absolute Quantification in Frequency-Domain Diffuse Optical Spectroscopy

Spectroscopy Journal, Journal Year: 2025, Volume and Issue: 3(2), P. 14 - 14

Published: April 13, 2025

Accurate estimation of optical properties and hemodynamic parameters is critical for advancing frequency-domain diffuse spectroscopy (FD-DOS) techniques in clinical neuroscience. However, conventional FD-DOS models often assume planar air–tissue interfaces, introducing errors anatomically curved regions such as the forehead or infant heads. This study evaluates impact incorporating tissue curvature into forward analysis. Using simulations phantoms, we demonstrate that reduce absorption coefficient from 20% to less than 10% high-curvature scenarios. Within curvatures tested, even minor mismatches resulted significantly lower those observed approximations (p < 0.001). In low-curvature regions, yielded comparable (<5% both cases). When applied human data, our proposed model increased hemoglobin concentration estimates by 10–15% compared standard semi-infinite models, closer physiological expectations. Overall, these results quantitatively accounting improves accuracy property estimation. We propose a numerical framework achieves this fast reliable manner, robust tool research applications complex regions.

Language: Английский

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Recent Developments in Instrumentation of Functional Near-Infrared Spectroscopy Systems

Applied Sciences, Journal Year: 2020, Volume and Issue: 10(18), P. 6522 - 6522

Published: Sept. 18, 2020

In the last three decades, development and steady improvement of various optical technologies at near-infrared region electromagnetic spectrum has inspired a large number scientists around world to design develop functional spectroscopy (fNIRS) systems for medical applications. This been driven further by availability new sources detectors that support very compact wearable system designs. this article, we review fNIRS from instrumentation point view, discussing associated challenges state-of-the-art approaches. beginning, fundamentals as well light-tissue interaction NIR are briefly introduced. After that, present basics instrumentation. Next, recent continuous-wave, frequency-domain, time-domain discussed. Finally, provide summary these modalities an outlook into future technology.

Language: Английский

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The Validation of a Portable Functional NIRS System for Assessing Mental Workload

Sensors, Journal Year: 2021, Volume and Issue: 21(11), P. 3810 - 3810

Published: May 31, 2021

Portable functional near-infrared spectroscopy (fNIRS) systems have the potential to image brain in naturalistic settings. Experimental studies are essential validate such fNIRS systems. Working memory (WM) is a short-term active that associated with temporary storage and manipulation of information. The prefrontal cortex (PFC) area involved processing WM. We assessed PFC during n-back WM tasks group 25 college students using our laboratory-developed portable system, WearLight. designed an experimental protocol 32 task blocks four different pseudo-randomized difficulty levels. hemodynamic response was computed from data evaluated responses due these tasks. observed incremental mean activation induced by increasing load. left-PFC more activated compared right-PFC. performance seen be related responses. results proved functioning WearLight system cognitive load imaging. Since wearable operated wirelessly, it possible measure environment, which could also lead development user-friendly brain–computer interface system.

Language: Английский

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