Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries

Neurophotonics, Год журнала: 2024, Номер 11(01)

Опубликована: Янв. 27, 2024

SignificanceThe non-invasive measurement of cerebral blood flow based on diffuse optical techniques has seen increased interest as a research tool for perfusion monitoring in critical care and functional brain imaging. Diffuse correlation spectroscopy (DCS) speckle contrast (SCOS) are two such that measure complementary aspects the fluctuating intensity signal, with DCS quantifying temporal fluctuations signal SCOS spatial blurring pattern. With increasing use these techniques, thorough comparison would inform new adopters benefits each technique.AimWe systematically evaluate performance flow.ApproachMonte Carlo simulations dynamic light scattering an MRI-derived head model were performed. For both SCOS, estimates sensitivity to changes, coefficient variation measured flow, contrast-to-noise ratio calculated. By varying data collection between methods, we investigated different strategies, including altering number modes per detector, integration time/fitting time measurement, laser source delivery strategy.ResultsThrough across metrics simulated detectors having realistic noise properties, determine several guiding principles optimization report over range properties tissue geometries. We find outperforms terms ideal case here but note requires careful experimental calibrations ensure accurate measurements flow.ConclusionWe provide design by which development systems their flow.

Язык: Английский

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Coherent light scattering from cellular dynamics in living tissues

Reports on Progress in Physics, Год журнала: 2024, Номер 87(3), С. 036601 - 036601

Опубликована: Март 1, 2024

This review examines the biological physics of intracellular transport probed by coherent optics dynamic light scattering from optically thick living tissues. Cells and their constituents are in constant motion, composed a broad range speeds spanning many orders magnitude that reflect wide array functions mechanisms maintain cellular health. From organelle scale tens nanometers upward size, motion inside tissue is actively driven rather than thermal, propelled hydrolysis bioenergetic molecules forces molecular motors. Active can mimic random walks thermal Brownian but mean-squared displacements far equilibrium display anomalous diffusion through Lévy or fractional walks. Despite average isotropic three-dimensional environment cells tissues, active single light-scattering objects often pseudo-one-dimensional, for instance as displacement persists along cytoskeletal tracks membranes displace normal to cell surfaces, albeit isotropically oriented three dimensions. Coherent natural tool characterize such dynamics because persistent directed induces Doppler shifts scattered light. The frequency-shifted partial waves complex media interfere produce speckle reveals tissue-scale processes contrast imaging fluctuation spectroscopy. Low-coherence interferometry, optical coherence tomography, diffusing-wave spectroscopy, diffuse-correlation differential microscopy digital holography offer detection methods shed on processes. In health-care applications, altered states health disease motions imprint statistical fluctuations For instance, efficacy medical therapeutics be monitored measuring changes they induce spectra

Язык: Английский

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Compact and cost-effective laser-powered speckle contrast optical spectroscopy fiber-free device for measuring cerebral blood flow

Journal of Biomedical Optics, Год журнала: 2024, Номер 29(06)

Опубликована: Май 31, 2024

SignificanceIn the realm of cerebrovascular monitoring, primary metrics typically include blood pressure, which influences cerebral flow (CBF) and is contingent upon vessel radius. Measuring CBF noninvasively poses a persistent challenge, primarily attributed to difficulty accessing obtaining signal from brain.AimOur study aims introduce compact speckle contrast optical spectroscopy device for noninvasive measurements at long source-to-detector distances, offering cost-effectiveness, scalability while tracking (BF) with remarkable sensitivity temporal resolution.ApproachThe wearable sensor module consists solely laser diode board camera. It can be easily placed on subject's head measure BF sampling rate 80 Hz.ResultsCompared single-fiber-based version, proposed achieved gain about 70 times, showed superior stability, reproducibility, signal-to-noise ratio measuring distances. The distributed in multiple configurations around head.ConclusionsGiven its scalability, simplicity, this laser-centric tool offers significant potential advancing monitoring technologies.

Язык: Английский

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Portable, high speed blood flow measurements enabled by long wavelength, interferometric diffuse correlation spectroscopy (LW-iDCS)

Scientific Reports, Год журнала: 2023, Номер 13(1)

Опубликована: Май 31, 2023

Diffuse correlation spectroscopy (DCS) is an optical technique that can be used to characterize blood flow in tissue. The measurement of cerebral hemodynamics has arisen as a promising use case for DCS, though traditional implementations DCS exhibit suboptimal signal-to-noise ratio (SNR) and sensitivity make robust measurements adults. In this work, we present long wavelength, interferometric (LW-iDCS), which combines the longer illumination wavelength (1064 nm), multi-speckle, detection, improve both SNR. Through direct comparison with based on superconducting nanowire single photon detectors, demonstrate approximate 5× improvement SNR over channel LW-DCS measured signals human subjects. We show equivalence extracted between LW-iDCS, feasibility LW-iDCS at 100 Hz source-detector separation 3.5 cm. This performance potential enable unlock novel cases diffuse spectroscopy.

Язык: Английский

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Interferometric speckle visibility spectroscopy (iSVS) for measuring decorrelation time and dynamics of moving samples with enhanced signal-to-noise ratio and relaxed reference requirements

Optics Express, Год журнала: 2023, Номер 31(19), С. 31253 - 31253

Опубликована: Авг. 25, 2023

Diffusing wave spectroscopy (DWS) is a group of techniques used to measure the dynamics scattering medium in non-invasive manner. DWS methods rely on detecting speckle light field from moving and measuring decorrelation time quantify medium's dynamics. For DWS, signal-to-noise (SNR) determined by ratio between measured standard error measurement. This SNR often low certain applications because high noise variances signal intensity, especially biological with restricted exposure emission levels. To address this photon-limited problem, we investigated, theoretically experimentally, an interferometric visibility (iSVS) compared more traditional methods. We found that iSVS can provide excellent performance through its ability overcome camera noise. also proved system has relaxed constraints reference beam properties. function properly, only require exhibit local temporal stability, while incident angle, phase intensity uniformity do not need be constrained. flexibility potentially enable unconventional implementation schemes.

Язык: Английский

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Study of Time-Resolved Dynamics in Turbid Medium Using a Single-Cavity Dual-Comb Laser

ACS Photonics, Год журнала: 2024, Номер unknown

Опубликована: Июнь 5, 2024

In measuring cerebral blood flow (CBF) noninvasively using optical techniques, diffusing-wave spectroscopy is often combined with near-infrared to obtain a reliable index. Measuring the index at determined depth remains ultimate goal. this study, we present simple approach dual-comb lasers where simultaneously measure absorption coefficient (μ

Язык: Английский

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Diffuse Correlation Spectroscopy: A Review of Recent Advances in Parallelisation and Depth Discrimination Techniques

Sensors, Год журнала: 2023, Номер 23(23), С. 9338 - 9338

Опубликована: Ноя. 22, 2023

Diffuse correlation spectroscopy is a non-invasive optical modality used to measure cerebral blood flow in real time, and it has important potential applications clinical monitoring neuroscience. As such, many research groups have recently been investigating methods improve the signal-to-noise ratio, imaging depth, spatial resolution of diffuse spectroscopy. Such included multispeckle, long wavelength, interferometric, depth discrimination, time-of-flight resolution, acousto-optic detection strategies. In this review, we exhaustively appraise plethora recent advances, which can be assess limitations guide innovation for future implementations that will harness technological improvements years come.

Язык: Английский

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Decoding diffuse light scattering dynamics in layered tissues: path length versus fluctuation time scale

Optics Letters, Год журнала: 2023, Номер 48(22), С. 6056 - 6056

Опубликована: Ноя. 1, 2023

Dynamic multiple light scattering (DMLS) has found numerous applications, including soft matter physics and biomedical optics. Yet biological tissues may have complex internal geometries, presenting a challenge for noninvasive measurements. Deciphering laminar dynamics is crucial to accurately interpret tissue or organ physiology. Seminal DMLS work noted that one can probe deeper layers indirectly by analyzing fluctuations on shorter time scales. Recent technologies enabled probing directly at longer path lengths. The following question arises: are the indirect direct approaches synergistic redundant? Here, adding an optical switch path-length-filtered interferometric diffusing wave spectroscopy, we experimentally address this in context of forearm occlusion study. We find both afford better distinction layered than either approach alone. This motivates further development methods integrate decorrelation scale length tissues.

Язык: Английский

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Pixelated gradient thickness optical filter for visible light spectroscopy

Applied Optics, Год журнала: 2024, Номер 63(13), С. 3537 - 3537

Опубликована: Апрель 8, 2024

A miniature low-cost pixelated gradient thickness optical filter is proposed to achieve spectroscopy in the visible wavelength range. The consists of a two-dimensional array metal-dielectric-metal thin films arranged Fabry-Pérot configurations with discretely varying cavity thicknesses. wavelength-selective characterization each performed by measuring transmittance over equipped CMOS image sensor, and its performance as spectroscopic module evaluated illuminating different monochromatic wavelengths on it. target spectra are successfully reconstructed from output signals recorded sensor respective filters. technological competence will enable use handheld devices widen application range day-to-day life.

Язык: Английский

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Tunable dynamical tissue phantom for laser speckle imaging

Biomedical Optics Express, Год журнала: 2024, Номер 15(8), С. 4737 - 4737

Опубликована: Июнь 17, 2024

We introduce a novel method to design and implement tunable dynamical tissue phantom for laser speckle-based in-vivo blood flow imaging. This approach relies on stochastic differential equations (SDE) control piezoelectric actuator which, upon illuminated with source, generates speckles of pre-defined probability density function auto-correlation. The validation experiments show that the can generate dynamic closely replicate both surfaces as well deep reasonably wide range accuracy.

Язык: Английский

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