Journal ArticleDOI
Near-infrared light propagation in an adult head model. II. Effect of superficial tissue thickness on the sensitivity of the near-infrared spectroscopy signal
Eiji Okada,David T. Delpy +1 more
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TLDR
Light propagation in adult head models is predicted by Monte Carlo simulation to investigate the effect of the superficial tissue thickness on the partial optical path length in the brain and on the spatial sensitivity profile and results indicate that it is not appropriate to use the mean optical length as an alternative to the partial Optical path length to compensate the NIRS signal for the difference in sensitivity caused by variation of the shallow tissue thickness.Abstract:
It is important for near-infrared spectroscopy (NIRS) and imaging to estimate the sensitivity of the detected signal to the change in hemoglobin that results from brain activation and the volume of tissue interrogated for a specific source-detector fiber spacing. In this study light propagation in adult head models is predicted by Monte Carlo simulation to investigate the effect of the superficial tissue thickness on the partial optical path length in the brain and on the spatial sensitivity profile. In the case of source-detector spacing of 30 mm, the partial optical path length depends mainly on the depth of the inner skull surface whereas the spatial sensitivity profile is significantly affected by the thickness of the cerebrospinal fluid layer. The mean optical path length that can be measured by time-resolved experiments increases when the skull thickness increases whereas the partial mean optical path length in the brain decreases when the skull thickness increases. These results indicate that it is not appropriate to use the mean optical path length as an alternative to the partial optical path length to compensate the NIRS signal for the difference in sensitivity caused by variation of the superficial tissue thickness.read more
Citations
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TRINITY: A three-dimensional time-dependent radiative transfer code for in-vivo near-infrared imaging
TL;DR: In this paper, a three-dimensional time-dependent radiative transfer code, TRINITY (Time-dependent Radiative transfer In Near-Infrared TomographY), for in-vivo diffuse optical tomography (DOT) was developed based on the design of long radiation rays connecting boundaries of a computational domain.
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Combined Non-Invasive Optical Oximeter and Flowmeter with Basic Metrological Equipment
TL;DR: The purpose of this study is to develop a new instrument for non-invasive optical oximetry by means of substantiating and creating amore informative tissue oximeter with an enhanced number of measured parameters and equipped with the basic metrological tools—imitational measures.
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Targeting brain regions of interest in functional near-infrared spectroscopy-Scalp-cortex correlation using subject-specific light propagation models.
Lin Cai,Tomonori Nitta,Sho Yokota,Takayuki Obata,Eiji Okada,Hiroshi Kawaguchi,Hiroshi Kawaguchi,Hiroshi Kawaguchi +7 more
TL;DR: In this article, a sensitivity-based matching (SBM) method was proposed to obtain the scalp-cortex correlation between emission-detection probe pairs on the scalp and the underlying brain regions in fNIRS measurements.
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Comparison of Hemodynamic Responses in the Prefrontal Cortex According to Differences in Self-Efficacy:
TL;DR: Compared prefrontal activation measured with near-infrared spectroscopy across 89 undergraduate students categorized into three groups based on their General Self-Efficacy Scale scores indicates less left prefrontal activation in the low self-efficacy group than in the moderate self- efficacy group.
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Simple Method for Improving the Sensitivity of Functional Near-Infrared Spectroscopy: A Simulation and Phantom Study
TL;DR: In this article, a novel method for canceling the skin blood flow in functional near-infrared spectroscopy is proposed to improve the accuracy of measurement of oxygen consumption in brain tissue.
References
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Estimation of optical pathlength through tissue from direct time of flight measurement
TL;DR: 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, and this result has been verified in a phantom material.
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Spatial and temporal analysis of human motor activity using noninvasive NIR topography
Atsushi Maki,Yuichi Yamashita,Yoshitoshi Ito,Eiju Watanabe,Yoshiaki Mayanagi,Hideaki Koizumi +5 more
TL;DR: It was found that the regional change in cerebral blood volume in the primary motor area overlaps the global change around the motor cortex.
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Near-infrared optical properties of ex vivo human skin and subcutaneous tissues measured using the Monte Carlo inversion technique
TL;DR: The absorption and transport scattering coefficients of c Caucasian and negroid dermis, subdermal fat and muscle have been measured for all wavelengths between 620 and 1000 nm and the optical properties of caucasian dermis were found to be approximately twice those of the underlying fat layer.
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A Monte Carlo model for the absorption and flux distributions of light in tissue
Brian C. Wilson,Gerhard Adam +1 more
TL;DR: A Monte Carlo computer model has been used to predict the distribution of absorbed dose in homogeneous tissues of different absorption/scattering ratios, for illumination both by external light beams and via implanted optical fibers.
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Optical imaging in medicine: II. Modelling and reconstruction
TL;DR: This paper considers models based on radiative transfer theory and its derivatives, which are either stochastic in nature (random walk, Monte Carlo, and Markov processes) or deterministic (partial differential equation models and their solutions).