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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Journal ArticleDOI
Reduced Temporal Activation During a Verbal Fluency Task is Associated with Poor Motor Speed in Patients with Major Depressive Disorder
Tomohiko Kiriyama,Rumi Tanemura,Yoshihiro Nakamura,Chiaki Takemoto,Mariko Hashimoto,Hirohiko Utsumi +5 more
TL;DR: It is suggested that reduced activation in the left temporal region in patients with MDD could be a biomarker of poor motor speed, and NIRS may be useful as a noninvasive, clinical measurement tool for assessing motor speed in these patients.
Journal ArticleDOI
In vivo and noninvasive measurement of a songbird head’s optical properties
TL;DR: In vivo measurements of the absorption coefficient and the reduced scattering coefficient of the caudal nidopallium area of the head of a songbird (the zebra finch) are performed.
Journal ArticleDOI
Voxel-based measurement sensitivity of spatially resolved near-infrared spectroscopy in layered tissues.
TL;DR: Findings on the measurement sensitivity of SRS at each voxel and in each layer can support the correct interpretation of measured values when near-infrared oximetry or functional near- Infrared spectroscopy is used to investigate different tissue structures.
Journal ArticleDOI
Effect of sensor location on regional cerebral oxygen saturation measured by INVOS 5100 in on-pump cardiac surgery.
TL;DR: Regional cerebral oxygen saturation was significantly lower at the upper than lower forehead during on-pump cardiac surgery, however, disagreements in detection of cerebral regional oxygen desaturation were only significant at 1 h after initiation of aortic cross-clamping.
Journal ArticleDOI
Comparison of prefrontal hemodynamic responses and cognitive deficits between adult patients with autism spectrum disorder and schizophrenia.
Shenghong Pu,Kazuyuki Nakagome,Takahiro Satake,Hiroaki Ohtachi,Masashi Itakura,Takehiko Yamanashi,Akihiko Miura,Katsutoshi Yokoyama,Hiroshi Matsumura,Masaaki Iwata,Izumi Nagata,Koichi Kaneko +11 more
TL;DR: In this article, the authors compared cognitive profiles and their association with the prefrontal function between the two groups, and found that the ASD group showed a similar level of cognitive impairment with the mild level subgroup of schizophrenia, while the HCs had much weaker hemodynamic responses in the left DLPFC, left frontopolar cortex (FPC), and left inferior frontal gyrus.
References
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Journal ArticleDOI
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.
Journal ArticleDOI
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.
Journal ArticleDOI
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).