Journal Article10.1088/0967-3334/23/2/306
Quantitative evaluation of the relative contribution ratio of cerebral tissue to near-infrared signals in the adult human head: a preliminary study.
TL;DR: The present method opened the door to the possibility of selectively obtaining optical signals attributed to cerebral tissue by estimating the contribution ratio of the cerebral tissue to optical signals at the probe distances of 2, 3 and 4 cm.
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Abstract: Combining spatially- and time-resolved spectroscopies, we attempted to quantitatively evaluate the contribution ratio of the partial mean pathlength of cerebral tissue to the observed overall mean pathlength, in which haemoglobin concentrations were selectively changed by administration of acetazolamide. When acetazolamide was administered, the observed increases in oxygenated haemoglobin depended on the probe distance, which became progressively larger at distances of 2, 3 and 4 cm. Increases in oxygen saturation were detected at 3 and 4 cm spacing, but not at 2 cm. Assuming that the modified Lambert–Beer's law can exist in the inhomogeneous structure of the head, then, we could estimate the contribution ratio of the cerebral tissue to optical signals at the probe distances of 2, 3 and 4 cm as 33%, 55% and 69%, respectively. Using these values, we recalculated acetazolamide-induced concentration changes in oxygenated-haemoglobin in the cerebral tissue, which resulted in the same values at distances of 2, 3 and 4 cm as expected. Thus, our present method opened the door to the possibility of selectively obtaining optical signals attributed to cerebral tissue.
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Citations
Principles, techniques, and limitations of near infrared spectroscopy.
TL;DR: NIRS is a noninvasive and relatively low-cost optical technique that is becoming a widely used instrument for measuring tissue O2 saturation, changes in hemoglobin volume and, indirectly, brain/muscle blood flow and muscle O2 consumption.
Functional near-infrared optical imaging: utility and limitations in human brain mapping.
TL;DR: NIRS will not only open a window on brain physiology for subjects who have rarely been examined until now, but also provide a new direction for functional mapping studies.
518
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
TL;DR: 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.
386
Applications of Functional Near-Infrared Spectroscopy (fNIRS) Neuroimaging in Exercise⁻Cognition Science: A Systematic, Methodology-Focused Review.
TL;DR: This review aims to summarize the current methodological knowledge about fNIRS application in studies measuring the cortical hemodynamic responses during cognitive testing, and in cross-sectional studies accounting for the physical fitness level of their participants.
373
Towards a standard analysis for functional near-infrared imaging.
Matthias L. Schroeter,Markus M. Bücheler,Karsten Müller,Kâmil Uludağ,Kâmil Uludağ,Hellmuth Obrig,Gabriele Lohmann,Marc Tittgemeyer,Arno Villringer,D. Yves von Cramon +9 more
TL;DR: The present study suggests that the general linear model and spatially resolved spectral analysis can be used as standard statistical approaches for optical imaging data, particularly because they are almost independent of the assumed differential path length factors.
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