Special Section on Functional Near Infrared Spectroscopy, Part 1

Low-resolution mapping of the effective attenuation coefficient of the human head: a multidistance approach applied to high-density optical recordings

[+] Author Affiliations
Antonio M. Chiarelli, Edward L. Maclin, Kathy A. Low

University of Illinois, Beckman Institute, Urbana, Illinois, United States

Sergio Fantini

Tufts University, Department of Biomedical Engineering, Medford, Massachusetts, United States

Monica Fabiani, Gabriele Gratton

University of Illinois, Beckman Institute, Urbana, Illinois, United States

University of Illinois, Department of Psychology, Champaign, Illinois, United States

Neurophoton. 4(2), 021103 (Apr 21, 2017). doi:10.1117/1.NPh.4.2.021103
History: Received January 3, 2017; Accepted March 30, 2017
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Abstract.  Near infrared (NIR) light has been widely used for measuring changes in hemoglobin concentration in the human brain (functional NIR spectroscopy, fNIRS). fNIRS is based on the differential measurement and estimation of absorption perturbations, which, in turn, are based on correctly estimating the absolute parameters of light propagation. To do so, it is essential to accurately characterize the baseline optical properties of tissue (absorption and reduced scattering coefficients). However, because of the diffusive properties of the medium, separate determination of absorption and scattering across the head is challenging. The effective attenuation coefficient (EAC), which is proportional to the geometric mean of absorption and reduced scattering coefficients, can be estimated in a simpler fashion by multidistance light decay measurements. EAC mapping could be of interest for the scientific community because of its absolute information content, and because light propagation is governed by the EAC for source–detector distances exceeding 1 cm, which sense depths extending beyond the scalp and skull layers. Here, we report an EAC mapping procedure that can be applied to standard fNIRS recordings, yielding topographic maps with 2- to 3-cm resolution. Application to human data indicates the importance of venous sinuses in determining regional EAC variations, a factor often overlooked.

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© 2017 Society of Photo-Optical Instrumentation Engineers

Citation

Antonio M. Chiarelli ; Edward L. Maclin ; Kathy A. Low ; Sergio Fantini ; Monica Fabiani, et al.
"Low-resolution mapping of the effective attenuation coefficient of the human head: a multidistance approach applied to high-density optical recordings", Neurophoton. 4(2), 021103 (Apr 21, 2017). ; http://dx.doi.org/10.1117/1.NPh.4.2.021103


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