TY - JOUR
T1 - Low-resolution mapping of the effective attenuation coefficient of the human head
T2 - A multidistance approach applied to high-density optical recordings
AU - Chiarelli, Antonio M.
AU - Maclin, Edward L.
AU - Low, Kathy A.
AU - Fantini, Sergio
AU - Fabiani, Monica
AU - Gratton, Gabriele
N1 - Publisher Copyright:
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).
PY - 2017
Y1 - 2017
N2 - 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.
AB - 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.
KW - baseline optical properties of tissue
KW - brain imaging
KW - diffuse optical tomography
KW - effective attenuation coefficient (EAC or μ eff)
KW - functional near infrared spectroscopy
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U2 - 10.1117/1.NPh.4.2.021103
DO - 10.1117/1.NPh.4.2.021103
M3 - Article
C2 - 28466026
AN - SCOPUS:85018738281
SN - 2329-423X
VL - 4
JO - Neurophotonics
JF - Neurophotonics
IS - 2
M1 - 021103
ER -