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Neurophotonics

Sensitivity of near-infrared spectroscopy and diffuse correlation spectroscopy to brain hemodynamics: simulations and experimental findings during hypercapnia
Author(s): Juliette J. Selb; David A. Boas; Suk-Tak Chan; Karleyton C. Evans; Erin M. Buckley; Stefan A. Carp
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Paper Abstract

Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) are two diffuse optical technologies for brain imaging that are sensitive to changes in hemoglobin concentrations and blood flow, respectively. Measurements for both modalities are acquired on the scalp, and therefore hemodynamic processes in the extracerebral vasculature confound the interpretation of cortical hemodynamic signals. The sensitivity of NIRS to the brain versus the extracerebral tissue and the contrast-to-noise ratio (CNR) of NIRS to cerebral hemodynamic responses have been well characterized, but the same has not been evaluated for DCS. This is important to assess in order to understand their relative capabilities in measuring cerebral physiological changes. We present Monte Carlo simulations on a head model that demonstrate that the relative brain-to-scalp sensitivity is about three times higher for DCS (0.3 at 3 cm) than for NIRS (0.1 at 3 cm). However, because DCS has higher levels of noise due to photon-counting detection, the CNR is similar for both modalities in response to a physiologically realistic simulation of brain activation. Even so, we also observed higher CNR of the hemodynamic response during graded hypercapnia in adult subjects with DCS than with NIRS.

Paper Details

Date Published: 6 August 2014
PDF: 15 pages
1(1) 015005 doi: 10.1117/1.NPh.1.1.015005
Published in: Neurophotonics Volume 1, Issue 1
Show Author Affiliations
Juliette J. Selb, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)
David A. Boas, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)
Suk-Tak Chan, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)
Karleyton C. Evans, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)
Erin M. Buckley, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)
Stefan A. Carp, Athinoula A. Martinos Ctr. for Biomedical Imaging (United States)


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