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

Research output: Contribution to journalArticle

259 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2915-2922
Number of pages8
JournalApplied Optics
Volume42
Issue number16
Publication statusPublished - 2003 Jun 1

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Light propagation
Near infrared spectroscopy
optical paths
Brain
infrared spectroscopy
Tissue
Infrared radiation
skull
propagation
sensitivity
Detectors
Cerebrospinal fluid
brain
Hemoglobin
Infrared imaging
Chemical activation
spacing
cerebrospinal fluid
Fibers
detectors

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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