Analysis of light propagation in a realistic head model by a hybrid method for optical brain function measurement

Yosuke Ogoshi, Eiji Okada

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    Near infrared spectroscopy (NIRS) is used to measure the change in blood volume and oxygenation in the brain cortex induced by functional brain activation. The development of an adequate model to calculate light propagation in the head is very important because the light is strongly scattered in the tissue and this causes ambiguity in the volume of tissue interrogated with a source-detector pair of the NIRS instrument. In this study, a two-dimensional realistic head model is generated from a MRI scan of a human adult head. The light propagation in the head model is calculated by the hybrid Monte Carlo-diffusion method to obtain the change in detected intensity caused by a focal absorption change in the grey matter or in the white matter to discuss the relationship between the depth of the activated region and the sensitivity of the NIRS signal. The sensitivity to the activated region in the white matter steeply decreases with an increase of the depth of the activated region because the spatial sensitivity profile is mainly confined to the grey matter. The contribution of the focal brain activity to the NIRS signal is determined by not only the depth of the activated region from the head surface but also the depth of the activated region from the brain surface.

    Original languageEnglish
    Pages (from-to)264-269
    Number of pages6
    JournalOptical Review
    Volume12
    Issue number3
    DOIs
    Publication statusPublished - 2005 May 1

    Keywords

    • Biomedical optics
    • Brain function measurement
    • Diffusion equation
    • Light propagation
    • Monte Carlo simulation

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics

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