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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 11, Iss. 21 — Oct. 20, 2003
  • pp: 2717–2729

Optimization of the signal-to-noise ratio of frequency-domain instrumentation for near-infrared spectro-imaging of the human brain

Vlad Toronov, Enrico D’Amico, Dennis Hueber, Enrico Gratton, Beniamino Barbieri, and Andrew Webb  »View Author Affiliations

Optics Express, Vol. 11, Issue 21, pp. 2717-2729 (2003)

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Frequency-domain near-infrared spectro-imaging offers significant advantages over the continuous-wave method in human brain applications. However, the drawback of existing instruments is a low signal-to-noise ratio for measured phase and modulation depth changes caused by cerebral activation. In this paper we show that in the case of the geometry specific for the activated area in the human brain, the SNR can be significantly improved by increasing the modulation frequency. We present the results of two studies: one performed experimentally using a sub-nanosecond pulsed light source and a spherical absorbing inhomo geneity immersed in a highly scattering solution, and the other performed numerically using Monte Carlo simulations of light transport in an MRI-based digital phantom of the adult human head. We show that changes caused by the absorbing inhomogeneity in both phase and modulation depth increase with frequency and reach maximum values at frequencies between 400 and 1400 MHz, depending on the particular source-detector distance. We also show that for the human head geometry an increase of the modulation frequency from 100 to 500 MHz can increase the phase SNR 2–3 times, and the modulation depth SNR up to 10 times.

© 2003 Optical Society of America

OCIS Codes
(170.0170) Medical optics and biotechnology : Medical optics and biotechnology
(170.5270) Medical optics and biotechnology : Photon density waves
(170.5280) Medical optics and biotechnology : Photon migration

ToC Category:
Research Papers

Original Manuscript: July 31, 2003
Revised Manuscript: October 9, 2003
Published: October 20, 2003

Vlad Toronov, Enrico D'Amico, Dennis Hueber, Enrico Gratton, Beniamino Barbieri, and Andrew Webb, "Optimization of the signal-to-noise ratio of frequency-domain instrumentation for near-infrared spectro-imaging of the human brain," Opt. Express 11, 2717-2729 (2003)

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