Phasor representation of oxy- and deoxyhemoglobin concentrations: what is the meaning of out-of-phase oscillations as measured by near-infrared spectroscopy?

Feng Zheng; Angelo Sassaroli; Sergio Fantini

doi:10.1117/1.3483466

1 July 2010 Phasor representation of oxy- and deoxyhemoglobin concentrations: what is the meaning of out-of-phase oscillations as measured by near-infrared spectroscopy?

Feng Zheng, Angelo Sassaroli, Sergio Fantini

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Journal of Biomedical Optics, Vol. 15, Issue 4, 040512 (July 2010). https://doi.org/10.1117/1.3483466

Abstract

We propose a phasor representation for oscillations at a given frequency (or relatively narrow frequency band) of hemoglobin concentrations in tissue, as well as hemoglobin concentrations measured by near-infrared spectroscopy. This representation provides a straightforward visualization of the phase relationships between oscillations of oxy-, deoxy-, and total hemoglobin concentrations ([HbO], [Hb], and [HbT], respectively). We observe that measured oscillations of [Hb] and [HbO] with a phase difference that is neither 0 nor must result from the combination of different physiological processes that are out of phase (or time shifted) with respect to each other. Finally, we propose the use of cross-correlation phasors to map phase relationships and correlation levels among hemoglobin oscillations measured at spatially distinct locations at a given frequency. Such a representation may find a natural application in the study of functional connectivity networks in the brain.

©(2010) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Feng Zheng, Angelo Sassaroli, and Sergio Fantini "Phasor representation of oxy- and deoxyhemoglobin concentrations: what is the meaning of out-of-phase oscillations as measured by near-infrared spectroscopy?," Journal of Biomedical Optics 15(4), 040512 (1 July 2010). https://doi.org/10.1117/1.3483466

Published: 1 July 2010

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