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Abstract:
Since a functional near-infrared spectroscopy monitor is a small and flexible tool, it can well be integrated with blood flow monitors. In the first part of the publication we show, that laser-doppler-flow measurements on the scalp return stimulus induced blood-volume changes. The effect of these changes on CW-NIRS measurements is demonstrated using frequency-domain-system capable of distinguishing absorption changes in superficial layers from those in the bulk tissue. The relationship between cerebral blood flow and cerebral hemoglobin concentration is studied in the second part of the publication. We present a visual stimulation experiment where changes in posterior cerebral artery flow velocity (PCA-Fv) were continuously monitored bilaterally by transcranial doppler sonography. Combining this approach with CW-NIRS imaging shows that the change in the arterial blood flow velocity occur approximately 1s before the deoxy-hemoglobin changes.
