Investigation of human brain hemodynamics by simultaneous near‐infrared spectroscopy and functional magnetic resonance imaging

TLDR

The study aimed to compare simultaneous NIRS and fMRI cerebral hemodynamic signals and evaluate how superficial skin and skull layers affect the NIRS measurement. Functional maps of the motor cortex were produced by both NIRS and fMRI during alternating finger‑motion and rest blocks. Both modalities showed well‑aligned activity centers, and subjects with minimal superficial tissue fluctuations exhibited a strong temporal correlation between BOLD and deoxy‑hemoglobin signals.

Abstract

The aim of this study was to compare functional cerebral hemodynamic signals obtained simultaneously by near infrared spectroscopy (NIRS) and by functional magnetic resonance imaging (fMRI). The contribution of superficial layers (skin and skull) to the NIRS signal was also assessed. Both methods were used to generate functional maps of the motor cortex area during a periodic sequence of stimulation by finger motion and rest. In all subjects we found a good collocation of the brain activity centers revealed by both methods. We also found a high temporal correlation between the BOLD signal (fMRI) and the deoxy‐hemoglobin concentration (NIRS) in the subjects who exhibited low fluctuations in superficial head tissues.