Study of local cerebral hemodynamics by frequency-domain near-infrared spectroscopy and correlation with simultaneously acquired functional magnetic resonance imaging

The aim of our study was to explore the possibility of detecting hemodynami c changes in the brain using the phase of the intensity modulated optical s ignal. To obtain optical signals with the highest possible signal-to-noise ratio, we performed a series of simultaneous NIRS-fMRI measurements, with s ubsequent correlation of the time courses of both measurements. The cogniti ve paradigm used arithmetic calculations, with optical signals acquired wit h sensors placed on the forehead. Measurements were done on seven healthy s ubjects. In five subjects we demonstrated correlation between the hemodynam ic signals obtained using NIRS and BOLD fMRI. In four subjects correlation was found for the hemodynamic signal obtained using the phase of the intens ity modulated signal. (C) 2001 Optical Society of America.