Correlation analysis between prefrontal oxygenation oscillations and cerebral artery hemodynamics in humans

The objective of this study is to assess the correlation between the prefrontal cerebral oxygenation oscillations measured by near-infrared spectroscopy (NIR) and cerebral artery hemodynamic parameters as measured by transcranial Doppler (TCD). A total of thirty subjects were recruited from the university to participate in this study. The cerebral oxygenation signal and TCD hemodynamic parameters were monitored on separate days. The cerebral oxygenation signal was monitored for 10min from the left prefrontal lobe using NIRS. TCD monitoring was performed to measure the hemodynamic parameters including end diastolic, peak systolic, and mean cerebral blood flow velocities. Pulsatility index (PI) and resistance index (RI) were calculated automatically. With spectral analysis based on wavelet transform of NIR signal, five frequency intervals were identified (I, 0.005-0.02Hz, II, 0.02-0.06Hz, III, 0.06-0.15Hz, IV, 0.15-0.50Hz and V, 0.50-2.0Hz). Significant negative correlation was found between the cerebral [Hb] and [HbO2] oscillations in frequency intervals from I to V and the PI or RI in left external carotid artery (ECA) (p<0.005). Also weak negative correlation was found between the cerebral [Hb] and [HbO2] oscillations in frequency intervals III, IV, V and the mean velocity in left middle cerebral artery (MCA) (p<0.05). The results suggested that the cerebral oscillations measured from the frontal lobe were closely related to the pulsatility of ECA and reflect partly the vessel stiffness of MCA.