Brain Perfusion Assessment by Optical Contrast Tracking Using Time-Resolved Fluorescence Detection

In this paper we present methodological studies on construction and application of optical brain monitoring system utilizing time-resolved detection of fluorescence excited in the dye circulating in the human brain. Series of Monte Carlo simulations and time-resolved measurements of diffuse reflectance and fluorescence were carried out. Measurements on physical phantoms allowing for assessment of dynamic inflow of Indocyanine Green (ICG) were performed. Finally, in-vivo measurements on the healthy subjects as well as patients with brain perfusion insufficiencies were carried out during intravenous administration of ICG. Obtained results show good signal-to-noise ratio for fluorescence signals. The simulations and phantom experiments allowed to optimize conditions of the measurement - dose of the dye injected and source-detector separation used in the in-vivo experiments. Preliminary analysis of signals obtained during in-vivo measurements in patients show that the fluorescence measurements can be used to assess brain perfusion insufficiencies.