NIRS Brain Studies with a New Hemodynamic Model: Coherent Hemodynamics Spectroscopy and Functional Neuroimaging

Abstract: A new hemodynamic model relates tissue hemoglobin concentration to blood volume, flow, and oxygen consumption. It affords a quantitative analysis of hemodynamic oscillations (Coherent Hemodynamics Spectroscopy) and transients in neuroimaging. OCIS codes: (170.0170) Medical optics and biotechnology; (170.2655) Functional monitoring and imaging; (170.4580) Optical diagnostics for medicine 1. Basic approach to the derivation of the new hemodynamic model Electrical or fluid dynamic equivalent networks have been commonly used to model the cerebral vasculature [1]. These approaches must necessarily introduce a number of approximations to the complex structure of the microvascular cerebral network, and their refinements may result in a large number of model parameters. The model presented here is based on a conceptually new approach that results in a set of equations that relate fNIRS (functional near-infrared spectroscopy) and fMRI (functional magnetic resonance imaging) signals to a set of steady state and dynamic parameters that characterize the cerebral hemodynamics and metabolic rate of oxygen. The detailed description of this hemodynamic model has been reported in [2,3]. The basic idea behind this new model is to conceptually separate the arterial, capillary, and venous vascular compartments in the brain, considering that each individual red blood cell in the blood stream will trave