Stefan Alexandru Carp1, Maria Angela Franceschini1, David Alan Boas1, Young Ro Kim1
The cerebral metabolic rate of oxygen (CMRO2) is a physiological parameter closely linked to neural activation as well as to various disease states. Hypercapnic calibration is used to calibrate the BOLD-CBF-CBV relationship under the assumption of iso-metabolic blood flow increase during CO2 inhalation. Simultaneous near infrared optical measurements of cerebral blood volume, blood flow and oxygen extraction can also be used to monitor CMRO2 changes, albeit at low spatial resolution. We use these optical measurements during graded hypercapnia to test the iso-metabolic assumption, and demonstrate an apparent increase in brain metabolism at higher inhaled CO2 levels.