1Center for Magnetic Resonance Research,Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, United States; 2Center for Magnetic Resonance Research,Department of Radiology, University of Minnesota, Minneapolis, MN, United States
Perfluorocarbon (PFC) emulsion is a promising technique to treat diseases with compromised oxygenation such as ischemia, air embolism and trauma. In the present study, the injection of PFC emulsion to the normal rat led to decreases of the oxyhemoglobin saturation (%HbO2) in the vein (up to 36% at 170 minutes after the injection) and the Blood-Oxygen-Level-Dependent (BOLD) signal in the rat brain cortex (up to 7.5% at 160 minutes after the injection). These changes might be due to the stronger adsorption of oxygen to the PFC than that of hemoglobin, thus, the conversion of HbO2 to deoxyhemoglobin (dHb) occurs when the PFC and hemoglobin are competing for the limited oxygen content. In addition, we found that the images of BOLD signal reduction after the PFC emulsion injection show a similar spatial pattern as that of resting-state cerebral blood flow (CBF) maps, which is consistent with the fact that CBF dominates the BOLD signal. Therefore, the PFC emulsion potentially can be used as an fMRI contrast agent to assess the function of the tissue in addition to the treatment of oxygenation compromised diseases.