Noninvasive quantification of whole‐brain cerebral metabolic rate of oxygen (CMRO2) by MRI

Cerebral metabolic rate of oxygen (CMRO₂) is an important marker for brain function and brain health. Existing techniques for quantification of CMRO₂ with positron emission tomography (PET) or MRI involve special equipment and/or exogenous agents, and may not be suitable for routine clinical studies. In the present study, a noninvasive method is developed to estimate whole‐brain CMRO₂ in humans. This method applies phase‐contrast MRI for quantitative blood flow measurement and T₂‐relaxation‐under‐spin‐tagging (TRUST) MRI for venous oxygenation estimation, and uses the Fick principle of arteriovenous difference for the calculation of CMRO₂. Whole‐brain averaged CMRO₂ values in young, healthy subjects were 132.1 ± 20.0 μmol/100 g/min, in good agreement with literature reports using PET. Various acquisition strategies for phase‐contrast and TRUST MRI were compared, and it was found that nongated phase‐contrast and sagittal sinus (SS) TRUST MRI were able to provide the most efficient and accurate estimation of CMRO₂. In addition, blood flow and venous oxygenation were found to be positively correlated across subjects. Owing to the noninvasive nature of this method, it may be a convenient and useful approach for assessment of brain metabolism in brain disorders as well as under various physiologic conditions. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.