Comparing Activation-Induced Changes in Cerebral Oxygen Metabolism Measured by Calibrated fMRI and [15O]O2-PET

Motivation: Evaluate the accuracy of calibrated functional MRI (c-fMRI) for measuring relative changes in CMRO2. Goal(s): Compare activation-induced increases in CMRO2 measured by c-fMRI to measurements from [15O]O2-PET. Approach: Data acquired on a PET/MRI scanner while participants performed finger tapping. Calibrated fMRI protocol involved hypercapnia. [15O]O2-PET images acquired at rest and during tapping. Results: Good agreement in the average CMRO2 increase in the sensorimotor cortex between the two methods, although the variability for c-fMRI was considerably greater. Impact: This study is the first direct comparison of c-fMRI to [15O]O2-PET and demonstrated the accuracy of the MRI method.