Functional and metabolic MRI techniques have been rapidly evolving and have tremendous potential for clinical brain disorders research. Clinical activation fMRI studies are performed at 1.5 and at 3.0 Tesla using blood oxygenation level dependent (BOLD) contrast method and arterial spin tagging (AST) techniques. Reproducible alterations Cerebral Blood Flow (CBF) were observed in healthy controls receiving intravenous infusions of a cyclo-oxygenase inhibitor (COX) 1, indomethicin with almost complete suppression of the alteration of CBF to 6% carbon dioxide at rest. In contrast, high dose oral COX 2 inhibitors did not suppress CBF measures in healthy controls that may be due to either an inability to interact with receptors in the brain or possibly do to an insufficient dose or poor absorption of the medication. We observed that while indomethacin reduced the CBF increase during sensori-motor activation paradigms it did not significantly affect oxygen consumption (CMRO2) in the motor cortex of the brain during activation. The ratio of the activation-induced CBF increase in the presence and absence of indomethacin was 0.54 +/- 0.08 (p < 0.001), while the ratio of the CMRO2 increase in the presence and absence of the drug was 1.02 +/- 0.08 p = not significant. These results suggest there by combining BOLD/AST studies one can evaluate the effect of drugs on cerebral oxygen consumption during activation.
