Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
-
J. Cereb. Blood Flow Metab. · Nov 2009
Cerebral blood flow, blood volume, and oxygen metabolism dynamics in human visual and motor cortex as measured by whole-brain multi-modal magnetic resonance imaging.
The development of neuroimaging methods to characterize flow-metabolism coupling is crucial for understanding mechanisms that subserve oxygen delivery. Functional magnetic resonance imaging (fMRI) using blood-oxygenation-level-dependent (BOLD) contrast reflects composite changes in cerebral blood volume (CBV), cerebral blood flow (CBF), and the cerebral metabolic rate of oxygen consumption (CMRO(2)). However, it is difficult to separate these parameters from the composite BOLD signal, thereby hampering MR-based flow-metabolism coupling studies. ⋯ This approach allows for CBV, CBF, and CMRO(2) to be estimated, yielding (mean+/-s.d.): DeltaCBF=63%+/-12%, DeltaCBV=17%+/-7%, and DeltaCMRO(2)=13%+/-11% in the visual cortex, and DeltaCBF=46%+/-11%, DeltaCBV=8%+/-3%, and DeltaCMRO(2)=12%+/-13% in the motor cortex. Following the visual and motor tasks, the BOLD signal became more negative (P=0.003) and persisted longer (P=0.006) in the visual cortex compared with the motor cortex, whereas CBV and CBF returned to baseline earlier and equivalently. The proposed whole-brain technique should be useful for assessing regional discrepancies in hemodynamic reactivity without the use of intravascular contrast agents.