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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. Here, a novel, noninvasive CBV-weighted MRI approach (VASO-FLAIR with 3D GRASE (GRadient-And-Spin-Echo)) is used in conjunction with CBF-weighted and BOLD fMRI in healthy volunteers (n=7) performing simultaneous visual (8 Hz flashing-checkerboard) and motor (1 Hz unilateral joystick) tasks. 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.

Original publication

DOI

10.1038/jcbfm.2009.107

Type

Journal article

Journal

J Cereb Blood Flow Metab

Publication Date

11/2009

Volume

29

Pages

1856 - 1866

Keywords

Adult, Blood Volume, Blood Volume Determination, Brain, Cerebrovascular Circulation, Contrast Media, Humans, Kinetics, Magnetic Resonance Imaging, Motor Cortex, Oxygen, Oxygen Consumption, Spin Labels, Visual Cortex