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Abstract #0513

Cerebral Blood Flow (CBF) and Cerebral Blood Volume (CBV) Coupling Differs During Neuronal and Vascular Tasks

Manus Joseph Donahue1,2, Robert D. Stevens3, Jun Hua1,2, Alan Huang1,2, James J. Pekar1,2, Peter CM van Zijl1,2

1Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; 2FM Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; 3Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA

A common BOLD quantification approach employs a hypercapnic stimulus to evaluate CBF contributions. This method assumes that the neuronal hemodynamic response is due to increased metabolism causing release of vasodilatory CO2/H+ and that CBV/CBF coupling is equal for neuronal and vascular stimuli. Using breath hold as vascular stimulus and visual activation as neuronal stimulus, we found (n = 9) a similar CBF response and a doubling of the CBV response for breath hold versus visual stimulation. These results challenge the assumption of invariance in CBF/CBV coupling and suggest BOLD calibration should account for both CBF and CBV changes.