Jun Hua1, Robert Stevens1, Manus J. Donahue1,2, Alan J. Huang1, James J. Pekar1, Peter C.M. van Zijl1
1Department of Radiology, The Johns Hopkins University, Baltimore, MD, United States; 2Department of Clinical Neurology, Oxford University, Oxford, United Kingdom
Changes in CBF/CBV/arterial-CBV(CBVa)/post-arterial-CBV(CBVpa) were measured in human brain during breath-hold and visual stimulation. δCBV/CBV was larger during breath-hold (54.9+/-5.8%) than visual stimulation (28.2+/-5.2%), a difference primarily originating from δCBVpa/CBVpa (54.5+/-4.9% vs. 22.2+/-3.8%); δCBVa/CBVa (53+/-6%) and δCBF/CBF (61+/-7%) were comparable in both tasks. During breath-hold, vasodilation distributed proportionally among arterial and post-arterial compartments, whereas, during visual stimulation, relative change in CBVa was greater than that in CBVpa. Our data indicate that the coupling between arterial-CBV and CBF was largely preserved during both tasks (rCBVa=rCBF0.86+/-0.05), while the relationship between total-CBV and CBF was substantially different between breath-hold (rCBV=rCBF0.90+/-0.05) and visual (rCBV=rCBF0.52+/-0.04) stimulation.