An Investigation of the VASO Contrast Mechanism Reveals a Novel Method for Quantifying Cerebral Blood Flow
Donahue M, Lu H, Jones C, Pekar J, van Zijl P
Johns Hopkins University, Johns Hopkins University
Vascular space occupancy (VASO)-dependent fMRI is a novel imaging technique sensitive to microvascular CBV changes. We demonstrate that, at high resolution at 3T, VASO effects become too large to originate from CBV effects alone. We show that an arterial spin labeling contribution exists due to the use of a non-selective inversion pulse and that a large influence from CSF will cause VASO gray matter signal changes to become more negative than previously expected. When all contributions are considered, multi-TR VASO experiments can be designed that allow for extraction of CBF and CBV within a single pulse sequence.