In Vivo Verification of the Intravascular BOLD Effect

There has been much controversy over the brain/vein debate in functional magnetic resonance imaging (fMRI). Low resolution studies create a broad pattern of signal enhancement upon brain activation which could be from brain or blurred vessels. Our goal is to validate the blood oxygenation level dependent (BOLD) model and its mechanisms in relation to blood flow and susceptibility changes. We investigate the visibility of small vessels in the brain using high spatial resolution. Flow-compensated sequences are used to obtain susceptibility information and velocity-encoded sequences to measure velocities.