MR gradient echo imaging of intravascular blood oxygenation: T₂* determination in the presence of flow

The T₂* relaxation time of blood varies with its oxygen saturation. To evaluate the feasibility of imaging intravascular blood oxygenation in humans using a conventional 1.5T MR system, we have implemented a method to measure T₂* of blood despite the presence of pulsatile flow. The method was tested in a) stationary and flow phantoms, b) blood samples at different levels of oxygen saturation, and c) a human hypoxia model. Our results demonstrate the ability of cardiac‐triggered, flow compensated gradient echo imaging to obtain reproducible T₂* measurements of flowing blood in vivo.