Using saturation bands to null signal from inflowing blood in single-slice fMRI: Toward a rapidly sampled black-blood functional contrast

Motivation: Magnetization-preparation schemes using inversion recovery measure aspects of hemodynamics like perfusion and blood volume, but their temporal resolution is limited by physiology, i.e., long blood arrival/transit times. Goal(s): To study brain hemodynamics at high temporal resolutions with novel inflow saturation. Approach: We applied saturation bands on both sides of a rapidly-sampled single imaging slice to suppress inflow-related signal and produce black-blood functional contrast sensitive to macrovascular blood volume. Results: Phantom experiments show successful suppression of inflow signal with flow-velocity-dependence at low- and high-velocity regimes but independence at mid-regime. Human brain vessels exhibited partial signal suppression, with more functional suppression seen in larger vessels. Impact: Fast blood nulling may be achievable using local saturation bands contiguous to an imaging slice rather than a global inversion slab, enabling functional contrasts sensitive to macrovascular blood flow-velocity and volume suitable for studying fast hemodynamics in specific vascular compartments.