Localized blood flow imaging using quantitative flow-enhanced signal intensity.

Flow-enhanced signal intensity (FENSI) was previously introduced as a novel functional imaging method for measuring changes in localized blood flow in response to a stimulus. However, FENSI was limited to a qualitative functional MRI tool, due to magnetization transfer effects and different tagging plane profiles between tag and control images. In this work, a revised FENSI acquisition is proposed to enable quantitative imaging, which is capable of providing absolute localized blood flow maps free from magnetization transfer and slice profile errors. The feasibility and accuracy of measuring microvascular (arteriole, capillary, and venule) blood flow by using quantitative FENSI was validated by our phantom studies. Additionally, localized cerebral blood flow, 366 ± 45 μL/min/cm(2) in gray matter and 153 ± 23 μL/min/cm(2) in white matter, was measured in healthy subjects during resting state, whereas a flow change of 73 ± 13% was detected during a visual task.