Functional imaging with FENSI: flow-enhanced signal intensity.

Flow measurement methods for functional MRI (fMRI) are desirable as they are more closely tied to neuronal activity than the commonly used blood oxygenation techniques. In this work we introduce a flow-based functional imaging method. The method, called flow enhancement of signal intensity (FENSI), is an extension of the diffusion enhancement of signal and resolution (DESIRE) method from MR microscopy. The FENSI method offers a localized flow-weighted signal across a very thin slice (0.4 mm in this study) that provides a signal enhancement that is dependent on the velocity and direction of the flow. The FENSI method was implemented on a human 3 T system and applied to a blocked visual cognitive task. Activation maps showed good localization and the measured signal changes of around 10% were in good agreement with the predicted enhancements.