High spatiotemporal resolution radial encoding single vessel fMRI

High-field preclinical functional MRI (fMRI) has enabled the high spatial resolution mapping of vessel-specific hemodynamic responses, i.e. single-vessel fMRI. In contrast to investigating neuronal sources of the fMRI signal, single vessel fMRI focuses on elucidating its vascular origin, which can be readily implemented to identify vascular changes relevant to vascular dementia or cognitive impairment. However, the limited spatial and temporal resolution of fMRI has hindered hemodynamic mapping of intracortical microvessels. Here, we implemented the radial encoding MRI scheme to measure BOLD signals of individual vessels penetrating the rat somatosensory cortex. Radial encoding MRI is employed to map cortical activation with a focal field of view (FOV), allowing vessel-specific functional mapping with 50x50 {micro}m in-plane resolution at 1 to 2 Hz sampling rate. Besides detecting refined hemodynamic responses of intracortical micro-venules, the radial encoding-based single-vessel fMRI enables the differentiation of the intravascular and extravascular effects from the draining venules.