1. A method of referenceless phase velocity mapping using balanced steady-state free precession magnetic resonance imaging, the method comprising: with a MRI system, providing at least one balanced steady state free precession (SSFP) pulse sequence of RF pulses and balanced gradient pulses; setting an echo time (TE) of the at least one SSFP pulse sequence equal to about one half of a sequence repetition time (TR) to refocus all off-resonant spins at a time of image acquisition; for each of the at least one SSFP pulse sequences, acquiring a single MRI image; for each MRI image: selecting within the MRI image a region of interest (ROI) inside of static tissue adjacent to a vessel or structure of interest; approximating the image phase within the ROI of static tissue by fitting to a smoothly varying function; and obtaining a residual phase image Θ(r) by subtracting the approximated image phase of the static tissue from an image phase of a larger field of view (FOV) including the vessel or structure of interest; and collectively using the residual phase image Θ(r) derived from each MRI image to map velocity in at least one dimension within the vessel or structure of interest, wherein the number of dimensions is equal to the number of acquired MRI images.