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 a balanced steady state free precession (SSFP) pulse sequence of RF pulses and balanced gradient pulses; setting the echo time (TE) of the SSFP pulse sequence equal to about one-half the sequence repetition time (TR) of the SSFP pulse sequence; selecting 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; 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 using one or more residual phase images to map velocity within the vessel or structure of interest.