This invention provides methods for non-invasive, real-time measuring and/or monitoring of local blood flow in a subject. Methods of the invention generally include the steps of obtaining Doppler shift images of at least two planes intersecting blood vessels at the scanned location determining Doppler angles using the Doppler shift images and then using the Doppler angles thus determined together with the Doppler shift signals to arrive at a measure of the volumetric blood flow. Also provided are systems and software for performing the methods.
