1. A method of measuring real-time spatially localized velocity distribution in a region of a body comprising the steps of: (a) placing said body in a static magnetic field along a first axis (z), (b) applying magnetic gradient pulses along two orthogonal axes (x,y) and an RF excitation pulse to selectively excite said region, (c) applying a cyclical magnetic readout gradient along an excitation axis, said gradient having lobes with increasing area, (d) sampling a magnetic resonance signal while applying said readout gradient, said magnetic resonance signal including velocity distribution along a spatial dimension on said readout axis, and (e) obtaining a velocity distribution along said spatial dimension.