Apparatus and methods are provided for complex flow imaging and analysis that is non-invasive, accurate, and time-resolved. It is particularly useful in imaging of vascular flow with spatiotemporal fluctuations. The apparatus is an ultrasound-based framework called vector projectile imaging (VPI) that can dynamically render complex flow patterns over an imaging view at millisecond time resolution. The VPI apparatus and methods comprise: (i) high-frame-rate broad-view data acquisition based on steered plane wave firings； (ii) flow vector estimation derived from multi-angle Doppler analysis coupled with data regularization and least-squares fitting； and (iii) dynamic visualization of color-encoded vector projectiles with flow speckles displayed as adjunct.
