Conventional ultrasound Doppler imaging using classic FIR and IIR wall filters prohibits visualization of the small vessels due to strong Fourier spectral overlap between tissue and blood echoes. A clutter removal method is proposed that utilizes spatiotemporal coherence of the plane wave imaging data to significantly suppress tissue clutter signal obtained over extended ensembles which can be modelled as a low-dimensional process. To reject background signal due to additive noise while preserving important structural features, a morphological filtering was proposed. To provide additional intensity balance and suppress spurious structures, a vessel enhancement processing based on Hessian-based filtering was proposed. This new imaging method is solely based on ultrasound and enables visualization of the small vessels at superb resolutions without using any type of contrast enhancing agents. The initial in vivo results in several organs highlight the utility of this type of imaging in both preclinical and clinical settings. In clinical applications, this method may provide a versatile tool for monitoring angiogenesis which may provide invaluable diagnostic and prognostic information.
