Coherent Flow Imaging: A Power Doppler imaging Technique Based on Backscatter Spatial Coherence

Power Doppler imaging is a commonly used method for the detection of flow. The direction of flow is lost with power Doppler, but it has greater sensitivity to flow compared to velocity estimation techniques. Power Doppler imaging can be degraded if thermal noise is large or if slowly moving reverberation clutter passes through the wall filter. We have developed a power Doppler imaging technique, based on the same principles as power Doppler, but uses the coherence of backscattered blood signal rather than the complex backscattered signal. This technique, called SLSC power Doppler, is less sensitive to clutter-based signals and thermal noise. We show in simulations, phantom, and in vivo experiments that the detected flow demonstrates a smoother, fuller profile and is more robust to the presence of thermal noise. The technique can also utilize fewer ensemble samples to obtain satisfactory detection of flow.