The estimation of 3-D blood flow through vessels represents one of the most challenging aspects both in clinics and in research. Through the measurement of the volume flow it is possible to prevent many cardiovascular diseases, which are among the main causes of deaths all over the world. Currently, because of the limitations existing in the modern ultrasound systems, there is no efficient solution to estimate the volume flow. In recent years an interesting approach, capable to evaluate the volumetric blood flow from the cross-sectional imaging plane was conceived. This approach is based on detecting the out-of-plane velocity component by using the speckle decorrelation (SDC) and the in-plane velocity components by using the ultrasound imaging velocimetry (UIV).