Blood velocity direction estimated by correlation

Blood flow measurement usually yields only the longitudinal component of the velocity. However, when strait vessels are considered, a single parameter, the angle Θ between ultrasound beam and blood flow associated to the longitudinal velocity profile, allow complete hemo-dynamic characterisation. This paper describes a technique that allows one to extract Θ from the correlation function of the echo signal, examined as a function of time and space displacements. The underlying theory is developed, and preliminary experimental results are presented