Estimation of the angle between ultrasound beam and blood velocitythrough correlation functions

摘要

Correlation functions, calculated on the ultrasonic echoesnscattered by blood, provide a rich harvest of information concerning thenlocal speed, which has often been underestimated; in particular, bloodnflow measurement usually yields only the longitudinal component of thenvelocity, even if significant information about the speed direction cannbe extracted. In this paper it is shown how correlation functions,ncalculated on the dependency of both time and space displacements, allownus to evaluate the angle Θ between ultrasound beam and blood flow;nwhen straight vessels are considered, this single parameter, combinednwith the longitudinal velocity profile, permits the complete hemodynamicncharacterization. The underlying theory is developed and preliminarynexperimental results are presented