Ultrasound blood velocity estimation

Modern ultrasound scanners have the ability to show a cross-sectional view of the blood flow in the human body in real time. The images can be used for studying the heamodynamics of the body and thereby pathological conditions for flow in the vessels and heart can be diagnosed. The projects seeks both to characterize these systems and to enhance their diagnostic value by developing new algorithms for making the velocity estimation more accurate and eliminate errors associated with the techniques. The development of models for characterizing the systems has resulted in the book "Estimation of Blood Velocities using Ultrasound: A signal processing approach." published by Cambridge University Press in 1996, which was also accepted for the Dr.Techn. dissertation in 1996.
Another aim for the project is to develop a method for estimating the velocity vector and thereby overcome the limitation of present commercial systems, which only measures the component along the acoustic beam. This will allow the display of the velocity independent of the angle between the blood vessel and the propagation direction of the sound. The research is performed in collaboration with the Danish company B-K Medical A/S.
The distribution of velocities within a vessel can also be found by these methods. This is often used for detecting vessel constrictions or plaque on the inside of the vessel wall. The distribution shown in traditional systems is often very noisy and does not directly correspond to the smooth distribution that is found in the vessel. A new method based on a Lattice filter has therefore been developed and implemented on a real-time signal processing system capable of performing one billion multiplications and additions per second.