2-D blood vector velocity estimation using a phase shift estimator

In this PhD thesis a method for 2-D blood velocity estimation called the transverse oscillation method (TO) is investigated. The thesis is divided into two parts. In the first part the basic principles in conventional 1-D flow estimation are described, and the state of the art for 2-D velocity estimation is discussed.

The TO method is introduced, and the basic theory behind the method is explained. This includes the creation of the acoustic fields, beamforming, echo-canceling and the velocity estimator.In the second part of the thesis the eight papers produced during this PhD project are presented. Here the TO method is tested both in simulations using the Field II program and in flow phantom experiments using the RASMUS scanner.

Both simulations and flow phantom experiments indicate that the TO method can estimate the 2-D vector velocity with an acceptable low bias and standard deviation when the angle between the blood and the ultrasound beam is above $50^\circ$. Furthermore, the TO method is tested in-vivo where the scannings are performed by skilled sonographers.

The in-vivo scannings resulted in a sequence of 2-D vector CFM images which showed 2-D flow patterns in the bifurcation of the carotid artery.