The Department has a long history of research within diagnostic ultrasound, and the activities now covers a wide range of applications, that now also stretches into acoustofluidics, bioacoustics, and industrial applications. The talk will focus on three main topics: arterial characterization, measurements of dolphin sonar beams, and a new imaging technique named magnetomotive ultrasound imaging.

Today, global measures of the condition of the vascular system can be obtained in the form of for instance the pulse wave velocity. Ten years ago an MD, a collaborator of our group, made a discovery while testing a new ultrasound system. She noticed that there seemed to be a longitudinal movement of the arterial wall, revealed only because of the increased image quality of the new image system. The movement was quantified using a modified speckle tracking algorithm, and has now given rise to a number of new research questions and better possibilites for local quantification of the condition of arteries.

An ultrasound project which has not a direct relation to diagnostic ultrasound, is the measurements of the sonar beam of dolphins. However, there might be lessons to learn how dolphins detect their echoes, and what type of beams they produce. The measurement system consisting of a 47 element hydrophone array will be described together with findings that may point to the fact that the dolphin use both of their sound generating organs to modify the shape of the beam, akin to what is used at DTU for transverse Doppler processing.

Magnetomotive ultrasound imaging is  a new technique where superparamagnetic ironoxide nanoparticles are used as a contrast agent for ultrasound imaging. The technique is based on the application of a time varying magnetic field to the object to be imaged. The field acts to move the particles and thereby the surrounding tissue, and the movement can be picked up with standard ultrasound Doppler or correlation techniques. Results from phantom studies will be presented, along with simulations of vibrational phenomena that produce artefactual signals.