One of the main topics of the chair is imaging techniques that are able to visualize molecular processes at the cellular level (molecular imaging).

Here, the sensitive detection of ultrasound contrast agents plays a major role. Ultrasound contrast agents currently usually consist of nanoshell-stabilized gas bubbles (microbubbles) that are only a few micrometers in diameter.

When microbubbles are insonified with sound pulses that have center frequencies in the diagnostic range, the bubbles can be excited to nonlinear oscillation. This is an important property that can be exploited for the detection of contrast agents. Thus, the signal ratio between contrast agent and tissue can be increased by amplifying signal components arising from nonlinearity and suppressing signal components arising from linear systems. However, sound propagation and scattering in tissue can only be assumed to be approximately linear, so that the achievable signal ratio between tissue and contrast agent is degraded, especially at large penetration depths as well as high amplitudes. Nonlinear systems theory will be used to develop imaging techniques that exploit differences in the nonlinearity of sound propagation and oscillation of microbubbles, thereby improving contrast agent imaging.

Contacts: Stefanie Dencks and Georg Schmitz


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