Ankündigung des Promotionsvortrags von: Herrn Andreas Riexinger
Intravoxel Incoherent Motion Imaging allows the simultaneous measurement of tissue diffusion and perfusion properties in different organs. In this thesis, the originally introduced biexponential model as well as a less known triexponential model will be discussed. IVIM parameters are difficult to reproduce, and therefore most studies are not comparable. For this reason, the aim of this work was to increase the reproducibility of the determined IVIM parameters.
First of all, the magnetic field dependence of the IVIM parameters of both models was investigated using two magnetic field strengths. This showed a dependence of the diffusion coefficient and the pseudo-diffusion coefficient of the biexponential model on the used magnetic field strength.
To further increase the reproducibility of the triexponential IVIM parameters, the choice of measurement points for sampling the triexponential signal curve was optimized for application in the liver. The optimized distribution was compared with distributions already used in the literature by simulations and in vivo measurements.
Due to the livers position in relation to the heart, the pulsation of the heart leads to a reduced signal in the area of the left liver lobe. In a clinical study it was tested whether the so-called pulsation artifact can be reduced by a breathhold in expiration or inspiration. There was no difference in either of the two breathing techniques used.
Another clinical study investigated the influence of external pressure in the form of a compression stocking, as well as the intensive strain on the calf muscles, on the biexponential IVIM parameters of the complete lower leg muscles. The results of the study show no influence of compression, at all points in time.
(Vortrag auf Englisch)
Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind aufgrund der momentanen Situation nicht öffentlich. Diesen Verfahrensteilen folgt ein ebenfalls nicht öffentliches Rigorosum von 45 Minuten.