| Popis: |
The work in this thesis falls into three sections: (i). the development and application of a computer simulation of the MRI experiment based on the Bloch Equations incorporating all flow and motion effects that would be expected in the body, (ii). a theoretical analysis of factors affecting the efficacy of perfusion and diffusion imaging techniques and (iii). the proposal and evaluation of a new technique for the MRI measurement of perfusion. The simulation provided a powerful analytical tool used in the theoretical work of this thesis. The modularity of the design will enable simple development for future applications. The purpose of the theoretical analysis was to resolve many of the controversial issues arising from the various diffusion and perfusion imaging techniques including: the applicability of the various techniques in different in-vivo systems, the effects of motion artifacts, noise and eddy currents. Some conclusions of great significance were arrived at specifically the importance chosing a flow measurement technique appropriate to the tissue and flow type and the severe effects of motion artifacts in IVIM and phase display imaging. From this analysis a new perfusion imaging technique was derived which was implemented and evaluated in a perfusion phantom and in the calf muscle. Very good results were achieved in the phantom studies, and the results from the calf muscle were promising. On a clinical MRI system the technique could prove very useful. |
