Assessment of Tumor Vascularization Using Magnetic Resonance Imaging

Magnetic resonance imaging and image processing techniques for quantification of patho-physiological parameters of tumor microvacularization have been developed. Using the new developed methods it was possible to gain in- vivo information of the tumor microenvironment that was similar to that acquired from surgical specimens using histological examinations. Several, recently performed histological studies strongly implicate the microvessel density in tumors as one of the most decisive factors regarding the development of metastasis and the probability of survival. Tumor neovascularization plays a pivotal role in tumor growth and the intravasation of cells. A method for quantifying vascularization in-vivo would be invaluable to examine the relationship between tumor neovascularization, tumor growth and invasiveness. Further fields of interest for such a method are the changes of the vascular system during cancer therapy. During project realisation several new approaches could be realized for different sub-problems. A scanning sequence that enables the determination of contrast media concentration with the arterial blood plasma and within the investigated tissue was one important item. Another point was a procedure to calculate the temporal changing longitudinal relaxation rate using experimentally determined calibrating curves, which include non-linear effects. Furthermore it was shown that a correct analysis of tracer exchange kinetics in tumors is only possible using deconvolution methods. Template fitting and singular value decomposition have been applied successfully for that purpose. The integration of morphological and functional information within one MR-procedure, as realized during the project, was an essential step forward to "one shop stop" examinations. Additionally, methods and procedures resulting from the projects are an excellent basis for future MRI applications in related areas and in the field of molecular imaging.