Die Bestimmung der Änderung des Sauerstoffverbrauchs unter funktioneller Aktivierung mittels Kernspintomographie
The goal of this thesis was to develop a method allowing the estimation of oxygen consumption change during functional activation using magnetic resonance imaging. For the calculation of oxygen consumption changes it was assumed that ATP is exclusively produced by aerobic glycolysis. Knowing the difference of blood oxygen saturation between arterial and venous blood and the blood flow one is able to calculate the cerebral metabolic rate of oxygen CMRO2. The changes in CMRO2 can then be calculated by DCMRO2/CMRO2=(1+DCBF/CBF)(1-DYv/(Ya-Yv)). Using this relationship, methods were developed and validated which allow the estimation of blood flow changes DCBF/CBF as well as oxygen saturation changes of venous blood DYv/(Ya-Yv) during functional activation. The best results for the estimation of blood flow changes are obtained by arterial spin labeling. Changes in venous blood oxygenation are measured with the help of the dependence of the BOLD effect on venous blood oxygenation and the blood volume CBV. The combination of the arterial spin labeling technique with an EPI-module for image acquisition allows the simultaneous measurement of blood flow changes and changes in signalintensity due to the BOLD effect. Changes in blood volume are observable after injection of an intravascular paramagnetic contrast agent. For the experiments, anesthetized rats were used which were stimulated by constant current pulses applied by needle electrodes in one paw. The developed methods were validated by comparing measured changes of blood flow, blood volume and signalintensity changes due to the BOLD-effect with values found in the literature. For the first time it is possible to obtain all hemodynamic parameters characterizing the BOLD effect in one animal. With this method, a mismatch in the location of activation between BOLD based activation maps and pefusion based activation maps was found.
info:eu-repo/classification/ddc/540, Chemie
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