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Basic information about a final thesisAdditional informationAdditional information about the final thesis follows. Click on the language link to display the information in the desired language.
|Language of final thesis:||English|
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|Title of the thesis:||Optimal use of proton in vivo spectroscopy methods for assessment of metabolic state of biological tissue at high magnetic fields|
|Summary:||Proton (1H) in vivo magnetic resonance spectroscopy (MRS) is a very valuable and noninvasive tool, which enables the insight into the metabolism of living organisms. Its great advantage is its variability, with which it is possible to adjust the parameters of the measurements to allow the detection of various metabolites from specific volumes. In the theoretical part of this work, the basic principles of magnetic resonance were introduced, especially their in vivo application. Localization methods were explained, both single voxel spectroscopy (SVS) and multivoxel chemical shift imaging (CSI). The importance of the magnetic field homogeneity in the volume of interest was emphasized. The necessity of suppression of unwanted dominant signals in the spectra, emerging from water or lipids, was mentioned. In the analysis and quantification section, various processing steps and recommended corrections of the data were described, together with quantifications approaches that led to comparable results. The aim of the practical part of the work was to apply, optimize and develop methods of in vivo 1H MRS to investigate three different research questions at high magnetic fields. The first study was performed on a preclinical 4.7 T scanner and was designed to detect metabolite changes in a rat brain model of vascular dementia induced by occlusion of three cerebral arteries. The SVS method was applied. Although no significant changes in the metabolite concentrations were detected, which could be explained by neurocompensation mechanisms, the method allowed the reliable quantification of six metabolites. The second study, performed on a 7 T scanner focused on the carnosine molecule in the human calf muscle and its changes in the spectrum following acute physical excercise. The SVS method was employed. The concentration of carnosine was not affected after the excercise, but its peak in the spectrum was split. This suggested the existence of various compartments of carnosine, with different pH levels induced by the excercise. The third study dealt with the detection of intramyocellular lipids (IMCL) in the calf muscle at 7 T. A new CSI sequence was developed for this purpose, called FIDESI, which allowed the detection of FID with minimum time delay and a signal with a long echo time in one measurement, from the whole axial plane of the calf. This new sequence provided results comparable to those of previously published studies about IMCLs and, in a relatively short measurement time enabled the detection of spectra not only from all the muscles in the calf, but also from bone marrow and subcutaneous lipids as well. In the final discussion, selected methods were compared and their selection was explained and discussed with regard to their specific application.|
|Key words:||in vivo MRS, proton spectroscopy, magnetic resonance, SVS, CSI|
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