Persons at STU
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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:||New magnetic resonance techniques for measurement and monitoring of the physiological functions|
|Summary:||In today's modern era, there are many technological devices available to clinicians allowing the examination of the man's insides non-invasively for diagnostic or follow-up purposes. The best example of such measurement technology is the magnetic resonance (MR) scanner, which is typically used for soft tissue imaging, but it is usable also for tissue composition and metabolism measurements via magnetic resonance spectroscopy and for functional imaging. Despite the technical advances of our time and the great progress of past years, the acquired data do not always match the diagnostic requirements, because of the methodological or technical limitations. The aim of this dissertation thesis was to propose several MR based methods for measurement and monitoring of physiological processes (e.g. blood flow, breathing or muscle energy metabolism) to improve the performance of MR sequences used in clinical or research practice. First part of the thesis describes a method for measurement of MR contrast changes caused by sweating, on which also the developed measurement subsidiary system and post-processing software were tested. Significant changes in signal intensity of the skin area, where the severe sweating was present, were detected. This change in MR contrast has to be thought of when evaluating MR skin data. Second part is dedicated to optimization of the acquisition sequence for the blood flow monitoring through blood oxygenation level dependent (BOLD) contrast at low field and to enhance the measured BOLD signal, as due to restricted sensitivity is BOLD imaging not commonly used at low field systems. The use of alcohol and caffeine for enhancement of the BOLD contrast and optimized acquisition in the early stages after the administration has been proposed. Significant BOLD effect was measured already 10-15 minutes after the consumption, thus no additional pre-measurement delays were introduced. Third part of the thesis targeted on the improvement of the MR spectroscopy of the human liver. New acquisition sequence monitoring the movement of the diaphragm while breathing was developed and implemented. Real-time navigation during the data acquisition and also during the preparation phases was tested on moving phantom, volunteers and also patients. Our results clearly showed that monitoring of breathing motion using navigators during the measurement and preparation phases significantly improves the liver spectra quality. This can improve early diagnosis of different liver diseases e.g. tumors. In the last part of the thesis was the potential time resolution of the magnetization transfer (MT) investigated, in regard of the possibility of slow metabolic changes observation, what was not possible as yet. We were able to show that five-times finer temporal resolution can be achieved for the MT experiments in human calf muscle at 7 T, in comparison to a 3 T system. Time-resolved MT could be an attractive tool for future studies of human muscle metabolism with 31P-MRS, furthermore the increased spectral quality can be used for localized measurements of specific muscle types. New magnetic resonance techniques for monitoring of the physiological functions proposed in this thesis, especially the method for measurement of enhanced BOLD signal and the new measurement sequence for navigated liver spectroscopy have high potential to improve the performance of the dedicated MR measurements.|
|Key words:||magnetic resonance, measurement methods, physiological functions, liver spectroscopy, muscle metabolism, low field BOLD imaging|
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