Objective To determine T-1 and T-2 relaxation times of healthy pancreas parenchyma at 7 T using a multi-transmit system. Materials and methods Twenty-six healthy subjects were scanned with a 7 T MR... Show moreObjective To determine T-1 and T-2 relaxation times of healthy pancreas parenchyma at 7 T using a multi-transmit system. Materials and methods Twenty-six healthy subjects were scanned with a 7 T MR system using eight parallel transceiver antennas, each with two additional receive loops. A Look-Locker sequence was used to obtain images for T-1 determination, while T-2 was obtained from spin-echo images and magnetic resonance spectroscopy measurements with different echo times. T-1 and T-2 times were calculated using a mono-exponential fit of the average magnitude signal from a region of interest in the pancreas and were tested for correlation with age. Results The age range of the included subjects was 21-72 years. Average T-1 and T-2 relaxation times in healthy pancreas were 896 +/- 149 ms, and 26.7 +/- 5.3 ms, respectively. No correlation with age was found. Conclusion T-1 and T-2 relaxation times of the healthy pancreas were reported for 7 T, which can be used for image acquisition optimization. No significant correlations were found between age and T-1 or T-2 relaxation times of the pancreas. Considering their low standard deviation and no observable age dependence, these values may be used as a baseline to study potentially pancreatic tissue affected by disease. Show less
The aim of this thesis was to develop methods to enable the use of 7 Tesla MRI in clinical practice. A number of technical developments have been performed to facilitate clinical studies and to... Show moreThe aim of this thesis was to develop methods to enable the use of 7 Tesla MRI in clinical practice. A number of technical developments have been performed to facilitate clinical studies and to achieve the full potential of high field. Studies have been performed for imaging of different anatomies of the human body, including visualization of the right coronary artery and high resolution imaging of the brain in patients with neurodegenerative diseases Show less
A spectrometer for Electron Paramagnetic Resonance (EPR), operating at the very high microwave frequency of 275 GHz in both continuous wave (cw) and pulsed mode, is described and its capabilities... Show moreA spectrometer for Electron Paramagnetic Resonance (EPR), operating at the very high microwave frequency of 275 GHz in both continuous wave (cw) and pulsed mode, is described and its capabilities are illustrated. A superconducting magnet provides the magnetic field up to 12 Tesla and experiments are possible between room temperature and 5 K. The system utilizes pseudo-optical techniques to minimize microwave losses and a single-mode resonator is used to maximize the microwave field at the sample position. The material under study can also be subjected to a radiofrequency radiation field to enable Electron Nuclear Double Resonance (ENDOR) experiments. Technical details of the design and the operation are presented. First results are discussed which demonstrate the increased sensitivity and resolution compared to experiments at lower microwave frequencies. These concern various materials, ranging from semi-conductors to proteins, including an aqueous solution of a proxyl radical at room temperature. ENDOR performance is illustrated with data from a sample of zinc-germanium-phosphide (ZnGeP2) doped with Manganese (Mn). Separate chapters cover experiments on the organic semiconductor P3HT and the observation of Dynamic Nuclear Polarization (DNP) in zinc oxide (ZnO). Show less
