Speck, Oliver
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Speck, Oliver
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Speck, Oliver
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Item-typ:Veröffentlichung, Acquisition and Processing Techniques for Image-Based Prospective Motion Correction in Magnetic Resonance Imaging(2018-10-22); ; ; The sensitivity to subject motion is one of the major reasons of image quality degradation in magnetic resonance imaging (MRI). Subjects need to be very calm to maintain the relationship between spatial image information and subject anatomy throughout the scan. In case of moving subjects, prospective motion correction can regain this relationship by constantly adapting the image slice positioning to follow the subject in real time. This requires continuous estimates of the current motion state, which is complicated for a variety of MRI applications. In this dissertation, image-based prospective motion correction techniques are developed to increase the image quality as well as quantitative imaging parameters in diffusion-weighted imaging, high-resolution 2D imaging and functional MRI.Dissertation490 198 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Towards motion-insensitive Arterial Spin Labeling perfusion imaging(2022-03-31); ; ; Perfusion measurements in brain and liver are of high clinical interest. Arterial spin labeling (ASL) magnetic resonance imaging (MRI) has the potential to be an alternative to invasive measurements of perfusion using contrast agent-based techniques. However, the clinical application of ASL is currently limited due to a severe sensitivity to subject motion. The goal of this thesis was to develop novel methods which address the motion sensitivity of ASL sequences. The developed techniques include novel optimized approaches for background suppression, an automatic detection of breathholds during ASL experiments to suppress respiratory motion artifacts, prospective correction of respiratory motion during free-breathing scans as well as three-dimensional retrospective motion correction using a 3D GRASE PROPELLER (3DGP) readout. In addition, a novel 3DGP reconstruction, allowing joint estimation of motion and geometric distortion, is presented. Algorithms are implemented and validated in brain and liver ASL perfusion imaging using healthy volunteers. Finally, recommendations for future improvements of the developed techniques are given.Dissertation714 229