Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 9 of 9 for “"partial volume effects"”.
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Improved accuracy in susceptibility-based OEF measurements by mitigation of partial-volume effects via combined magnitude and phase reconstruction
… limit produce unreliable measurements due to partial-volume effects. We demonstrate a method for obtaining more reliable OEF measurements beyond this limit by performing a joint reconstruction using both the magnitude and phase of the complex-valued MRI signal. This method is validated both in …
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Fabrication and Testing of a Microchannel Network Phantom for MRI Velocimetry
… Slice thickness, order of image acquisition, partial volume effects, and acceleration effects are investigated, and show little effect on the measured flow rates. Examination of anatomical MR images show that the channels decreased in height during fabrication, which explains some of the …
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Optimization of the Fair Technique for Specific Brain Region Perfusion Studies
… inversion with a control for off-resonance effects) for quantifying cerebellum perfusion. The data indicate that FAIR ASST yields more robust CBF (cerebral blood flow) measurements. OPTIMAL FAIR (orthogonally-positioned tagging imaging method for arterial labeling of FAIR) was developed and …
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MR-assisted PET data optimization for simultaneous dual-modality imaging in dementia
… image degradation due to subject movements; partial volume effects correction is required due to the relatively limited spatial resolution. Although many applications could benefit from these methodological improvements, in this thesis we focused on dementia. MRI and PET are widely used and …
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Intercomparison of medical image segmentation algorithms
… it suffers from artefacts including noise, partial volume effects and intensity inhomogeneities.Brain, being a very complicated structure, its precise segmentation is particularly necessary to delineate the borders of anatomically distinct regions and possible tumors. Many algorithms have …
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Advanced Methods for Diffusion MRI Data Analysis and their Application to the Healthy Ageing Brain
… dispersion simultaneously. Fourthly, free water volume fraction estimates provided by the free water diffusion tensor imaging (fwDTI) are shown to be useful to detect and remove voxels corrupted by cerebrospinal fluid (CSF) partial volume effects. Finally, dMRI techniques are applied to the …
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MRI-based treatment plan simulation and adaptation for ion radiotherapy using a classification-based approach
… on the reference CT. Finally, a target volume shift was simulated and employing a hybrid approach, a treatment plan adapted to the shift was optimized on the basis of a so-called corrected CT. The latter consisted of a reference CT, in which a volume around the target was replaced by …
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High-Resolution Diffusion Tensor Imaging and Human Brain Connectivity
… with diverse diffusion properties. As such, partial volume effects introduce a strong bias which can lead to spurious measurements, especially in regions with a complex tissue structure such as interdigitating crossing fibers or in convoluted cortical folds near the grey/white matter …
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fMRI for mapping the plastic somatotopy of primary somatosensory cortex - Development and clinical applications
Functional magnetic resonance imaging (fMRI) is a widely used tool for studying brain function in vivo. The technique is based on acquiring brain images sensitive to the physiological response following neural activation, and hence, allows brain activity to be examined and documented. In this …