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 20 of 130 for “"phase contrast"”.
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Advances in Magnetic Resonance Phase‐Contrast Velocity Mapping
Phase-contrast MRI is used to assess functional flow parameters of the cardiovascular system. Long scan times of three-dimensional flow encoded MRI in particular have, however, hampered the acceptance of the method in a clinical routine setting. Furthermore, concerns have recently been raised about …
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X-ray phase contrast imaging of preclinical atherosclerosis
… methods lack the combination of resolution and contrast required to characterize atherosclerotic plaque. Recently, a new mode of medical imaging known as X-ray phase contrast imaging (XPCI) has been shown to produce exceptional contrast in soft tissues, and has the potential to noninvasively …
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Compact tomographic X-ray phase-contrast imaging of breast cancer
… of spatial resolution and soft-tissue contrast necessary to visualize pathological changes in the breast. X-ray phase-contrast imaging (XPCI) has emerged as a promising modality for providing enhanced soft tissue differentiation due to its inherent source of contrast being derived from …
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In vivo imaging of cortical porosity by synchrotron phase contrast micro computed tomography
… hypothesized that using synchrotron propagation phase contrast µCT, cortical porosity could be imaged in vivo in rats at a dose on the same level as those used currently for trabecular bone analysis. Using the BMIT-BM beamline, I determined the optimal propagation distance and used ion chamber …
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Investigations into Optically Controlled Phase Contrast, Polarisation Switchable Narrow Band RF Detection Techniques.
… an investigation into S-band microwave frequency phase-contrast imaging. Resolution is a critical issue so system enhancements such as optical remote connection and polarisation-dependant sensing have been implemented within an end-to-end sensing system. Initially, the feasibility of …
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Capabilities and limitations of Phase Contrast Imaging techniques with X-rays and neutrons
Phase Contrast Imaging (PCI) was studied with the goal of understanding its relevance and its requirements. Current literature does not provide insight on the effect of a relaxation in coherence requirements on the PCI capabilities of an imaging system. This problem is all the more important since …
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An experimental study of turbulence by phase-contrast imaging in the DIII-D takamak
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.
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Phase contrast imaging measurements and modeling of short wavelength turbulence in the DIII-D tokamak
The DIII-D phase contrast imaging (PCI) diagnostic has been upgraded and used to measure turbulence in the outer plasma region (0.7 < r/a < 1). These upgrades extended its operational range to high frequencies (10 kHz - 10 MHz), short wavelength (2 - 30 cm-1), and improved the signal-to-noise ratio …
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A study of reversed shear Alfvén eigenmodes in Alcator C-Mod with phase contrast imaging
… shear equilibria during the current ramp-up phase and sawtoothing phase are studied through the spatial and temporal characteristics of the RSAEs. Analysis of the spatial structures of RSAEs measured by phase contrast imaging, and interpreted with a synthetic diagnostic using numerical …
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A Novel Method to Assess Pulse Wave Velocity using Single Velocity Encoding in Phase Contrast Imaging
… of pulse wave velocity (PWV) using conventional phase contrast magnetic resonance imaging (PC-MRI) is recognized as a standard technique to assess arterial stiffness by measuring the arrival times of blood velocity waveforms. Conventional PC-MRI requires the acquisition of two sets of complex …
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A combined phase contrast imaging and heterodyne interferometer system for multiscale fluctuation measurements on DIII-D
… a heterodyne interferometer to the pre-existing phase contrast imaging (PCI) system, both of which measure line-integrated electron-density fluctuations. The port-space footprint is minimized by using a single 10.6 pm CO2 laser and a single beampath. With temporal bandwidths in excess of 1 MHz, …
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Studies of ICRF mode conversion with phase contrast imaging and full-wave simulations in Alcator C-Mod
… codes be validated against experiment. The phase contrast imaging (PCI) technique has been used on Alcator C-Mod to measure directly the rf waves. The measurements were compared to predictions of full-wave simulations using a synthetic diagnostic method. The measured mode converted wave …
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Developing a Microbubble-based Contrast Agent for X-ray Phase Contrast Imaging to Detect Neovasculature in Breast Cancer
X-ray phase contrast imaging (XPC) generates contrast from refraction and scattering of X-rays, unlike absorption in conventional radiology. This technique greatly improves the sharpness of boundaries and reveals micro-structured tissues that are not easily detected by conventional absorption-based …
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An investigation of CSF dynamics and biochemical composition in normal pressure hydrocephalus utilizing the phase contrast MRI scanning
… these can not be relied upon completely. Cine Phase contrast MRI scanning is a more sophisticated technique of examining the flow of CSF through different regions of the brain. This study prospectively investigated the role of cine phase contrast MRI scanning in calculating the various CSF flow …
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Turbulence and transport studies with phase contrast imaging in the Alcator C-Mod tokamak and comparisons with gyrokinetic simulations
An upgraded phase contrast imaging (PCI) diagnostic is used to study turbulence and transport in Alcator C-Mod. The upgraded PCI system is capable of measuring density fluctuations with high temporal (2 kHz-5 MHz) and wavenumber (0.5-55 cm-1) resolution. An upgrade of the system has enabled PCI to …
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Comparative imaging of surgical small intestinal disease in dogs: evaluation of pre-operative contrast-enhanced ultrasound, intra-operative contrast-enhanced ultrasound, and triple-phase contrast-enhanced computed tomography
… revision, and lead to sepsis or death. Currently contrast-enhanced computed tomography (CT) is the standard of care for evaluating ischemic lesions of the bowel in humans. Contrast-enhanced ultrasound (CEUS) is an alternative method for evaluating tissue perfusion whose utility for evaluation of …
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Using Deep Learning to Extract Multicellular Aggregation Features of Myxococcus xanthus
… difficulty in segmenting dense aggregates from phase-contrast alone), we developed a generative adversarial network (GAN) that synthesizes fluorescence microscopy images from phase-contrast images. This approach combines the ease of phase-contrast acquisition with the quantitative advantages of …
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Understanding and measuring flow in aortic stenosis with MRI
… resonance (CMR) may be a useful alternative. Phase contrast CMR can measure ow and velocity, therefore it is theoretically possible to estimate the main determinant of severity aortic valve area, using the continuity approach. However, it was found that the phase contrast estimate of stroke …
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