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Title: Rapid Dynamic Contrast-Enhanced M.R.I. using Reduced k-Space and Constrained Reconstruction for the Characterization of Liver Tumours
Author: White, Mark James
ISNI:       0000 0004 2678 9652
Awarding Body: Institute of Cancer Research (University Of London)
Current Institution: Institute of Cancer Research
Date of Award: 2007
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The aim of this work was to improve liver tumour characterization using dynamic contrast-enhanced MRI, where the liver is imaged rapidly following the injection of a paramagnetic contrast agent. Such dynamic studies can provide useful information about hepatic blood flow. However, they remain a practical challenge due to the competing requirements of spatial and temporal resolution needed to characterize briefly-enhancing arterial structures while retaining adequate coverage. Dynamic data can be acquired rapidly using reduced central k-space sampling, where spatial resolution is sacrificed for speed during some parts of the acquisition and high-resolution reference scans are acquired separately. Several constrained reconstruction algorithms that incorporate this additional reference data were evaluated, focussing on variants of Data Replacement Technique (DRT) and Generalized Series (GS) reconstruction. Novel methods using adaptive filtering and mixed enhancement models, potentially appropriate for liver imaging, were also developed. Reconstructions of various types of enhancement were evaluated using numerical simulations and twelve dynamic liver studies acquired from three patients with colorectal liver metastases. Quantitative comparisons are presented. The liver moves both within and between breath-holds. Experimental data was used to assess these variations, and a simple, robust, fast method of motion correction based on tracking the location of the diaphragm was implemented and tested. This approach was then incorporated into constrained reconstruction. A novel methodology for mapping the Hepatic Perfusion Index from dynamic MR data was implemented. It was applied to twenty-five further dynamic liver studies, acquired from patients with liver metastases and controls with normal liver function.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available