The purpose of this project was to assess techniques which could be implemented in clinical cardiac MRI using a moderate gradient performance imaging system in order to aid in the assessment of myocardial function. Possible improvements in image contrast were assessed using four different magnetisation preparation schemes applied prior to MR image acquisition in order to aid in the delineation of myocardial borders, and therefore improve cardiac image assessment quality. The usefulness of several novel T2*-weighted acquisition techniques were assessed in clinical cardiac applications in order to indirectly assess myocardial perfusion. Four magnetisation preparation schemes were applied in order to attempt to improve image contrast in short axis gradient-echo cardiac MRI; T2, T1, Magnetisation Transfer Contrast (MTC), and Double Inversion (DI). The T2, and preparation schemes proved to be the most effective, showing an initial improvement in image contrast by approximately 100% and proving effective in improving image contrast over the entire imaging duration {550 ms through the cardiac cycle). The MTC preparation scheme showed a 50% improvement in image contrast, again being effective over the entire imaging duration. The DI preparation scheme proved useful in creating a black blood gradient-echo image but showed no improvement in contrast throughout the imaging duration (since the DI preparation technique is essentially a 'snapshot' technique). Recent developments in cardiac MRI have moved towards assessment of myocardial perfusion, using first-pass contrast-enhancement imaging. This approach requires assessment of a large enough volume of the heart to allow assessment of perfusion as well as retaining a high temporal resolution of 7 or 2 seconds, and therefore a more modem high performance imaging system. For moderate performance gradient MR systems an alternative method of assessing myocardial perfusion is therefore required. Several novel techniques to assess myocardial T2* values in order to indirectly infer myocardial perfusion are introduced. The use of an original multi-echo gradient-echo imaging sequence to acquire T2* pixel-maps was investigated in phantoms and compared with commercially available sequences in order to validate its use.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:327018 |
| Date | January 2000 |
| Creators | Semple, Scott I. K. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602018 |
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