Background: Qualitative magnetic resonance imaging methods, such as T2-weighted (T2W) imaging, are commonly used for cardiac tissue characterisation. However, these are sensitive to image artefact, and results are unreliable. Modified Look-Locker inversion recovery (MOLLI) provides robust, quantitative T1 imaging in the myocardium, but it is subject to limitations: its T1 measurement accuracy is dependent on heart rate, it exhibits banding artefacts, and a lengthy breath hold is required. In this thesis, some MOLLI variants were developed with the aim of mitigating these problems. Furthermore, MOLLI was applied to two different patient groups for comparison with a typical T2W method. Methods: MOLLI variants used alternative k-space trajectories, gradient-echo readouts, startup preparations, and sampling schemes, and were tested in silico, in vitro and in vivo—in healthy volunteers. In patients, conventional MOLLI was compared to T2W spectral attenuated inversion recovery (SPAIR) for oedema detection in both acute ST-segment elevation myocardial infarction (STEMI), and Takotsubo cardiomyopathy (TCM). RESULTS: Simulation, phantom and volunteer data showed that a linear sweep up (skipped pulse pair) startup preparation enables improved T1 measurements. A MOLLI variant with a reduced sampling scheme performed similarly to conventional MOLLI, allowing for shorter breath holds. Different k-space trajectories did not significantly affect T1 measurement accuracy, but precision varied: possibly due to artefacts. For oedema identification, MOLLI performed significantly better than T2W-SPAIR in STEMI patients, and the two were comparable in TCM patients. In all patients, remote myocardium showed an elevated T1 relative to healthy volunteers, suggesting remote inflammation. Conclusions: It was shown that MOLLI T1 mapping can delineate oedema in acute STEMI and TCM patients, producing measurements that are more robust and reproducible than those made with T2W SPAIR. A number of improvements were suggested in this work, but there is still substantial scope for developing the MOLLI T1 mapping pulse sequence.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:589488 |
| Date | January 2013 |
| Creators | Cameron, Donnie |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202753 |
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