The assessment of Myocardial Blood Flow (MBF) is an important measure in clinical practice for evaluating the health of the heart. Multiple imaging methods have been employed to measure MBF, including applications of nuclear medicine, x-ray and contrast enhanced Magnetic Resonance Imaging (MRI). However, each of these modalities suffers from drawbacks, such as invasiveness due to radiation or intravenous contrast injection, difficulty in quantitation, and limited repeatability. The aim of this thesis was to develop a non-invasive, quantitative and repeatable MRI method for the measurement of MBF, by applying the techniques of Arterial Spin Labelling (ASL). A novel cardiac ASL sequence was designed and thoroughly tested by simulation and phantom experiment. The method was applied in vivo in three slices of the human heart, to our knowledge the first cardiac ASL acquisition in multiple slices, in ten healthy volunteers. The resulting values of mid-ventricular MBF, averaged over multiple measurements, compared well with the literature values from multiple modalities. Repeat measures were then used in order to characterise the reproducibility and variation inherent in the method, showing that the expected change in MBF would be detectable with the ASL sequence. Segmental values of MBF, according to the AHA standard model, were also calculated and these compared well to previous PET literature. This work has been published in the journal Magnetic Resonance in Medicine. Further to this work, the new cardiac ASL sequence was optimised with the ultimate goal of single breath hold acquisitions. The optimised sequence was shown to improve the results in terms of the balance between good signal-to-noise ratio and reducing spatial and temporal variation in MBF values. Though improvements were made, there remained a large variation in the measured values of MBF, meaning single breath hold acquisition in a clinical context is not yet practical. In addition to the optimisation, the online scanner reconstruction software was altered to produce parametric maps of both T<sub>1</sub> and MBF direct to the scanner operator. The sequence, along with online reconstruction is available for use in our laboratory for future clinical trials in the heart and liver.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:736092 |
| Date | January 2017 |
| Creators | Keith, Graeme A. |
| Contributors | Robson, Matthew |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ora.ox.ac.uk/objects/uuid:a2662a4e-d619-465e-80ce-04fd690b348b |
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