| Summary: | <p>Phosphorus Magnetic Resonance Spectroscopy (31P-MRS) is unique in its ability to study high-energy phosphate metabolism noninvasively; when applied in the human heart, 31P-MRS is a sensitive marker of the occurrence and progression of heart failure. To date, 31P-MRS has been hindered by the inherent low signal-to-noise ratio (SNR) of acquisitions. In recent years, however, whole-body 7 T MRI scanners have brought a step change in the available SNR, increasing the precision of cardiac 31P-MRS measurements.</p>
<p>The work in this thesis quantifies how the increased SNR afforded by using a 7 T scanner translates into improved reproducibility of human 31P-MRS in the heart. A ‘short’ (6.5 minute) uttra-short echo chemical shift imaging (UTE-CSI) protocol is also established that is both sufficiently short and reproducible to allow multiple 7 T 31P-MRS spectra to be acquired in the same scanning session. This ‘short’ UTE-CSI scan is used in a proof-ofprinciple study testing the feasibility of a using a commercially available ketone ester drink as a treatment for heart failure in diabetic subjects.</p>
<p>Finally, a novel multiple spin-echo 31P CSI sequence is developed. The limitations of a low, varying transmit field are overcome by designing a novel composite refocusing pulse. While scanning restrictions due to the COVID-19 pandemic meant that this sequence is not yet tested in vivo, simulations are performed to explore the potential of this sequence to measure cardiac 31P transverse relaxation times and further improve SNR of cardiac 31P-MRS at 7 T.</p>
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