Development and Validation of Cardiovascular MR Imaging and Spectroscopy at 7 Tesla

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Magnetic Resonance Imaging (MRI) allows us to image the inside of the human body non-invasively. Pioneered in the brain, this technique has become invaluable over the last 5-10 years for imaging the heart in the clinic. MRI scanners operate at a magnetic field strength of 1.5Tesla (T). We have pioneered the use of 3T scanners, and have most recently purchased the highest field strength commercially available human scanner (7Tesla). Imaging at higher field strength results in more signal, and thus, the images are obtained quicker, or with higher spatial resolution. The areas that we will develop at 7T are those that are limited by low SNR (signal-to-noise ratio) at 1.5 and 3T. These include imaging the coronary arteries, imaging the oxygenation of the blood, and using magnetic resonance spectroscopy to measure the energy-rich metabolites in the human heart. Coronary artery imaging is particularly important as these vessels are critical to supplying blood to the heart (blockages cause heart attack). The higher SNR of 7T will show the blood and walls of these vessels at higher resolution than has previously been possible with MRI enabling us to visualise small plaques and subtle damage. The metabolic condition of the heart is another important area of research where we in Oxford are world leaders. A technique called magnetic resonance spectroscopy reveals the biochemistry of the heart. Levels of phosphocreatine and adenosine triphosphate, which are essential energy-providing metabolites, can give an indication of damage even before functional changes become apparent. At 7T, the higher spatial resolution enables the MRS examination of small regions in the heart, equivalent to those presently required in a clinical examination (impossible at lower field strength). Additional projects will build on these methods to look at oxygen supply, the degree of fibrous scar tissue, and the blood supply from small vessels in the heart. Clinically these developments have the potential to transform MR imaging of cardiac metabolism, oxygenation, and coronary plaque biology from a niche research tool into a mainstream diagnostic measure that can treat the patient as an individual, enabling doctors to monitor the progress of a disease or the response to therapy over time. These techniques would contribute significantly to improving cardiovascular health and to relieving the burden of cardiovascular disease. Our plans are highly novel, and we would be the first site in the UK, and one of an elite group world-wide developing cardiac MR at 7T.