Advanced cardiac magnetic resonance imaging in heart failure and coronary artery disease

Recent technical developments have increased the scope for cardiac MRI as a research tool. This work presents novel approaches to the assessment of patients with coronary disease and heart failure. The thesis explores coronary physiology and microarchitecture, ischaemia and perfusion CMR, and in particular the quantification of ischaemia. In addition, in-vivo cardiac diffusion tensor imaging is employed to characterize microarchitecture in heart failure. This work comes to a number of conclusions. We have been able to show, for the first time in patients with heart failure, that even in patients who have thinned and remodelled ventricles, quantitative assessment with high resolution quantitative CMR is feasible and reproducible. Our work is also the first to perform assessment of the prognostic use of quantitative perfusion CMR - in a large group of unselected patients presenting with suspected coronary disease, we have investigated the prognostic value of a quantitative approach. This observational study proposes that this performs at least as well as visual assessment by expert readers. Furthermore, the thesis explores the correlation between CMR and PET using a specialized cardiac phantom which simulates perfusion and a hybrid CMR-PET scanner. In this setting, we have concluded that there is excellent correlation between MR, PET and known true perfusion values. This thesis also presents work on the use of cardiac diffusion tensor imaging in dilated cardiomyopathy, the first study to do so using a dual-phase in-vivo approach. We have been able to demonstrate significant differences in fibre and sheetlet orientation by comparison to controls. Our study used biomechanical modelling and strain data from 3D tagging CMR. Overall this work adds to the body of knowledge of quantitative perfusion CMR analysis and cardiac DTI and merits further larger studies, particularly with regard to translation to the clinical setting.