Established and Emerging Techniques of Cardiovascular Magnetic Resonance Imaging in Coronary Artery Disease

Background.
In patients with coronary artery disease (CAD), multi-parametric cardiovascular magnetic resonance (CMR) provides detailed information about the myocardial tissue composition and its function. This thesis aims to investigate how myocardial tissue composition characteristics influence its function. Additionally, this thesis aims to develop methods for time-resolved, three-dimensional flow imaging in-vitro and in health.
Methods.
We have prospectively recruited and conducted multi-parametric CMR in 76 patients with ST-elevation myocardial infarction (STEMI), 44 patients with stable chest pain and 35 healthy volunteers.
Results.
Study 1 and 2 evaluated if CMR derived function parameters are associated with the presence of microvascular obstruction (MVO) or intramyocardial haemorrhage (IMH) in STEMI patients. Study 1 demonstrated the diagnostic accuracy of mitral annular plane systolic excursion (MAPSE) to detect MVO/IMH. Study 2 demonstrated that peak global longitudinal strain (GLS) is most strongly associated with MVO/IMH when compared to other myocardial deformation parameters. Study 3 demonstrated that during first-pass perfusion stress CMR, at peak hyperemic stress, GLS is reduced in the presence of a perfusion defect in patients being investigated for CAD. Study 4 demonstrated that acute ECV-maps can reliably quantify area at risk and final infarct size (at 3-month follow) in reperfused STEMI patients. Study 5 investigated 3 main acceleration methods for 4-dimensional flow (4D Flow) in phantoms and healthy volunteers. In phantoms, all 4D Flow methods underestimated peak velocity but their mean errors were within reasonable limits for clinical applications. In volunteers, 4D echo planer imaging (EPI) method had the shortest acquisition time, best agreement with 2-dimensional phase contrast, best internal consistency between mitral and aortic valve flows.
Conclusions.
CMR derived longitudinal functional parameters of the left ventricle are associated with pathologies predominantly in the sub-endocardium and could be used as a surrogate imaging markers. ECV-maps offer an alternative to IS quantification. 4D EPI is the most robust acceleration method for whole-heart flow assessment.