[Contribution of MRI in the evaluation of ischemic heart diseases]

The high spatial and temporal resolution of MRI provides accurate identification of left ventricular endocardial and epicardial contours. Cine-MRI allows reliable and reproducible measurements of end-systolic and end-diastolic volumes, ejection fraction and left ventricular mass. These measurements are not based on any geometrical hypothesis and so remain valid in presence of ventricular deformation as observed after myocardial infarctions. The value of cine-MRI has been demonstrated in ischaemic heart disease for the study of regional left ventricular function, by analysis of left ventricular segmental function and systolic thickening of the myocardial walls. Cine-MRI may also be performed during pharmacological stress. In coronary patients without ventricular dysfunction at rest, stress cine-MRI enables detection of segmental wall motion abnormalities or reduction of systolic thickening in potentially ischaemic territories. Cine-MRI may contribute to be study of myocardial viability. Regional myocardial perfusion may also be assessed using the rapid sequences of imaging and contrast agents opacifying the intravascular compartment. In coronary patient, underperfused regions may there by be detected. The most rapid imaging techniques enable visualisation of the proximal segments of the coronary arteries and the measurement of blood velocity in the coronary arteries and the calculation of coronary reserve. Simultaneous analysis under basal conditions and after pharmacological stress of global and segmental left ventricular function and of myocardial perfusion, associated with the possibility of imaging the proximal coronary arteries and of measuring the velocity of coronary flow, makes MRI a complete non-invasive method of evaluating patients with ischaemic heart disease.