Evaluation of ischemic heart disease and viability by cardiac MRI.

In ischemic heart disease, cardiac MRI, besides being the gold standard for evaluation of quantitative ventricular function, enables evaluation of myocardial wall thickness, T2-weighted imaging for myocardial edema and infarct quantification and transmurality. Delayed hyperenhancement sequences are highly predictive of scar formation, being associated with myocyte necrosis. The extent and transmurality of delayed hyperenhancement has prognostic implications and is inversely proportional to the degree of functional recovery after acute myocardial infarction. A greater transmural extent of infarction (eg, hyperenhancement involving >50% of the wall thickness) can predict regions that are less likely to improve in function after therapy. The ultimate focus of MRI in ischemic heart disease is in diagnosis, quantification of myocardium at risk, salvageable myocardium, perfusion defects and differentiation of viable myocardium from non viable myocardium to enable prognostication.