["Dead or alive?": how and why myocardial viability imaging by cardiac MRI works]

Myocardial viability imaging by contrast-enhanced MRI has supported the broad acceptance of cardiac MRI as a valuable clinical tool in cardiology over the last few years. The late enhancement (delayed enhancement, late gadolinium enhancement) technique has emerged as an easy-to-perform and robust method for identifying and quantifying myocardial scars. In the condition of acute myocardial infarction, MRI offers important prognostic information regarding anticipated left ventricular changes ("remodeling") and future cardiac events. In coronary artery disease patients with chronic infarction, the extent of late enhancement reliably predicts the outcome of global and regional left ventricular function after revascularization. In particular, CAD patients with severely impaired left ventricular function benefit from preoperative viability imaging before bypass surgery. The present paper describes the definitions and physiology of viable and non-viable myocardium as well as the pathophysiologic basis of late enhancement. The process from the correct setting of imaging protocols via the interpretation of late enhancement images to the stating of the correct diagnosis and estimation of viability is followed. The background of the successful development of the late enhancement method towards the new reference standard in myocardial viability imaging is described.