Magnetic resonance imaging for myocardial viability.

Detection of myocardial viability is an important issue that needs to be addressed when patients with dysfunctional myocardium are considered to be revascularised. The pathophysiological substrate may include myocardial hibernation, myocardial stunning, or both. The greatest benefit is in terms of myocardial function recovery and prognosis is obtained if the revascularised vascular territory contains viable myocardium. Viable myocardium can be detected with nuclear techniques (SPECT, PET), low dose dobutamine stress echocardiography and MRI. With MRI robust detection of viable myocardium can be performed with delayed enhancement (with gadolinium contrast agent), low dose dobutamine stress, and stress/rest perfusion imaging. For recovery of myocardial function there are relatively small differences between all available techniques, whereas for improvement of prognosis all techniques perform equally. Myocardial delayed enhancement imaging can also visualise micro-embolisation as a result of percutaneous coronary intervention. Furthermore, MRI delayed enhancement enables differentiation between ischaemic and non-ischaemic heart disease and can identify specific cardiomyopathies.