Myocardial contractility and contractile reserve, regional perfusion, structural alterations and the capacity to predict functional reserve of viable but dysfunctional zones are some of the information provided by magnetic resonance imaging (MRI), which can be considered as a “onestop-shop” study. Viable but dysfunctional myocardial tissue (hibernating and stunned myocardium) can be identified by MRI with high accuracy by use of specific techniques and sequences. The importance of early identification may be derived from two types of data: • The mortality rate is four times higher in patients treated with medical therapy than in revascularised patients. • Recognition of nonvital areas enables patients to avoid the risks associated with revascularisation. Cine cardiac MRI lies at the basis of the study of myocardial vitality, based on the rationale that contractile dysfunction is linked to ischaemic suffering. One of the main advances brought about by cine cardiac MRI has been the introduction of steady-state free precession (SSFP), better known by its commercial names of true-FISP or FIESTA (depending on the manufacturer). In addition to classic cine sequences, cine-tagging is a method that utilises a sequence of radiofrequency impulses immediately after the echocardiogram (ECG) R-wave to obtain presaturation bands, oriented perpendicularly to the image plane. These bands or tags are visualised as intersecting hypointense lines overlying the myocardium during the cardiac cycle, and their movement (or lack of it) facilitates the detection of dyssynergic segments. However, in the evaluation of myocardial vitality, the study of wall kinetics utilising cine MRI showed only a 66% concordance compared with fluorodeoxyglucose-positron emission tomography (FDG-PET). The combined use of perfusion sequences and delayed enhancement (DE) with paramagnetic contrast agent (CA) to evaluate myocardial vitality renders the diagnostic accuracy of MRI comparable to that of PET,1,2 with the advantages of having better spatial resolution (a fundamental characteristic to evaluate the extension of wall damage, subendocardial, transmural infarct, etc) and of being a noninvasive and less costly investigation.
MRI evaluation of post-infarct residual myocardial viability / De Filippo M ; Zompatori M. - In: HOSPITAL HEALTHCARE EUROPE. - ISSN 1479-1943. - (2007), pp. 5-8.