Signal intensity enhances diagnostic capacity in myocardial infarction

Over the past years cardiovascular magnetic resonance (CMR) imaging has become one of the most prominent noninvasive imaging modalities in cardiovascular medicine [1–5]. Using CMR imaging, a wide variety of diseases can be detected varying from coronary artery disease, myocardial viability, vein graft disease to congenital heart disease [6–18]. An interesting application of CMR is the detection and quantification of infarcted myocardium in humans and experimental animals by a technique called delayed-enhancement CMR [19–25]. With this technique a gadolinium CMR contrast agent is injected intravenously followed by a long interval in which the perfused area has lost the contrast, whereas the infarcted area has slowly gained some contrast and releases that contrast with a long delay. The infarcted area is ‘‘enhanced’’ by this delay and this in vivo determined infarct size has been found to correlate well with postmortem determined infarct size [26– 28]. Particularly in non-transmural infarction the area of late gadolinium enhancement correlated only weakly with the infarct size determined by perfusion scintigraphy [29]. The occurrence of microvascular obstruction causes dark zones in the area of late gadolinium enhancement as appearance of gadolinium is obstructed [30, 31]. Over time, the area of delayed gadolinium enhancement becomes progressively smaller due to scar formation and hypertrophy of surviving myocardium. These late gadolinium enhancement techniques use T1-weighted images and are used regularly in clinical cardiology and experimental research. In this issue of the International Journal of Cardiovascular Imaging, Choi et al. [32] investigated to which extent useful information is present in T2weighted images of porcine hearts with reperfused myocardial infarction. For over 25 years it is known that in the acutely infarcted heart the signal intensity in T2-weighted images correlates well with myocardial edema [33, 34]. This ‘‘edema imaging’’ on T2weighted images was shown to be dependent of infarct age: edema-associated hyper-intense zones in T2weighted images resolved over time and the area of T2 abnormality delineated the area at risk rather than the infarcted area [35]. In the present study [32], the left anterior descending artery (LAD) was occluded for 90 or 180 min followed by reperfusion for 90 min. In total 15 pigs were studied of which 9 pigs underwent 90 min of LAD occlusion followed by 90 min of reperfusion, whereas the other 6 pigs underwent 180 min of LAD occlusion followed by 90 min of reperfusion. The Editorial comment at the article titled ‘‘Investigation of T2weighted signal intensity of infarcted myocardium and its correlation with delayed enhancement magnetic resonance imaging in a porcine model with reperfused acute myocardial infarction’’ by Choi et al. doi:10.1007/s10554-009-9425-6.