Investigation of T2-weighted signal intensity of infarcted myocardium and its correlation with delayed enhancement magnetic resonance imaging in a porcine model with reperfused acute myocardial infarction.

To assess the signal pattern in T2-weighted images (T2WI) and determine its relation to persistent microvascular obstruction (PMO) and intramyocardial hemorrhage in a porcine model with reperfused acute myocardial infarction. Left anterior descending artery was occluded (90 or 180 min) and reperfused (90 min). T2WI and delayed-enhanced magnetic resonance images (DE-MRI) were acquired. The T2WI signal pattern, T2WI contrast ratio, PMO, and intramyocardial hemorrhage were evaluated, and their interrelationships were analyzed. The infarct area on T2WI was recorded as a homogeneous high-intensity signal or as low- or iso-intensity signals. The contrast ratio of the T2WI in the cases with PMO was significantly lower than that in those without PMO (1.38 +/- 0.25 vs. 1.89 +/- 0.31, P < 0.05), and it showed significant inverse correlation with the extent of PMO observed in DE-MRI images (r =-0.8, P < 0.05). The extent of PMO correlated strongly with that of intramyocardial hemorrhage (r = 0.97, P < 0.05). The abnormal signal area in the T2WI was larger than the infarct area in the DE-MRI images (47.0 +/- 9.9% vs. 37.8 +/- 9.9%, P < 0.05) and the infarct area observed after TTC staining (47.0 +/- 9.9% vs. 37.4 +/- 8.4%, P < 0.05). We observed variable T2WI signal patterns for the infarcted myocardium. Lower T2WI contrast ratios significantly correlated with the extent of PMO in DE-MRI and intramyocardial hemorrhage in the gross specimen.