Abstract

Background: Late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) is a standard for imaging of myocardial infarction (MI). However, it has been reported the usefulness of quantification of the T1 relaxation time for the characterization of old MI. Our aim is to quantitatively assess myocardial injury and viability without contrast mediums in acute MI.

Methods: Twenty patients with acute MI underwent CMR within 1 month after reperfusion therapy. We assessed the native and post-contrast T1 mappings, native T2 mappings, and LGE in cross section. MIs were classified as “transmural” (> 75% of the area was transmural) and “non-transmural” (< 75% of the area was transmural). Transmural MIs were further classified into endocardial or epicardial types, while non-transmural MIs were classified into infarcted, salvaged, and remote. We defined 50% on the epicardial side of the region with high T2-weighted imaging as epicardial 50% area.

Result: In non-transmural MI, the native T1 and T2 values of the infarcted and salvaged areas were higher than the remote area. Additionally, native T1 value of the infarcted area was higher than the salvaged area. However, there was no significant difference between transmural MI types for any variables. Last, native T1 value of the epicardial 50% area was significantly prolonged in transmural MI than in non-transmural MI.

Conclusion: Native T1 value is useful for myocardial injury evaluation. Furthermore, transmural and non-transmural MI could be detected by T1 mapping of epicardial 50% areas without contrast mediums in the acute phase of MI.