Background Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is an accurate and reproducible method to delineate nonviable myocardium following myocardial infarction (MI). However, in the early stages following acute MI, LGE has been shown to overestimate the size of the infarct zone by up to 30%. The causes for this are unclear, and may be related to tissue remodelling, intracellular contrast uptake, or expansion of the interstitial space. Myocardial oedema is a feature of reperfused acute MI, and oedematous myocardium has been associated with early contrast enhancement. We hypothesised that the presence of tissue oedema is also related to late enhancement, and contributes to overestimation of infarct size in acute MI.

Methods 46 patients received CMR examination at 3.0T at 2 days following reperfused ST-elevation acute MI, with follow-up imaging at 10 days and 3 months. Short-axis T2-weighted imaging and cine imaging were performed, as well as LGE imaging 16–20 min following administration of 0.1 mmol/kg gadolinium DTPA. Oedema volume was measured on T2-weighted imaging and scar volume measured on LGE imaging, both quantified using a semi-automated histogram-based threshold method.¹ Change in scar volume and change in oedema volume were compared between day 2 and day 10, and between day 2 and 3 months.

Results 46 patients were studied (38 males (83%), age 58 ± 10 years). 27 (59%) completed imaging at day 10 and 39 (85%) at 3 months. Mean scar volume decreased by 7 ml (23%, p < 0.01) at 10 days and 9 ml (28%, p < 0.01) at 3 months. There was significant correlation between change in oedema volume and change in scar volume from day 2 to day 10 (r = 0.62, p < 0.01) and day 2 to 3 months (r = 0.66, p < 0.01) (Figure 1). Stratifying patients into two groups based on mean change in oedema volume, patients with more change in oedema had significantly higher change in scar volume (Figure 2).

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Abstract 132 Figure 1

Change in LGE volume over time correlates with change in oedema volume as measured by T2

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Abstract 132 Figure 2

Patients with higher than median change in T2 volume have significantly larger change in LGE volume at day 10 and at 3 months

Conclusion LGE CMR overestimates scar volume acutely following acute reperfused MI. This overestimation correlates with the volume of myocardial oedema detected acutely.

Reference 1 Sjögren et al. J Cardiovasc Magn Res 2012