Abstract 17813: Magnetic Resonance T2 Mapping Enables Hemorrhage Isualization After Acute Myocardial Infarction in Swine

Abstract

Introduction: Myocardial hemorrhage secondary to myocardial infarction (MI), as detected by MRI, is related to microvascular obstruction (MVO), which is associated with adverse prognosis. T2-based imaging methods are sensitive to hemorrhage (T2 shortening). Recently, edema detection (T2 elevation) through quantitative T2 maps has been shown more robust than qualitative clinical T2-weighted (T2W) imaging.

Hypothesis: Quantitative T2 mapping may be a reliable indicator for hemorrhage following MVO.

Methods: T2W MR imaging with turbo spin echo (TSE), T2 mapping with gradient echo, early (3 min, EGE) and late (15-20 min, LGE) phase-sensitive inversion recovery gadolinium enhanced imaging were carried out 2 to 7 days following MI induction in a swine model (n=7). Representative slices from each swine were selected for quantitative analysis. Hemorrhage was identified as the low intensity area surrounded by higher intensity edema in both T2W images and T2 maps (Fig 1). MVO was defined as the low intensity core inside the MI using EGE and LGE. Additionally, T2 values within hemorrhage were compared to those of healthy myocardium.

Results: Hemorrhage, as detected with T2 mapping, showed good correlation with MVO (Fig 1). T2 values in hemorrhage were significantly lower than in healthy myocardium (p<0.0001) (Fig 2). Time post contrast infusion affected extent of measured MVO as evident from EGE and LGE images. Although T2W imaging detected hemorrhage within zones of elevated T2 (edema), areas were different from those measured by more accurate T2 mapping.

Conclusions: Quantitative T2 mapping is a promising tool for hemorrhage detection following acute MI.