Non-contrast T1 and T2 relaxometry characterizes reperfusion injury of acute MI in swine

Background Reperfusion injury in acute myocardial infarction (MI) results in edema, necrosis, microvascular obstruction (MVO), and intramyocardial hemorrhage (IMH), the latter presents an interesting clinical target. [1] Cardiovascular MRI has been shown capable of characterizing all of these tissue components. Other than MVO, which is currently detected by flow-deficient regions in contrast enhanced imaging, all other tissue components can be identified by T1 and T2 (T2*). Theoretically, the byproducts of blood breakdown observed with IMH lead to decreased T1 and T2 (T2*). [2] Conversely, free water accumulation (edema) and necrosis lead to increased T1 and T2. [2] Hence, direct and quantitative measurement of relaxation rates is promising in myocardial tissue characterization, avoiding ambiguity typical of weighted images (i.e. T2-weighted spin-echo), undesired signal loss from T2* (weighted) images or the uncertainty introduced by contrast agent kinetics. Hypothesis: Combined T1 and T2 mapping can characterize reperfused MI without contrast agents.