High-resolution whole-heart 3D T 2 mapping can assess tissue heterogeneity of chronic MI in swine

Background Remodeling of myocardium after infarction (MI) is linked to ventricular arrhythmias. [1] It has been demonstrated that the presence of scar containing isthmuses of viable myocardium resulting in a heterogeneous zone (HZ) with altered conduction properties which may be part of the critical substrate for post-MI ventricular tachycardia. [2,3] Late gadolinium-enhanced (LGE) imaging is used for MI visualization, clearly depicting infarct size and transmurality due to the excellent contrast achieved between scar and viable tissue. However, with LGE uncertainty can be introduced by contrast agent kinetics. [4] Furthermore, LGE can lack information on tissue heterogeneity beyond “gray” areas that result from partial volume averaging and are assumed to be representative of the HZ. Conversely, scar tissue also exhibits increased T2, as fibrosis, primarily composed of collagen, increases interstitial water per unit volume. [5] Hence, direct and quantitative measurement of T2 relaxation time may be a feasible alternative for delineating viable myocardium and fibrosis with the additional benefit of depicting tissue heterogeneity.