Cardiovascular magnetic resonance TE-averaged susceptibility weighted imaging of reperfused intramyocardial hemorrhage.

Background In the setting of acute myocardial infarction (AMI), therapeutic and spontaneous reperfusion of ischemic myocardium can lead to interstitial intramyocardial hemorrhage (IMH) which is associated with microvascular obstruction (MVO) and subsequent adverse clinical outcomes. Imaging without contrast agents (native imaging) can be used in AMI patients for additional myocardial tissue characterization. Native T1 and T2 weighted imaging and quantitative measurements have been reported to detect myocardial edema and depict the myocardial area at risk. IMH affects T1, T2 and T2* relaxation as well as susceptibility and the feasibility of several MR image contrasts (T1, T2, T2* and gradientecho phase) has been demonstrated for the depiction of IMH. Susceptibility weighted imaging (SWI) uses a type of image contrast different from traditional spin density, T1 or T2 weighted MR imaging. In the present work, we report our experience with myocardial SWI imaging (combined gradient-echo magnitude and phase imaging) for the detection of IMH. We propose TE image averaging and gray-scale inversion as a means of providing a single image with good image SNR and excellent contrast for the detection of IMH.