Bright-Blood T2-Weighted MRI Has High Diagnostic Accuracy for Myocardial Hemorrhage in Myocardial Infarction A Preclinical Validation Study in Swine

Background-Myocardial hemorrhage after myocardial infarction (MI) usually goes undetected. We investigated the diagnostic accuracy of bright-blood T-2-weighted cardiac MRI for myocardial hemorrhage in experimental MI. Methods and Results-MI was created in swine by occluding the left anterior descending (n=10) or circumflex (n=5) coronary arteries for 90 minutes followed by reperfusion for <3 days (n=2), 10 days (n=7), or 60 days (n=6). MRI was performed at 1.5 T, using bright-blood T-2-prepared steady-state free-precession, T-2* and early (1 minute) and late (10-15 minutes) gadolinium enhancement (EGE, LGE, respectively) MRI. Left ventricular sections and histology were assessed for hemorrhage by an experienced cardiac pathologist blinded to the MRI data. Hypointense regions on T-2-weighted and contrast-enhanced MRI were independently determined by 3 cardiologists experienced in MRI who were also blinded to the pathology results. Eighty ventricular pathological sections were matched with MRI (n=68 for EGE MRI). All sections with evidence of MI (n=63, 79%) also exhibited hyperintense zones consistent with edema on T-2-weighted MRI and infarct on LGE MRI. Myocardial hemorrhage occurred in 49 left ventricular sections (61%) and corresponded with signal voids on 48 T-2-weighted (98%) and 26 LGE-MRI (53%). Alternatively, signal voids occurred in the absence of hemorrhage in 3 T-2-weighted (90% specificity) and 5 LGE MRI (84% specificity). On EGE MRI, 27 of 43 cases of early microvascular obstruction corresponded with hemorrhage (63% sensitivity), whereas 5 of 25 defects occurred in the absence of hemorrhage (80% specificity). The positive and negative predictive values for pathological evidence of hemorrhage were 94% and 96% for T-2-weighted, 84% and 55% for LGE MRI, and 85% and 56% for EGE MRI. Conclusions-Bright-blood T-2-weighted MRI has high diagnostic accuracy for myocardial hemorrhage. (Circ Cardiovasc Imaging. 2011;4:738-745.)