Bright-Blood T 2 -Weighted MRI Has High Diagnostic Accuracy for Myocardial Hemorrhage in Myocardial Infarction

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Abstract
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.