Abstract 3415: Cardiovascular Magnetic Resonance Accurately Detects Myocardial Hemorrhage in Reperfusion Injury
Introduction Hemorrhage can complicate reperfusion injury in myocardial infarction, but no in vivo imaging method exists. We hypothesized that a T2*-weighted cardiovascular magnetic resonance imaging (CMR) sequence accurately detects myocardial hemorrhage in vivo.
Methods Reperfused myocardial infarcts were generated in 14 dogs by ligation of the LAD for 3– 6 hours. At day 3, a CMR study was performed using established sequences for quantification of function, microvascular obstruction and myocardial infarction in short axis slices covering the entire myocardium. For hemorrhage, a T2*-weighted multi-echo gradient-echo sequence was applied (TE=35msec, TR=1 RR, FOV 380x280mm, matrix 256 x 192). A segmental analysis was performed using 6 segments per slice: T2*-segments were considered hemorrhagic when signal intensity was >2 standard deviations below the mean of remote myocardium. The contrast-to-noise ratio of hemorrhagic segments over normal segments was assessed. Post-mortem TTC staining was performed with infarcted and hemorrhagic areas analyzed with the same segmental approach. In vivo/ ex vivo correlation statistics were performed.
Results In 14 dogs, 378 segments were assessed. Of the T2* CMR segments, 10.2% were excluded due to artifacts; 27 segments yielded a signal drop consistent with hemorrhage (see figure⇓). The correlation with ex vivo TTC staining was R=0.79 and contrast-to-noise ratio was 9.2±3.4. Sensitivity to detect a hemorrhagic segment was 77%, specificity 99%.
Conclusion T2*-weighted CMR accurately detects reperfusion hemorrhage in vivo. The method may be applied in patients to study hemorrhage as a complication of reperfusion injury.