Objective: Imaging to determine myocardial infarct size is difficult in the emergency setting because the current gold standards, MRI and nuclear medicine techniques, are difficult to perform in unstable patients. Delayed enhanced MDCT has recently been proposed as a technique to study contrast uptake in infarcted myocardium. In this study, we compared the extent of acute myocardial infarction as measured by delayed enhanced MDCT performed immediately after percutaneous coronary intervention (PCI) without an additional iodine injection with that measured by delayed gadolinium-enhanced MRI.
Subjects and methods: Nineteen consecutive patients presenting with primary acute myocardial infarction underwent delayed enhanced MDCT immediately after coronary angioplasty and underwent delayed enhanced MRI within 8 days of angioplasty. Only patients with a thrombolysis in myocardial infarction (TIMI) score of 0 or 1 of the culprit coronary artery before endovascular angioplasty and TIMI score of 2 or 3 after angioplasty were selected. Comparison of delayed enhanced MDCT and delayed enhanced MRI was performed by three observers and focused on identifying the involved segments and determining the transmural extent of enhancement and infarct size.
Results: The mean signal intensity was significantly higher in the involved territory than in healthy myocardium: 197 +/- 81 H versus 71 +/- 20 H, respectively (p < 0.0001). We found significant agreement between delayed enhanced MDCT and delayed enhanced MRI for the number of involved segments, transmural extent of enhancement, and infarct size (r(2) = 0.74, 0.76, and 0.67, respectively; p < 0.0001) with good interobserver reproducibility (kappa = 0.8).
Conclusion: The results of our study show that delayed enhanced MDCT allows accurate visualization of early myocardial contrast uptake compared with delayed enhanced MRI and does not require an additional contrast injection after PCI.