Objective: The objective of our study was to analyze comprehensive MRI findings of aborted myocardial infarction (MI) in terms of the area at risk, late enhancement, and perfusion on initial and follow-up studies compared with overt MI.
Subjects and methods: Eleven cases of aborted MI and 18 cases of overt MI were included in this study. We evaluated the location and signal pattern of infarction on both T2-weighted imaging and delayed enhancement MRI. For quantitative analysis, we calculated the size and contrast ratio of the myocardial signal abnormality compared with remote myocardium on T2-weighted imaging and delayed enhancement MRI. We also evaluated the regional systolic function on cine MRI and the perfusion abnormality on first-pass perfusion MRI. Six months after initial imaging, MRI was repeated to see changes in enhancement pattern and functional indexes.
Results: T2-weighted images of all patients showed homogeneous high signal intensity (SI) along the vascular territory of the culprit lesion. MRI of patients with aborted MI showed no (n = 5) or minimal (n = 6) delayed enhancement. Compared with overt MI cases, aborted MI cases also were significantly smaller (p = 0.001) and showed significantly lower SI (p = 0.002) of the enhancing region on delayed enhancement MRI. On follow-up delayed enhancement MRI, the enhancing region was smaller in most cases. All aborted MI cases except one showed hypokinesia and a perfusion defect at the corresponding vascular territory on the initial MRI, but these abnormal findings had normalized on follow-up MRI.
Conclusion: The characteristic MRI findings of aborted MI are the absence of or minimal enhancement on delayed enhancement MRI compared with overt MI. On follow-up MRI of aborted MI cases, the area at risk, minimal enhancement, and perfusion defect had normalized.