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Updated: Apr 15, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
Differential MR delayed enhancement patterns of chronic myocardial infarction between extracellular and intravascular
Jian Wang1, Bo Xiang2, Hung Yu Lin3
1Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Street, Wuhan, Hubei, China 430022; National Research Council of Canada, 435 Ellice Avenue, Winnipeg, Manitoba, Canada R3B 1Y6; Department of Physiology, Faculty of Medicine, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 3P5.
Objectives:
Because the distribution volume and mechanism of extracellular and intravascular MR contrast media differ considerably, the enhancement pattern of chronic myocardial infarction with extracellular or intravascular media might also be different. This study aims to investigate the differences in MR enhancement patterns of chronic myocardial infarction between extracellular and intravascular contrast media.
Materials And Methods:
Twenty pigs with myocardial infarction underwent cine MRI, first pass perfusion MRI and delayed enhancement MRI with extracellular or intravascular media at four weeks after coronary occlusion. Myocardial blood flow (MBF) was determined with microsphere measurement. The infarction histopathological changes were evaluated by hematoxylin and eosin staining and Masson's trichrome method.
Results:
Cine MRI revealed the reduced wall thickening in chronic infarction compared with normal myocardium. Moreover, significant wall thinning in chronic infarction was observed in cine MRI. Peak first-pass signal intensity didn't significantly differ between chronic infarction and normal myocardium no matter what kinds of contrast media. At the following delayed enhancement phase, extracellular media-enhanced signal intensity was significantly higher in chronic infarction than in normal myocardium. Conversely, intravascular media-enhanced signal intensity was almost equivalent among chronic infarction and normal myocardium. At four weeks after infarction, MBF in chronic infarction approached to that in normal myocardium. Large thick-walled vessels were detected at peri-infarction zones. The cardiomyocytes were replaced by scar tissue consisting of dilated blood vessels and discrete fibers of collagen.
Conclusions:
Chronic infarction was characterized by the significantly reduced wall thickening and the definite wall thinning. First-pass myocardial perfusion defect was not detected in chronic infarction with two media due to the significantly recovered MBF and well-developed collateral vessels. Infarction remodeling enlarged the extracellular compartment, which was available for extracellular media but not accessible to intravascular media. Extracellular media identified chronic infarction as the hyper-enhancement; nonetheless, intravascular media didn't provide delayed enhancement.
Insights
Extracellular contrast media highlight chronic myocardial infarction with hyper-enhancement, unlike intravascular media. This difference arises because infarction remodeling increases extracellular space, accessible to extracellular agents but not intravascular ones.
Area of Science:
- Cardiovascular Imaging
- Magnetic Resonance Imaging (MRI)
- Myocardial Infarction
Background:
- Chronic myocardial infarction exhibits distinct structural changes.
- Extracellular and intravascular contrast media have different distribution patterns.
- Understanding these differences is key for accurate MRI assessment.
Purpose of the Study:
- To investigate MR enhancement pattern differences in chronic myocardial infarction.
- Compare extracellular versus intravascular contrast media effects.
- Determine the optimal contrast agent for visualizing chronic infarction.
Main Methods:
- Twenty pigs with induced myocardial infarction were studied.
- Performed cine, first-pass perfusion, and delayed enhancement MRI.
- Assessed myocardial blood flow (MBF) and histopathology.
Main Results:
- Chronic infarction showed reduced wall thickening and thinning.
- No significant difference in first-pass perfusion between infarct and normal myocardium.
- Extracellular media showed significantly higher enhancement in infarct areas.
- Intravascular media showed similar enhancement in infarct and normal areas.
- MBF recovered, and collateral vessels developed in chronic infarcts.
Conclusions:
- Chronic infarction remodeling enlarges the extracellular space.
- Extracellular media accurately identify chronic infarction via hyper-enhancement.
- Intravascular media do not provide delayed enhancement for chronic infarction.
- MRI assessment of chronic infarction depends on contrast agent type.
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