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Occlusive and reperfused myocardial infarcts: differentiation with Mn-DPDP--enhanced MR imaging
M Saeed1, S Wagner, M F Wendland
1Department of Radiology, University of California, San Francisco 94143.
Abstract:
To assess whether the administration of manganese N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid (DPDP) permits differentiation between occlusive and reperfused infarcts, the authors subjected rats to either 6 hours of left coronary artery occlusion (n = 13) or 2 hours of occlusion followed by 4 hours of reperfusion (n = 10) before magnetic resonance (MR) imaging. Electrocardiographic-gated T1-weighted images were obtained before and for 1 hour after injection of 400 mumol/kg of Mn-DPDP. On T1-weighted images obtained before injection of Mn-DPDP. no significant differences in signal intensity were observed between normal and infarcted regions. Use of Mn-DPDP permitted delineation of the area of infarction. The pattern of enhancement in the injured zone was different for occlusive and reperfused myocardial infarcts. In rats with occlusive infarcts, In rats with occlusive infarcts, three well-defined zones were seen. Epicardium and endocardium were enhanced, while the midmyocardial zone was hypointense. The midmyocardial signal intensity gradually increased during the 60 minutes after injection. In rats with reperfused infarcts, the injured area was uniformly and intensely enhanced. Histologic examination confirmed the presence and location of myocardial infarct. Mn-DPDP may improve the detection and delineation of acute myocardial infarcts, demonstrate perfusion of the infarct, and permit discrimination between reperfused and occlusive infarcts.
Insights
Manganese DPDP (manganese N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid) helps differentiate between occlusive and reperfused myocardial infarcts using MRI. This contrast agent aids in detecting and characterizing acute infarcts.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Biomedical Engineering
Background:
- Differentiating between occlusive and reperfused myocardial infarcts is crucial for guiding treatment.
- Magnetic resonance (MR) imaging offers potential for non-invasive assessment of myocardial infarction.
- Novel contrast agents are needed to enhance the diagnostic capabilities of MR imaging in cardiology.
Purpose of the Study:
- To evaluate the efficacy of manganese N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid (Mn-DPDP) in distinguishing between occlusive and reperfused myocardial infarcts in a rat model.
- To assess the ability of Mn-DPDP to delineate infarct size and characteristics using MR imaging.
Main Methods:
- Rats underwent either 6 hours of left coronary artery occlusion (occlusive infarct model) or 2 hours of occlusion followed by 4 hours of reperfusion (reperfusion infarct model).
- Electrocardiographic-gated T1-weighted MR images were acquired before and up to 60 minutes after intravenous injection of Mn-DPDP (400 mumol/kg).
- Histological examination was performed to confirm infarct presence and location.
Main Results:
- Before Mn-DPDP administration, no significant signal intensity differences were observed between normal and infarcted myocardium.
- Mn-DPDP administration enabled clear delineation of the infarct area.
- Occlusive infarcts showed a distinct three-zone enhancement pattern (epicardial and endocardial enhancement with mid-myocardial hypointensity), which evolved over time.
- Reperfused infarcts exhibited uniform and intense enhancement throughout the injured area.
- Histology confirmed the MR findings regarding infarct presence and location.
Conclusions:
- Mn-DPDP effectively delineates acute myocardial infarcts on T1-weighted MR images.
- The enhancement patterns of Mn-DPDP differ significantly between occlusive and reperfused infarcts, allowing for discrimination.
- Mn-DPDP holds promise for improving the detection, characterization, and perfusion assessment of acute myocardial infarction using MR imaging.