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Updated: Oct 15, 2026
Histological Quantification of Chronic Myocardial Infarct in Rats
Published on: December 11, 2016
Normal and infarcted myocardium: differentiation with cellular uptake of manganese at MR imaging in a rat model
J Bremerich1, M Saeed, H Arheden
1Department of Radiology, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA.
Purpose:
To assess whether normal myocardium can be distinguished from infarction at magnetic resonance (MR) imaging with low doses of manganese dipyridoxyl diphosphate (Mn-DPDP).
Materials And Methods:
After 1-hour coronary arterial occlusion and 2-hour reperfusion, three groups of eight rats each were injected with 25, 50, or 100 micromol of Mn-DPDP per kilogram of body weight. The longitudinal relaxation rate (R1) in normal myocardium, reperfused infarction, and blood was repeatedly measured at inversion-recovery echo-planar imaging before and for 1 hour after the administration of contrast material. Afterward, several animals from each group were examined at high-spatial-resolution inversion-recovery spin-echo (SE) MR imaging.
Results:
Manganese accumulated in normal myocardium but was cleared from reperfused infarction and blood. One hour after the administration of Mn-DPDP, R1 in normal myocardium (1.53 sec(-1) +/- 0.03, 1.73 sec(-1) +/- 0.03, and 1.94 sec(-1) +/- 0.02, respectively, for 25, 50, and 100 micromol/kg) was significantly (P <.05) faster than that of reperfused infarction (0.99 sec(-1) +/- 0.03, 1.11 sec(-1) +/- 0.03, and 1.48 sec(-1) +/- 0.06). Normal myocardium appeared hyperintense on T1-weighted inversion-recovery SE MR images and was clearly distinguishable from reperfused infarction.
Conclusion:
Mn-DPDP-enhanced inversion-recovery echo-planar and SE MR images demonstrated retention of manganese in normal myocardium and clearance of manganese from infarction. Mn-DPDP has characteristics similar to those of widely used thallium and may be useful in the assessment of myocardial viability at MR imaging.
Insights
Low doses of manganese dipyridoxyl diphosphate (Mn-DPDP) effectively distinguish normal heart muscle from infarction using magnetic resonance (MR) imaging. This contrast agent shows retention in healthy tissue and clearance from damaged areas, aiding in myocardial viability assessment.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Radiology
Background:
- Assessing myocardial viability after infarction is crucial for patient management.
- Magnetic resonance (MR) imaging offers high-resolution anatomical detail.
- Novel contrast agents are needed to improve tissue characterization in cardiovascular MR.
Purpose of the Study:
- To evaluate the efficacy of low-dose manganese dipyridoxyl diphosphate (Mn-DPDP) in differentiating normal myocardium from infarcted tissue using MR imaging.
- To determine if Mn-DPDP can be retained in healthy myocardium while being cleared from areas of infarction.
Main Methods:
- Rats underwent coronary artery occlusion followed by reperfusion.
- Groups of rats received varying low doses of Mn-DPDP (25, 50, or 100 micromol/kg).
- Longitudinal relaxation rates (R1) were measured using inversion-recovery echo-planar imaging and spin-echo MR imaging before and after contrast administration.
Main Results:
- Manganese (Mn-DPDP) demonstrated retention in normal myocardium but was cleared from reperfused infarction and blood.
- Significantly faster R1 values were observed in normal myocardium compared to infarcted regions one hour post-injection.
- T1-weighted inversion-recovery spin-echo MR images clearly distinguished hyperintense normal myocardium from hypointense infarcted areas.
Conclusions:
- Mn-DPDP-enhanced MR imaging effectively visualizes manganese retention in normal myocardium and clearance from infarction.
- Mn-DPDP exhibits properties similar to thallium, suggesting its potential utility in assessing myocardial viability.
- This contrast agent may offer a valuable tool for cardiovascular MR diagnostics.
