Myocardial infarction quantification with Manganese-Enhanced MRI (MEMRI) in mice using a 3T clinical scanner

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Biomedical Engineering

Background:

• Manganese (Mn(2+)) is an established intracellular MR contrast agent for assessing cardiomyocyte viability and myocardial infarction in animal models.
• Manganese-Enhanced MRI (MEMRI) has not been previously validated for acute infarction assessment in mouse coronary occlusion-reperfusion models.

Purpose of the Study:

• To evaluate the efficacy of MEMRI in quantifying acute myocardial infarction volume in a mouse model.
• To assess global and regional cardiac function using MEMRI before and after contrast agent injection.
• To establish an optimized MEMRI protocol for use on a clinical 3T MRI scanner.

Main Methods:

• A dose-response curve was established to optimize the Manganese (Mn(2+)) injection protocol.
• Infarction volume was measured using MEMRI and compared against 2,3,5-triphenyltetrazolium chloride (TTC) staining as the gold standard.
• Global function (Ejection Fraction) and regional function (percent wall thickening) were assessed before and after Mn(2+) injection.

Main Results:

• MEMRI measurements of infarction volume showed a strong correlation with TTC staining.
• Ejection fraction should be measured prior to Mn(2+) injection to prevent contrast-induced bias.
• Percent wall thickening accurately reflects infarct-related contraction deficits and can be measured before or after Mn(2+) injection.

Conclusions:

• MEMRI is a reliable method for assessing acute myocardial infarction volume in mice using a clinical 3T scanner.
• MEMRI provides valuable data on cardiac function, with specific considerations for timing of measurements relative to contrast injection.
• This study provides a foundation for longitudinal cardiac disease research in mice on clinical MRI platforms.