Early Gadolinium Enhancement for Determination of Area at Risk: A Preclinical Validation Study

Area of Science:

• Cardiovascular imaging
• Myocardial infarction research
• Diagnostic techniques in cardiology

Background:

• Controversy exists regarding whether cardiac magnetic resonance (CMR) enhancement in acute myocardial infarction solely represents irreversibly injured myocardium.
• Early gadolinium enhancement (EGE) is proposed to measure the area at risk (AAR) in acute myocardial infarction, correlating with T2-weighted imaging, but requires pathological validation.

Purpose of the Study:

• To determine if early gadolinium enhancement (EGE) via cardiac magnetic resonance (CMR) accurately depicts the area at risk (AAR) in a canine model of reperfused myocardial infarction.
• To validate EGE as a measure of AAR using microsphere blood flow analysis.

Main Methods:

• Eleven dogs underwent 2 hours of coronary artery occlusion followed by 48 hours of reperfusion.
• EGE imaging was performed 3 minutes post-contrast, with late gadolinium enhancement imaging between 10-15 minutes.
• Area at risk (AAR) was defined by microsphere blood flow analysis (<2 SD from remote myocardium); infarct size was determined by triphenyltetrazolium chloride.

Main Results:

• EGE size showed no significant difference compared to AAR by microspheres (44.1 ± 15.8% vs. 42.7 ± 9.2%, p=0.61) with strong correlation (r=0.88, p<0.001).
• EGE size was significantly larger than infarct size determined by triphenyltetrazolium chloride and late gadolinium enhancement (p<0.001 for both).
• No difference was observed between EGE size and enhancement on native T1 and T2 maps.

Conclusions:

• Early gadolinium enhancement (EGE) at 3 minutes post-contrast correlates well with the area at risk (AAR) determined by microsphere analysis in reperfused myocardial infarction.
• EGE reflects both reversibly and irreversibly injured myocardium, indicating it represents the AAR rather than solely infarct size.