Subacute myocardial infarction: assessment by STIR T2-weighted MR imaging in comparison to regional function

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging
• Myocardial Infarction Research

Background:

• Elevated T2 signal intensity (SI) on MRI is common in myocardial infarction, but its association with myocardial viability remains debated.
• Some research suggests high T2 SI indicates irreversible myocardial injury, while others report conflicting findings.
• This study aimed to clarify the relationship between increased T2 SI and myocardial function, a marker of viability, in patients with reperfused subacute myocardial infarction.

Observation:

• T2-weighted Short Tau Inversion Recovery (STIR) MRI was used to assess myocardial tissue in 10 healthy volunteers and 17 patients with myocardial infarction.
• Signal-to-noise (S/N) ratios were measured in normal and infarcted myocardial segments and compared to regional systolic function.
• All patients exhibited elevated STIR T2 SI in infarcted regions.

Findings:

• Significantly increased S/N ratios were observed in infarcted myocardium compared to normal myocardium (P < 0.0001).
• Transmural elevation of T2 SI was detected in 32% of myocardial segments that maintained preserved systolic function.
• No significant difference in S/N ratios was found in normal myocardium between volunteers and patients.

Implications:

• Increased STIR T2 SI can be present in transmural post-ischemic myocardial regions that retain preserved function.
• T2 SI alone is not an exclusive indicator of non-viable myocardium following reperfused subacute myocardial infarction.
• These findings challenge the exclusive use of T2 SI as a marker for irreversible myocardial injury and highlight the importance of assessing myocardial function for viability.