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Letters to the Editor

Reply to Elsayed and Poullis

Cardiothoracic Centre, Monaco, Montecarlo, Italy

Received 23 September 2008; accepted 24 September 2008.

^_* Corresponding author. Address: Cardiothoracic Centre Monaco, Avenue D’Ostende 11, Monaco, Montecarlo, Italy. Tel.: +39 329 5662258; fax: +39 02 36522640. (Email: fabiola_sozzi{at}yahoo.it).

Key Words: Magnetic resonance imaging • Myocardial infarction • No-reflow

We thank the Editor for giving us the opportunity to reply to Elsayed and Poullis’ letter to the Editor [1]. We would like to thank also Elsayed and Poullis for their interest on our case report. We agree with their comments on T₂-weighted images as a useful tool in characterization of myocardial tissue. T₂-weighted cardiovascular magnetic resonance imaging (MRI) depicts infarct-related myocardial edema as a marker of acute myocardial infarction (MI) [2]. Water has a very high T₂ constant, therefore it gives a very strong T₂ signal. Consequently, T₂-weighted images differentiate acute from chronic MI. In our case we used conventional T₂-weighted imaging of edema with a turbo spin-echo readout with dark-blood preparation [3] [T₁ was a typing mistake].

Historically, non-invasive assessment of myocardial viability has been problematic. Myocardial injury can be broadly characterized as either reversible or irreversible. Within irreversibly injured (infarcted) regions microvascular perfusion can vary from nearly normal to nearly zero, even in the presence of an open infarct-related artery (no-reflow). Advances in imaging modalities have improved visualization of no-reflow, showing its frequency to be higher than was estimated by clinical judgment alone. MRI, by means of cine-MRI, T₂-weighted image and contrast-enhanced MRI, has emerged as a promising approach to the examination of these regions in patients with MI. After acute coronary event MRI can readily define several different zones of myocardium: normal tissue, non-necrotic stunned tissue, and necrotic tissue with or without microvascular damage. These zones are defined by examining contractility using cine-MRI and tissue characteristics using a contrast-enhanced technique, after administering a gadolinium-based contrast agent. Normal tissue is represented as a tissue with normal contractility, without late enhancement; stunned tissue is characterized by a reduced contractility, without late enhancement. Infarct pattern is defined as an area of hyperenhancement alone or as noticeable hypoenhanced area within a region of hyperenhancement. These different areas of enhancement occur secondary to differences in the wash-in kinetics of the gadolinium contrast agent. Areas of hypoenhancement (‘dark’) have reduced signal intensity after contrast administration secondary to a delay in fill-in of the contrast agent. Hyperenhanced (‘bright’) areas reflect necrotic tissue with intact microvasculature. Hypoenhanced areas within areas of hyperenhancement reflect necrotic tissue with damaged microvasculature (no-reflow zones). It has been reported that no-reflow is associated with reduced left ventricular ejection fraction, left ventricular remodeling, and poor clinical outcomes, placing patients with this effect in a high-risk group among reperfused patients [4].

Areas of acute or chronic infarction may be difficult to distinguish using cine or delayed enhancement MR images. Both acute and chronic infarctions are shown as akinetic zones with bright areas on delayed enhancement MRI. In the case of no-reflow presence T₂-weighted images provide a means of differentiating acute and chronic MI by the edema visualization.

References

1. Elsayed H, Poullis M. T2 weighted images as a useful tool in determining myocardial viability in patients performing cardiac MRI. Eur J Cardiothorac Surg 2009;35:201.[Free Full Text]
2. Abdel-Aty H, Zagrosek A, Schulz-Menger J, Taylor AJ, Messroghli D, Kumar A, Gross M, Dietz R, Friedrich MG. Delayed enhancement and T2-weighted cardiovascular magnetic resonance imaging differentiate acute from chronic myocardial infarction. Circulation 2004;109:2411-2416.[Abstract/Free Full Text]
3. Simonetti OP, Finn JP, White RD, Laub G, Henry DA. "Black blood" T2-weighted inversion-recovery MRI of the heart. Radiology 1996;199:49-57.[Abstract/Free Full Text]
4. Ito H, Maruyama A, Iwakura K, Takiuchi S, Masuyama T, Hori M, Higashino Y, Fujii K, Minamino T. Clinical implications of the ‘no-reflow’ phenomenon: a predictor of complications and left ventricular remodeling in perfused anterior wall myocardial infarction. Circulation 1996;93:223-228.[Abstract/Free Full Text]

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Vincent Dor Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sozzi, F. B. Articles by Dor, V. Search for Related Content PubMed Articles by Sozzi, F. B. Articles by Dor, V. Related Collections Coronary disease Myocardial infarction