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Balanced steady-state free precession cardiovascular magnetic resonance imaging of edema in reperfused acute myocardial infarcts - a translational study in animals and men

Introduction

Edema imaging is usually performed using T2-weighted STIR imaging. We hypothesized that balanced steady-state-free-precession (b-SSFP) sequences also have sensitivity to detect edema in acute reperfused ST-elevation myocardial infarction (STEMI).

Methods

The study was conducted in mini-pigs and patients with acute reperfused STEMI. In the mini-pigs, myocardial infarction was created by angiographically guided balloon occlusion of the proximal left circumflex coronary artery for ninety minutes. The animals were imaged on day 2 or 3 after experimental ischemia/reperfusion.

For the clinical arm, patients from the coronary care unit were included within four days after successful percutaneous coronary intervention for STEMI.

All CMR images were obtained on a 1.5 T clinical system (Siemens, Germany), using the following sequences in a short axis orientation (slice thickness 10 mm, 0 gap): conventional cine SSFP, T2-STIR (patients only), late enhancement (10 min after injection of 0.2 mmol/kg Gd-DTPA), applying typical sequence parameters. Semi-quantitative threshold-based image analysis of late enhancement images (LE) identified the infarct region and infarct area was calculated. In the infarction zone and remote myocardium, on corresponding T2-STIR and SSFP images, signal and contrast, as well as the area of edema were measured and compared using paired t-tests, correlation statistics.

Results

In 13 pigs, the area of high SSFP signal and the area of LE correlated with R = 0.83. Signal intensity in the infarction zone on SSFP was higher than in the remote zone (203.5 ± 28.7 (edema) vs. 148 +/- 19.8 (remote), p < 0.001), with a contrast-to-noise ratio of 37 ± 13.

In 16 patients (age 57 ± 8 years, 3 female, STEMI location anterior/septal n = 9, lateral n = 1, inferior n = 6) on T2-STIR images, the signal intensity in the infarct zone was higher than signal in remote myocardium (351 ± 109 (edema) vs. 222 ± 81 (remote), p < 0.001), and the same was observed on SSFP (252 ± 35 (edema) vs. 163 ± 32 (remote), p < 0.001). Contrast-to-noise ratio efficiency (CNReff), corrected for voxel size, was not different between T2-STIR and b-SSFP (CNReff T2-STIR 77 ± 37 vs. CNReff b-SSFP 65 ± 30, p = 0.30). The edematous volumes as measured by T2-STIR correlated well with the volumes measured by b-SSFP (R = 0.78, p < 0.001), but on T2-STIR were little larger than on b-SSFP (volume of edema T2-STIR 6.4 ± 2.1 ml vs. SSFP 4.9 ± 1.9 ml, p = 0.03). Infarct volumes on LGE were 4.2 ± 1.6 ml Figure 1.

Figure 1
figure1

A representative set of edema weighted B-SSFP and T2-STIR images with difference STEMI locations in patients. Note the close correspondence between hyperintense territories identified by B-SSFP and T2-STIR acquisitions and the confirmation of infarcted territories on late-enhancement images (PSIR-LE).

Conclusion

Myocardial Edema in both, experimental and clinical STEMI, can be detected using SSFP imaging with contrast similar to T2-STIR.

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Correspondence to Andreas Kumar.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Kumar, A., Beohar, N., Arumana, J.M. et al. Balanced steady-state free precession cardiovascular magnetic resonance imaging of edema in reperfused acute myocardial infarcts - a translational study in animals and men. J Cardiovasc Magn Reson 12, O76 (2010). https://doi.org/10.1186/1532-429X-12-S1-O76

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Keywords

  • Cardiovascular Magnetic Resonance
  • Late Enhancement
  • Cardiovascular Magnetic Resonance Imaging
  • Remote Myocardium
  • Left Circumflex Coronary Artery