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JACC Cardiovasc Imaging. 2015 Dec;8(12):1379-1389. doi: 10.1016/j.jcmg.2015.08.015.

Contrast-Enhanced CMR Overestimates Early Myocardial Infarct Size: Mechanistic Insights Using ECV Measurements on Day 1 and Day 7.

Author information

1
Department of Clinical Physiology and Nuclear Medicine, Lund University, Lund, Sweden.
2
Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden.
3
Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Lund, Sweden.
4
Department of Clinical Physiology and Nuclear Medicine, Lund University, Lund, Sweden; Centre for Mathematical Sciences, Lund University, Lund, Sweden; Department of Biomedical Engineering, Faculty of Engineering, Lund University, Sweden.
5
Department of Clinical Physiology and Nuclear Medicine, Lund University, Lund, Sweden. Electronic address: Hakan.Arheden@med.lu.se.

Abstract

OBJECTIVES:

This study aimed to investigate whether an overestimation of infarct size on cardiac magnetic resonance (CMR) versus triphenyltetrazolium chloride (TTC) exists acutely and whether it remains after 7 days in an experimental pig model and to elucidate possible mechanisms.

BACKGROUND:

Overestimation of infarct size (IS) on late gadolinium enhancement CMR early after acute myocardial infarction has been debated.

METHODS:

Pigs were subjected to 40 min of left anterior descending artery occlusion and 6 h (n = 9) or 7 days (n = 9) reperfusion. IS by in vivo and ex vivo CMR was compared with TTC staining. Extracellular volume (ECV) was obtained from biopsies using technetium 99m diethylenetriamine pentaacetic acid (99mTc-DTPA) and light microscopy. TTC slices were rescanned on CMR enabling slice-by-slice comparison.

RESULTS:

IS did not differ between in vivo and ex vivo CMR (p = 0.77). IS was overestimated by 27.3% with ex vivo CMR compared with TTC (p = 0.008) acutely with no significant difference at 7 days (p = 0.39). Slice-by-slice comparison showed similar results. A significant decrease in ECV was seen in biopsies of myocardium at risk (MaR) close to the infarct (sometimes referred to as the peri-infarction zone) over 7 days (48.3 ± 4.4% vs. 29.2 ± 2.4%; p = 0.0025). The ECV differed between biopsies of MaR close to the infarct and the rest of the salvaged MaR acutely (48.3 ± 4.4% vs. 32.4 ± 3.2%; p = 0.013) but not at 7 days (29.2 ± 2.4% vs 25.7 ± 1.4%; p = 0.23).

CONCLUSIONS:

CMR overestimates IS compared with TTC acutely but not at 7 days. This difference may be explained by higher ECV in MaR closest to the infarct acutely that decreases during 7 days to the same level as the rest of the salvaged MaR. The increased ECV in the MaR closest to the infarct day 1 could be due to severe edema or an admixture of infarcted and salvaged myocardium (partial volume) or both. Nonetheless, this could not be reproduced at 7 days. These results have implications for timing of magnetic resonance infarct imaging early after acute myocardial infarction.

KEYWORDS:

extracellular volume; magnetic resonance imaging; myocardial infarction

PMID:
26699107
DOI:
10.1016/j.jcmg.2015.08.015
[Indexed for MEDLINE]
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