Edema by T2-weighted imaging in salvaged myocardium is extracellular, not intracellular
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Edema by T2-weighted imaging in salvaged myocardium is extracellular, not intracellular Martin Ugander1*, Paul S Bagi1, O Julian Booker1, Li-Yueh Hsu1, Abiola J Oki1, Andreas Greiser2, Peter Kellman1, Anthony H Aletras1, Andrew E Arai1 From 2011 SCMR/Euro CMR Joint Scientific Sessions Nice, France. 3-6 February 2011 Introduction T2-weighted MRI can image myocardial edema in salvaged, non-infarcted myocardium. However, it is unclear whether this edema is mostly intra-, extracellular, or balanced. Purpose We tested the hypothesis that edematous non-infarcted myocardium would show a balanced increase in both the intra- and extracellular volume. Methods Dogs (n=10) underwent coronary occlusion (2h) and reperfusion (4h). 1.5T CMR images (Siemens) were taken before and 45 minutes into contrast administration (0.15mmol/kg Gd-DTPA bolus followed by 0.003mmol/kg/min infusion). Myocardial T1 was measured by modified Look-Locker imaging (MOLLI), infarction by late gadolinium enhancement (LGE) imaging, and edema by T2-prepared SSFP. T1 and R1 (1/ T1) pixel maps were generated from MOLLI images. Contrast agent concentration is proportional to change in R1 between pre- and post contrast. ECV was defined
as [1-hematocrit] * [DeltaR1myocardium (R1post-R1pre contrast)]/[DeltaR1blood], thus yielding a quantitative pixel map of the ECV ranging from 0-100%. Change in left ventricular mass between baseline and post-reperfusion was quantified by cine SSFP imaging. The change in non-contrast tissue T1 by T1-mapping was assumed to linearly reflect swelling for both the region of infarction determined by LGE and salvaged myocardium at risk determined by non-contrast T1 mapping. In combination with ECV measurements, these measurements allowed for quantification of the absolute myocardial intra- and extracellular volume at baseline and in salvaged myocardium. Data is presented as mean±SD.
Results Following reperfusion, edema in salvaged myocardium showed an increase in extracellular volume (4.0±1.7 vs. 2.4±1.1 ml, p=0.006, n=9) but no increase in intracellular volume (7.5±3.3 ml vs. 7.5±3.3 ml, p=1.0, n=9) compared to pre-occlusion baseline. Consequently, salvaged myocardium (Arrows in Figure 1) had an ECV of 34±7%, which was greater than normal myocardium
Figure 1 Edema in non-infarcted, salvaged myocardium (arrows) displays an increased extracellular volume by quantitative ECV imaging.
1 National Institutes of Health, Bethesda, MD, USA Full list of author information is available at the end of the article
© 2011 Ugander et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Ugander et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):P70 http://jcmr-online.com/content/13/S1/P70
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(24±3%, p=0.04, n=10) and less than infarc
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